Journal of The Mechanics and Physics of Solids最新文献

{"title":"Micromechanics-inspired granular thermodynamics: A constitutive model for multidirectional cyclic shearing","authors":"Zhichao Zhang ,&nbsp;Kenichi Soga","doi":"10.1016/j.jmps.2025.106170","DOIUrl":"10.1016/j.jmps.2025.106170","url":null,"abstract":"<div><div>A new micromechanics-inspired thermodynamic constitutive model is developed for fluid-saturated granular materials. The model development begins with the conceptual assumption that a granular material, when subjected to an external load, is supported by networks of microscopic force chains, including strong and weak force networks. The model also considers the heterogeneous nature of the fabrics in these force networks and describes these micro-level fabrics as a set of distributed fabric tensors. Using non-equilibrium thermodynamic principles, the micro-level behaviors in the strong and weak force networks are homogenized into two macro-level spaces: fabric-transformed space and real space. The model employs fabric-dependent granular hyperelasticity with free and residual elastic potentials, which leads to a fabric-dependent yielding criterion evaluated from the instability of micro-level elasticity. The granular plastic relationships are thermodynamically derived in combination with the concepts of fluidization index and granular temperature. Consequently, the thermodynamic transformations of stresses, strains, and plastic dissipative flows in the two macro-level spaces are derived. The model developed is capable of simulating granular fluidization (i.e., cyclic liquefaction). Its performance is validated by simulating undrained cyclic tests of Monterey No. 0/30 sand under different types of multidirectional non-proportional cyclic paths. The analysis of the developments in yielding and various internal factors of this model provides valuable insights into the mechanisms governing the critical state and non-coaxial cyclic behavior of granular materials.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"200 ","pages":"Article 106170"},"PeriodicalIF":5.0,"publicationDate":"2025-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hypo-elasticity, Cauchy-elasticity, corotational stability and monotonicity in the logarithmic strain","authors":"Patrizio Neff ,&nbsp;Sebastian Holthausen ,&nbsp;Marco Valerio d’Agostino ,&nbsp;Davide Bernardini ,&nbsp;Adam Sky ,&nbsp;Ionel-Dumitrel Ghiba ,&nbsp;Robert J. Martin","doi":"10.1016/j.jmps.2025.106074","DOIUrl":"10.1016/j.jmps.2025.106074","url":null,"abstract":"&lt;div&gt;&lt;div&gt;We combine the rate formulation for the objective, corotational Zaremba–Jaumann rate &lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;ZJ&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;mrow&gt;&lt;mo&gt;[&lt;/mo&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;mo&gt;]&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;ZJ&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mo&gt;sym&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;ξ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mi&gt;v&lt;/mi&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt; operating on the Cauchy stress &lt;span&gt;&lt;math&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;, the Eulerian rate of deformation &lt;span&gt;&lt;math&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and the spatial velocity &lt;span&gt;&lt;math&gt;&lt;mi&gt;v&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; with the novel “corotational stability postulate” &lt;span&gt;&lt;span&gt;&lt;span&gt;(CSP)&lt;/span&gt;&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;〈&lt;/mo&gt;&lt;mrow&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;ZJ&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;mrow&gt;&lt;mo&gt;[&lt;/mo&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;mo&gt;]&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;〉&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mo&gt;∀&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mo&gt;∈&lt;/mo&gt;&lt;mo&gt;Sym&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;∖&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;{&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;}&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;to show that for a given isotropic Cauchy-elastic constitutive law &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;mo&gt;↦&lt;/mo&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; in terms of the left Cauchy–Green tensor &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;F&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, the induced fourth-order tangent stiffness tensor &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;ZJ&lt;/mo&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; is positive definite if and only if for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;̂&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mo&gt;log&lt;/mo&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;:&lt;/mo&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, the strong True-Stress–True-Strain monotonicity condition &lt;span&gt;&lt;span&gt;(TSTS-M&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;)&lt;/span&gt;&lt;/span&gt; in the logarithmic strain is satisfied: &lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;span&gt;(TSTS-M++)&lt;/span&gt;&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;sym&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;log&lt;/mo&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;̂&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mo&gt;log&lt;/mo&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;∈&lt;/mo&gt;&lt;msubsup&gt;&lt;mrow&gt;&lt;mo&gt;Sym&lt;/mo&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;6&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;⟹&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mrow&gt;&lt;mo&gt;〈&lt;/mo&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;̂&lt;/mo&gt;&lt;/mrow&gt;&lt;/mover&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mo&gt;log&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;B&lt;/mi&gt;&lt;/mro","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"202 ","pages":"Article 106074"},"PeriodicalIF":5.0,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144137697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Learning constitutive relations from experiments: 1. PDE constrained optimization","authors":"Andrew Akerson ,&nbsp;Aakila Rajan ,&nbsp;Kaushik Bhattacharya","doi":"10.1016/j.jmps.2025.106128","DOIUrl":"10.1016/j.jmps.2025.106128","url":null,"abstract":"<div><div>We propose a method to accurately and efficiently identify the constitutive behavior of complex materials through full-field observations. We formulate the problem of inferring constitutive relations from experiments as an indirect inverse problem that is constrained by the balance laws. Specifically, we seek to find a constitutive relation that minimizes the difference between the experimental observation and the corresponding quantities computed with the model, while enforcing the balance laws. We formulate the forward problem as a boundary value problem corresponding to the experiment, and compute the sensitivity of the objective with respect to model using the adjoint method. The resulting method is robust and can be applied to constitutive models with arbitrary complexity. We focus on elasto-viscoplasticity, but the approach can be extended to other settings. In this part one, we formulate the method and demonstrate it using synthetic data on two problems, one quasistatic and the other dynamic.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"201 ","pages":"Article 106128"},"PeriodicalIF":5.0,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143907822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hybrid variable spiking graph neural networks for energy-efficient scientific machine learning","authors":"Isha Jain ,&nbsp;Shailesh Garg ,&nbsp;Shaurya Shriyam ,&nbsp;Souvik Chakraborty","doi":"10.1016/j.jmps.2025.106152","DOIUrl":"10.1016/j.jmps.2025.106152","url":null,"abstract":"<div><div>Graph-based representations for samples of computational mechanics-related datasets can prove instrumental when dealing with problems like irregular domains or molecular structures of materials, etc. To effectively analyze and process such datasets, deep learning offers Graph Neural Networks (GNNs) that utilize techniques like message-passing within their architecture. The issue, however, is that as the individual graph scales and/ or GNN architecture becomes increasingly complex, the increased energy budget of the overall deep learning model makes it unsustainable and restricts its applications in applications like edge computing. To overcome this, we propose in this paper Variable Spiking Graph Neural Networks (VS-GNNs) and their hybrid variants, collectively termed VS-GNN architectures, that utilize Variable Spiking Neurons (VSNs) within their architecture to promote sparse communication and hence reduce the overall energy budget. VSNs, while promoting sparse event-driven computations, also perform well for regression tasks, which are often encountered in computational mechanics applications and are the main target of this paper. Three examples dealing with the prediction of mechanical properties of materials based on their microscale/ mesoscale structures are shown to test the performance of the proposed VS-GNNs architectures in regression tasks. We have compared the performance of VS-GNN architectures with the performance of vanilla GNNs, GNNs utilizing leaky integrate and fire neurons, and GNNs utilizing recurrent leaky integrate and fire neurons. The results produced show that VS-GNN architectures perform well for regression tasks, all while promoting sparse communication and, hence, energy efficiency.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"200 ","pages":"Article 106152"},"PeriodicalIF":5.0,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The geometric nature of homeostatic stress in biological growth","authors":"A. Erlich ,&nbsp;G. Zurlo","doi":"10.1016/j.jmps.2025.106155","DOIUrl":"10.1016/j.jmps.2025.106155","url":null,"abstract":"<div><div>Morphogenesis, the process of growth and shape formation in biological tissues, is driven by complex interactions between mechanical, biochemical, and genetic factors. Traditional models of biological growth often rely on the concept of homeostatic Eshelby stress, which defines an ideal target state for the growing body. Any local deviation from this state triggers growth and remodelling, aimed at restoring balance between mechanical forces and biological adaptation. Despite its relevance in the biomechanical context, the nature of homeostatic stress remains elusive, with its value and spatial distribution often chosen arbitrarily, lacking a clear biological interpretation or understanding of its connection to the lower scales of the tissue. To bring clarity on the nature of homeostatic stress, we shift the focus from Eshelby stress to growth incompatibility, a measure of geometric frustration in the tissue that is the primary source of residual stresses in the developing body. Incompatibility, which is measured by the Ricci tensor of the growth metric at the continuous level, can be potentially regulated at the cell level through the formation of appropriate networks and connections with the surrounding cells, making it a more meaningful concept than homeostatic stress as a fixed target. In this geometric perspective, achieving a homeostatic state corresponds to the establishment of a physiological level of frustration in the body, a process leading to the generation and maintenance of the mechanical stresses that are crucial to tissue functionality. While residual stress can be induced through either active contraction or differential growth, the latter is the focus of this work. In this work we present a formulation of biological growth that penalises deviations from a desired state of incompatibility, similar to the way the Einstein–Hilbert action operates in General Relativity. The proposed framework offers a clear and physically grounded approach that elucidates the regulation of size and shape, while providing a means to link cellular and tissue scales in biological systems.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"201 ","pages":"Article 106155"},"PeriodicalIF":5.0,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143904247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical modeling of cantilevered bigon arm mechanics under gravity","authors":"Axel Larsson,&nbsp;Sigrid Adriaenssens","doi":"10.1016/j.jmps.2025.106136","DOIUrl":"10.1016/j.jmps.2025.106136","url":null,"abstract":"<div><div>Elastic Rod Networks (ERNs) formed from interconnected slender, elastic rods can undergo large nonlinear displacements, resulting in phenomena like multi-stability and increased geometric stiffness. By varying the networks’ physical properties and boundary conditions, ERNs can be tailored for applications in mechanical metamaterials, aerospace engineering and soft robotics. Bigon arms are a type of multi-stable ERN composed of bistable bigon units, which are made up of two flat and slender strips, joined at prescribed intersection angles. The global geometry of bigon arms may be tuned by varying the individual units’ strip length, width-to-thickness ratio and intersection angles. Bigon arms can be utilized in reconfigurable structures, for example acting as grippers or moving autonomous robotic systems. However, the configuration space of fixed-angle bigon arms has not been explored in depth, and the influence of gravity on their mechanical behavior has not yet been investigated. In this study, we address this knowledge gap for bigon arm design by formulating a Boundary Value Problem (BVP) to model the displacements of bigon arms under gravity loading. The numerical simulations are validated with decimeter scale physical models. Our results unveil three distinct regions for the bigon arm mechanical behavior: a stable region, a multi-stable region, and one transitionary region connecting the first two. Ultimately, this study provides insights of the parameters influencing the design of adaptive bigon arms and offers an outlook for their future design development.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"200 ","pages":"Article 106136"},"PeriodicalIF":5.0,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cracking and wrinkling morphomechanics of animal skins","authors":"Shiyuan Chu ,&nbsp;Jinshuai Bai ,&nbsp;Xi-Qiao Feng","doi":"10.1016/j.jmps.2025.106167","DOIUrl":"10.1016/j.jmps.2025.106167","url":null,"abstract":"<div><div>Through the long history of evolution, the skins of animals have developed different geometric patterns that confer multiple functions adapted to various environments. To achieve flexibility, which is critical for their predation and survival, the skins must undergo large deformations, with relatively lower energy dissipation and stress levels. To this end, rich surface patterns can be observed on the skins of different animals, for example, cracked fragments on crocodiles, surface wrinkles on dogs, and intricately patterned scales on fishes. In this paper, we investigate how the skin patterns of animals are determined by morphomechanics and reveal that, apart from wrinkling, cracking is another essential morphomechanical strategy. A core–shell model is established to reveal how the surface patterns of the skins are affected by the biological activities, body sizes, and skin curvatures of the animals. A non-dimensional parameter is defined to differentiate the skin patterns governed by surface wrinkling and fragmentation mechanisms. For thin and soft skins (e.g., humans, frogs, and dogs), surface wrinkling is easier to occur, while for thick and stiff skins (e.g., crocodiles and dinosaurs), they evolve into cracked fragments to avoid high stresses during larger deformation. The theoretical results are in good agreement with a wide range of animals. Furthermore, scaling laws are provided for the geometric features of the morphological patterns of cracking-regulated skins. This work not only helps uncover the secrets underlying the skin morphogenesis of animals, but also hold potential applications in paleontological reconstructions and designs of biomimetic soft robots.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"200 ","pages":"Article 106167"},"PeriodicalIF":5.0,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143874622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crack propagation behavior in metal matrix composites: A coupled nonlocal crystal plasticity and phase field modelling","authors":"Yukai Xiong ,&nbsp;Jianfeng Zhao ,&nbsp;Qinglei Zeng ,&nbsp;Fuping Yuan ,&nbsp;Xu Zhang","doi":"10.1016/j.jmps.2025.106164","DOIUrl":"10.1016/j.jmps.2025.106164","url":null,"abstract":"<div><div>The aluminum matrix composite is known for its lightweight and high strength, while its application is limited in various fields due to its low fracture strain. Configuring reinforcements in metal matrix composites (MMCs) is effective in improving the strength-ductility synergy of metallic materials; however, the underlying mechanisms have yet to be elucidated, and an optimizing strategy is to be explored. This study developed a coupled crystal plasticity (CP) and phase field (PF) model to investigate the toughening mechanisms of MMCs. The CP module incorporates a dislocation flux-based nonlocal model, while the PF module considers the influence of geometrically necessary dislocations (GNDs) on crack initiation and propagation. This coupled model effectively captures the initiation of cracks near the interface due to the accumulation of GNDs at the grain boundary and particle surface. Systematic simulations comprehensively reveal the effects of particle distribution and particle strength on the fracture strain. The findings suggest that arranging particles near grain boundaries improves ductility when particle damage is ignored. However, experimental observations reveal that particles undergo damage during deformation. Only when particle damage is incorporated, does the model accurately reflect the enhanced ductility in scenarios where particles are distributed within the grain interior aligning better with experimental findings. This research enhances our understanding of the damage mechanisms in MMCs and provides valuable insights into their microstructural design.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"200 ","pages":"Article 106164"},"PeriodicalIF":5.0,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inflation and instabilities of a spherical magnetoelastic balloon","authors":"Nadeem Karim Shaikh,&nbsp;Ganesh Tamadapu","doi":"10.1016/j.jmps.2025.106146","DOIUrl":"10.1016/j.jmps.2025.106146","url":null,"abstract":"<div><div>This study explores the instabilities during the axisymmetric inflation of an initially spherical magnetoelastic balloon, modeled as a magnetizable Ogden material, under combined internal pressure and a non-uniform magnetic field generated by current-carrying coils. The nonlinear interplay of geometric and material effects leads to governing equations sensitive to bifurcations and instabilities. A coordinate singularity at the poles of the balloon is identified within the system of governing differential equations, which is resolved through an appropriate choice of field variables and L’Hôpital’s rule. Stability analysis reveals that as inflation progresses, axisymmetry is broken through a supercritical pitchfork bifurcation, resulting in a pear-shaped equilibrium. This symmetry is later restored through a reverse subcritical pitchfork bifurcation, forming an isolated loop of pear-shaped solutions containing stable and unstable branches in the case of a six-parameter Ogden material model (SPOM). The onset of symmetry-breaking bifurcations is influenced by material parameters and magnetic field intensity, with critical values beyond which such bifurcations are suppressed. Both symmetry-preserving and pear-shaped configurations are stable under small asymmetric perturbations in both magnetic and non-magnetic cases. Snap-through transitions between pear-shaped and axisymmetric configurations are also observed.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"200 ","pages":"Article 106146"},"PeriodicalIF":5.0,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143874619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A multiscale constitutive model for the elasticity of clay nanoparticle assemblies","authors":"Hejian Zhu ,&nbsp;Andrew J. Whittle ,&nbsp;Roland J.-M. Pellenq","doi":"10.1016/j.jmps.2025.106140","DOIUrl":"10.1016/j.jmps.2025.106140","url":null,"abstract":"<div><div>Due to its particulate nature, the mechanical properties of bulk clay are determined by interparticle forces and fabrics of particle assemblies. A thorough study of the connection between properties across length scales is crucial to a fundamental understanding of the mechanisms behind the complex mechanical behavior of clays and clayey soils. This paper demonstrates the development of a multiscale constitutive model for describing the small-strain elastic properties of illite, based on the results of coarse-grained mesoscale molecular dynamic simulations for monodisperse assemblies of illite primary particles. The formulation consists of a homogenization scheme linking the potential energy of the system with an optimal parameter set describing the mesoscale fabric of the particles, and a perturbation scheme describing the change of the parameters in response to infinitesimal strains applied to the systems. The small strain elastic stiffness tensors are calculated as the second-order derivative of the potential energy with respect to the infinitesimal strain. The results from model prediction are validated against the stiffness properties interpreted from numerical simulations as well as experimental findings from prior research studies. The multiscale constitutive model is able to effectively capture the elastic properties of illite in terms of magnitude and material symmetry purely based on the information of interparticle forces and fabrics.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"200 ","pages":"Article 106140"},"PeriodicalIF":5.0,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143874620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}