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Chapter 9
Common Case Studies of Marine Structural Failures
Goran Vukelić and Goran Vizentin
Additional information is available at the end of the chapter
Provisional chapter
© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons
Attribution License (, which permits unrestricted use, distribution,
and reproduction in any medium, provided the original work is properly cited.
DOI: 10.5772/intechopen.72789
Common Case Studies of Marine Structural Failures
GoranVukelić and GoranVizentin
Additional information is available at the end of the chapter
Marine structures are designed with a requirement to have reasonably long and safe
operational life with a risk of catastrophic failures reduced to the minimum. Still, in
a constant wish for reduced weight structures that can withstand increased loads,
failures occur due to one or several following causes: excessive force and/or tempera-
ture induced elastic deformation, yielding, fatigue, corrosion, creep, etc. Therefore, it
is important to identify threats aecting the integrity of marine structures. In order
to understand the causes of failures, structure’s load response, failure process, pos-
sible consequences and methods to cope with and prevent failures, probably the most
suitable way would be reviewing case studies of common failures. Roughly, marine
structural failures can be divided into structural failures of ships, propulsion system
failures, oshore structural failure, and marine equipment failures. This book chapter
will provide an overview of such failures taking into account failure mechanisms, tools
used for failure analysis and critical review of possible improvements in failure analysis
Keywords: marine structures, failure analysis, fracture, fatigue, failure
1. Introduction
Marine structures must comply with such design requirements that the probability of fail-
ures or stability loss of parts and/or complete structures is reduced to minimum. Studies and
analysis of marine structural failures had shown that a signicant percentage of failures were
a consequence of inadequate design due to lack of operational considerations, incomplete
structural elements evaluations, and incorrect use of calculation methods.
Structural safety level is determined during design process by dening specic structural
elements, material properties, and functional requirements based on the expected lifetime
of the structure, ramications of eventual failures and costs of failures. Time dependency
© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons
Attribution License (, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
of strength and loads has to be taken into account because the strength of a structure will
decrease with time while the load is varying through the lifetime of the structure.
Successful material selection process implies reconciling requirements like suitable strength
of material, sucient level of rigidity, appropriate heat resistance, etc. Structures that are
susceptible to crack growth need to be made of materials selected on the basis of fracture
mechanics parameters. Fracture mechanics parameters that dene material resistance to crack
propagation are usually determined through experimental research, but nowadays some of
the experiments can be successfully substituted with numerical analysis. Material fracture
behavior is usually estimated using some of the well-established fracture parameters, like
stress intensity factor (K), J-integral or crack tip opening displacement (CTOD). Besides that,
fatigue limit has to be taken into account, also. It has become customary to perform an opti-
mal fatigue design analysis as an integral part of design calculations. Such analyses are also
largely based on data and procedures developed from experimental and empirical research.
Marine structural failures can be divided into three main groups: failures of ships, oshore
structures, and marine equipment. This book chapter will provide an overview of most com-
mon case studies of such failures. Further, failure mechanisms will be emphasized and tools
used for failure analysis outlined. Possible improvements in failure analysis techniques are
discussed in the end of the chapter.
2. Common case studies
2.1. Ship structural failures
Maybe the most notable case of ship failures are failures of Liberty ships in the early 1940s.
These failures gave a serious boost in the development of fracture mechanics. Ships, mass
produced in assembly line style out of prefabricated sections as an all-welded construction,
exhibited nearly 1500 cases of brile fractures with 12 ships breaking in half. The results of
failure investigation had shown that inadequate grade of steel allowed for brile fracture at
low temperatures. Further, rectangular hull openings, such as hatch square corners, that coin-
cided with a welded seam acted as stress concentrations points and crack origins [1].
There has been a considerable amount of failures in recent times, also. For instance, structural
failure of container ship MOL Comfort [2, 3] in 2013. A yearlong failure investigation con-
centrated on nding the possibility of fracture occurrence and structural safety level. Results
had shown that the hull fracture originated from the boom bu joint in the midship part.
A possibility that the load’s upper limit exceeded strength’s lower limit was also estimated
using probabilistic approach. Furthermore, safety inspections of the MOL Comfort sister
ships have shown buckling deformations (concave and convex) of the boom shell plating of
up to 20 mm (4 mm allowable) in height observed near the center line. Finally, a numerical
analysis of the ship hull taking the load history into account was done. After the investigation,
it was concluded that the load of the vertical bending moment probably exceeded the hull
girder ultimate strength when the deviations of the uncertainty factors are taken into account,
Failure Analysis and Prevention136
which caused the boom shell plates to buckle due to excessive load. The reduction of breadth
of boom shell plate between girders increased the stress in the girder which yielded in the
lower part resulting in the collapse occurs in the middle part of the ship, at the boom, near
the center line.
Bilge keels structures are used to enhance the transverse stability of ships. Cracks have been
noticed in various ships in the internal structure of the bilge keels and on the connecting
points to the ship’s hull. Failure analysis of the damage can identify the causes of failure and
the analysis results serve as basis for design improvements. It has been shown, both theoreti-
cally and applying FEM analysis, that the failure locations in bilge keels structures occur in
the stress concentration regions that are present due to the structure geometry commonly
used, therefore new structural elements are proposed that signicantly reduce the possibility
of failure occurrence [4].
Corrosively aggressive cargo (acids, alkalis, etc.) can represent a danger to the integrity of
ship structures. In the case of the “Stolt Roerdam” freighter, which sank during the cargo
loading in the port, the investigation (visual, macrofractographic, and chemical) following the
sinking has shown that the residue valve has cracked due to a design-specic stress (stier
main valve was missing), thus causing a leak of the acid that accelerated the corrosion process
of the oor panels in the area of the leak. Also, the valve gaskets were made of a material not
resistant to acid which also contributed to the speed of the leak [5].
Marine engines and propellers produce dynamic loads on their supportive structures which
can lead to fatigue failures. One of the most stressed components of the engine structure is
the bearing bushing foundation. A state-of-the-art design procedure for the bearing girders is
comprised of essential procedures such as bearing loads determination, stresses calculation,
and the bearing girder fatigue strength assessment [6]. The fatigue and structural durabil-
ity analysis is conducted for multi-axial stresses and opens the possibility to construct light-
weight engines.
2.2. Propulsion system failures
The propulsion system has a pivotal role on ships. A typical marine propulsion system is
comprised of main engine, driving device, marine shaft, and propeller. Most of the failures
occur on the propulsion shaft that is subjected to various types of loading during operation
(torque moment, bending moment, axial thrust force, and transversal loads). The operating
environment of the propulsion system is characterized by signicant changes in temperatures
and humidity, aggressive atmosphere, long-lasting interrupted operating time, and varia-
tions in load amplitudes. The risk of failures of the propulsion system additionally increases
with the severity of sea and weather conditions as they have a direct eect on the dynamics
of the load variation. All of the above has direct inuence on fatigue behavior and life time of
the propulsion shaft.
Shaft keys are recognized as a potential origin of growing cracks. The geometry of the ends of
keyways represents a stress concentration factor in the cases of torque transmission through
shaft keys for dynamic vibrational loads. Faulty machining of shaft key elements (key groove,
Common Case Studies of Marine Structural Failures
keyway, and key) geometry, inadequate run out radii, or material imperfection can be root
causes of torsional fatigue failure in shaft keys. The characteristic torsional failure indicator
is the crack paern that initiates at the end of the keyway and propagates in a 45° rotational
direction in a helical shape. Also, interaction between engine body and hull must be taken into
account, especially thermal loads that can aect the integrity of shafts and can be successfully
solved numerically [7], Figure 1.
A case study [8] has shown that inadequate torsional vibration calculation parameters (shaft
elements stiness and damping, natural frequencies, safety factors) and a subsequent poor
design of the shaft’s keyway cause failures. In this case a root cause analysis was done by the
analytical stress calculation process MIL G 17859D and VDI 3822 standards. A FEM model
was used in order to verify the existing fracture characteristics and causes.
An alternative to shaft key joints are spline joints, which are press ed to other shaft ele-
ments. Analysis of spline joint failure [9] shows that the press ing of the joining elements
can cause surface deformation which in turn causes surface cracks formation. Cracks usu-
ally start on the spline teeth at the shaft junction zone. Torsional fatigue caused by uctuat-
ing stress promotes crack growth and propagation. Inhomogeneity of the shaft material can
additionally assist crack propagation. In this case, visual and macroscopic inspection was
performed, followed by material chemical analysis, hardness measurement, optical, and scan-
ning electron microscope (SEM) microstructure analysis with X-ray dispersive analysis of
particles under the SEM.
Bolted connections are used in collar coupling of shaft elements and in propeller blades con-
nections. The changes of rotation direction of the shaft results in torque moment overloading
Figure 1. Engine body-ship hull interaction and thermal loads presenting a threat to structural integrity.
Failure Analysis and Prevention138
Common Case Studies of Marine Structural Failures
Oshore pipelines are usually damaged in the form of dents and gouges, which reduces its
static and dynamic load bearing capacity as well as the fatigue life reduction in comparison
to undamaged pipelines. The extent of the fatigue lifetime change depends on the type of the
dent, and it can be analyzed and assessed analytically or numerically (FEM) [14]. Fatigue life
analysis helps in the decision on the necessity of repairs and/or replacement of the damaged
pipelines, i.e., planning of inspection and maintenance activities. Oshore pipelines segments
are usually connected by welds which usually contain surface of embedded defects which
exhibit large plastic strain characteristics if fracture occurs. In such cases, nonlinear elastic
plastic fracture response should be modeled [15].
Subsea structures are subjected to signicant external pressure loads which makes structural
buckling a dominant failure mechanism. Ultra-deep water subsea separators are key equip-
ment of subsea production in oshore petroleum industry. An experimental and numerical
investigation on buckling and post-buckling of a 3000 m subsea separator has been done by
Ge et al. [16]. The analysis has shown that the buckling behavior of deep sea structures can
be assessed accurately applying numerical nonlinear global buckling analysis, proven by the
comparison with experimental analysis results.
2.4. Marine equipment failure
This section deals with failures of marine equipment such as port or dock cranes, cables and
ropes, pressure vessels-mounted onboard ships, and underwater pipelines.
Cranes can be subject to unexpected sudden events which can be divided into accidents and
emergencies. Catastrophic failure of a dockside crane jib [17] occurred in the proximity of the
standing tower, near the connection of the jib’s three main tubes to the tower. Upon the visual
inspection of the fracture surfaces, the presence of a large pre-existing crack was evident.
The crack originated from a seam weld and propagated through one of the main pipes of
the crane jib space frame. The failure occurred during maneuvering with no load aached.
During the investigation crane material properties were obtained experimentally (tensile tests
and Charpy impact tests) and the crane design was veried by FE analysis. Fatigue analy-
sis was conducted, according to standards (FEM 1.001, Eurocode 3), for the welding joints
and the pipes. Failure mode analysis was done from fracture mechanics and plastic collapse
approaches. All of the analysis and investigations brought to the conclusion that the fatigue
design of the jib structure was not done according to standards and that the nal failure was
determined by plastic collapse, after a long stable propagation period of a dominant crack
which originated at the edge of a seam weld.
As for the pressure vessel failures, there are two main reasons for failures, i.e., pressure part
failure (safety valves failures, corrosion, and low water level) or fuel/air explosions in the fur-
nace (gas or liquid fuel leaks). Inadequate construction characteristics of high pressure tubes can
cause failures. An investigation of a prematurely ruptured high-pressure oil tube has shown that
inadequate pipe type (longitudinally welded instead of seamless) and material (design speci-
ed material replaced by a lower grade one) as well as inadequate installation procedures (not
enough pipe clamps which allowed vibrations) resulted in vibration induced fatigue crack [18].
Failure Analysis and Prevention140
All equipment on marine structures is maintained and serviced continuously. In case of a
malfunction, in-situ repairs are often performed. The quality of workmanship and material
choice do have a great importance in such cases. Bending stresses in equipment elements that
should be subjected only to tensile stress (ropes, wires, etc.) can cause failure of such elements.
Numerical analysis of dierent wire rope cross section congurations is performed in order to
determine remaining fatigue of operating wire ropes in dockside cranes [19], Figure 2.
Subsea umbilicals are composite cable and small diameter tubular bundles deployed on the
seabed in conjunction with oshore installations for oil or gas exploitation. These tubes are
loaded by alternating internal pressure and exposed to sea currents, i.e., dynamic loading [20].
Cracks in this type of equipment result in leaks and loss of load-carrying capacity. Umbilical
tubes experience loss of circularity in shape (ovalization) and are subjected to re-rounding pro-
cedures by applying boost pressure prior to service which also translates in fatigue loading.
3. Failure causes and mechanisms
The strength of a structure represents a limit state of loading conditions above which the
structure loses ability to achieve its specied required function. As long as the actual strength
of the structure is kept higher than the actual loading demands, a given marine structure can
be deemed safe. Otherwise, structural failures will occur.
Structural failure can be dened as loss of the load-carrying capacity of a component or
member within a structure or of the structure itself (including global failure modes like
capsizing, sinking, positioning system failures, etc.). The failure can result in catastrophic
Figure 2. Numerical analysis of remaining fatigue life of a wire rope.
Common Case Studies of Marine Structural Failures
damage (i.e., complete loss of the structure itself) or partial structure damage when the
structure can be repaired or recovered. Global failures can more often result in fatal casual-
ties, while smaller and localized structural damage may result in pollution and recoverable
structural damage.
Structural failure is initiated when the material in a structure is stressed to its strength limit,
thus causing fracture or excessive deformations. The structural integrity of a marine structure
depends on load conditions, the strength of the structure itself, manufacturing and materials
quality level, severity of service conditions, design quality as well as various human elements
that have eects during exploitation of the structure.
There are two distinctive groups of failure causes. The rst group is comprised of unforesee-
able external or environmental eects which exert additional loading on the structure result-
ing in over-load. Such eects are extreme weather (overloads), accidental loads (collisions,
explosions, re, etc.), and operational errors. The second group comprises the causes for fail-
ures that occur either during the design and construction phase (dimensioning errors, poor
construction workmanship, material imperfections) or due to phenomena growing in time
(fatigue), both resulting in reduced actual strength in respect to the design value. All of the
listed causes can partially or completely be a result of human factor.
The process of fatigue failure itself is highly complex in nature and it is dependent on a large
number of parameters. The factors are numerous and perhaps the most signicant are mean
stress (distribution), residual stresses, loading characteristics and sequence, structural dimen-
sions, corrosion parameters, environmental temperature, design criteria fabrication methods
and quality.
Failure mechanisms that usually occur in marine structures can be progressive (excessive
yielding, buckling, excessive deformations) or sudden (brile and fatigue fractures). Excessive
yielding and brile fractures occur when the load exceeds critical strength, while buckling
and fatigue fractures depend on time and specic load conditions.
4. Failure analysis tools
The analysis methods can be grouped into methods that use nominal stresses (typical for stan-
dard codes) acting to a structure or part of a structure and then compare the stress amplitude
to nominal S-N curves. This approach is appropriate for structures that are standardized, and
therefore well backed up with statistical experimental data that can be used as initial assump-
tions for fatigue analysis. The alternative is the evaluation of local stresses inuence to fatigue
(notch stress factors, N-SIF).
Some authors [21] divide fatigue analysis methods in two groups: S-N approach based on fatigue
tests and fracture mechanics approach. The rst method is used for fatigue design purpose using
simplied fatigue analysis, spectral fatigue analysis, or time domain fatigue analysis to deter-
mine fatigue loads. The second method is used for determination of acceptable aw size, pre-
diction of crack growth behavior, planning maintenance of the structure, and similar activities.
Failure Analysis and Prevention142
The latest trend in failure analysis development is the unication of analysis methods and
procedures [2224], in order to obtain a comprehensive procedure of structural failure analy-
sis that would cover main failure modes and enable a safer and more ecient design, manu-
facture and maintenance processes.
4.1. Experimental tools
Nondestructive testing and examination (NDT and NDE), as well as structural health moni-
toring (SHM), of structures play a signicant role in fracture analysis and control procedures.
Any method used must not alter, change, or modify the failed condition, but must survey
the failure in a nondestructive mode so as to not impact, change, or further degrade the fail-
ure zone. This kind of examination provides input values for fracture analysis, which yields
results that dene inspection and maintenance intervals for the structure and represent input
values for life prediction estimates. Structures are inspected at the beginning of their service
life in order to document initial aws which determine the starting point of the structure
fatigue life prediction. The most commonly used procedures for marine structures are optical
microscopy, scanning electron microscopy (SEM), GDS, and acoustic emission (AE) testing.
Optical microscopy is a common and most widely used NDT analysis method which enables
rapid location and identication of most external material defects. This technique is often
used in conjunction with micro-sectioning to broaden the application. One of the main disad-
vantages is the narrow depth-of-eld, especially at higher magnications.
Scanning electron microscopy is an extension of optical microscopy in failure analysis. The
use of electrons, instead of a light source, provides much higher magnication (up to 100,000×)
and much beer depth of eld, unique imaging, and the opportunity to perform elemental
analysis and phase identication. The examined item is placed in a vacuum enclosure and
exposed with a nely focused electron beam. The main advantage of this method is minimal
specimen preparation activity due to the fact that the thickness of the specimen does not pose
any inuence to the analysis, ultra-high resolution, and 3D resulting appearance of the test
object. Various analyses of marine structures and equipment have been conducted using SEM
[2528], one of them being analysis of speed boat steering wheel fracture, Figure 3.
As it is well known, structural supporting members emit sounds prior to their collapse, i.e.,
failure. This fact has been the basis of the development of scientic methods of monitoring
and analysis of these sounds with the goal to detect and locate faults in mechanically loaded
structures and components. AE provides comprehensive information on the origin of a dis-
continuity (aw) in a stressed component and also provides information about the develop-
ment of aws in structures under dynamic loading. Discontinuities in stressed components
release energy which travels in the form of high-frequency stress waves. Ultrasonic sensors
(20 kHz–1 MHz) receive these waves or oscillations and turn them into electronic signals
which are in turn processed on a computer yielding data about the source location, intensity
frequency spectrum, and other parameters that are of interest for the analysis. This method
is passive, i.e., no active source of energy is applied in order to create observable eects as in
other NDT methods (ultrasonic, radiography, etc.). Three sources of acoustic emissions are
recognized, namely primary, secondary, and noise. The primary sources have the greatest
Common Case Studies of Marine Structural Failures
structural signicance and originate in permanent defects in the material that manifest as local
stresses, either on microstructural or macrostructural level. The amount of acoustic emission
energy released, and the amplitude of the resulting wave, depends on the size and the speed
of the source event. The main advantages of AE compared to other NDT methods are that AE
can be used in all stages of testing. Additionally, it is less sensitive to changes in geometry, the
scanning is remote and it gives real-time evaluation [29]. The disadvantages are the sensitivity
to signal aenuation in the structure, less repeatability do to the uniqueness of emissions for a
specic stress/loading conditions, and external noise inuence on accuracy.
4.2. Analytical tools
Although various analytical models have been proposed by a number of authors, no compre-
hensive model exists. Analytical methods have been developed for prediction of progressive
structural failures of marine structures [30]. The nite element modeling approach for predic-
tion of the development of failures is accurate, but can be time consuming. Analytical pro-
cedures, based on spectral fatigue analysis, beam theory, fracture mechanics, and structural
factors, can provide solutions in considerably less time when needed.
The goal is to dene approaches for computing the fracture driving force in structural com-
ponents that contain cracks. The most appropriate analytical methodology for a given situa-
tion depends on geometry, loading, and material properties. The decisive choice factor is the
character of stress. If the structure behavior is predominantly elastic, linear elastic fracture
mechanics can yield acceptable results. On the other hand, when signicant yielding precedes
fracture, elastic-plastic methods, such as referent stress approach (RSA) and failure assessment
diagram (FAD), need to be used. Since a purely linear elastic fracture analysis can yield invalid
and inaccurate results, the safest approach is to adopt an analysis that spans the entire range
from linear elastic to fully plastic behavior. One of the methods that can be applied is the FAD
Figure 3. Experimental analysis of fractured speed boat steering wheel coupled with numerical analysis.
Failure Analysis and Prevention144
The FAD approach has rst been developed from the strip-yield model and it uses two param-
eters which are linearly dependent to the applied load. This method can be applied to ana-
lyze and model brile fracture (from linear elastic to ductile overload), welded components
fatigue behavior, or ductile tearing. The stress intensity factors are dened on the basis of the
structure collapse stress and the geometry dependence of the strip-yield model is eliminated
[31, 32]. The result is a curve that represents a set of points of predicted failure points, hence
the name failure assessment diagram. The failure assessment diagram is basically an alterna-
tive method for graphically representing the fracture driving force.
Depending on the type of the equation used to model the eective stress intensity factors the
FAD approach can be sub-divided into the strip-yield based FAD, J-based FAD, and approxi-
mated FAD. The J-based FAD includes the eects of hardening of the material, while the
simplied approximations of the FAD curve are used to reduce the calculation times of the
analysis. When stress-strain data are not available for the material of interest generic FAD
expressions may be used [33], which assume that the FAD is independent of both geometry
and material properties. The simplied curves proved adequate for most practical applica-
tions due to the fact that design stresses are usually below yield point. Fracture analysis in
fully plastic regime requires an elastic-plastic J analysis.
Marine structures are subjected to dynamic load that are characterized by exactly unpredict-
able, stochastic changes of value (environmental factors). Most fracture mechanics analyses
are deterministic, therefore a need to view fracture probabilistically for real world condi-
tions arise. The probabilistic fracture analysis overlaps the probability distributions of driving
force in the structure and toughness distribution in the structure to obtain a nite probabil-
ity of failure. Probabilistic methods can take into account time-dependent crack growth and
stress corrosion cracking by applying appropriate distribution laws. Most practical situations
exhibit randomness and uncertainty of the analysis variables so numerical algorithms for
probabilistic analysis may be needed to apply. The well-known Mote Carlo method has been
proven to be suited to accompany FAD models in cases of uncertainties.
Recently, normative institutions have been involved in projects and research, together with
industry, in order to establish probabilistic methods for planning in-service inspection for fatigue
cracks in oshore structures. DNV-issued recommendations on how to use probabilistic methods
for jacket structures, semisubmersibles, and oating production ships [34]. Basically, the goal of
probabilistic method is to replace inspection planning based on engineering assessment of fatigue
and failure consequences with mathematical models for the inuence of exploitation, fatigue
causes, and crack propagation characteristics on the lifetime of the structure to obtain a more reli-
able and secure assessment methodology independent of the engineers’ level of expertise.
Li and Chow [35] have developed a fatigue damage model by formulating a set of damage
coupled constitutive and evolution equations in order to write a computer software that could
predict the behavior of oshore structures under dynamic load. The fatigue damage model is
based on sea wave’s characteristics statistics. The model also includes historical damage data.
Cui [36] has focused his research on the requirement for accurate fracture growth predictions
that preceding fatigue strength assessment methods, mainly based on cumulative fatigue
Common Case Studies of Marine Structural Failures
damage theory using stress-endurance curves (S-N), have not taken into account. The eects
of initial defects and load sequence are included in the prediction model. A fatigue crack prop-
agation theory has been proposed as technically feasible and adoptable method for fatigue
life prediction using commercial FEA/FEM software packages for the calculation processes.
The need for a database of the size and distribution of initial defects for marine structures is
Li et al. [37] have developed an improved procedure for creation of standardized load-time
history for marine structures based on a short-term load measurement. The need for load-time
history arises from the dependency fatigue crack growth behavior to load sequence eect.
It is known that small variations in the initial (basic) assumptions for a fatigue analysis can
have signicant inuence for the predicted crack growth time. As mentioned above, the S-N
based calculations are sensitive to input parameters values and denitions [38]. As the occur-
rence of a crack is not strictly deterministic, probabilistic methods for the prediction of crack
behavior and sizes, based on fatigue crack propagation theory, can resolve accuracy prob-
lems. Probabilistic methods require extensive database of standardized load-time histories for
marine structures, based on extensive experimental research, which can be used in analysis
4.3. Numerical tools
The eective application of numerical methods in fracture mechanics and fatigue analysis
begun with the development of computer science in the second half of the twentieth cen-
tury. Various methods were used (nite dierence method, collocation methods, and Fourier-
transformations) but the nite element method (FEM) has been established as a standard due
to its universality and eciency. FEM enables complicated crack conguration analysis under
complex loads and non-linear material behavior.
Recent years have brought a signicant development and increase in accessibility of com-
mercial computational software and hardware for nite element analysis applications, marine
structures included. This enables more advanced and detailed fatigue and fracture analysis
even for more complex large-scale structures. Furthermore, numerical tools can be used to
complement or even substitute experimental analyses, as in the material selection stage in
design process [39], Figure 4.
As the extent of scientic material published on this maer is very ample, here recently devel-
oped methods will be briey described and referenced.
Extended FEM (X-FEM) is the most recent nite element method developed and is used
mainly for fracture mechanics applications. Based on the nite element method and fracture
mechanics theory, X-FEM can be applied to solve complicated discontinuity issues including
fracture, interface, and damage problems with great potential for use in multi-scale computa-
tion and multi-phase coupling problems. The method has been introduced in 1999 [40] and
since then further developed by various authors. The basic idea of the method is to reduce
the re-meshing around the crack to a minimum. The improvements enabled the crack to be
represented in the FE model independently from the mesh itself [40, 41]. The solution for the
Failure Analysis and Prevention146
problem of modeling curved cracks was developed by forming higher order elements [42].
Improved XFEM methods are continuously being developed by various researchers as the
method has been proven as very valuable.
Various computer software packages for fatigue crack growth analysis have been developed
by NASA. FASTRAN is a life-prediction code based on the crack-closure concept and is used
to predict crack length against cycles from a specied initial crack size to failure for many
common crack congurations found in structural components. NASA FLAGRO v2 fatigue
crack growth computer program developed as an aid in predicting the growth of pre-existing
aws and cracks in structural components using a two-dimensional model which predicts
growth independently in two directions based on the calculation of stress intensity factors.
Recently, specic numerical automatic crack box technique (CBT) has been developed in
order to enable to perform ne fracture mechanics calculations in various structures without
global re-meshing [43]. The algorithm can be used for FEM calculations with ABAQUS code.
The method represents an improvement as only the specic crack zone has to be re-meshed
Figure 4. Numerical prediction of material fracture behavior using FE models of fracture mechanics standardized
specimens in order to get dependence of J-integral to crack growth.
Common Case Studies of Marine Structural Failures
which results in simpler and time saving calculations. Also, the method allows the analysis of
the inuence of plastic material characteristics on the crack growth path.
5. Conclusions
This chapter provided an overview of common failures of marine structures taking into
account failure mechanisms and tools used for failure analysis. As shown, the majority of
employed failure analysis is comprised of visual, analytical, and mechanical inspection meth-
ods in the aempt to identify failure causes. The working conditions in which marine struc-
tures operate are often stochastic in nature and strongly dependent on weather conditions at
sea as well on loading conditions of the structure. The complexity of failure analysis accentu-
ates the need for numerical simulation of possible catastrophic scenarios during the entire
lifetime span of the structure. If the marine structures coupled with the relevant data collected
during maintenance procedures are numerically modeled than a tool for failure prediction
can be developed. Therefore, complete analysis comprising analytical, experimental, and
numerical research is desirable to obtain satisfying results.
The materials and data in this publication have been obtained through the support of the
International Association of Maritime Universities (IAMU) and The Nippon Foundation in Japan.
Author details
Goran Vukelić* and Goran Vizentin
*Address all correspondence to:
Faculty of Maritime Studies Rijeka, University of Rijeka, Rijeka, Croatia
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Common Case Studies of Marine Structural Failures
... Usually, SMAW is making hundreds of joints with several kilometers of welding lines to construct a ship. These welding lines on mild steel plates are more vulnerable than the plate itself due to number of reasons including lamellar tearing arising in joints especially in which the fusion boundary of the weld is parallel to the plate surface [3,4]. In addition, the weld seam is left with residual stresses that lie around the yield strength of the material. ...
... Various factors of structural failure can cause damage to the ship so that it can affect operations [3]. Marine structures must comply with the design requirements in such a way that the probability of failure can be reduced to a minimum [4] . In addition, the strength of the structure of the ship or marine structure affects the durability of the structure itself. ...
... These problems should be further examined, using alternative methods and approaches to provide a complete explanation of the phenomenon of weariness. This problem must be discovered in advance and addressed entirely to avoid future disasters [8][9][10]. The purpose of this study is to determine the effects of geometric shapes, material types, and loading types on the fatigue phenomenon occurring in ship structures using the hot spot stress approach. ...
Full-text available
This paper presents a numerical procedure based on the finite element (FE) method using ANSYS Workbench software to analyse fatigue phenomena in ship structures. Fatigue failure prediction is used as a stress–life approach, when the stress is still in a linear area. This condition is frequently referred as high-cycle fatigue. Five geometric shapes taken from midship points on the structure of a ship are sampled. There are four types of materials: HSLA SAE 950X, medium-carbon steel, SAE 316L, and SAE 304L. The types of loading imposed on each sample include three conditions: zero-based, zero mean, and ratio. Mesh convergence analysis is conducted to determine the most effective mesh shape and size for analysing the structure. The results showed that the configuration of the geometric shapes, materials used, loading schemes, and mean stress theory affect the fatigue characteristics of the structure.
... One of them can be a failure of the propulsion or steering system that makes one unable to steer a vessel. The part of the steering system that is most susceptible to damage is the propeller shaft [1] which is subject to the following changeable factors: bending moment, torque moment, axial thrust force, temperature and corrosive environment. The risk of the occurrence of a fatigue crack in the propeller shaft increases along with the severity of weather conditions as they exert a direct influence on the dynamics of shaft loading. ...
Full-text available
When a vessel looses steerage, it may be due to a failure of the main engine. Such an instance is discussed in the article. A fault of a single exhaust valve resulted in an exponential spread of the destruction of other parts of the engine: the second exhaust valve split into three pieces, openings were knocked out in the head and in a piston, valve seats cracked, an opening appeared in one of the seats allowing cooling water to enter into a cylinder, the surface of the cylinder underwent plastic strain, pieces of the valves got into the turbocharger, where they caused minor damage. Due to a high degree of plastic strain, the surfaces of the cracks in the damaged elements have lost their original features; therefore, the author was able to identify only a hypothetical cause and course of the destruction process. In the conclusion, the author emphasises the significance of engine operation monitoring and fault diagnosis for the sake of safety of maritime transport.KeywordsFailureMarine engineValvesDiagnostics
... Laser vibrometry allows carrying out measurements using a laser beam [26,27,31,46]. It enables measurements of vibrations in a non-contact and non-invasive way. ...
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The paper presents the measurement process and test results for six thin-walled plates with different dynamic characteristics caused by different defects of welded joints. The tests were carried out using non-destructive testing (NDT). The authors made an attempt to determine the validity of the use and degree of effectiveness of the tests based on laser vibrometry in detecting defects in welded joints. The tests of welded plates were carried out using displacement laser sensors and piezoelectric accelerometers, while the source of vibration extortion was a modal hammer. In the adopted measurement methodology, the application of accelerometers was to obtain the reference data, which allowed for comparison with the measurement data obtained from the laser vibrometer. The analysis of the obtained measurement data, in the fields of time and frequency, made it possible to verify the correctness of the data obtained by means of laser vibrometry and to determine the requirements which are necessary for the correct performance of NDT tests and in the future structural health monitoring (SHM) system of welded joints with the use of a laser vibrometer. The mathematical model developed in the MSC software Pastran-Nastran was also used in the work. The model was developed for the purpose of mutual verification of the measurement and calculation tests. At the present stage of work, it can be stated that the results obtained by laser vibrometry methods should be treated as a supplement to the research conducted with traditional piezoelectric accelerometers. In certain situations, they can be used as an alternative to accelerometers, due to the fact that laser sensors do not require direct contact with the examined object. Where the object under test may be in a strong electromagnetic field, optical sensors are better suited than contact sensors.
Conference Paper
Instability is one of the factors causing damage and injury that results in permanent disability. To increase the stable load-carrying capacity, a simplified and efficient computational method for determining the first critical load is necessary for the structure's structural design, application and safety. This study aims to determine the characteristics of the critical bending moment M bcr and the critical torsion moment M Tcr due to geometric size variations in the square, diamond, and circle cross-sectional hollow pipes so that consideration of the selection of hollow pipe size and cross-sectional shape is obtained under pure bending and pure torsion to minimize the occurrence of instability of the structure. The geometric size variation is carried out by changing the value of a/t in the quadrilateral pipe, the value of D/t in the circular pipe, and the length of the pipe L in each cross-sectional shape. This research was conducted using Finite Element Analysis-based software with linear and nonlinear buckling analyses. The moment load is given at the centre point of the model end, and the boundary conditions are set to see the deformation on the mid-span section of the pipe. The results showed that M bcr and M Tcr were inversely proportional to the values of a/t, D/t, and . The largest value of M bcr belongs to the circular pipe. The value of M bcr in the diamond pipe is greater than the square pipe but getting closer to the same as the value of L increases the M Tcr value of both cross-sections is the same. The M Tcr curve in the cross-section of the circle has a higher degree of steepness than the square and diamond cross-section. At the same value, the more the value of a/t and D/t increases thickness change has more compared to the circular pipe. At the same L, the greater the value of a/t and D/t, the difference in the M bcr between the cross-section of the circle and the quadrilateral is smaller, but the difference in M Tcr tends to be the same. At the same value of a/t and D/t, the oval deformation value and angle of twist will get bigger, but the M bcr and M Tcr values are getting smaller and will be constant at a given pipe length.
Conference Paper
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Committee Mandate Mandate: Concern for the safety and structural reliability of subsea production systems for oil and gas offshore. This shall include subsea equipment for production and processing, flowlines and risers, with emphasis on design, fabrication, qualification, installation, inspection, maintenance, repair, life extension and decommissioning. Structural design for flow assurance and safe underwater operations shall be considered. Introduction The offshore and subsea industry is getting more complex with higher pressures, higher temperatures and increased water depths. Technology developments and impacts for the subsea industry are driven both by economic factors and by sustainability issues. These factors will enhance for novel subsea concepts like all-electric, new subsea processing technologies, further integration between process control and process safety systems and use of sensors to monitor process condition and integrity of safety systems. This report focuses mainly on the traditional subsea technology related to oil and gas fields where the attention will be on efficiency, safety, environment, digitalization and life extension. This is the second term of the Specialist Committee V.8 Subsea Technology and as the previous report provided a more introductory outline to subsea technology, the following report will focus more in depth on the main trends seen by the industry like autonomous operations and operational challenges to accommodate for higher pressures, temperatures and ultradeep waters. Hence, areas like installation of subsea equipment have only been briefly discussed and operation for emergencies has been left out since this was thoroughly addressed by the previous committee. The next level from electrification is to further explore the concept of subsea power distribution with the goal to provide power, ranging from 750 kW to more than 11 MW, to subsea systems, from pumps to compressors. All the major subsea players like GE Oil & Gas, ABB, TechnipFMC, Aker Subsea and Baker Hughes, are developing different concepts which are further discussed in Chapter 2. Another trend is the need for higher pressure and higher temperature (HPHT) and often in combination with ultradeep waters. One of the fields that have taken the new specifications for HPHT equipment is the 2,000psi rated subsea hydraulic junction plates including connection hardware for deployment at Chevron's Anchor development in the U.S. Gulf of Mexico just put in order. Hence, focus on safe design and new and updated design standards are presented in chapter 3. The demanding subsea environments challenge the boundaries of traditional engineering alloys and our understanding of degradation mechanisms that could lead to failure, new materials and fabrication of these have been discussed in chapter 4. Carbon capture and storage (CCS) has been identified as a key abatement technology for achieving a significant reduction in CO2 emissions to the atmosphere where pipelines are likely to be the primary means of transporting CO2 from point-of-capture to sites. There is currently a strong interest to explore the use of pipelines for hydrogen transport, hence new pipeline trends and design assessment like strain based and leak limit states are discussed in chapter 5. For the subsea industry, one of the main drivers is to put power on the seabed where subsea facilities are becoming all-electric. This technology will ensure huge capital cost savings for field developments and reduction in CO2 emission will become important. Chapter 6 deals with different riser concepts from traditional steel catenary, top tension and flexible risers to novel concepts like Thermoplastic Composite Pipe (TCP) and Carbon-Fibre-Reinforced Polymer (CFRP) risers and umbilicals. The Macondo accident was an eye opener for the whole industry, and the Petroleum Safety Authorities of various countries challenged the industry on different levels to mitigate above associated risks and implement barrier management at the design stage. One of the challenges is the increased focus on design of subsea production system for oil and gas offshore in terms of safety and structural reliability of the system and its inherent management. Chapter 7 deals with structural integrity management, including inspection methods and advances in repair systems. The subsea industry faces a combination of market forces from authority, strict regulation and societal pressure over climate change, chapter 8 addresses structural reliability assessment and safety of subsea systems. Several of the offshore fields are approaching the end of their design life and a cost-effective solution to maximize production is to document that life extension is feasible for an asset, different solutions are discussed in chapter 9 including decommissioning.
Fatigue failure is a phenomenon that often occurs in mechanical structures, especially in components that receive direct cyclic loading, e.g., marine facilities, automobiles, critical infrastructure, reservoirs, turbines, nuclear reactors, and features that work in extreme conditions. Several factors can affect fatigue resistance, including applied material type, environment temperature, microstructure state, residual stress, corrosion, and crack initiation. Accurately estimating fatigue life is critical. A variety of variables must be taken into the calculation to reduce the risk of dangerous failure. In this paper, a series of development and achievement reviews on the relevant phenomena and advanced research related to fatigue assessment is conducted. Consideration of fatigue assessment methodology, e.g., laboratory experiment and numerical calculation, is discussed to summarize relevant effects to characteristics of stress life, strain life, frequency-based, and fracture mechanic approaches. The review also presents the relationship of previous research and its relevance to the development of the recent study. The purpose of this paper is to provide state-of-the-art investigations as well as demonstrate the challenges of uncharted problems.
This article brings to attention learning from the failure - blackout, loss of propulsion and near grounding - of Viking Sky cruise ship which occurred in Hustadvika, Norway, in March 2019. Failures and accidents in the cruise ship industry attract the global media and can severely impact reputation and business performance of companies and authorities involved. A system approach investigation and analysis - CAST - was employed with the aim to maximize learning from the Viking Sky’s failure through a systematic approach and to contribute to failure reduction in the cruise ship industry. Three main recommendations emerged from this study: an overview of the accident or failure precursors and resilience indicators; safety recommendations for other cruise ships; lessons and strategies of actions for the increased cruise operations in the Arctic and Antarctic areas. It was found that several accident or failure precursors, for example, a low level of lubricating oil, the failure of a turbocharger, an inoperative large diesel generator, lack of functionality for safety equipment due to bad weather, and others precursors contributed to failure and highly critical situation encountered by Viking Sky in Hustadvika. Resilience indicators such as the master’s immediate decision to launch mayday, the crew preparedness, and the way how the emergency situation was handled were found to have positive impacts on critical situation of Viking Sky. This article highlights also that adaptations and improvement of standards and regulations for harsh environmental conditions can play an important role in prevention of marine accidents. Furthermore, for a better understanding of correlation between environmental loads and their effects on machinery systems, digital solutions such as digital twin for condition monitoring of cruise ships in the Polar areas are seen as possible innovative solutions yet to be fully implemented in the marine industry.
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Preface Failure analysis has gradually become the crucial method in investigating engineering com‐ ponents or machine failures. The costs of repair and operation breakdowns make an alarm‐ ing sign for designers, engineers and manufactures on whether or not to keep the existing machines, worthwhile of repairing, or the machines or components need to be redesigned. This book covers recent advancement methods used in analysing the root of engineering failures and the proactive suggestion for future failure prevention. The techniques used, es‐ pecially non-destructive testing such X-ray, is well described. The failure analysis covers materials for metal and composites for various applications in mechanical, civil and electri‐ cal applications. The modes of failures that are well explained include fracture, fatigue, cor‐ rosion and high-temperature failure mechanisms. The administrative part of failures is also presented in the chapter of failure rate analysis. The book will bring you on a tour on how to apply mechanical, electrical and civil engi‐ neering fundamental concepts and to understand the prediction of root cause of failures. The topics explained comprehensively the reliable test that one should perform in order to investigate the cause of machines, component or material failures at the macroscopic and microscopic level. I hope the material presented in this book, is not too theoretical and you find the case study, the analysis will assist you in tackling your own failure investigation case. Last but not least, I would like to thank all authors who made their contribution and sup‐ port for this book to be realised. Prof. Dr. Aidy Ali Department of Mechanical Engineering, Faculty of Engineering, National Defence University of Malaysia (UPNM), Kuala Lumpur, Malaysia
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Wire ropes in marine applications often encounter relatively fast and noticeable wear, a result of the fatigue to which they are exposed coupled with harsh operational conditions. This paper addresses some of the aspects of fatigue damage that occur in wire ropes. Using the finite element method, stress and fatigue analysis of three different design types (6 × 7, 7 × 7, 8 × 7) of wire rope is performed. The size of the wire rope cross-section area is varied in order to simulate the progressive damage of the wires so that consequential stress levels and remaining fatigue life can be numerically predicted. The aim was to provide a better understanding of the mechanical behavior of damaged wire ropes under various conditions, since an appropriate choice of wire rope design could then be made from engineering and economic points of view. Additionally, potential failures can be predicted, resulting in effective maintenance and the avoidance of potential risks of rope failure, especially important regarding economical and safety aspects of transportation in the marine industry.
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The U.S. Liberty Ship Building Program in World War II set a record—a total of 2700 Liberty Ships were built in 6 years, in order to support the battle against Nazi-Germany. However, numerous vessels suffered sudden fracture, some of them being split in half. This paper demonstrates and investigation of the Liberty Ships failure and problems, which reveals that the failures are caused by a combination of three factors. The welds produced by largely unskilled work force contain crack type flaws. Beyond these cracks, another important reason for failure associated with welding is the hydrogen embitterment; most of the fractures initiate at deck square hatch corners where there is a stress concentration; and the ship steel has fairly poor Charpy-Impact tested fracture toughness. It has been admitted that, although the numerous catastrophic failures were a painful experience, the failures of the Liberty Ships caused significant progress in the study of fracture mechanics. Considering their effect, the Liberty Ships are still a success.
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During the inspection of a North Sea oil and gas platform a crack was identified on the crankshaft of a compressor. Subsequently, the component was decommissioned and a failure examination undertaken to determine the mechanism of failure. The crankshaft was analysed using a range of inspection, measurement and fractographic techniques. Magnetic particle inspection (MPI) indicated that the crack extended for the majority of the shaft's length, rotating through approximately 225 degrees of the shaft's circumference. Laser scanning verified the dimensions and concentricity of the crankshaft were in accordance with the manufacturer's specifications. On sectioning the crack and forcing it open, complex fracture features were revealed. Optical and scanning electron microscopy were used to examine these features as well as the surface of the crankshaft. The investigation determined that the mechanism of failure of the crankshaft was probably corrosion fatigue, initiating from localised corrosive attack on the crankshaft's surface.
Full-text available
Failure of a cracked steering wheel is studied in this paper. Steering wheel, mounted on a speed boat, had cracks emanating from one of the fastener holes until final fracture occurred. Failure analysis, combining experimental and numerical techniques, was performed. Experimentally, fasteners torque moments were measured, visual inspection performed and material type determined (aluminum alloy AA 6061). Additionally, scanning electron microscopy examination was employed to characterize the microstructure of the fractured surface. Using finite element analysis, stress analysis of a cracked steering wheel was conducted. Stress intensities of uncracked and cracked steering wheel were compared to find out about stress concentration points. Possible causes of crack occurrence include excessive fastener torque moment, fretting between fastener and hole combined with poor machining that left marks that serve as potential crack initiation points. Obtained results are valuable for predicting fracture behavior of the cracked steering wheel and can be taken as a reference for design and exploitation process of such component.
The paper presents analysis of displacement of a propulsion system shaft line and a crankshaft axis caused by temperature of marine, slow-speed main engine. Detailed information of thermal displacement of a power transmission system axis is significant during a shaft line alignment and a crankshaft springing analysis and during designing of structural health monitoring (SHM) system. A warmed-up main engine is a source of deformations of an engine body as well as a ship hull in the area of an engine room and hence axis of a crankshaft and a shaft line. Engines' producers recommend the model of parallel displacement of the crankshaft axis under the influence of an engine heat. This model may be too simple in some cases (especially for SHM systems). The paper presents computations of MAN B&W K98MC type engine mounted on 3000 TEU container ship. The engine body is much stiffer than its foundation pads and ship hull (double bottom) - boundary conditions of the engine. Especially for the high power marine engines correct model of the boundary conditions plays a key role during the analyses. Presented numerical analyses are based on temperature measurements of the main engine body and the ship hull during a sea voyage. Numerical analyses were performed using Nastran software based on Finite Element Method. The FEM model of the engine body comprised over 800 thousand degree of freedom (dof); the model of the ship hull contains over 200 thousand dof. Both models are analysed separately; the mutually interaction between them is taken into account by heat transfer and special model of boundary conditions. The specialized SHM system dedicated to marine propulsion systems working in very bad environmental conditions is the future aim of the research.
Two types of stainless steels are compared in this paper, austenitic X15CrNiSi25-20 and martensitic X20Cr13, based on their numerically predicted fracture behavior. There are engineering applications where both of the steels can be considered for use and where these materials can be exposed to crack occurrence and growth, so proper distinction between them is desirable. Comparison is made on the basis of (Formula presented.)-integral values that are numerically determined using finite element (FE) stress analysis results. FE analysis is performed on compact tensile (CT) and single-edge notched bend (SENB) type specimens that are usually used in standardized (Formula presented.)-integral experimental procedures. Calculated (Formula presented.)-integral values are plotted versus crack growth lengths for mentioned specimens. Results show somewhat higher values of (Formula presented.)-integral for steel X20Cr13 than X15CrNiSi25-20. Further, when comparing (Formula presented.)-integral values obtained through FE model of CT and SENB specimen, it is noticed that CT specimens give somewhat conservative results. Results obtained by this analysis can be used in predicting fracture toughness assessment during design process.
Ultra-deep water subsea separator, bearing huge external pressure, is a key equipment of subsea production in the offshore petroleum industry. In this paper, the buckling and post-buckling behavior of a 3000 m subsea separator is analyzed by numerical and experimental methods. In simulation, the nonlinear global buckling analysis, including nonlinear material and initial imperfections, is performed to analyze the global buckling behavior of the ultra-deep water subsea separator. In the experiment, a two circumferential lobe mode is present and the buckling deformation is asymmetrical. The comparison of numerical and experimental results has shown the numerical results that indicate a similar behavior and deformation mechanism. The nonlinear global buckling analysis proposed in this paper can numerically simulate the buckling process of the ultra-deep subsea separator with good accuracy. Finally, the influences of length to diameter ratio, ovality, and support on global buckling are researched.
This new reference describes the applications of modern structural engineering to marine structures. It will provide an invaluable resource to practicing marine and offshore engineers working in oil and gas as well as those studying marine structural design. The coverage of fatigue and fracture criteria forms a basis for limit-state design and re-assessment of existing structures and assists with determining material and inspection requirements. Describing applications of risk assessment to marine and offshore industries, this is a practical and useful book to help engineers conduct structural design.
Due to the nature of the fatigue phenomena it is well known that small changes in basic assumptions for fatigue analysis can have significant influence on the predicted crack growth lives. Calculated fatigue lives based on the S–N approach are sensitive to input parameters. Fracture mechanics analysis is required for prediction of crack sizes during service life in order to account for probability of detection after an inspection event. Analysis based on fracture mechanics needs to be calibrated to that of fatigue test data or S–N data. Calculated probabilities of fatigue failure using probabilistic methods are even more sensitive to the analysis methodology and to input parameters used in the analyses. Thus, use of these methods for planning inspection requires considerable knowledge and engineering skill. Therefore the industry has asked for guidelines that can be used to establish reliable inspection results using these methods. During the last years DNV GL has performed a joint industry project on establishing probabilistic methods for planning in-service inspection for fatigue cracks in offshore structures. The recommendations from this project are now included in a Recommended Practice. The essential features of the probabilistic methods developed for this kind of inspection planning are described in this paper.
The assessment of the residual strength of a damaged ship is a key element of ABS’ Rapid Response Damage Assessment (RRDA) program. When determining the residual strength, it is important to understand how the initial structural damage can spread in response to sea wave dynamic loads and can lead to a gradual reduction of the ship’s residual strength. This progressive, time-dependent structural failure caused by cracks emanating from the damaged area could eventually lead to total hull girder collapse. This is why it is important to quantify the progressive structural failure over time when assessing the residual strength of the damaged ship. Until now, progressive structural failure analysis has been conducted numerically using the Finite Element (FE) modeling approach. While this approach is accurate, it is extremely time-consuming, which makes it inappropriate for incident response, where time for decision-making is very limited. In order to overcome this limitation, an alternative analytical modeling approach for assessing the progressive structural failure of a damaged ship is proposed. This paper presents a new comprehensive procedure for analytical prediction of crack propagation under sea wave loading using spectral fatigue analysis, beam theory, fracture mechanics and an equivalent stress intensity factor (SIF) range concept. The SIF range obtained analytically is validated by FE modeling of a damaged ship subjected to sea wave dynamic loading. The procedure for analytical prediction of the crack propagation is demonstrated for a typical, modern 170,000 DWT bulk carrier in a full load condition. The results of this research can be used to support informed decision-making when analyzing a vessel’s residual strength for the transit voyage from the accident location to a repair facility.