Calvin Rans

Delft University of Technology | TU · Aerospace Structures and Materials (ASM)

View Video Presentation: https://doi.org/10.2514/6.2022-1351.vid The Faculty of Aerospace Engineering at the Delft University of Technology has an active learning philosophy which is embedded in its curriculum. The first year project Design and Construction is run in the second semester. The course aims to provide “hands-on” experience to students...

The fatigue performance of additively manufactured auxetic meta-biomaterials made from commercially pure titanium has been studied only recently. While certain assumptions have been made regarding the mechanisms underlying their fatigue failure, the exact mechanisms are not researched yet. Here, we studied the mechanisms of crack formation and prop...

Single-lap shear (SLS) joints are straightforward to manufacture. This makes them especially attractive for testing polymer composite welded joints. Owing to local heating, which is characteristic of composite welding processes, the production of more geometrically intricate joints (such as double-lap or scarfed joints) or bigger joints (such as en...

Surface morphology of adherends is an important factor to take into consideration when studying and improving the performance of an adhesive bonded joint. In this study, the adhesion performance three different surface morphologies of Selective Laser Melted (SLM) Ti6Al4V was studied. The three surface morphologies were created by manufacturing the...

The United States Air Force (USAF) Guidelines for the Durability and Damage Tolerance (DADT) certification of Additive Manufactured (AM) parts states that the most difficult challenge for the certification of an AM part is to establish an accurate prediction of its DADT. How to address this challenge is the focus of the present paper. To this end t...

Meta-biomaterials offer a promising route towards the development of life-lasting implants. The concept aims to achieve solutions that are ordinarily impossible, by offering a unique combination of mechanical, mass transport, and biological properties through the optimization of their small-scale geometrical and topological designs. In this study,...

In this study, different surface pretreatments were applied to clean and activate titanium alloy surfaces. The samples were subjected to grit blasting treatments using two different pressures and afterwards, a UV/Ozone treatment was applied at different times to study the wettability and surface oxidation of the titanium samples. Scanning electron...

Since welded joints in structures are known to be critical regions for crack initiation and growth, study of fatigue crack growth behavior of welded joints under various loading scenarios are essential. In present study, two groups of experiments were conducted. At first, fatigue crack growth behavior of Al5083 butt welded joint subjected to mixed...

Fatigue is a major cause of failure in several industries, and in many practical cases, local mixed-mode conditions prevail at the crack front. The effect of plane mode mixity on the crack growth rate and crack growth direction has been investigated. Fatigue crack growth experiments have been conducted on aluminum alloy Al5083-H111 for several mode...

Redistribution of residual stress during crack growth in butt welded joint of Al5083-H111 was studied. Furthermore, the effect of post weld heat treatment and removing the weld reinforcements on fatigue crack growth rate was investigated. Three dimensional simulations of welding process and fatigue crack growth were conducted. It was shown that rem...

Understanding and characterizing crack growth are central to meeting the damage 11 tolerance and durability requirements delineated in USAF Structures Bulletin EZ-SB-19-01 for the 12 utilization of Additive Manufacturing (AM) in the sustainment of aging aircraft. In this context, the 13 present paper discusses the effect of different AM processes,...

The application of Strain Gauges (SG) as recommended by the ASTM standards provides accurate strain measurements in isotropic materials. However, their use in composite materials becomes more challenging due to their anisotropic nature. In this study, we hypothesized that the use of the Distributed Sensing System (DSS) and the 3D Digital Image Corr...

Although aerospace traditionally has always had a multidisciplinary approach to engineering and design, the increasing complexity of aircraft and spacecraft and the rapid digitization within the aerospace industry has led to a large number of related engineering and scientific disciplines such as electrical engineers, computer scientist to work muc...

The effect of mixed mode overload on the retardation of pure mode I cyclic loading has been investigated experimentally on Al5083-H111. Two models for extension of the Wheeler retardation model are proposed in order to calculate retardation of fatigue crack growth subjected to mixed mode overload. The first proposed model can predict retardation wi...

Weight reduction of transportation vehicles can be achieved with the use of composite and fibre metal laminate (FML) materials. An important safety characteristic of these lightweight materials is their impact resistance compared to that of traditionally used automotive materials: steel and aluminum. In this study, low-velocity impact (LVI) was con...

Weight reduction of transportation vehicles can be achieved with the use of composite and fibre metal laminate (FML) materials. An important safety characteristic of these lightweight materials is their impact resistance compared to that of traditionally used automotive materials: steel and aluminum. In this study, low-velocity impact (LVI) was con...

The present study reports on the evaluation of residual stress field formation and distribution in Central Cut Plies (CCP) specimens. Real-time measurements were performed using a distributed sensing fiber optic system based on Rayleigh Backscattering, which was successfully able to capture strain distribution inside the adhesive layer at every 0.6...

Thermoplastic composite spot welded joints are more well-suited for carrying shear load rather than peel load. However, peel load is difficult to be eliminated in single-lap joint configuration. In this paper, a series of mechanical tests were carried out to study the effects of the spot spacing and the number of welded spots on the secondary bendi...

An often heard complaint is the inability of students to apply their learning at a higher level in Bloom’s taxonomy. However, the challenge in teaching basic forensic engineering prin- ciples to students and achieving a higher Bloom’s learning hierarchy is time. As a Master’s elective course within a two-year Aerospace Engineering curriculum, limit...

A challenge in developing an in-depth understanding of the crack growth resistance of Additively Manufactured materials is the fact that their mechanical properties have been shown to be both process and part-geometry dependent. Up to now, no studies have investigated the influence of off-axis (beyond the three orthogonal build orientations) orient...

Mechanically fastened joints are susceptible to the presence of multiple-site damage (MSD) cracks in the critical fastener row. Different from the MSD growth in joints consisting of metallic substrates, the two coupled metal crack growth and interfacial delamination propagation failure mechanisms in Fibre Metal Laminates (FMLs) make the prediction...

The lack of a widely-accepted test standard for characterizing the mode II fatigue disbond growth behavior of adhesively bonded interfaces is a challenge to the research community in terms of producing consistent and repeatable results. Typically, researchers apply the End Notch Flexure specimen, which is already used for static delamination studie...

In the context of the prevalence of thin-walled metallic aerospace structures, the added resistance to crack propagation offered by a built-up structure is desirable from a damage tolerance standpoint. The analysis of failure in such structures, however, is limited by the lack of crack opening solutions. This paper develops analytical models that c...

In this study, we tried to quantify the isolated and modulated effects of topological design and material type on the mechanical properties of AM porous biomaterials. Towards this aim, we assembled a large dataset comprising the mechanical properties of AM porous biomaterials with different topological designs (i.e. different unit cell types and re...

Statement of significance: Meta-biomaterials are a special class of metamaterials with unusual or unprecedented combinations of mechanical, physical (e.g. mass transport), and biological properties. Topologically complex and additively manufactured meta-biomaterials have been shown to improve bone regeneration and osseointegration. The mechanical...

Fibre Metal Laminates (FMLs) are a hybrid metal-composite laminate technology known for their superior resistance to fatigue crack growth compared to monolithic metals. This crack growth behaviour has been the subject of many studies, resulting in numerous empirical and analytical models to describe the complex damage growth phenomenon in the mater...

This paper presents a theoretical and experimental study on Multiple-site Damage (MSD) crack growth behaviour in Fibre Metal Laminates (FMLs). The prediction model is developed based on a simplified analysis of the effects of load redistribution on a single crack in FMLs containing multiple cracks. Test results show that the crack growth accelerate...

This paper proposes an analytical model for predicting the non-symmetric crack growth and accompanying delamination growth in FMLs. The general approach of this model applies Linear Elastic Fracture Mechanics, the principle of superposition, and displacement compatibility based on the understanding of deformation behaviour in eccentrically cracked...

This paper provides an experimental investigation into the pin loading effects on the crack growth behaviour in Fibre Metal Laminates. The pin loading effects and bypass loading effects are incorporated in two different tested joints. The analysis of the test results shows that pin loading dominates the crack growth only in the vicinity of the pin...

The in-plane and out-of-plane mechanical behaviour of both ultrasonically spot-welded and mechanically fastened joints was investigated by double-lap shear and pull-through tests, respectively. Spot-welded specimens showed comparable onset failure load and significantly higher joint stiffness compared to mechanical fasteners when carrying shear loa...

The in-plane and out-of-plane mechanical behaviour of both ultrasonically spot-welded and mechanically fastened joints was investigated by double-lap shear and pull-through tests, respectively. Spot-welded specimens showed comparable onset failure load and significantly higher joint stiffness compared to mechanical fasteners when carrying shear loa...

Additively manufactured (AM) porous metallic biomaterials are considered promising candidates for bone substitution. In particular, AM porous titanium can be designed to exhibit mechanical properties similar to bone. There is some experimental data available in the literature regarding the fatigue behavior of AM porous titanium, but the effect of s...

When teaching Engineering to students it is important that we not only teach about how to engineer new things but also look at the failures and performance problems from an engineering point-of-view. The field that studies this part of engineering is known as Forensic Engineering. At the Faculty of Aerospace Engineering at Delft University of Techn...

Large classroom sizes are a reality university educators need to contend with, particularly in the first year of a given cohort within a degree programme. Activating and engaging students in these large classroom environments present numerous sets of challenges. These challenges are exacerbated by student learning development needs in the early sta...

Ultrasonic welding is a promising assembly technique for thermoplastic composites and it is well-suited for spot welding. In this paper, the in-plane and out-of-plane mechanical behaviour of ultrasonically spot-welded and mechanically fastened joints are investigated by double-lap shear and pull-through tests, respectively. Special attention was pa...

In this study, mode II fatigue crack growth utilizing Central Cut Plies (CCP) specimens is considered, in order to assess the durability of bonded composite repairs. Fatigue tests were performed with unidirectional carbon-epoxy specimens and adhesive film co-cured. A back-face strain technique was applied to obtain strain data using a fiber optics...

The primary objective of this research study was to evaluate the capabilities for measuring strain of a composite UAV wing with an embedded optical fiber connected to a Rayleigh backscattering distributed sensing system. This research paper summarizes the manufacturing procedure used during the instrumentation of the composite UAV wing. In addition...

This paper presents an analytical model for fatigue crack growth prediction in Fibre Metal Laminates (FMLs) containing discretely notched layers. This model serves as a precursor in the development of a simplified prediction methodology for modelling the effect of load redistribution on a single crack in FMLs containing Multiple-site Damage (MSD) s...

Innovative hybrid materials developed at Delft University of Technology (e.g., ARALL and GLARE) dramatically reduce life-cycle costs and offer a great opportunity for service life extension of legacy aircraft. Replacement or repair of damaged aircraft components requires high-strength composite materials with high tailorability, fatigue, and impact...

This paper relates the experiences of lecturers at Delft University of Technology in the designing and running of a Master course in Forensic Engineering. Rather than traditional face-to-face lectures, use of real-life evidence-based learning was made in the form of training for and execution of a mock aircraft accident investigation. The culminati...

The effect of an adhesive support on the Mixed-Mode fatigue properties of a metal-to-metal bonded interface was evaluated. Pure Mode I, pure Mode II, and Mixed-Mode fatigue disbond tests were conducted on supported and unsupported bonded samples. The fracture surfaces were observed and related to the fatigue disbond growth rate. The supporting syst...

An experimental investigation aimed at identifying the presence and onset of an asymptotic stable fracture region in the mode II fatigue delamination growth behaviour of composites is presented. The study is motivated by the possibility that experimental data sets, particularly those obtained at high R-ratios, may unknowingly contain data points wi...

This study is motivated by the possibility that experimental data sets, particularly those obtained at high R-ratios, may unknowingly contain data points within the asymptotic stable fracture region that influence its perceived log-linear behaviour and the fit of various loglinear delamination growth models. Results from the experimental investigat...

Adhesive bonding has been increasingly used for part manufacturing and repair of composite aircraft structures. This work focuses on static and fatigue performance of bonded composite joints under mixed mode I/II loading. A series of experiments was performed on bonded composite joint specimens with load mixities (GII/G) of 0, 0.2, 0.4, 0.6 and 0.8...

Finite element anlysis (FEA), supported by experimental data, was performed on a common specimen for delamination growth characterisation, in which multiple delaminations were present, in order to study interactions between these delamiations. In contrast to the commonly held assumption that interaction effects between delaminations of unequal leng...

A model was developed to predict disbond growth due to constant amplitude fatigue loading in a simple bonded repair configuration. The model uses a Paris relation to relate disbond growth to the strain energy release rate (SERR), which is calculated numerically as a function of the disbond length. An iterative combination of these two relations all...

An analytical model for stress intensity factors in cracked skin panels containing bonded stiffening elements, based on the principles of superposition and displacement compatibility, is presented. The methodology permits assessment of the influence of stiffening elements ahead, behind, and over top of the skin panel crack tip, and allows the influ...

Export Date: 21 June 2013, Source: Scopus, CODEN: CASMF, :doi 10.1016/j.compositesa.2012.04.008, Language of Original Document: English, Correspondence Address: Pärnänen, T.; Department of Applied Mechanics, School of Engineering, Aalto University, P.O. Box 14300, FI-00076 Aalto, Finland; email: tuomas.parnanen@aalto.fi, References: Ostrovsky, I.,...

This paper provides an overview of experimental feasibility studies that have been undertaken to evaluate the damage tolerance characteristics of an aluminum/glass-epoxy Fibre Metal Laminate panel containing local carbon-epoxy reinforcements. The goal of the reinforcements is to increase overall skin panel stiffness, thus attracting load away from...

This paper presents a novel hybrid structural concept for improving the damage tolerance of a thin panels subjected to fatigue, such as the skin of an aircraft fuselage. The concept is based on the hybrid fiber/metal laminate technology used as a fuselage skin material in the Airbus A380. By tailoring the stiffness of an fiber/metal laminate locall...

Fibre metal laminates (FMLs) are a family of hybrid metallic-polymer matrix composite materials with superior fatigue and damage tolerance behaviour. Although technically a composite material, they share many behaviour features more in common with their metallic constituents. This chapter introduces the FML material concept and discusses the static...

A robust crack growth prediction tool has been developed for a class of hybrid skin materials known as Fibre Metal Laminates (FMLs) which has been thoroughly validated for fatigue loading cases at room temperature. This paper provides a brief overview of this predictive model and presents an investigation into its predictive capabilities at various...

This paper is concerned about the detection of low velocity impact damages on composite materials and monitoring of damage behaviour during compressive loading using shearography. Carbon epoxy composite laminated samples were impacted with three different energy levels, before inspection with shearography. Compression loading was applied in steps t...

Cited By (since 1996):6, Export Date: 21 June 2013, Source: Scopus, CODEN: CSTCE, :doi 10.1016/j.compscitech.2010.11.010, Language of Original Document: English, Correspondence Address: Rans, C.; Structural Integrity Group, Faculty of Aerospace Engineering, Delft University of Technology, P.O. Box 5058, 2600 GB Delft, Netherlands; email: C.D.Rans@t...

This paper presents and discusses some of the recent advancements that have been achieved in the development of the FML concept for thin single-aisle fuselage structures. It is shown that the inherent damage tolerant nature of this concept can be further exploited for these structural applications.

Cited By (since 1996):6, Export Date: 21 June 2013, Source: Scopus, CODEN: EFMEA, :doi 10.1016/j.engfracmech.2010.03.041, Language of Original Document: English, Correspondence Address: Khan, S.U.; Aerospace Materials and Structures, Faculty of Aerospace Engineering, Delft University of Technology, P.O. Box 5058, 2600 GB Delft, Netherlands; email:...

This paper provides an overview of the evolution of methodologies to assess fatigue and damage tolerance of hybrid laminated structures. The transition from metallic methodologies towards full hybrid methodologies is evaluated and discussed. The transition is illustrated with the assessment of fatigue initiation and damage growth in FMLs. In additi...

The interference fit provided by solid rivets induces a residual stress field beneficial to the fatigue performance of riveted lap joints. Attributing benefits in crack growth nucleation and growth behaviour within this residual stress field is non-trivial. Once fatigue cracks become visible on the surface of a joint they have already grown beyond...

Cited By (since 1996):6, Export Date: 21 June 2013, Source: Scopus, CODEN: IJFAD, :doi 10.1016/j.ijfatigue.2008.09.008, Language of Original Document: English, Correspondence Address: Alderliesten, R.; Structures and Materials Laboratory, Faculty of Aerospace Engineering, Delft University of Technology, P.O. Box 5058, 2600 GB Delft, Netherlands; em...

This paper presents a damage tolerant philosophy for bonded aircraft structures and repairs. The approach presented utilizes a strain energy release rate approach for predicting bond line delamination growth and a stress intensity factor approach for predicting adherent cracking. The novel addition to the method lies within the coupled analysis of...

Conference code: 85394, Export Date: 21 June 2013, Source: Scopus, Language of Original Document: English, Correspondence Address: Khan, R.; Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft, Netherlands; email: R.khan@tudelft.nl, References: Harris, B., (2003) Fatigue in Composites., , Cambridge England...

Conference code: 89175, Export Date: 21 June 2013, Source: Scopus, Language of Original Document: English, Correspondence Address: Paletti, L.; Delft University of Technology, Delft, 2629 HS, Netherlands, References: Schijve, J., (2001) Fatigue of Structures and Materials, , Kluwer Academic Publishers, Dordrecht;, Sponsors: MOOG; FTI; ACRA Control

Conference code: 85394, Export Date: 21 June 2013, Source: Scopus, Language of Original Document: English, Correspondence Address: Rans, C.D.; Technical University of Delft, Kluyverweg 1, 2629 HS, Delft, Netherlands; email: C.D.Rans@tudelft.nl, References: Hosoi, A., High-cycle fatigue characteristics of quasi-isotropic CFRP laminates (2007) Adv. C...

A robust crack growth prediction tool has been developed for a class of hybrid skin materials known as Fibre Metal Laminates (FMLs) which has been thoroughly validated for fatigue loading cases at room temperature. This paper provides a brief overview of this predictive model and presents an investigation into its predictive capabilities at various...

An analytical model for load transfer in a mechanically fastened joint is presented. The model includes the effect of the main load transfer mechanisms: bearing and friction. The influence of the bypass load, secondary bending and fastener fit is neglected. The load splitting between the considered load mechanisms can be evaluated by defining a spl...