Science topic

# Fracture Mechanics - Science topic

Fracture mechanics is the study of the influence of loading, crack size, and structural geometry on the fracture resistance of materials containing natural flaws and cracks. When applied to design, the objective of the fracture mechanics analysis is to limit the operating stress level so that a preexisting crack would not grow to a critical size during the service life of the structure.

Questions related to Fracture Mechanics

In fracture, the various expressions of

*G*the crack extension force per unit length of the crack-front (or energy release rate) show invariably a linear dependence of*G*with the crack half-length*c*. This is true whatever the shape (planar or non-planar) of the crack and the form*f*of the crack-front (*f*can be developed in Fourier forms). Hence some expressions of*G*(see*relation*(2.25), page 37 in Lawn (1993) Second Edition, for example) provided for the*DCB*specimens are under question. Are these concerned with crack propagation?For failure analysis, sometimes parts received contains fully rusted fracture surface and surrounding areas. Is there an acid solution out there for soaking the parts or spraying solution to the corroded area to remove the corrosion products and obtain a clean surface for analysis?

Hi, I want to analyze a crack in 2d and 3d and find displacement of the Part Block due to that Crack and loading.

My question is as I want to create periodic Sine load applying for several second or minutes, which Solver in Step module suits best and also which method of crack analysis (XFEM, contour integral or VCCT)?

Dear RG Members,

I’m currently working on extracting data of multiple .rst/.rth files, which are having same mesh and same node numbering, using PyANSYS/PyMAPDL. The end target is to use this data for LCF/Creep/Creep-fatigue/fracture calculations. Currently this data extraction is done manually, we want to automate this process.

The elements I am using is plane77 (with axisymmetric option) for thermal analysis and plane 183 (axisymmetric) for structural analysis (in ANSYS).

Please look at the figure attached.

I want to provide path for all my rth/rst files and respective load/substep numbers for which I want to extract data. On pressing confirm a popup will ask for node number and desired data (temperature/stress/strain/creep strain) for that node number should be there in the output column from all these files (that's the wish). First row data (temperature from a rth file for steady state thermal run) I was able to extract. Got stuck in the second row where I want von Mieses stress from a steady state structural run.

However, when I attempt to parse the result sets using result.parse_step_substep(), I receive only integer indices representing the result sets, rather than a tuple containing the actual load step and substep numbers. For example, my .rst file shows 3 result sets, but the step info returned is simply 0, 1, and 2, without any clear mapping to the original load step and substep numbers from the simulation. Is there a current method within PyMAPDL to directly retrieve data based on specific load step and substep numbers (e.g., Load Step 3, Substep 5), rather than relying on the result set indices?

Thank you for your help and support in advance.

Regards

NC

The aim of the research here is to prevent the propagation of the crack in the fabricated elastic medium with useful applications.

I am looking to purchase a photography kit for onsite metallurgical investigations, such as capturing photos of worn areas, hot tears, cold tears etc. Could anyone suggest me a good macro-photography kit / camera combination for this purpose. Thank you.

Can an elliptic crack (small enough to remain a single entity, with

**no internal pressure or shear force**) inside an isotropic material (no boundary effect) be expanded in its own plane under**externally applied shearing stresses**only?If yes, how did you show that? Do we have experimental evidence for the process?

A simple crack system (

*Figure***1**) can be readily studied to estimate the Hertzian conoidal crack angle and length, and also the stress intensity factor.This is a 3

*-D*brittle elastic half-space on the flat boundary*Ox*1*x*3 of which a rectilinear contact pressure along*Ox*3 is exerted by a cylinder whose axis is parallel to*x*3; the cylinder lies along Ox3 on the flat boundary. A planar straight-front crack inclined by an angle*θ*with respect to*x*1*x*3 is present under the action of the load along*x*2 due to the cylinder. The relevance of this modelling may be understood as follows. A slab of cylinder with thickness*dx*3 at spatial position*O’*(0*,*0*, x*3) exerts elastic fields (displacement and stress) proportional to those of a point load at*O’*(proportionality coefficient*dx*3). Physically, this corresponds to the action of a spherical indenter to which is associated a conoidal fracture surface for sufficiently large load (Roesler (1956) as quoted by Frank and Lawn (1967)). The coalescence of conoidal cracks from different slabs of cylinder along*Ox*3 would produce planar fracture surface envelops parallel to*x*3 at large crack lengths. Therefore, we expect the modelling in**Figure****1**to provide the experimentally observed fracture surface inclination angle*θ*and crack length*l*as a function of critical load*P*by both a spherical indenter and cylinder. This is the essence of the modelling depicted schematically in**Figure****1**.Cross-slip, twinning and fracture are major deformation modes adopted by loaded materials. It appears sound that these apparently different deformation mechanisms can be analysed on the equal manner!

Can we restrict the vertical and horizontal displacement in two directions for the lower semicircular in bottom hole of CT specimen and apply incremental displacement in the upper semicircular in top hole?

Or is it done some other way?

Hello all,

I need to pre-crack a steel specimen with the following dimensions.

W = 25mm, a

_{n}= 6mm, B = 5mmHow do I identify the force required for the pre-crack initiation?

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The motivation comes from the following common observation. Blocks of stone with large dimensions (say of the order of three meters or larger) can be easily fractured into two pieces. First, cylindrical holes are introduced at top surface using drills. Second, fracture is initiated from the holes with the help of sledgehammers and wedges. Without any additional action, the crack will move with time downward other very large distance and separate the block of stone into two parts. The fracture surface is perfectly flat. What is the reason?

Under dominant mode I loading, planar cracks have been observed to move from zero velocity

*v=*0; for a certain value*v= v*_{1}, these turn into non-planar crack configurations. An explanation is offered below.Hello Researchers,

To conduct fracture toughness tests for pipeline material how do you machine specimen using pipelines with small thicknesses (ex 7mm)?

According to ASTM E399, how do you satisfy the ligament length condition with a smaller specimen?

Thank you

I see a lot of equations work very well without Pi then it is needed to use Pi in fracture machines.

Fatigue fracture surfaces of broken high strength materials exhibit rough conoidal cracks at the vertex of which are located inclusions or heterogeneities

Experimental: The observations refer to Sakai et al. (2002), Abdesselam et al. (2018), Stinville et al. (2018) ... These cracks have been named “fish-eye marks” by two former authors and their formations have been divided into three stages: (

*i*) formation of the characteristic area as a fine granular area (FGA); (*ii*) crack propagation to form the fish-eye (i.e. according to us “rough conoidal crack”); (*iii*) rapid crack propagation to cause the catastrophic fracture.This subject is important because evidence of conoidal rough cracks is observed experimentally on various macrographs of broken specimens, under fatigue for instance. Our recent works (see below in answers) provides associated physical quantities.

YES! THIS HAS BEEN SHOWN IN “PLANAR CRACKS IN UNIFORM MOTION UNDER MODE I AND II LOADINGS” (ANONGBA 2020).

Earlier works have suggested that crack speeds

*v*could not exceed Rayleigh wave velocity, in the subsonic velocity regime (*v< ct*transverse sound wave velocity).This question deserves to be posed and clarified. It is at this price that we will be able to consider an improvement involving analyses including new concepts. The answer to this question is given below.

Hello everyone,

I am currently investigating the phenomenon known as the Indentation Size Effect (ISE) using the Finite Element Method (FEM). My research involves conducting indentation tests through simulation using ABAQUS.

Here are some specifications of the model:

- It is a 2D axisymmetric model.
- The indenter is represented as a rigid body and possesses a semi-angle of 70.3°.
- The specimen material is assumed to be homogeneous and isotropic, characterized by an ideal elastoplastic model.
- Mesh is refined near the indenter tip to capture stress concentration accurately.
- Contact Interaction: Surface-to-surface contact, Tangential behaviour - Frictionless, Normal behaviour - Hard Contact.

I have conducted simulations at various depths, ranging from 500 nm to 5000 nm. To determine the hardness, I have employed the Oliver-Pharr Method. According to the concept of ISE, the hardness should decrease as the indentation depth or load increases. However, in my results, I have observed that the hardness remains almost constant regardless of the depth. Consequently, I am unable to observe the anticipated trend associated with the Indentation Size Effect in my findings.

For your convenience, I have attached the .cae file and the hardness vs indentation depth plot.

I would greatly appreciate any assistance or insights you can provide to help me address this issue.

Thank you all in advance.

Dear researchers,

I am currently researching the issue of fracture in thin steel plates containing holes. Some scholars have already conducted static tensile fracture tests on plates with holes [1], and the test model is shown in the attachment. I have derived the stress distribution field under static tensile conditions. However, in my practical applications, the specimen is subjected to high loading rates, where the tensile force approximates an impulse force. Therefore, the static results can only serve as a reference. I would like to further investigate the fracture mechanisms in the transient tensile behavior of the steel plate, including the influence of the distribution of cracks near the hole and hole geometry on the results. It would be ideal to obtain theoretical solutions. Could you provide me with some suggestions or references regarding the research direction? Thank you for your attention.

[1] Wang W and Jiang L 2011 Fracture Mode of High Strength Steel Thin Plates with Elliptical Hole. In: 2011 Fourth International Conference on Information and Computing, pp 338-41

I am currently deriving the stress intensity factor for a crack at the edge of a circular hole in a plate. The integral form of the stress intensity factor is as follows:

I would like to inquire if there are any innovative approaches or potential combinations with emerging theoretical methods for solving this equation. Could you please provide some insights on this matter? Alternatively, are there any recommended reference books and papers on this topic?

Thank you for your time and attention.

In fracture mechanics, the obsolete principle of stress intensity factor K (SIF) is still used, even though it has a limited validity and questionable interpretation.

What experience do you have and what is your opinion?

This subject is very important because evidence of circular cracks is observed experimentally on various macrographs of broken specimens, under fatigue for instance. Our recent work (see below in answers) provides associated physical quantities.

Abaqus provides the option to define the mode mix ratio based on energy or traction. The traction-based mixed mode response ( Mode I/II problem) where pure Mode I and II traction separation relation is already defined in the input file. Is the Abaqus interpolates for the intermediate mode mix ratios?

My research mate Fernando Coelho came up with this excellent terminology regarding a novel publication about using mechanical pull-off testing for failure pattern analysis for adhesives. This is already standardized via ISO 10365.

However, it is important to note that even 40 years ago, Hutchinson and Sue (1992) already applied fracture analysis tests correctly to address this issue - and not pull-off tests.

What do you think about this issue?

Is it correct to use simple pull-off testing for fracture analysis?

Let me know in the comments below!

PS: You can also watch the disussion flowing on LinkedIN

In fracture mechanics, there are several test specimen, such as the C(T) specimen, and when assessing the crack growth behoavior, to determine the threshold stress intensity factor, a precrack is needed prior to perform the crack propagation test?

In fracture mechanics, the principle of linear-elastic strain energy release rate GIc is still widespreadly applied, even though it has a limited validity and questionable interpretation.

What experience do you have and what is your opinion?

The ʺstress intensity factorsʺ concept is known from Irwin (1948, 1957) who linked these to the energy release rate (crack extension force per unit length of the crack front) in the case of a crack in a two-dimensional crack analysis. In practice (to be used in three dimensions), the crack is viewed planar (

*Ox*1*x*3) with a straight front running indefinitely in the*x*3-direction, perpendicular to the crack propagation*x*1-direction. In this situation, the utility of the stress intensity factor is apparent. For an arbitrary crack front in three dimensions, please see what follows.Could you please tell me what is according to you the best conference on Fracture Mechanics to attend? Especially for surface hardened steel materials used in aeronautics applications ? Thanks for your help ;)

Hello researchers,

If a cyclic load is used for fatigue crack growth testing, why does it require pre-crack with a cyclic load?

Isn't it the same thing?

Hello everyone,

I want to investigate the debonding behavior of the matrix-particle interface in a particulate composite with spherical particles in a two-dimensional matrix, using the Abaqus Dynamic Explicit solver.

I used General Contact (Explicit), with cohesive behavior and Johnson -cook damage formulation. However, stress concentration is occurred at matrix, and the stress is not transferred to the particles. Also, interface perpendicular to force direction is deboned very early. I think my interface definition is not correct, any help would be highly appreciated.

I sam earching a preporcessor program for fracture mechanics analysis using abaqus, I am doubting between zencrack and feacrack, I wonder if someone has experience with these programs and can help me to select which one (or another program) is better.

I want to use it for 3D studies

In the paper "Predicting thermally induced edge-crack initiation using finite fracture mechanics" by S. Dölling, et al. in Eng.Frac.Mech. 252 (2021) 107808, which is discussed on the iMechanica platform as ESIS blog paper #35, I find that what I would call a two-parameter fracture criterion is presented as a "finite fracture mechanics" methodology. The two parameters are the energy release rate and a stress criterion. This is a sub-group of the large variety of two-parameter criteria, I find the denotation "finite fracture mechanics" somewhat cryptic.

Nevertheless, I accept it as it is, but I have a question regarding the physical background of the method: As I understand it the fracture processes are not modeled. Considering this, how is it possible to know if the autonomy of these processes is preserved by the two-parameter criterion? Not always I assume, but when?

Disclaimer: I could have used the comment opportunity that iMechanica offers, but this is only for members. After having had my membership application rejected several times, it was suggested I use this platform instead.

Sophie B. Lange

Currently I am modelling a timber beam with bolted connection using Abaqus CAE. I'm using displacement control as loading in my analysis. In order to get a good load-displacement curve (elastic and plastic region) for my result, I need to define plasticity and damage properties for my wood material. I also want to see the failure mode (damage zone) of the connection. Can anyone help me to solve this problem? Thank you.

Hello All,

I'm looking into measuring crack growth rate using the DCPD method and was wondering if it is possible to use a "bench top power supply" and a multimeter with higher accuracy? Or do I need to have specialized equipment for DCPD measurement?

The materials I'm interested are iron alloys and aluminum alloys.

Compact tensions specimen thickness =< 13mm

Cheers,

Rashiga

I'd like some opinions. What are the major challenges in fatigue and fracture mechanics?

I discovered two distinct phenomena when cracks begin to form at α and β phases in titanium alloys. How does this difference mechanism come about?

It is difficult to capture the descending branch in the

**stress- strain diagram**of the material in an experimental direct tension protocol (see**Figure (a)**: tension behavior). The flexibility of the loading system causes premature specimen collapse. This is due to the**release of stored strain energy**in the loading equipement. It has been argued that it is feasible to measure this**softening behavior**when a sufficiently controlled**strain rate**is used. Given these facts, the following questions arise:**Is it possible to measure the softening behavior of plain concrete in an experiment?****Is there any experimental evidence of this measurement being possible when using a sufficiently controlled strain rate?**

**What are the good research Areas/topics in Structural Engineering for Ph.D.?**- Can anyone suggest to me research topics related to
**Fatigue and fracture mechanics of Concrete**? - Kindly suggest me a good
**review article regarding the studies performed in Structural engineering related to Fatigue life analysis of fiber reinforced concrete/ Flexural fatigue performance of concrete made with recycled materials**? - Kindly suggest me research topics related
**Flexural-Fatigue Properties of Sustainable Concrete Pavement Material ?**

Dear experts in fracture mechanics, I need help in choosing a model to track crack propagation using numerical simulations. If anyone could provide me with any suggestions, articles, tutorials, or reference books where I can study (to understand the basic concept of J-integral and SIF) and which model to choose and how to implement it numerically, it will be highly appreciated.

Looking forward to your precious responses.

Thank you

Izaz Ali

Can I be assisted with guidelines to linear elastic fracture mechanics in timbers?

In fracture mechanics, we accept that quasi-brittle materials such as concrete have a strain-softening branch under tensile stresses. The branch that can be obtained from a Direct Tensile Test. Accordingly to CEB-FIP, it is possible to characterize this branch by means of the fracture energy. Recently, our research team has been trying to find experimentally this branch in hollow concrete blocks (HCB) employing displacement-controlled tests, at very slow velocities (as low as 0.0005 mm/s), in a servo-hydraulic testing machine. However, it has not been possible to capture this softening branch.

The experimental results that we have had the opportunity to review, which are reported in the specialized literature, make us think that there is a problem with the testing equipment (inertia and stiffness of the machine) and that it could not be an intrinsic characteristic of the material.

After these arguments, we would appreciate your help to get some insight on the following:

1) Is it possible to obtain experimentally a strain-softening branch for quasi-brittle materials, using the Direct Tensile Test, particularly for plain concrete or HCBs?

2) Is this softening branch really a property of the material? Or is it just an apparent behavior generated by the testing machine and the measurement devices used, I mean, due to the way these devices work?

If it exists, does the speed at which it occurs need to be of an order of magnitude lower than 0.0005 mm/s? And finally, if that’s the case, does it make sense to use it in the interesting research problems?

In linear elastic fracture mechanics (LEFM), only the stress intensity factor seems to be used. LEFM implies the same r

^{−1/2}singularities of stress and strain at the crack tip. Very few articles on fatigue use the strain intensity factor. Formally, the two factors could be related by Hooke's law. What is the reason why the strain intensity factor is not used in the same way as the stress intensity factor? A search for strain intensity factor returns only stress intensity factor. Why is the strain intensity factor more or less ignored?R.M. Christensen states that "fracture mechanics in the brittle range ... require(s) formulations in terms of stress." https://www.failurecriteria.com/isitstressorstra.html

Is anything wrong with the strain intensity factor?

I am trying to find out how to identify specified parameters of ductile damage material in its stress-strain curve in Abaqus. I could identify the Young's modulus and the yield stress, but not the fracture energy. How do I identify this in my results?

For now I am simulating a simple tensile test in y-direction on a one-element model (1x0.2x1).

Cast iron is metal, not ceramic. But it is brittle, and quite strong. What can be additives that can be added to increase its strength, corrosion resistance and high temperature stability so that it can be used in place of hard ceramics in structural application? on can it not be qualified as a ceramic even if its microstructure is predominantly intermetallic?

Looking for a motivated Ph.D. candidate to work in the field of additive manufacturing with the background of mechanical engineering and material science.

Deadline for application: February 14, 2020

How to model delamination results from matrix cracking with XFEM?

Dear all,

I need to do 2D multicrack propagation in a composite laminate (GFRP) in tensile load. I have 3 parts namely (0-90-0 degrees plies). And I already have existing cracks which you can see below in attached pictures. Cracks propagate well, but when it comes to the boundary I couldn’t see correct delamination behavior. Is it possible to simulate delamination because of matrix cracking in Abaqus? I both tried cohesive surface and elements. With the elements it says I cant define XFEM crack zone for the cohesive element. With the surface, during loading I see some overclosures and clearances.

Here are my material properties.

Cohesive Surface:

Knn=Kss=Ktt= 1e6 N/mm3 (which I am not so sure)

Damage Initiation: Maxs damage initiation criteria Normal=Shear1=Shear2=3.4MPa.

Damage evolution criteria: Mixed mode behavior=BK(Power=2.2)

Fracture energy: Normal=Shear1=Shear 2= 0.27 N/mm2.

Also, frictionless tangential behavior, and hard contact.

For 0 degrees ply

Damage Initiation: Maxps=807MPa

Damage evolution criteria: Mixed mode behavior=BK(Power=2.2)

Fracture energy: 0.5, 0.5, 0.01 N/mm

Elastic, type=ENGINEERING CONSTANTS 35100.,9600.,9600., 0.3, 0.3, 0.3, 4000.,4000.4000.,

For 90 degrees ply, I just swap E11 and E33 values, and maxps=15MPa

Can someone suggest me how I can model it and if my material properties are reasonable?

Regards

Berkay

if plastic zone (rp) is obtained from maximum stress intensity (=del. K/(1-R)). How to determine plastic zone (rp) from log-log da/dN

I know this question has been asked in this forum but want to rephrase it as there have been some features that came for Ansys. Can anyone please tell from their experience which one is better? For example, I have used Ansys and felt it has some limitations e.g. in XFEM. As it can not be directly used using UI in the benchmark. Also in 3D, it is unstable. Also, all of them in Ansys fail in Anisotropic material. But I don't have experience in ABAQUS.

Kindly let us know what are your insights.

With regards

Biswabhanu Puhan

How to define quarter-point element at the crack front, in a Static Structural analysis with a 3D CAD model in Ansys Workbench? Is there an APDL command that can be used in WB do to so?

Peel stress singularities occur at the bi-material interface of the free edges of, for example, a steel-adhesive-steel sandwich specimen of say 500 mm in length, 100 mm in width, and 10 mm thickness (5 mm adhesive thickness) under longitudinal cyclic tension due to the difference in Young's modulus and Poisson's ratio of the two materials.

The singularity can be relatively economically investigated in a very fine cross-sectional finite element (FE) model representing the as manufactured geometry using the generalized plain strain approach (ANSYS), for example, see attached picture. The finer the mesh gets the larger gets the local peel stress peak at the bi-material free edge interface. The graph shows the equivalent stress according to Beltrami (similar to von Mises).

The load amplitude is chosen from a fatigue load spectrum of a cyclic test and is thus that small that linear elasticity holds for the average stress according to classical laminated plate theory (CLPT) in the adhesive. Now, this local stress peak, however, gets already as large (factor of 10 of the average equivalent stress) that it could be dedicated to a plastic deformation and failure. In reality, i.e., in the experiment, we would not see such a failure after say the first 100 load cycles. Thus, there is a discrepancy between linear elasticity theory and reality. The material seems to withstand these peaks.

For the static strength analysis one could use a non-linear stress-strain curve to circumvent the "problem" and lower the peaks and use then fracture mechanics to quantitatively evaluate such situations, but this requires the modeling and relatively expensive analysis of possible crack orientations in all possible dimensions due to the multi-axial stress state. Therefore, fracture mechanics does not seem to be an applicable method to evaluate the fatigue damage for a load spectrum whose stress vector components vary over time and thus with them the critical crack planes .

Another technique is to extract the stress value at a critical distance from the edge and then extrapolate a "more realistic" stress peak. But how to define such a critical distance on a physically sound basis and how does the extrapolation function look?

Do you have any other ideas how to extract a realistic stress value from the finite element model for a fatigue analysis?

Hi all,

I'm interested in testing the Hydrogen Embrittlement of several metals. I

Interms of fracture testing and fatigue crack growth rate testing I want to know the difference between the following.

1. Long time H2 exposure in an environmental chamber -> conducting tests in ambient enviroment.

2. Long time H2 exposure in an environmental chamber -> conducting tests in a H2 exposed environment.

Are there design equations for concrete sectors based on fracture mechanics parameters?

using the fracture parameters KIc or Gf to design concrete section as using compressive strength in design equation

Does a single-valued description exist for isotropic materials?

I'm trying to study cracked structures under a compressive load taking into account contact between the crack lips.

I would like to know if the method of extrapolation by displacement remains valid to calculate the stress intensity in this case or other valid methods.

And if you can send me some references containing the same study.

What is the best finite element modeling software packages for modeling non-linear and fracture analysis of CONCRETE? I've had some with ABAQUS standart/explicit, but I would like to learn if there is a better software for non-linear behaviour and fracture mechanics of concrete according to your experiences.

Best regards.

Hello everyone,

I am trying to develop an

**analytical model**to study the propagation of fracture in**reinforced concrete structures**. I would really appreciate it if anyone could suggest to me the optimal analytical model to study the crack propagation.Thanks in advance

Regards,

Pawan

How to define a crack at symmetry plane? Is it right idea? Crack seam we cant specify at symmetry edge (As crack seam can be specified at interior face of 2D). How to handle this type of situation? I need to find KI for different crack lengths. Its possible to find without define seam. But I m not confident about the results. If same crac length defined inside the face (other than symmetry edge) with partition, I can get crack tip stress field. But at symmetry without seam Im not getting. (Of course we cant get, That I can understand) What may be alternate for this? Anyone have Idea, pl share.

Recently, I came into contact with a new discipline named chemo-mechanical coupling. I found that chemo-mechanical coupling phenomena exist in many research areas, ranging from development of advanced batteries, biomechanical engineering, hydrogen embrittlement, and high temperature oxidation, etc. Although it is very important in engineering field, I can't know the main mechanisms of coupled chemical and mechanical interactions. Can you give me some suggestions? Such as, some related publications or research project. Thanks very much.

I am planning to use the

**Discrete Element Method**for**propagation of Fracture**in**Reinforced concrete Structures**. Which book would be the best start to study**Discrete Element Method**from the beginning?Dear All,

I want to model crack growth in a plate using ABAQUS XFEM method. Here is
my question about it: How to calculate Stress intensity factor in XFEM
when crack growth in ON?

At this time, when I using ABAQUS XFEM with allowing for crack growth and request for SIF through History output request,

It says that SIF could not be produced when crack growth in XFEM is ON.

Best,

adel,

I want to simulate the growth of a crack due to fatigue. My model consists of shell elements that are non-planar. I wanted to use the XFEM available in Abaqus, but in its documentation was written that:

" XFEM is available only for three-dimensional solid and two-dimensional planar models; three-dimensional shell models are not supported. "

So the question is that are there any software to simulate crack growth in non-planar parts modeled with shell elements?

I've heard of some software like FRANC3D or ZenCrack, but I'm not sure if they're capable of doing this.

Regards

Good afternoon!

FE software ANSYS provides SIFs calculation in fracture mechanics for 3 modes by CINT command for isotropic elastic material for example. Does command CINT calculate SIFs for orthotropic material or anisotropic material correctly or not? Does calculation method with CINT command in ANSYS take into account anisotropy or orthotropy of material?

In engineering, the damage that can be detected is usually called crack. But how to describe the small cracks which cannot be measured in the early stage of damage? Can we give a universal definition? Greatly appreciate your review.

I have reviewed some books about fracture mechanics, but I cannot explain microstructure damage with engineering fracture mechanics theory, such as fatigue damage of metals with micro-defects. Is there any outstanding work in this field? If so, can you share it with me? Greatly appreciate your answer and providing good practices in engineering.

Many thanks!