International Journal of Solids and Structures最新文献

Predicting fracture toughness of heterogeneous composites is an important and challenging problem in physics and mechanics. The dependence of effective toughness on elastic properties of phases remains unclear. Considering that energy plays an essential role in crack propagation, an energy approach is proposed to obtain effective toughness in this study. We built the relationship between effective toughness and the homogenized local surface energy. The energy is constructed by generalizing Eshelby’s equivalent inclusion formulation to heterogeneous case, which couples physical features with elastic properties. An analytical formula of effective toughness can be derived for heterogeneous composites. Based on this formula, effects of toughness and elastic properties of the phases are discussed in depth, which reveals that how elastic heterogeneity can influence the effective toughness fundamentally. It is demonstrated that the predictions of concretes and metal toughening glasses agree well with experimental evidences.

All-solid-state batteries (ASSBs) are high-energy, high-power batteries. To enhance the understanding of the electrochemical-mechanical behavior in ASSBs across different scales, we developed a multi-physics and multi-scale modeling framework. This framework incorporates elastoplastic finite deformation and electrode microstructures of ASSBs, and the role of gradient plasticity in the governing equation for multiple physical fields was discussed. Utilizing X-ray computed tomography, we reconstructed the microstructure through a machine learning (ML)-informed image segmentation process. Our study clarifies the impact of electrode microstructures on concentration, stress, voltage, delamination and buckling from AM to electrode scale. Comparative analysis of the Feret diameter distribution of active materials (AMs) shows that ML-informed image segmentation outperforms two traditional segmentation methods. We observed that the asynchronous diffusion saturation of AMs, varying in shape and size, significantly influences the electrochemical-mechanical behavior of ASSBs, resulting in complicated debonding indices and J-integral distribution at the interface. The proposed upscaling homogenization procedure is demonstrated to be efficient for buckling analysis, with the shape mode closely matching existing experimental observations. These results shed light on the critical multi-physics and multi-scale coupling mechanisms in ASSBs.

The stress field in the hydride precipitation zone is examined, under conditions of hydrogen chemical equilibrium and constant temperature, in the case of non-hardening metals, by applying slip-line theory. It is proven that the hydride precipitation zone, in any geometry, is a constant stress area. In this area, the principal stresses are equal to the respective principal stresses, before hydride precipitation, minus the difference of hydrostatic stress before and after hydride precipitation. The general relations are applied to the case of a stationary sharp mode-I plane-strain crack and the deviations from Prandtl-field are derived, in the [-π/4, +π/4] sector ahead of the tip, where hydrides precipitate. In this case, the hydride precipitation sector is characterized by a constant hydride volume fraction. In addition, hydride precipitation is associated with the development of elastic sectors along the crack faces and the reduction of the centered fan sectors; the relation between hydride precipitation zone stress trace and the extent of the centered fan sector is presented. The mode-I plane-strain blunted crack is also considered and the deviations from the logarithmic spiral slip-lines is discussed together with the reduction of hydride volume fraction as the blunted crack-tip is approached. A general fracture criterion, based on the strength of hydride platelets, is derived, which indicates that fracture occurs, when a critical hydride precipitation zone stress trace dominates. The criterion is applied, under the condition of a dominant K-field annulus, surrounding the plastic zone, and the estimated threshold stress intensity factor of delayed hydride cracking correlates favorably with experimental measurements.

This work introduces a finite element model updating (FEMU) identification scheme to determine the material parameters of an anisotropic metal plasticity model. Surround digital image correlation (DIC) data is collected from tensile tests on mildly notched flat specimens and it is used to minimize specimen alignment errors when comparing simulations and experiments. The front surface displacement fields and resultant force history are leveraged to calibrate a Whip-Bezier based material model in a computationally-efficient procedure, which treats the pre- and post-necking regimes separately. Experimental data from specimens with a larger notch radius (NT20) serve as the training set, while data from specimens with a smaller notch radius (NT6) are used for validation. Analysis of identification methods using datasets from virtual experiments highlights the improved generalization ability of the full-field approach compared to solely using force–displacement curves. However, this work also demonstrates that through-thickness necking in real notched tensile experiments is asymmetric. This can hinder the identification of the large strain segment of hardening laws, especially when a FEMU approach incorporates full-field information from one specimen surface only. Consequently, it is recommended to use advanced finite element models that capture asymmetric localized strain fields or to base the identification of large strain hardening responses on experiments that achieve large strains without asymmetric through-thickness strain localization, such as in-plane torsion tests.