Extreme Mechanics Letters最新文献

{"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}

{"title":"Multiple broad bandgaps soundproofing for sectoral labyrinthine metamaterials","authors":"Erfan Asgari ,&nbsp;Abdolreza Ohadi ,&nbsp;Reza Hedayati","doi":"10.1016/j.eml.2025.102349","DOIUrl":"10.1016/j.eml.2025.102349","url":null,"abstract":"<div><div>Acoustic metamaterials are notable for their light weight and exceptional ability to control low-frequency sounds, making them ideal for applications requiring both soundproofing and ventilation. In this paper, metamaterials with various labyrinthine structures were designed using the space-coiling strategy, featuring sectoral labyrinthine resonators arranged in a circular pattern around a central circular passage for airflow. The noted metamaterials were categorized into four levels based on the use of different sectoral resonators. In level-1, all resonators were identical, while in levels 2, 3, and 4, two, three, and four different resonators were used, respectively. The sound insulation performance was evaluated through Sound Transmission Loss (STL) test using an impedance tube, as well as numerical simulations. The results indicated that the development of level-1 geometric configurations led to a shift in the STL curves toward higher frequencies and an increase in the width of the first bandgap. The widest observed bandgap was in the frequency range of 937–2078 Hz, covering approximately 55 % of the targeted frequency range (below 2000 Hz). With the introduction of higher-level configurations, multiple bandgaps, along with several peaks, appeared in the STL spectra. These multiple bandgaps result from Fano resonances generated by the various sectoral resonators. Fano resonances are inversely related to the effective length of each sectoral resonator, allowing for tuning to achieve different sound insulation performances. The maximum frequency coverage was approximately 50 % for level-2, around 40 % for level-3, and about 30 % for level-4.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102349"},"PeriodicalIF":4.3,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143911688","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":"Meta-fence for Rayleigh wave isolation","authors":"Hongjun Fan ,&nbsp;Yunhao Zhang ,&nbsp;Peng Jiang ,&nbsp;Le An ,&nbsp;Yanping Wang ,&nbsp;Yongquan Liu","doi":"10.1016/j.eml.2025.102350","DOIUrl":"10.1016/j.eml.2025.102350","url":null,"abstract":"<div><div>The protection of infrastructures against earthquakes has been a primary objective within the field of civil engineering. The emergence of seismic metamaterials has offered an unprecedented opportunity to design advanced aseismic structures over the last decade. However, a large number of subwavelength resonators that span multiple wavelengths are always required, resulting in a bulky size of existing seismic metamaterials. In this work, we introduce an aboveground single-layer meta-fence to omnidirectionally isolate Rayleigh waves. Based on mode conversion and reflection, the meta-fence can be configured into an enclosed region to effectively safeguard inner infrastructures by reducing the amplitude by 85 %. Furthermore, the designed meta-fence can operate across a wide frequency spectrum ranging from 17 to 200 Hz. Compared with previous seismic metamaterials, our scheme of meta-fence exhibits a distinct advantage in compact size, thereby enhancing applicability in earthquake protection.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102350"},"PeriodicalIF":4.3,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143921951","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":"Three-dimensional auxetic metamaterials with extremely tunable flexible behavior","authors":"Xiang Li ,&nbsp;Weitao Peng ,&nbsp;Rong Fan ,&nbsp;Yang Lu","doi":"10.1016/j.eml.2025.102351","DOIUrl":"10.1016/j.eml.2025.102351","url":null,"abstract":"<div><div>Flexible auxetic metamaterials has demonstrated significant potential in engineering applications. However, most existing flexible auxetic metamaterials are limited to two-dimensional (2D) designs, restricting their utility in real 3D engineering scenarios. Here we represent a versatile strategy for designing 3D auxetic metamaterials that showcase extraordinary flexibility, recoverability, and programmability which is accomplished by embedding truss lattice with elastic spring into rotating rigid frameworks. We exemplify this approach with the eccentric spring connected rotating octet truss structures (ROCT-S) through experimental, numerical, and theoretical analysis. Under in-plane tension, engineering stress of the proposed eccentric spring connected rotating octet truss structures in two directions (ROCT-S-2D) is approximately 9.4 × 10⁻⁶ of the base material’s modulus at an average strain of 161 %. Simultaneously, the programmable mechanical performance of the ROCT-S-2D under out-plane compression is decoupling with their in-plane performance and can be designed to support a load exceeding 12,800 times its own weight. The robust and adaptable mechanical performance of ROCT-S highlight its broad applicability, spanning electronics and biomedical devices to wearable flexible protective gear, paving the way for advanced 3D auxetic metamaterials in practical engineering solutions.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102351"},"PeriodicalIF":4.3,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906908","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":"Non-ordinary state-based peridynamic simulation of compressive large deformation and failure in hydrogel materials","authors":"Hao-Yu Liu ,&nbsp;Liu-Chao Qiu ,&nbsp;Yi Liu","doi":"10.1016/j.eml.2025.102348","DOIUrl":"10.1016/j.eml.2025.102348","url":null,"abstract":"<div><div>Hydrogel materials have broad application prospects in biomedical and other fields. Understanding the large deformation and failure characteristics of hydrogel materials is crucial for their engineering applications. However, simulating the compressive large deformation and failure behavior of hydrogel-like soft materials in three-dimensional scenarios is very challenging. This paper proposed a stabilized three-dimensional non-ordinary state-based peridynamics approach for simulating the compressive large deformation and failure behavior of hydrogel-like soft materials. To control numerical instabilities, a supplementary force state of zero-energy modes is introduced, and a second-order Reduced Polynomial hyperelastic model is applied for constitutive modeling. The computational framework employs an explicit dynamic solution method to simulate three-dimensional large deformation and failure of hyperelastic specimens with complex geometric configurations. Due to its nonlocal theory and mesh-free properties, the proposed method can effectively address the challenges of simulating large deformation and fracture failure of soft materials. First, different zero-energy control methods are validated, followed by an analysis of models with different grid spacings to verify the model's mesh convergence. Finally, compression failure tests of hydrogel spheres under different loading rates are simulated to verify the reliability and simulation performance of the proposed method. In compression failure scenarios, the predicted deformation and load-displacement responses are highly consistent with experimental observations, demonstrating the effectiveness and accuracy of the developed stabilized three-dimensional state-based peridynamics framework in predicting the failure behavior of soft materials under compressive large deformations.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102348"},"PeriodicalIF":4.3,"publicationDate":"2025-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143898780","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":"Topology optimization for creating nonreciprocal compliant mechanisms: Numerical and experimental investigations","authors":"Vahid Shobeiri ,&nbsp;Yi Min Xie","doi":"10.1016/j.eml.2025.102345","DOIUrl":"10.1016/j.eml.2025.102345","url":null,"abstract":"<div><div>In this study, a topology optimization technique is developed based on the bi-directional evolutionary structural optimization (BESO) method for the creation of nonreciprocal complaint mechanisms (NCMs). The internal contact surface model is proposed as a simple and innovative approach to making complaint mechanism systems nonreciprocal. The design problem is formulated as maximizing the flexibility of NCMs with a desired level of nonreciprocity subject to a volume constraint. Based on the BESO method, a novel type of NCMs is developed with potential applications in various engineering fields. The topology optimization of a nonreciprocal inverter mechanism is studied, and the effectiveness of the proposed method is verified through experiments. The numerical and experimental results indicate that topologically optimized designs of NCMs and their asymmetric deformation can be significantly controlled by the degree of nonreciprocity. The findings from this study can be used as a basis for designing a wide range of nonreciprocal structural systems.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102345"},"PeriodicalIF":4.3,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873810","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":"A method to characterize the cavitation pressure of soft matter under superimposed azimuthal shear","authors":"Alexandria Rogers ,&nbsp;Yuan Ji ,&nbsp;Vladimir Coon ,&nbsp;Christopher J. Karber ,&nbsp;Jacob A. Rogers ,&nbsp;Justin W. Wilkerson","doi":"10.1016/j.eml.2025.102325","DOIUrl":"10.1016/j.eml.2025.102325","url":null,"abstract":"<div><div>In many applications (<em>e.g.</em> contact sports, vehicular accidents, blunt force trauma, traumatic brain injury, drug delivery, surgeries), biological tissues and other soft matter are subject to complex, multi-axial stress states that can induce a variety of material deformation and failure modes. Cavitation is a particular soft matter failure mode that is insufficiently understood and poorly characterized. To the best of the authors’ knowledge, cavitation has only been investigated in initially stress-free samples. The lack of data for soft matter behavior under multi-axial stress states prevents the development and validation of generalized cavitation theories. This study introduces a superimposed shear cavitation (SSC) apparatus that enables an examination of the role torsional shear stress plays in cavity nucleation, expansion, and collapse in soft matter. Our proposed SSC test expands on the well-established needle-induced cavitation (NIC) experiment by housing the gel in a Taylor–Couette cell instead of a conventional beaker. This modification enables the application of azimuthal shear stresses to the gel sample prior to the insertion and pressurization of the syringe needle. To demonstrate its capability, our SSC apparatus was used to measure the critical pressure (<span><math><msub><mrow><mi>P</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>) of tri-block copolymer (PMMA-PnBA-PMMA) gel samples pre-loaded with various degrees of torsion. In a limited set of experiments, <span><math><msub><mrow><mi>P</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> was found to generally increase with increasing amount of applied pre-shear stress, in qualitative agreement with a generalized cavitation theory first introduced by Lopez-Pamies and co-workers, thereby providing some degree of evidence that the SSC apparatus is functioning as intended. Motion tracker particles embedded in the top surface of the gel provide additional evidence that the SSC apparatus generates the intended azimuthal pre-deformation field.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102325"},"PeriodicalIF":4.3,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143886448","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":"Spallation in homogeneous and gradient nano-grained high-entropy alloys","authors":"Xin Du ,&nbsp;Jianfeng Zhao ,&nbsp;Meizhen Xiang ,&nbsp;Fuping Yuan ,&nbsp;Xiaohu Yao ,&nbsp;Xu Zhang","doi":"10.1016/j.eml.2025.102342","DOIUrl":"10.1016/j.eml.2025.102342","url":null,"abstract":"<div><div>The strength and hardness can be improved by adjusting grain size in nano-grained structures. However, their behavior under extreme shock loading remains largely unexplored. This study investigates the shock wave response and spallation characteristics of homogeneous and gradient nano-grained CoCrFeMnNi high-entropy alloys (H-HEA and G-HEA) by molecular dynamics simulation. The results demonstrate that both H-HEA and G-HEA exhibit an elastic-plastic two-wave separation phenomenon, which diminishes with decreasing grain size. Notably, the spall strength of H-HEAs initially decreases and then increases as the grain size decreases, while G-HEA consistently shows superior spall strength compared to H-HEA. The findings suggest that GNG structures inherently possess better shock resistance. The spall strength is closely related to the nucleation ability of voids, which is dominated by the content of disordered structure. In nano-grained structures, voids mainly nucleate at grain boundaries, and the subsequent growth and coalescence lead to intergranular fracture. Additionally, shock loading induces various plastic mechanisms such as stacking faults, deformation twinning, and phase transformations. These findings underscore the critical role of microstructural design, especially GNG structure, in enhancing the shock mechanical properties of HEAs and contribute to the application of HEA in extreme shock environments.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102342"},"PeriodicalIF":4.3,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879202","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":"Negative-pressure soft pneumatic actuators enabled by asymmetrically distributed bending units","authors":"Zeyu Fu ,&nbsp;Tianyu Chen ,&nbsp;Haoran Zou ,&nbsp;Zhiwei Zhu ,&nbsp;Zichen Deng ,&nbsp;Yifan Wang","doi":"10.1016/j.eml.2025.102340","DOIUrl":"10.1016/j.eml.2025.102340","url":null,"abstract":"<div><div>Soft pneumatic actuators are highly flexible and can adapt to complex environments, attracting significant attention for their ability to operate in settings where rigid actuators cannot. Most existing soft pneumatic actuators are powered by positive pressure, which has the disadvantage of volume increase during operation and risk of exploding under large pressures. In this study, we designed a new type of soft actuator by inducing asymmetric bending deformation throughout a holey structure under negative pressure. Using finite element analysis and a theoretical model, we studied the effects of various geometric parameters on the structure's bending behavior. We found that the displacement of the circle's center from the central axis is a parameter with the most significant impact on the bending behavior of the structure. By designing circular holes with offset from the central axis, the structure can bend toward the offset direction during subsequent bending deformation. Based on this deformation mechanism, we designed a soft gripper that bends upon actuation and effectively picks up objects. We further designed a bi-directional gripper that bends towards both sides and a circular gripper that contracts towards the center upon evacuation to hold objects. These soft grippers’ grasping capabilities are validated by experimental tests. Finally, by arranging the holes in a wavy pattern within the structure, we created a crawling robot that moves forward through cyclic negative pressure actuation. These findings highlight the potential of leveraging bending behaviors in asymmetrically distributed holey structures for the development of negative-pressure driven soft actuators and robots.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"77 ","pages":"Article 102340"},"PeriodicalIF":4.3,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143870480","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}