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A previously developed constitutive model for short‐fiber reinforced thermoplastics is applied to an injection‐molded component with a complex geometry and microstructure. This macro‐scale continuum‐based model is able to capture the anisotropic viscoelastic‐viscoplastic response of the material. In injection‐molded short‐fiber composites, the anisotropic mechanical properties depend strongly on the fiber orientation distribution, which generally displays a marked variation throughout the product. This makes the material characterization and model application challenging. In this article, two characterization and model application strategies are proposed. These techniques, together with the developed constitutive model provide a strong tool for reliable prediction of the mechanical response of an injection molded product, where inputs to the finite element analysis are obtained directly from a numerical simulation of the injection molding process. In this article, from the output provided by an injection molding process simulation software such as Moldflow, the distribution of anisotropic elastic and plastic properties throughout the component is found and the data is imported to the finite element mesh. Mechanical tests are performed on a validation product and results are compared with model predictions from finite element simulations. Through this comparison, the performance of the constitutive model and also proposed procedures for characterization and model application are investigated.

In this paper a model for predicting fatigue delamination growth in laminated composites under high cycle fatigue is proposed. The model uses the cohesive zone approach and a two-scale continuum damage mechanics model. The behavior of the interface material is considered quasi-brittle at the macro scale while plastic deformations are allowed at the scale of micro-defects. The validity of the proposed model is investigated through several standard tests using experimental data from literature. Good agreement between the numerical and experimental results is observed. The model is also capable of simulating fatigue under variable amplitude loading. This feature of model is shown through several sample simulations.

This paper deals with high cycle fatigue delamination in composite materials. The cohesive zone approach along with the level set method is used to simulate fatigue-driven delamination growth. The cohesive zone method is used for calculation of the energy release rate at the crack front because of its superiority over the virtual crack closure technique (VCCT) for bi-material interfaces and non selfsimilar crack growth. Evolution of the crack front in 3D during fatigue growth is handled with the level set method. The damage variable in the cohesive zone formulation is changed according to the updated level set field. Benchmarks are used to evaluate the performance of the proposed approach in simulation of 3D delamination growth under fatigue loading.

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A three-dimensional, implicit gradient-enhanced, fully coupled thermomechanical constitutive model is developed within the framework of thermodynamic principles for NiTi shape memory alloys. This work focuses on unstable behaviors of NiTi samples under different thermomechanical loading conditions. Temperature variation and its coupling effect on non-local behavior of a shape memory alloy during a loading–unloading cycle at different strain rates are considered. The proposed constitutive equations are implemented into the finite element software ABAQUS, and the numerical investigations indicate that the used procedure is an effective computational tool for simulation of several behaviors of NiTi samples including phase front nucleation and propagation, stress–strain–temperature responses, and transformation-induced stress relaxation. The obtained results are shown to be in a good agreement with available experimental and numerical findings in the literature. The effectiveness of the model in removing mesh sensitivity is evaluated by investigating the mesh-dependence issue for the low strain rate problems through numerical examples.

In our previous study, we demonstrated that the time‐dependent failure of transversely loaded UD (unidirectional) glass/iPP is fully plasticity‐controlled and proposed a lifetime prediction method based on plasticity to predict transverse failure. In the present work, extending our previous study to other off‐axis angles, we aim to investigate the effect of the off‐axis angle on the time‐dependent failure of UD glass/iPP, and to propose a lifetime prediction method for the off‐axis failure. Glass/iPP specimens with different off‐axis angles are tested at various strain rates, creep, and fatigue loads to characterize the anisotropic, time‐dependent mechanical response. It is demonstrated that the influences of strain rate and fiber orientation angle on tensile strength are multiplicatively separable; also referred to as factorizable, enabling one to characterize the angle dependence at a single strain rate and the strain rate dependence at a single angle. Moreover, similar to transverse loading, off‐axis failure is also observed to be plasticity‐controlled. Based on these observations, the lifetime prediction method for the plasticity‐controlled transverse failure is extended to off‐axis loading using the aforementioned factorazibility, which resulted in lifetime predictions in agreement with the experimental creep and fatigue data.