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Showing papers in "Journal of Strain Analysis for Engineering Design in 2012"


Journal ArticleDOI
TL;DR: The model of 8-node-quadrangular mesh digital image correlation and its solving scheme based on the Newton–Raphson iteration have been constructed and the method is realized and then verified with speckle images produced by numerical simulations and real experiments.
Abstract: By using the 8-node-quadrangular isoparametric element to discretize the speckle image, a 8-node-quadrangular mesh-based digital image correlation method is proposed. The model of 8-node-quadrangul...

63 citations


Journal ArticleDOI
TL;DR: In this paper, the authors exploit the expected temporal regularity in the displacement fields to enhance the performance of a digital image correlation analysis, either in terms of spatial resolution, or in the terms of uncertainty.
Abstract: Most often, digital image correlation is used to analyse a sequence of images. Exploitation of an expected temporal regularity in the displacement fields can be used to enhance the performances of a digital image correlation analysis, either in terms of spatial resolution, or in terms of uncertainty. A general theoretical framework is presented, tested on artificial and experimental image series.

51 citations


Journal ArticleDOI
TL;DR: In this paper, the performance of three-dimensional orthogonal woven E-glass/epoxy composites under high velocity impact is analyzed using wave propagation and energy balance between the projectile and the target.
Abstract: Performance of three-dimensional orthogonal woven E-glass/epoxy composites under high velocity impact is presented. The analytical method used is based on wave propagation and energy balance between the projectile and the target. Different damage and energy absorbing mechanisms for a typical three-dimensional orthogonal woven composite are compression of the target directly below the projectile, compression in the surrounding region of the impacted zone, tension in the region consisting of primary yarns, tensile deformation in the region consisting of secondary yarns, shear plugging, bulge formation on the back face of the target, matrix cracking and friction between the target and the projectile. Experimental studies are also presented on high strain rate characterization, shear plugging behavior and high velocity impact behavior. For comparison, studies are also presented on the performance of two-dimensional plain weave E-glass/epoxy composites. A good match is observed between the analytical predictions and experimentally obtained limit velocities for complete penetration. It is observed that limit velocity for complete penetration for three dimensional woven composite is higher than that for two-dimensional plain weave composite.

40 citations


Journal ArticleDOI
TL;DR: In this article, the authors used an approximate analysis and the finite element method to predict residual stresses created in a steel beam by elastic-plastic bending, compared to experimental measurements.
Abstract: Residual stresses, created in a steel beam by elastic–plastic bending, are predicted using an approximate analysis and the finite element method. The predictions are compared to experimental measur...

38 citations


Journal ArticleDOI
TL;DR: In this article, a review of composite materials for high-velocity impact during their lifetime is presented, focusing on the recent advances in composites and their applications in the design of structures that will be subjected to high velocity impact.
Abstract: Composite materials are increasingly being used in the design of structures that will be subjected to high-velocity impact during their lifetime. In this review we will look at the recent advances ...

33 citations


Journal ArticleDOI
TL;DR: In this paper, a traction stress based shear strength definition is presented for correlating weldment test data obtained from standard specimens such as those stipulated by AWS B4.0 as well as for applications in general structural design applications when finite element methods are used.
Abstract: In this paper, a traction stress based shear strength definition is presented for correlating weldment test data obtained from standard specimens such as those stipulated by AWS B4.0 as well as for applications in general structural design applications when finite element methods are used. With this proposed approach, well-documented discrepancies in shear strength between transverse and longitudinal shear tests can now be reconciled, resulting in a single shear strength value regardless of specimen types and loading conditions. The method should provide a basis for achieving a quantitative weld sizing in fillet weld design for structural applications. The paper starts with a brief description of major issues associated with strength data interpretation using the conventional shear stress formula given in AWS B4.0 which is widely used by various industries. After posing a series of candidate static failure criteria, an existing finite element solution technique for dealing with stress concentration effect...

32 citations


Journal ArticleDOI
TL;DR: In this article, the authors proposed an approach for thermal stress evaluation and fatigue life assessment of work rolls in hot rolling mills using a simplified finite element approach, based on a plane model of work roll loaded on its boundary by rotating thermal actions for typical hot rolling configuration.
Abstract: The paper proposes an approach for thermal stress evaluation and fatigue life assessment of work rolls in hot rolling mills. Temperature and thermal stress distributions are calculated with a simplified finite element approach, based on a plane model of work roll loaded on its boundary by rotating thermal actions for a typical hot rolling configuration. A transient of one hour is simulated and the calculated temperature field is next applied as thermal loading in elastic–plastic mechanical simulation, to get thermal stresses and elastic–plastic strains in work roll. Calculated cyclic stresses and strains are finally used to estimate work roll service life, based on Universal Slopes equation that is modified to account for the multiaxial stress state. A comparison of results by three multiaxial fatigue criteria is provided. The obtained results show that, according to such multiaxial criteria, stress multiaxiality would have a great effect on fatigue life, despite it is generally neglected in approaches us...

29 citations


Journal ArticleDOI
TL;DR: Finite element modelling is increasingly used as an integral part of creep analyses for the integrity assessment of high-temperature structures as mentioned in this paper, which is an important consideration in such finite element si...
Abstract: Finite element modelling is increasingly used as an integral part of creep analyses for the integrity assessment of high-temperature structures. An important consideration in such finite element si...

28 citations


Journal ArticleDOI
TL;DR: In this paper, a finite element model was used to determine the residual stress magnitude and distribution in butt-welded pipes, and an efficient user subroutine was developed to consider the effects of phase transformation in the analysis.
Abstract: The thermo mechanical behavior of the welding process was analyzed using the finite element technique to determine the residual stress magnitude and distribution in butt-welded pipes. An efficient user subroutine was developed in a finite element model to consider the effects of phase transformation in the analysis. The calculated results verified using the determined data presented by Deng for similar weld joints and measured data by the hole drilling technique for dissimilar weld joint.Good correspondence between the finite element results and experimental data infers that the computational procedure developed in this study is an effective method for residual stress prediction in dissimilar welded joints. The effects of pipe wall-thickness, weld groove angle and root opening distance on welding residual stresses in dissimilar butt-welded pipes were studied using the prepared finite element model. It is observed that the pipe wall-thickness has important influences on the residual stress magnitude and di...

28 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of yarn Poisson's ratio, transverse and shear modulus on impact behaviors of a simple crimped yarn and a complete fabric have been carried out.
Abstract: A numerical model of ballistic impact on a two-dimensional Kevlar KM2® plain-woven fabric has been validated by experiment. This paper shows that it is necessary to experimentally measure material constants of yarns for having good input parameters of the model. Effects of yarn Poisson's ratio, transverse and shear modulus on impact behaviors of a simple crimped yarn and a complete fabric have been carried out. The effect of the Poisson's ratio can be negligible in both impact cases: on a single crimped yarn and a complete fabric. The same conclusion has been proven for the effect of the transversal modulus except the cases of its so low values that can cause yarn early damage. The shear modulus of a yarn appears to be an important material parameter that mainly influences the ballistic performance of a two-dimensional plain-woven fabric. When using a very high value of a shear modulus of yarn, a crimped single yarn is broken immediately after contact with projectile in pure shearing mode.

26 citations


Journal ArticleDOI
TL;DR: In this article, a conventional material behavior model can be extended to taking into account varying thermo-mechanical loading conditions in wide stress range, and the motivation for developing this model is given b...
Abstract: A conventional material behaviour model can be extended to taking into account varying thermo-mechanical loading conditions in wide stress range. The motivation for developing this model is given b...

Journal ArticleDOI
TL;DR: In this article, the mechanical responses including damage mechanisms for surface and interior parts of three-dimensional orthogonal woven composite have been analyzed by the multi-scale finite element method.
Abstract: The mechanical responses including damage mechanisms for surface and interior parts of three-dimensional orthogonal woven composite have been analyzed by the multi-scale finite element method. Based on fabric architecture and fiber volume fraction in the three-dimensional orthogonal woven composite, the meso-scale repeating unit cells model and micro-scale repeating unit cell model are established. The periodic boundary conditions are applied to the micro-repeating unit cell and meso-repeating unit cell models. Appropriate failure criteria and a post-damage constitutive model are used to simulate the failures of fiber/fiber-bundles and resin in the micro/meso-scale repeating unit cells. A new elastic material model with damage propagation is defined with the user-defined material subroutine in commercial finite element software package ABAQUS/Standard. Mechanical behaviors including initiation and propagation of damage in micro/meso repeating unit cells under different loadings have been simulated with th...

Journal ArticleDOI
TL;DR: In this article, the relationship between the primary welding parameters, i.e. current, traverse speed, plasma gas flow rate and the weld efficiency, was investigated using inverse finite element modelling.
Abstract: Finite element modelling of the experimentally obtained parametric envelopes for stable keyhole plasma arc welding was performed using a three-dimensional conical Gaussian heat source. Uncoupled steady-state and transient heat transfer analyses were performed to predict fusion zones and thermal histories. The heat source definition was validated against the experimentally obtained macrograph and thermal history for a representative stable keyhole condition. The paper investigates the relationships between the primary welding parameters, i.e. current, traverse speed, plasma gas flow rate and the weld efficiency, using inverse finite element modelling. The effect of the change of plasma gas flow rate on weld efficiency was estimated by iteratively changing the efficiency to match the experimental results. The numerical–experimental approach is proposed to establish relationships between welding parameters and weld efficiency which can be utilised to understand the underlying physics of keyhole plasma arc we...

Journal ArticleDOI
TL;DR: In this article, a constitutive model is proposed to predict the perforation of fiber reinforced plastic laminates by flat-nosed projectiles at high velocities, based on the concept of continuum damage mechanics and criteria for different failure modes.
Abstract: A numerical study is performed herein on the perforation of fiber reinforced plastic laminates struck normally by flat-nosed projectiles at high velocities. First, some previous constitutive models for fiber reinforced plastic composites are briefly reviewed and then a constitutive model is proposed to predict the perforation of fiber reinforced plastic laminates. The present constitutive model is developed based on the concept of continuum damage mechanics and criteria for different failure modes which take the quadratic form of various stress parameters. The effects of strain rate on the strength as well as the modulus of fiber reinforced plastic laminated materials are also considered in the model. It transpires that the present numerical simulations are in good agreement with experimental observations for the perforation of carbon fiber reinforced plastic, glass fiber reinforced plastic and kevlar fiber reinforced plastic laminates impacted by flat-ended projectiles in terms of deformation profile, ba...

Journal ArticleDOI
TL;DR: In this paper, an extended finite element method for sharp V-notches is developed, which allows the representation of notch faces independent of the mesh by enriching the finite element approximation of the nodes surrounding the notch tip with the first term of the notchtip asymptotic field and the nodes that intersect the notch faces with a jump enrichment function using a partition of unity method.
Abstract: An extended finite element method scheme for sharp V-notches is developed. The method allows the representation of notch faces independent of the mesh. This is achieved by enriching the finite element approximation of the nodes surrounding the notch tip with the first term of the notch tip asymptotic field and the nodes that intersect the notch faces with a jump enrichment function using a partition of unity method. The least-squares method is used to evaluate the stress intensity factors of sharp V-notches. Numerical simulations demonstrate the accuracy and the robustness of the proposed technique.

Journal ArticleDOI
TL;DR: In this paper, the effect of welding sequence and direction on reduction of welding-induced angular distortions in single-pass butt-welded 304 stainless plates and also their effect on residual stresses are investigated by numerical simulation.
Abstract: During arc welding process, non-uniform heating and cooling lead to non-uniform expansion and contraction of the weld and surrounding base metal which result in undesirable residual stresses and distortions in the welded joint. Among different types of welding distortions, angular distortions produced by butt welding of plates are of major concern in industry. Various methods are currently being used to control and reduce angular distortions. Among different types of distortion control methods the ones which can also reduce residual stresses are preferred. In this paper, the effect of welding sequence and direction on reduction of welding-induced angular distortions in single-pass butt-welded 304 stainless plates and also their effect on residual stresses are investigated by numerical simulation. Welding simulation has been performed using a three-dimensional thermo-elastic–plastic finite element model. In order to verify the numerical model, experiments have also been carried out and temperature historie...

Journal ArticleDOI
TL;DR: In this paper, the identification of elasto-plastic behavior parameters of aluminium alloy 2024-T3 using full-field measurements is considered, where an orthotropic Hill criterion including an isotropic hardening is considered.
Abstract: This paper is focused on the identification of elasto-plastic behaviour parameters of aluminium alloy 2024-T3 using full-field measurements. An orthotropic Hill criterion including an isotropic hardening is considered. Standard tensile tests provide a first set of parameters. Some of these parameters are optimised thanks to an inverse modelling including finite element analysis and experimental full-field displacement measurements. This so-called finite element model updated process is based on different specimen geometries which induced heterogeneous strain fields. Full-field measurements are provided by digital image correlation technique. The aim of this work is to study the impact of the specimen shape that gives the heterogeneous strain fields on the identification of isotropic hardening parameters. Results are compared and discussed.

Journal ArticleDOI
TL;DR: In this paper, an infinitely long shaft, press fitted into a hollow hub with bore rounded edges, is examined, and a normalizing parameter that accounts for the combined effects on the stress concentrations of the fillet radius, the shaft external radius and the interference level is introduced.
Abstract: This work addresses the issue of stress concentrations at the rounded edges of shaft–hub interference fits. An infinitely long shaft, press fitted into a hollow hub with bore rounded edges is examined. Limited to interference fits involving a solid shaft, Strozzi and colleagues introduced a normalizing parameter, which accounts for the combined effects on the stress concentrations of the fillet radius, the shaft external radius and the interference level. The aim of this work is to extend the field of application of the said normalizing parameter, to the case of interference fits involving a hollow shaft. By means of finite element analysis, run-on geometries with different hub and shaft aspect ratios (ratio between internal and external diameters), charts for stress concentration factors as functions of the normalizing parameter were drawn. Appropriate functions are proposed, which allow obtaining the stress concentration factors valid for the case of hollow shaft, starting from the stress concentration ...

Journal ArticleDOI
TL;DR: In this paper, a piecewise-linear parametric uniaxial tension and compression stress-strain model with a simplified post-peak response is developed to obtain the nonlinear load deflection response of epoxy resin materials which are considerably stronger in compression than tension.
Abstract: A piecewise-linear parametric uniaxial tension and compression stress–strain model with a simplified post-peak response is developed to obtain the nonlinear load deflection response of epoxy resin materials which are considerably stronger in compression than tension. This model could be used to obtain flexural strength when the complete post-peak behavior of the material in tension and compression is not available. The tension and compression stress–strain curves are bilinear for pre-peak response followed by a constant flow stress in tension and a constant yield stress in compression in the post-peak response. The simulations and experiments reveal the suitability of this model for predicting the three-point bending and four-point bending response. This model gives an upper bound estimate for flexural over-strength factor.

Journal ArticleDOI
TL;DR: In this article, the fictitious notch rounding concept is applied to V-shaped notches with root holes subjected to mode I loading and a fictitious notch radius ρf is determined as a function of the real notch radius.
Abstract: The fictitious notch rounding concept is applied here to V-shaped notches with root holes subjected to mode I loading. The fictitious notch radius ρf is determined as a function of the real notch r...

Journal ArticleDOI
TL;DR: In this paper, the influence of the areal density of a composite thin-plate, made of glass-fibre woven laminates and subjected to high-velocity impact, was analyzed.
Abstract: This work analyses the influence that the areal density of a composite thin-plate, made of glass-fibre woven laminates and subjected to high-velocity impact, exerts on perforation-threshold energy, contact time, and energy-absorption mechanisms. The perforation-threshold energy increased with the areal density. Also, the contact time increased at impact energies above the perforation-threshold energy and decreased below this threshold. The main energy-absorption mechanisms at impact energies close to that causing perforation were found to be the deformation and failure of the fibres, regardless of the areal density. For higher impact energies, the main mechanisms were fibre failure and the energy absorbed by acceleration of the laminate.

Journal ArticleDOI
TL;DR: In this paper, the response of composites, primarily carbon fiber reinforced plastic and glass fibre reinforced plastic-based laminates, to very high (hyper-velocity) impacts is discussed.
Abstract: The combination of high strength and low density has resulted in increasing use of composite materials in structures such as aerospace systems that may be subjected to high-velocity impact during their in-service lives. In this review we focus on recent work surrounding the response of composites, primarily carbon fibre reinforced plastic and glass fibre reinforced plastic-based laminates to very high (hyper)-velocity impacts. To this end, the review is divided into two halves. In the first, hypervelocity impacts (e.g. impacts with velocities greater than ca. 2 km/s) that are likely to be encountered by aerospace systems are considered; while in the second, resultant material behaviour – in the form of shock response – is discussed. This review is designed to (1) build on previous studies which have typically largely focused on high-velocity impacts from the perspective of spacecraft protection against on-orbit impact, and; (2) complement an earlier part which focused on the lower impact velocity regime a...

Journal ArticleDOI
TL;DR: In this article, the laser beam weldability of vario... has been investigated in the context of hot crack formation in high-alloy steels, and the results obtained with other welding techniques and test procedures cannot be transferred to laser beam welding.
Abstract: Due to significant developments over the last decades, laser beam welding has become a well-established industrial process offering high processing speeds and causing low component distortions. But an important issue currently preventing its intense use, especially in the energy or plant construction sector where high alloy steels are applied, concerns hot crack formation. Although considerable advances in understanding hot cracking mechanisms have been made, most of the known influencing factors are metallurgical in character. The thermo-mechanical effects are barely considered or quantified. Up to the present, there exist numerous hot cracking tests that were however conceived for welding methods other than laser beam welding. Considering the special features of the laser welding process, such as high cooling rates and the narrow process zone, results obtained with other welding techniques and test procedures cannot be transferred to laser beam welding. In this study, the laser beam weldability of vario...

Journal ArticleDOI
TL;DR: In this paper, the ability of the girth welds to withstand global plastic straining due to the nature of their installation process or harsh environmental conditions during operation is investigated, and the results show that the welds are able to withstand these pl...
Abstract: Some pipelines face global plastic straining due to the nature of their installation process or harsh environmental conditions during operation. The ability of the girth welds to withstand these pl...

Journal ArticleDOI
TL;DR: In this paper, the effect of hybridization on the ballistic limit (V50) was analyzed for plain-weave hybrid and non-hybrid composite composites, and the results showed that hybridization had no effect on the performance of the V50.
Abstract: This paper presents an experimental and numerical study to understand ballistic behavior of plain-weave hybrid and non-hybrid composites. The effect of hybridization on ballistic limit (V50) was in...

Journal ArticleDOI
TL;DR: In this paper, a semi-analytical homogenization method is used to derive effective properties of a plain woven composites from the material properties of the constituents, where the failure of a longitudinal tension and an open hole tension specimens were simulated in a multi-scale manner and verified experimentally.
Abstract: A numerical model capable of dealing with progressive degradation of plain woven composites in a computationally efficient manner is presented in this article. A semi-analytical homogenization method is used to derive effective properties of the composite from the material properties of the constituents. The progressive failure is described using nonlocal continuum damage mechanics where the driving internal variable for the damage is the nonlocal strain. The model was implemented into Abaqus/Explicit, where the failure of a longitudinal tension and an open hole tension specimens were simulated in a multi-scale manner and verified experimentally.

Journal ArticleDOI
TL;DR: In this article, the perforation threshold of composite metal laminates was investigated using a gas gun over a wide range of incident impact energies, and the fracture mechanisms in the two types of composite-metal hybrid material were elucidated by sectioning and polishing samples through the point of impact and also by measuring the residual deformation of the hybrid plates.
Abstract: The high-velocity impact response of fibre metal laminates based on a woven polypropylene fibre reinforced polypropylene, termed a self-reinforced polypropylene, and a glass reinforced polypropylene has been investigated. Two types of aluminium alloy were considered, these being the 2024-O and 2024-T3 alloys. Tests on these composite-metal hybrids were undertaken using a gas gun over a wide range of incident impact energies. In this study, attention focused specifically on the perforation threshold. Following impact, the fracture mechanisms in the two types of fibre metal laminates were elucidated by sectioning and polishing samples through the point of impact and also by measuring the residual deformation of the hybrid plates. Cross-sections of the failed samples highlighted significant plasticity within the volume of these hybrid materials, indicating that considerable energy had been absorbed in plastically deforming the aluminium and composite plies. The impact resistances of the various laminates were compared by determining their specific perforation energies. Here, it was shown that fibre metal laminates based on the glass reinforced polypropylene composite offer a slightly higher perforation resistance than the self-reinforced polypropylene fibre metal laminates. Also, the fibre metal laminates based on the stronger 2024-T3 alloy out-performed their 2024-O counterparts. Finally, the perforation resistances of the fibre metal laminates were predicted using the previously reported Reid-Wen impact perforation model. Good agreement was observed between this impact model and the measured experimental data

Journal ArticleDOI
TL;DR: Based on the available welding simulation approaches found in the literature, an alternative and simplified welding simulation approach is developed, called rapid dumping as mentioned in this paper, which is a sequential thermo-temperature simulation approach.
Abstract: Based on the available welding simulation approaches found in the literature, an alternative and simplified welding simulation approach is developed, called rapid dumping. It is a sequential thermo...

Journal ArticleDOI
TL;DR: In this paper, the authors report the results of a study into friction stir welds made in 12.7 mm-thick 12%-Cr steel plates using angle-dispersive neutron diffraction.
Abstract: In the present paper we report the results of a study into friction stir welds made in 12.7 mm-thick 12%-Cr steel plates. Residual stress measurements were performed using angle-dispersive neutron diffraction. Complete characterization of the three-dimensional residual stress state in friction stir weld samples was obtained by analysing diffracted peaks; peak broadening for identifying the regions of severe plastic deformation and the associated residual strain (eigenstrain) acting as the source of residual stress and peak shifting for evaluating residual elastic strains in the welded component. Three different methods were used to address the key issue of determining the d0 variation across the weld. The comb (or matchstick) method was compared with two other approaches: the balance method, and the zero traction method. It was found that a combination of the comb and the zero traction methods allows reliable residual strain/stress distributions.

Journal ArticleDOI
TL;DR: In this article, the tensile stress concentrations at geometric discontinuities in composites by altering the neighboring structural compliance and the possible influence on strength were investigated, and the results showed that the neighboring compliance can influence tensile strength.
Abstract: Reducing tensile stress concentrations at geometric discontinuities in composites by altering the neighboring structural compliance, and the possible influence on strength, are investigated. Compar...