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Showing papers in "International Journal of Damage Mechanics in 2015"


Journal ArticleDOI
TL;DR: In this article, a modified nonlinear fatigue damage accumulation model accounting for load interaction effects is presented, where the original model is based on physical property degradation of materials, from w...
Abstract: This paper presents a modified nonlinear fatigue damage accumulation model accounting for load interaction effects. The original model is based on physical property degradation of materials, from w...

95 citations


Journal ArticleDOI
TL;DR: In this paper, a two-dimensional micromechanical damage-healing model of micro-capsule-enabled selfhealing cementitious materials under compressive loading has been proposed.
Abstract: The use of microcapsule-enabled self-healing cementitious composite has high potential as a new repair method for the cracked concrete. It will evidently provide extended lifetime and security while reducing the maintenance costs and rates of occurrences of system failures by incorporating self-healing agents in microcapsules. Based on experimental observation and Taylor’s model, a two-dimensional micromechanical damage–healing model of microcapsule-enabled self-healing cementitious materials under compressive loading has been proposed. The proposed model can predict the healing effect on microcrack-induced damage quantitatively under compressive loading. The kinetic equations of damage–healing evolution and the formulations of compliance after healing are developed. Subsequently, the proposed model is validated by experimental data. Different system parameters of microcapsule-enabled self-healing concretes, such as the fracture toughness of healing agents, the degree of initial damage, the volume fractio...

57 citations


Journal ArticleDOI
TL;DR: While strength and toughness properties of construction steels are major mechanical properties with respect to the safety assessment of components, increasingly often requirements are defined on the safety properties of components.
Abstract: While strength and toughness properties of construction steels are major mechanical properties with respect to the safety assessment of components, increasingly often requirements are defined on th...

56 citations


Journal ArticleDOI
TL;DR: In this paper, the analysis of damage accumulation plays a key role in pre-vegetation and pre-deletion of cyclic loading of the human body, which is a damage accumulation process in which the material property deteriorates and degenerates continuously under cyclic load.
Abstract: Fatigue is a damage accumulation process in which the material property deteriorates and degenerates continuously under cyclic loading. The analysis of damage accumulation plays a key role in preve...

48 citations


Journal ArticleDOI
TL;DR: In this paper, it is shown that most engineering components in service are usually subjected to variable cyclic loading and it is important to predict fatigue life and deal with the issue about fatigue damage accumulation for the...
Abstract: Most of engineering components in service are usually subjected to variable cyclic loading. It is important to predict fatigue life and deal with the issue about fatigue damage accumulation for the...

46 citations


Journal ArticleDOI
TL;DR: In this paper, a generalized analytical formulation is presented for the prediction of ballistic impact behavior of 2D woven fabric composite laminates impacted with a rigid cylindrical projectile, and the formulatio...
Abstract: A generalized analytical formulation is presented for the prediction of ballistic impact behavior of 2D woven fabric composite laminates impacted with a rigid cylindrical projectile. The formulatio...

45 citations


Journal ArticleDOI
TL;DR: In this article, the maximum tangential strain energy density criterion presented in the past for damage analysis of brittle materials under mixed mode I/II loading is extended to general mixed mode II/III loading.
Abstract: The maximum tangential strain energy density criterion presented in the past for damage analysis of brittle materials under mixed mode I/II loading is extended to general mixed mode I/II/III in ord...

44 citations


Journal ArticleDOI
TL;DR: In this paper, two brittle fracture criteria were developed in terms of the notch stress intensity factors to predict mode I fracture in engineering components weakened by V-notches with end holes.
Abstract: In the present research, two brittle fracture criteria were developed in terms of the notch stress intensity factors to predict mode I fracture in engineering components weakened by V-notches with end holes (VO-notches). The criteria were based on the point stress and the mean stress failure concepts. To evaluate the validity of the criteria, first, 36 new fracture tests were conducted on a new notched specimen, namely the Brazilian disk containing central V-notch with end hole (VO-BD specimen) made of polymethyl-metacrylate. Three notch angles and four notch radii were considered in the experiments. Then, the experimentally obtained fracture loads were converted to the corresponding mode I notch fracture toughness values by mean of the finite element method in order to compare the test results with the theories. It was found that very good agreement exists generally between the experimental and theoretical results. Also, found in this research was that by increasing the VO-notch angle, the accuracy of th...

40 citations


Journal ArticleDOI
TL;DR: In this article, the extrinsic mechanism was considered in the form of architectural modification in laminates comprising two exterior layers of Al6061-5 vol.% SiCp and an interlayer of Al1050.
Abstract: Damage tolerance improvement in discontinuously reinforced aluminum matrix composites has been examined through both extrinsic and intrinsic approaches by researchers. In this study, extrinsic mechanism was considered in the form of architectural modification in laminates comprising two exterior layers of Al6061-5 vol.% SiCp and an interlayer of Al1050. Hot roll bonding was utilized to fabricate laminates since interfacial adhesion of layers was controlled by means of rolling strain. The interfacial strength and fracture resistance of specimens were examined by shear and three-point bending test, respectively. Achievements demonstrated that the quasi-static toughness of laminates tested in crack divider orientation was greater than that of monolithic samples. Also, it was revealed that the initiation, propagation, and total toughness were influenced by interfacial adhesion. In the other words, interfacial bonding played a major role in energy absorption during fracture. Enhancement of the interfacial adhe...

38 citations


Journal ArticleDOI
TL;DR: Based on the effective stress concept in continuum damage mechanics and the large deformation theory, a viscodamage model, coupled with Schapery-type nonlinear viscoelasticity and Perzyna-type viscoplasticity constitutive models, is used in order to simulate and predict the inelastic and time-dependent damage behavior of polymeric materials and their composites as mentioned in this paper.
Abstract: Based on the effective stress concept in continuum damage mechanics and the large deformation theory, a viscodamage model, coupled with Schapery-type nonlinear-viscoelasticity and Perzyna-type viscoplasticity constitutive models, is used in order to simulate and predict the inelastic and time-dependent damage behavior of polymeric materials and their composites. The thermo-viscodamage model is presented as a function of temperature, total effective strain, damage history, and a damage-driving force expressed in terms of the deviatoric stress invariants in the undamaged configuration. This expression for the damage force allows for the distinction between the influence of compression and extension loading conditions on damage nucleation and growth. Also, the ability of the constitutive model for predicting the tertiary creep, which shows the nonlinear behavior of polymers during damage growth and nucleation, is presented. The numerical algorithm for integrating the coupled constitutive model is implemented...

38 citations


Journal ArticleDOI
TL;DR: In this article, a meso-structure model of 3D-braided composites for the analysis of compressive behaviors and failure modes under quasi-static and high-strain rate compression is presented.
Abstract: This paper reports a meso-structure model of 3D-braided composites for the analysis of compressive behaviors and failure modes under quasi-static and high-strain rate compression. An idealized geometrical model of 3D-braided composite, which has the same preform meso-structure with four-step 3D-braided composite is established for finite element analyses of compressive behaviors. The compression stress–strain curves obtained from experimental along the in-plane and out-of-plane directions were used to validate the finite element analyses model. The agreement between the experimental and finite element analyses results proves the validity of the finite element analyses model. It was found that the finite element analyses model provides a way to obtain the locations of stress propagation, the 3D stress state and the progressive failure behavior. The numerical results also showed that the fiber tows in the surface and corner area of braided preform play an important role during both quasi-static and high-str...

Journal ArticleDOI
TL;DR: In this paper, a hybrid experimental-numerical methodology is presented for parameter identification of a mixed nonlinear hardening anisotropic plasticity model fully coupled with isotropic ductile damage accounting for microcracks closure effects.
Abstract: A hybrid experimental–numerical methodology is presented for the parameter identification of a mixed nonlinear hardening anisotropic plasticity model fully coupled with isotropic ductile damage accounting for microcracks closure effects. In this study, three test materials are chosen: DP1000, CP1200, and AL7020. The experiments involve the tensile tests with smooth and notched specimens and twotypes of shear tests. The tensile tests with smooth specimens are conducted in different directions with respect to the rolling direction. This helps to determine the plastic anisotropy parameters of the material when the ductile damage is still negligible. Also, in-plane torsion tests with a single loading cycle are used to determine separately the isotropic and kinematic hardening parameters. Finally, tensile tests with notched specimens and Shouler and Allwood shear tests are used for the damage parameters identification. These are con

Journal ArticleDOI
TL;DR: In this paper, the authors studied the mechanical response of rock under the combined effects of high temperature and mechanical load using the method of damage mechanics, which is a relatively new research direction of rock mecha.
Abstract: Study on the mechanical response of rock under the combined effects of high temperature and mechanical load using the method of damage mechanics is a relatively new research direction of rock mecha...

Journal ArticleDOI
TL;DR: In this article, a multi-dimensional space method is developed to simulate the crack growth under dynamic loads, where the generalized boundary condition is proposed to modify the matrices of stiffness, mass and damping.
Abstract: The extended finite element method (XFEM) has been widely used to investigate the moving cracks without any remeshing. The degrees of freedom (DOFs) of nodes around crack surfaces and crack tips are added to represent the discontinuous fields and asymptotic fields. However, the XFEM encounters some challenges in dynamic problems because the total number of DOFs increases with the crack growth, which leads to difficulty in iteration algorithm of time integration. In this paper, based on the XFEM, a multi-dimensional space method is developed to simulate the crack growth under dynamic loads. Every node, not limited to the nodes around crack tips and crack surfaces, has 12 DOFs in the domain containing one crack (12n DOFs in the domain containing n cracks). The generalized boundary condition is proposed to modify the matrices of stiffness, mass and damping. The modified matrices of stiffness, mass and damping are highly sparse, the additional central processing unit time is little and the use of internal mem...

Journal ArticleDOI
TL;DR: In this article, a variational model is developed for predicting stress transfer due to ply cracking in general cross-ply laminates subject to out-of-plane bending and biaxial in-plane loading.
Abstract: In the current study, a variational model is developed for predicting stress transfer due to ply cracking in general cross-ply laminates subject to out-of-plane bending and biaxial in-plane loading...

Journal ArticleDOI
Kun Luan1, Bohong Gu1
TL;DR: In this article, the authors reported the ballistic energy absorption of three-dimensional angle-interlock composite (3DAWC) based on a ballistic experiment and a theoretical model with high strain rate constitutive equation of fiber tows.
Abstract: This paper reports the ballistic energy absorption of three-dimensional angle-interlock composite (3DAWC) based on a ballistic experiment and a theoretical model with high strain rate constitutive equation of fiber tows. The 3DAWC panels were penetrated under a hemispherical–cylindrical steel projectile, while time testers recorded the initial velocities and residual velocities of projectile in this process. The damage modes of 3DAWC are observed and analyzed from the view of penetrated damage morphologies and experimental velocity data. In order to demonstrate the energy absorption mechanism with more accuracy, a multi-scale finite element model of 3DAWC under ballistic penetration is specially designed and established to calculate this ballistic event. The constitutive relationship of the Twaron® filament yarn in microstructural model is derived from the springs and dashpots model and compiled into user-defined material subroutine in commercial-available finite element software package LS-DYNA, which ca...

Journal ArticleDOI
TL;DR: In this article, the authors present a procedure for investigating local damages created in sandwich composites based on the processing of the recorded acoustic emission hits, which is based on an unsupervised approach.
Abstract: This work presents a procedure for investigating local damages created in sandwich composites. The proposed analysis is based on the processing of the recorded acoustic emission hits. Unsupervised ...

Journal ArticleDOI
TL;DR: In this paper, a unified viscoplastic constitutive model with damage was presented to describe creep-fatigue deformation behavior, and the primary improvement on the existing models is to introduce creep and fatigue d...
Abstract: A unified viscoplastic constitutive model with damage is presented to describe creep–fatigue deformation behavior. The primary improvement on the existing models is to introduce creep and fatigue d...

Journal ArticleDOI
TL;DR: In this article, an analytical formulation for the prediction of ballistic impact behavior of fabric targets is presented based on stress wave propagation in porous medium and energy balance between the rigid projectile and the fabric target.
Abstract: An analytical formulation is presented for the prediction of ballistic impact behavior of fabric targets. The formulation is based on stress wave propagation in porous medium and energy balance between the rigid projectile and the fabric target. During the ballistic impact event, energy lost by the projectile is absorbed by the fabric target through various damage and energy absorbing mechanisms such as compression of the fabric target directly below the projectile, compression in the region surrounding the impacted zone, shear plugging, stretching and tensile failure of yarns/layers in the region consisting of primary yarns, tensile deformation of yarns/layers in the region consisting of secondary yarns, conical deformation on the back face of the fabric target, in-plane friction between the warp and fill yarns and through the thickness friction between the moving projectile and the fabric target. The formulation presented considers both shear plugging and tensile failure of yarns during conical deformat...

Journal ArticleDOI
TL;DR: Two non-iterative solving approaches for mechanical systems composed of elements with saw-tooth constitutive laws have been described in the literature as mentioned in this paper, and the first algorithm called the loa...
Abstract: Two different non-iterative solving approaches for mechanical systems composed of elements with saw-tooth constitutive laws have been described in the literature. The first algorithm called the loa...

Journal ArticleDOI
Wei Wang1, Jian-Fu Shao1, Jian-Fu Shao2, Qi-Zhi Zhu1, W. Y. Xu1 
TL;DR: In this paper, a discrete viscoplastic damage model is proposed for the description of time-dependent behaviour of quasi-brittle rocks, where the local strains and stresses applied to microcracks are related to the macroscopic counterparts through appropriate kinematic and static conditions.
Abstract: A discrete viscoplastic damage model is proposed for the description of time-dependent behaviour of quasi-brittle rocks. This model is inspired by micromechanical considerations. Rocks are considered as quasi-brittle materials containing a spatial distribution of microcracks. Viscoplastic strains of rocks are generated by the time-dependent frictional sliding of microcracks surfaces while the damage of rocks is related to the growth of microcracks. The two inelastic mechanisms are coupled. The model is formulated in the framework of discrete thermodynamics of irreversible processes. The local strains and stresses applied to microcracks are related to the macroscopic counterparts through appropriate kinematic and static conditions. Specific viscoplastic flow rule as well as damage evolution law is defined for each family of microcracks. The validity of proposed model is verified through comparisons between numerical results and experimental data in triaxial compression tests and creep tests for sandstone.

Journal ArticleDOI
TL;DR: In this article, a micromechanics-based damage model able to describe the brittle response of initially anisotropic materials is presented, where a special emphasis is put on the account of damage-induced anisotropy and unilateral behaviour related to microcracks closure effects.
Abstract: A micromechanics-based damage model able to describe the brittle response of initially anisotropic materials is presented. A special emphasis is put on the account of damage-induced anisotropy and unilateral behaviour related to microcracks closure effects. These both features clearly influence the inelastic deformation of microcracked materials and lead to even more complex consequences in the context of initial anisotropy. The aim of this work is then to derive a new strain-based formulation which allows representing the related interactions between all these phenomena. This is achieved through a recent two-dimensional energy-based micromechanical analysis that accounts for the fully anisotropic multilinear response of orthotropic materials weakened by arbitrarily oriented microcracks. On the other hand, the thermodynamics framework gives a standard procedure for the development of the damage evolution law. Throughout the paper, attention is put on the mathematical and thermodynamical consistency of the model to avoid difficulties usually associated to the simultaneous description of damageinduced anisotropy and unilateral effects. In addition to elastic constants, the model requires the identification of only two parameters related to damage evolution. The model has been implemented within the commercial finite-element code ABAQUS, and various numerical simulations are presented to illustrate its capabilities. Especially, evolution of the material symmetry and influence of opening-closure states of microcracks on the damage process are illustrated in the case of brittle matrix composites subjected to different loading cases (axis and off-axis loads, tension and compression, tension followed by compression).

Journal ArticleDOI
TL;DR: In this paper, the bending deformation and damage of four-step 3D braided composite materials from experimental and finite element analyses approaches were reported and the load-deflection curves were obtained for analyzing the bending behaviors.
Abstract: This paper reports bending deformation and damage of four-step 3D braided composite materials from experimental and finite element analyses approaches. In experimental, the three-point bending deformation and damage of the braided composite materials were observed and the load–deflection curves were obtained for analyzing the bending behaviors. In finite element analyses, three types of repeating unit cell geometrical models were established to characterize the microstructures of 3D braided composite materials. The critical damage area failure criteria were employed in the finite element analyses. The repeating unit cell geometrical models and the finite element analyses were verified with the experimental results. The influences of structure parameters in the repeating unit cells on the bending behaviors were analyzed. It was found that the volume fraction of surface and corner repeating unit cells were around 30%, and their elastic modulus along axis Z was about 5 times that of inner repeating unit cell...

Journal ArticleDOI
TL;DR: In this paper, a generalized Irwin model was used to simulate a radial crack interacting with a coated-circular inclusion in a matrix, where the crack line was assumed to be at the angle of 90°'−'θ from a remote tensile loading.
Abstract: Elastic-plastic stress analysis on a radial crack interacting with a coated-circular inclusion in a matrix has been carried out with the aid of a generalized Irwin plastic zone correction. The crack line is assumed to be at the angle of 90° − θ from a remote tensile loading. In the mathematical formulation, the distributed dislocation method is used to simulate the crack. By solving a set of singular integral equations, three quantities, the effective stress intensity factor, the plastic zone size and the crack tip opening displacement (CTOD), are evaluated with the generalized Irwin model proposed. Numerical examples are given to show the influence of the key parameters such as the crack orientation angle θ, the normalized crack distance, the normalized coating phase thickness and the shear modulus ratio (μ2/μ3, coating phase/matrix) on the fracture behavior. The results indicate that the influence of angle θ is the greatest, while the effect of shear modulus ratio μ2/μ3 is relatively small. A validation...

Journal ArticleDOI
TL;DR: One of the commonly used approaches for the prediction of ductile fracture is the continuum damage mechanics model, in which the void density is represented by a continuum variable called damage as discussed by the authors. But this model is not suitable for ductile deformation.
Abstract: One of the commonly used approaches for the prediction of ductile fracture is the continuum damage mechanics model, in which the void density is represented by a continuum variable called damage. F...

Journal ArticleDOI
Robert Keqi Luo1
TL;DR: In this paper, an approach based on rebound energy (resilience) change is proposed to predict the Mullins damage effect with residual strain for a rubber product, manufactured in industry, was selected for experiment and verification.
Abstract: In industry, the important design parameters of rubber products are currently based on only the loading part of loading–unloading histories, e.g. load–deflection and the fatigue requirement. Rubber-like materials exhibit an appreciable change in their mechanical properties during the loading–unloading process, especially in the first few cycles from a virgin state. There is neither a universally well-defined approach to evaluate the Mullins damage effect on design aspects in industry, nor a reliable criterion to evaluate it for rubber products. An approach based on rebound energy (resilience) change is proposed to predict the Mullins damage effect with residual strain. A rubber product, manufactured in industry, was selected for experiment and verification. A Mullins indicator, in term of the maximum loading forces over the accumulated residual deflections over the loading–unloading cycles, is proposed for a criterion to evaluate the Mullins damage effect. It is indicated that the first loading–unloading cycle removes the Mullins effect by approximately 80% and a typical three loading–unloading cycles in industrial practice can remove Mullins effect by approximately 94%. More than three loading–unloading cycles are suggested to reach a state for achieving the required accuracy on smaller tolerance of design parameters. The proposed approach provides the reliable prediction on the first loading–unloading and subsequent reloading–unloading cycles, and can be used for engineering design and industrial applications. Nevertheless, the proposed approach should be further verified using more industrial cases.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the compression failure of thermoplastic composites made of jute/polypropylene by experimental and numerical studies and found that the loading conditions of laminates and the fibres orientation affect the failure load of the composites.
Abstract: In this work, the compression failure of thermoplastic composites made of jute/polypropylene is investigated by experimental and numerical studies. Two laminate specimen’s lengths with different fibre orientations have been considered to analyse this composite type response to a compressive solicitation. The applied numerical model permits to understand the mechanisms of damage and evolution in the laminate. The interlayer damage (delamination) and the intra-layer damage (matrix cracking) have been modelled by the combined use of the Cohesive Zones model (CZM) and the Matzenmiller, Lubliner and Taylor (MLT) mechanical model. It was found that the loading conditions of laminates and the fibres orientation affect the compression failure load of the thermoplastic composites.

Journal ArticleDOI
TL;DR: In this article, the authors highlight the assessment of creep damage of 11 years service-exposed reformer tube made up of HP-40 grade of steel of a petrochemical industry from replicated creep data.
Abstract: This paper highlights the assessment of creep damage of 11 years service-exposed reformer tube made up of HP-40 grade of steel of a petrochemical industry from replicated creep data. The existence ...

Journal ArticleDOI
TL;DR: In this paper, the authors describe virtually all known analytical models for predicting the protection properties of concrete shields against high-speed impact by rigid projectiles, including one-stage and two-stage models.
Abstract: We describe virtually all known analytical models for predicting protective properties of concrete shields against normal high-speed impact by rigid projectiles. Presented formulas can be directly used in practical calculations. Particular emphasis is given to widely used one-stage and two-stage models which are systemized in a hierarchical classification system using a unified approach. One-stage models employ the same formula along the whole trajectory of a projectile for calculating a force exerted on a penetrating projectile by a shield. In the case of two-stage models, a resistance force at the first stage of penetration is a linear function of the instantaneous depth of penetration while at the second stage of penetration normal stresses at every location on projectile-shield contact surface are polynomial function of normal velocity component. Conditions of continuity of the resistance force and velocity of a projectile are invoked in the transition point between these two sub-models. A wide variety of models can be devised by using different sub-models at each stage of penetration.

Journal ArticleDOI
TL;DR: In this article, a micromechanical modeling of the overall elastoplastic behavior and damage evolution in ductile porous geomaterials is presented, where the studied material is composed of a porous matrix that is embedded by linear elastic mineral inclusions.
Abstract: This paper is devoted to micromechanical modeling of the overall elastoplastic behavior and damage evolution in ductile porous geomaterials. The studied material is composed of a porous matrix that is embedded by linear elastic mineral inclusions. The solid phase of porous matrix is described by a pressure sensitive plastic model with a nonassociated flow rule. With a two-level homogenization procedure, the macroscopic plastic criterion of the heterogeneous material is deduced and takes into account the effects of pores and mineral inclusions. Then it is assumed that the material damage is related to progressive debonding of mineral inclusions. The Weibull’s statistical function is used to describe the varying probability of inclusion debonding. The debonded inclusions are considered as completely separated from the matrix and regarded as voids for simplicity. Finally, the proposed micro–macro model is applied to describe the macroscopic behavior of claystones. Comparisons between the numerical results an...