Extreme Mechanics Letters最新文献

{"title":"A coarse-grained model for nanocellulose with hydration interfaces revealing the anomalous mechanical enhancement","authors":"HaoWen Wan ,&nbsp;YuanZhen Hou ,&nbsp;JiaHao Li ,&nbsp;RongZhuang Song ,&nbsp;YinBo Zhu ,&nbsp;HengAn Wu","doi":"10.1016/j.eml.2025.102361","DOIUrl":"10.1016/j.eml.2025.102361","url":null,"abstract":"<div><div>Considering the humidity-sensitivity of nanocellulose, decoding the micromechanical mechanisms hidden in hydration interface is essential for tailoring the macroscopic properties. However, exiting mechanics frameworks based on molecular modeling remain challenging to predict the hydration interface-mediated mechanical behaviors of nanocellulose at the mesoscale, hindering the correlation from micro-interface to macro-mechanics. Herein, we developed a coarse-grained (CG) model integrating non-covalent interactions and fiber-level hierarchical stacking, which unveils the anomalous mechanical enhancement of nanocellulose with hydration interfaces. The CG model, validated by all-atom (AA) simulations, accurately captured the modulus and strength scale law with overlap length, until the fiber fracture-dominated saturated state. Our results revealed how hydration extent effects the interfacial mechanics, showing that moderate hydration can enhance both toughness and strength by plasticizing hydrogen-bonding networks, while excessive hydration weakening the shear strength. Beyond the limit that AA simulations can predict, an optimal overlap regime (∼120–180 nm) was identified, where hydration-mediated interfaces can enhance the strength and toughness simultaneously. This study established a cross-scale theoretical modeling framework bridging the microscale hydration interface and macroscale mechanical regulation of nanocellulose materials, which can provide the bottom-up rational guidance for designing strong and tough nanocomposites with weak non-covalent interfaces.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"78 ","pages":"Article 102361"},"PeriodicalIF":4.3,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144167210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantify the failure zone and elastic release zone: A new insight into intrinsic fracture of polymer networks","authors":"Wenjing Lu ,&nbsp;Chong Wang ,&nbsp;Zidi Zhou ,&nbsp;Shuai Xu ,&nbsp;Zishun Liu","doi":"10.1016/j.eml.2025.102362","DOIUrl":"10.1016/j.eml.2025.102362","url":null,"abstract":"<div><div>The intrinsic fracture energy of polymer networks describes the minimum energy required for crack propagation, excluding any inelastic dissipation within the bulk. Recent studies have demonstrated that the intrinsic fracture energy arises from two distinct contributions. The first contribution <span><math><msub><mrow><mi>Γ</mi></mrow><mrow><mi>f</mi></mrow></msub></math></span> is the energy dissipated by the rupture of polymer chains along the crack path, where these chains constitute the failure zone. The second contribution <span><math><msub><mrow><mi>Γ</mi></mrow><mrow><mi>e</mi></mrow></msub></math></span> is the elastic energy released from the relaxation of polymer chains adjacent to the broken chains, where these chains constitute the elastic release zone. While existing models could predict the intrinsic fracture energy of polymer networks successfully, a quantification of the two intrinsic fracture energy contributions remains elusive. Here, utilizing polyacrylamide hydrogel, we conduct a series of pure shear tests to measure the fracture energy. The size of real elastic release zone is precisely controlled in this study by varying the heights of pure shear samples. Then, for the first time, <span><math><msub><mrow><mi>Γ</mi></mrow><mrow><mi>f</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>Γ</mi></mrow><mrow><mi>e</mi></mrow></msub></math></span> of the polyacrylamide hydrogel are quantitatively identified based on the relationship between the apparent fracture energy and the height of sample. Moreover, our development of a modified loop-opening model represents a significant advancement in the field. This model accounts for polymer network imperfections and incorporates parameters with clear physical meanings, aligning remarkably well with our experimental findings. Based on our model, we propose a novel method for determining the size of failure zone. Furthermore, our findings offer insights into the discrepancies observed in fracture energy measurements obtained through various testing methods. This study enhances the understanding of intrinsic fracture mechanisms within polymer networks and lays the groundwork for the design of tougher polymer materials.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"78 ","pages":"Article 102362"},"PeriodicalIF":4.3,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144195751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Secondary instability and evolution of straight-sided blisters in cylindrical film-substrate systems","authors":"Jiahui Zhang ,&nbsp;Yi Sun ,&nbsp;Linghui He ,&nbsp;Yong Ni","doi":"10.1016/j.eml.2025.102360","DOIUrl":"10.1016/j.eml.2025.102360","url":null,"abstract":"<div><div>The regulation of buckle delamination morphologies in compressed thin films is crucial for ensuring material stability, particularly in systems with curved substrates. While substrate curvature is known to influence surface instabilities, its specific role in governing buckle delamination remains insufficiently understood. This paper investigates the secondary instability and evolution of straight-sided blisters in cylindrical film-substrate systems with both positive and negative curvature through theoretical analysis and finite element simulations. Linear stability analysis elucidates the dependence of critical buckling stress and wavelength on the amplitude and sign of curvature and Poisson’s ratio, revealing distinct instability regimes. The calculated phase diagrams for secondary instability mode selection indicate that symmetric modes dominate at small curvature and low Poisson’s ratios, while antisymmetric modes prevail at larger values. Finite element simulations not only validate the linear stability predictions, but also capture nonlinear evolution of straight-sided blisters into dendritically branched morphologies with dimple-like structures beyond secondary instability. These findings provide new insights into the interplay between curvature, material properties, and instability modes in compressed film-substrate systems.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"78 ","pages":"Article 102360"},"PeriodicalIF":4.3,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144190164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Frustrated domes: From planar metamaterials to load-bearing structures","authors":"Imtiar Niloy ,&nbsp;Lucas Annink ,&nbsp;Olivine Silier ,&nbsp;Chiara Daraio ,&nbsp;Paolo Celli","doi":"10.1016/j.eml.2025.102352","DOIUrl":"10.1016/j.eml.2025.102352","url":null,"abstract":"<div><div>We show that non-periodic, planar metamaterials can be turned into pop-up dome structures that are up-scalable and load-bearing. We do so by introducing a pin-jointed variation of such metamaterials. We illustrate the pop-up mechanics of these structures – dominated by the non-periodicity-induced frustration of a mechanism motion – via numerical simulations and experiments. We then show that joining together boundary nodes leads to self-standing domes that can bear significant loads, at least 20 times their own weight. Finally, we show that our idea can be easily scaled up to the meter-scale, and we illustrate that one can play around with the geometrical shape of the structural elements to obtain different pop-up shapes. Our work shows how metamaterials-related ideas that work at the tabletop-scale can be turned into concepts for innovative shape-morphing, load-bearing structures.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"78 ","pages":"Article 102352"},"PeriodicalIF":4.3,"publicationDate":"2025-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144167209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hexagonal tessellation-based mechanical metamaterials","authors":"Reza Moghimimonfared,&nbsp;Andrea Spaggiari,&nbsp;Luigi Grasselli,&nbsp;Luke Mizzi","doi":"10.1016/j.eml.2025.102356","DOIUrl":"10.1016/j.eml.2025.102356","url":null,"abstract":"<div><div>Mechanical metamaterials based on Euclidean polygonal tessellations represent a new class of architectured materials with the potential to exhibit a wide range of mechanical properties. In this work, we investigate a new class of systems based on the generic hexagonal tessellation with trigonal rotational symmetry and show how this tessellation has the potential to exhibit a wide range of Poisson’s ratios, including auxeticity, as well as a large spectrum of Young’s moduli whilst retaining transverse isotropy. The tessellation was characterized through geometric expressions in order to identify which combination of geometric parameters lead to realizable, concave or convex configurations and Finite Element simulations were used to evaluate the mechanical properties of these tessellations. Furthermore, three additively-manufactured prototypes, representative of the entire Poisson’s ratio range (i.e. negative, zero and positive Poisson’s ratio) were experimentally tested and analysed using Digital Image Correlation. The results obtained from both simulation and experimental approaches demonstrate the mechanical capabilities of these tessellations and indicate how new auxetic metamaterials may be found by exploring the vast design space afforded by Euclidean polygonal tilings.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102356"},"PeriodicalIF":4.3,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144137877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Implicit geometric descriptor-enabled ANN Framework for a unified structure-property relationship in architected nanofibrous materials","authors":"Bhanugoban Maheswaran,&nbsp;Komal Chawla,&nbsp;Abhishek Gupta,&nbsp;Ramathasan Thevamaran","doi":"10.1016/j.eml.2025.102346","DOIUrl":"10.1016/j.eml.2025.102346","url":null,"abstract":"<div><div>Hierarchically architected nanofibrous materials, such as the vertically aligned carbon nanotube (VACNT) foams, draw their exceptional mechanical properties from the interplay of nanoscale size effects and inter-nanotube interactions within and across architectures. However, the distinct effects of these mechanisms, amplified by the architecture, on different mechanical properties remain elusive, limiting their independent tunability for targeted property combinations. Reliance on architecture-specific explicit design parameters further inhibits the development of a unified structure–property relationship rooted in those nanoscale mechanisms. Here, we introduce two implicit geometric descriptors — multi-component shape invariants (MCSI) — in an artificial neural network (ANN) framework to establish a unified structure–property relationship that governs diverse architectures. The MCSIs effectively capture the key nanoscale mechanisms that give rise to the bulk mechanical properties such as specific-energy absorption, peak stress, and average modulus. Exploiting their ability to predict mechanical properties for designs that are even outside of the training data, we propose generalized design strategies to achieve desired mechanical property combinations in architected VACNT foams. Such implicit descriptor-enabled ANN frameworks can guide the accelerated and tractable design of complex hierarchical materials for applications ranging from shock-absorbing layers in extreme environments to functional components in soft robotics.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102346"},"PeriodicalIF":4.3,"publicationDate":"2025-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144089585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cylindrical cavity expansion for characterizing mechanical properties of soft materials","authors":"Jian Li ,&nbsp;Zihao Xie ,&nbsp;Hannah Varner ,&nbsp;S. Chockalingam ,&nbsp;Tal Cohen","doi":"10.1016/j.eml.2025.102343","DOIUrl":"10.1016/j.eml.2025.102343","url":null,"abstract":"<div><div>The low elastic modulus of soft materials, combined with geometric nonlinearity and rate dependence, presents significant challenges in the characterization of their mechanical response. We introduce a novel method for measuring the mechanical properties of soft materials under large deformations via cylindrical cavity expansion. In this method, a cylindrical cavity is fabricated in the material and expanded by volume-controlled injection of an incompressible fluid with simultaneous measurement of the applied pressure at the cavity wall. The relationship between applied pressure and deformation at the cavity wall is then employed to characterize the nonlinear mechanical properties. This method improves traditional volume-controlled cavity expansion testing and other needle-induced cavity expansion methods by precisely controlling the geometry and size of the initial defect or cavity, significantly enhancing both the accuracy and repeatability of the experimental results. We demonstrate the feasibility of the proposed method and validate it by measuring the mechanical properties of synthetic polydimethylsiloxane (PDMS) and comparing with reported values in the literature. Results indicate that the cylindrical cavity expansion method effectively captures the response of PDMS over a wide range of stiffness (shear modulus ranging from 5 kPa to 300 kPa) and exhibit high repeatability. The proposed method overcomes limitations in characterization of ultra-soft materials using traditional testing methods, such as challenges with fabrication and clamping in uniaxial tension testing and friction and adhesion effects in compression and indentation testing, thus enabling accurate and precise characterization.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102343"},"PeriodicalIF":4.3,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144134765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mode-coupled infinite topological edge state in bulk-lattice-merged mechanical Su–Schrieffer–Heeger chain","authors":"Yeongtae Jang ,&nbsp;Seokwoo Kim ,&nbsp;Minkyung Kim ,&nbsp;Guenil Kim ,&nbsp;Eunho Kim ,&nbsp;Junsuk Rho","doi":"10.1016/j.eml.2025.102334","DOIUrl":"10.1016/j.eml.2025.102334","url":null,"abstract":"<div><div>Band topology has emerged as a powerful tool for designing mechanical engineering systems, from phononic crystals to metamaterials. Various design principles — whether bulk-based or lattice-based — have been proposed and successfully implemented according to unit cell structures. Here, we present a bulk-lattice merged Su–Schrieffer–Heeger (SSH) chain constructed from single-column woodpile metamaterials. This system consists of a lattice array of cylindrical particles, where each particle’s bulk dynamics exhibits local resonance-mode coupling with wave propagation. We demonstrate that topological edge states emerge in direct correspondence with these local resonance modes, manifesting as mode-coupled topological states. Experimentally, we observe the initial emergence of these mode-coupled topological edge states, with their frequencies accurately predicted by nonlinear characteristic equations rooted in continuum dynamics and topological symmetry. Additionally, the system’s weak nonlinearity enables simultaneous frequency shifts, allowing multivariate tunability in its topological states.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102334"},"PeriodicalIF":4.3,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144106868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geometric dependence of curvature-induced rigidity","authors":"Hanzhang Mao ,&nbsp;Thomas G.J. Chandler ,&nbsp;Mark Han ,&nbsp;Saverio E. Spagnolie","doi":"10.1016/j.eml.2025.102341","DOIUrl":"10.1016/j.eml.2025.102341","url":null,"abstract":"<div><div>Bending the edge of a thin elastic material promotes rigidity far from its clamped boundary. However, this curvature-induced rigidity can be overwhelmed by gravity or other external loading, resulting in elastic buckling and large deformations. We consider the role of body geometry on this competition using experiments, numerical simulations, and reduced-order models. Finite element simulations are performed using a model nonlinear hyperelastic material, and a theoretical framework is proposed that incorporates small lateral curvatures, large longitudinal rotations, and a varying cross-sectional width. A particular focus is on the comparison between rectangular and triangular sheets, and trapezoidal sheets in between. Sheet geometry affects downward tip deflection by changing the relative importance of the sheet’s weight and the rigidity provided by curvature, often in subtle ways. In extreme cases, non-monotonic deflection is observed with increasing sheet length, and a region of hysteretic bistability emerges, becoming more pronounced with rectangular sheets and large imposed curvatures. These findings demonstrate the profound impact of geometry on the competition between curvature-induced rigidity and gravity-induced deformation in thin elastic materials.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102341"},"PeriodicalIF":4.3,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143943646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Force-biased chemical degradation in rubbery networks: Insights from discrete network simulations","authors":"Lucas Mangas Araujo,&nbsp;Laurence Brassart","doi":"10.1016/j.eml.2025.102344","DOIUrl":"10.1016/j.eml.2025.102344","url":null,"abstract":"<div><div>This study investigates the effect of force-assisted chemical reaction leading to chain scission on the mechanical and swelling behaviour of rubbery networks. A Discrete Network (DN) modelling approach is adopted, in which polymer chains are represented as entropic springs connected at crosslink points. Force-accelerated chain scission is simulated using a Kinetic Monte Carlo algorithm. The model further accounts for degradation-induced swelling due to solvent uptake and mass loss due to the release of chain clusters detached from the main network. Discrete Network simulations highlight the role of force heterogeneities on the degradation of mechanical properties. Chains bearing the largest forces are cut preferentially, which accelerates the reduction in modulus and loss of percolation. When degradation occurs under constraint, force-biased degradation leads to anisotropic residual elastic properties. These effects cannot be captured by a state-of-the-art micromechanics-based continuum model, which does not account for the redistribution of forces through the network. Overall, the discrete network framework provides a promising platform to study a broader range of mechano-chemical phenomena in elastomers and gels.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102344"},"PeriodicalIF":4.3,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143931890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}