{"title":"Peeling a rigid sphere from a stretched rubber substrate","authors":"Christopher W. Barney , Yue (Luna) Zheng","doi":"10.1016/j.eml.2025.102381","DOIUrl":"10.1016/j.eml.2025.102381","url":null,"abstract":"<div><div>Polymer coatings are an important technology where pre-stresses can develop during draping, drying, and cooling. This paper aims to quantify the impact that these stresses have on the indentation response. Spherical probe indentation is performed on a stretched and unstretched substrate where the evolution of the contact area is monitored. Consistent with previous works, it is found that the contact area becomes elliptical on stretched substrates. Further, it is observed that this ellipse dynamically evolves during the indentation and peel process. This change in contact area upon stretching is found to increase the apparent stiffness and decrease the adhesive response.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"79 ","pages":"Article 102381"},"PeriodicalIF":4.5,"publicationDate":"2025-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144723145","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-local elastic lattices with PT-symmetry and time modulation: From perfect trapping to the wave boomerang effect","authors":"Emanuele Riva","doi":"10.1016/j.eml.2025.102383","DOIUrl":"10.1016/j.eml.2025.102383","url":null,"abstract":"<div><div>Wave motion is fundamentally constrained by the dispersion properties of the medium, often making it challenging — or even impossible — to guide wave packets along desired trajectories, particularly when wave inversion is required. The paper illustrates how one-dimensional (1D) and two-dimensional (2D) non-Hermitian elastic lattices with time-varying non-local feedback interactions offer unprecedented wave guidance. By relaxing the constraint of Hermiticity while preserving <span><math><mi>PT</mi></math></span>-symmetry of the nonlocal interactions, it is herein built a framework where the dispersion transitions from positive to negative group velocity, passing through an intermediate regime characterized by a perfectly flat band across all momenta. This effect, realized within the unbroken <span><math><mi>PT</mi></math></span>-symmetric phase, is further enhanced by the time modulation of lattice parameters, thereby unlocking functionalities such as perfect trapping, where a wave packet is intentionally stopped, and the wave boomerang effect, where the wave packet is reversed or guided back to its initial position. The framework presented in this paper unlocks opportunities that extend beyond wave guidance, including information processing through dispersion engineering in elastic media.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"79 ","pages":"Article 102383"},"PeriodicalIF":4.3,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704221","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":"Inverse design of mechanical metamaterials balancing manufacturability and compactness: A case study on lattice cells","authors":"Jiacheng Xue, Hanmeng Bao, Tengfei Liu, Lingling Wu, Xiaoyong Tian, Dichen Li","doi":"10.1016/j.eml.2025.102395","DOIUrl":"10.1016/j.eml.2025.102395","url":null,"abstract":"<div><div>Mechanical metamaterials are artificially engineered structures designed to exhibit unique and extraordinary mechanical properties. In recent years, machine learning has provided a more efficient and systematic approach, enabling inverse design of mechanical metamaterials, which allow for a broader exploration of material properties and support the integration of multifunctionality, significantly speeding up the design process. Despite the many advantages of inverse design, metamaterials often involve a trade-off between competing performance metrics-such as manufacturability and structural compactness. Furthermore, these trade-offs should be dynamically adjusted based on different additive manufacturing conditions. To address this, we proposed a regressional and conditional generative adversarial network based multi-objective (RCGAN-MO) architecture, which simultaneously handles the inverse design and adjustable multi-objective optimization of mechanical metamaterials. The RCGAN-MO includes two trained neural networks: a generator and a predictor, along with a weighted multi-objective optimizer. As a case study, the RCGAN-MO architecture is applied to the inverse design of the relative compressive elastic modulus for a metamaterial, and metamaterials with different weight vector values in the multi-objective optimizer are achieved through 3D printed prototypes. This approach achieves high accuracy and could adjust the importance of manufacturability and compactness, offering a flexible, scalable solution for engineering metamaterials tailored to practical application demands.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"79 ","pages":"Article 102395"},"PeriodicalIF":4.3,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704220","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}
Xiaoqian Gao , Li Chen , Runkai Liu , Jing Wan , Huasong Qin , Yilun Liu
{"title":"Multiscale structure-mechanical property relationship and data-driven design of ultra-high temperature ceramics: A review","authors":"Xiaoqian Gao , Li Chen , Runkai Liu , Jing Wan , Huasong Qin , Yilun Liu","doi":"10.1016/j.eml.2025.102392","DOIUrl":"10.1016/j.eml.2025.102392","url":null,"abstract":"<div><div>Ultra-high temperature ceramics (UHTCs) exhibit exceptional melting points, superior oxidation resistance, and outstanding ablation performance, positioning them as indispensable materials for extreme-environment applications. However, their inherent brittleness, high density, limited elasticity, and poor fatigue resistance restrict broader implementation. This review presents a rigorous, multiscale examination of interrelationships between UHTC structural characteristics and mechanical behaviors, addressing critical knowledge gaps in failure mechanisms and state-of-the-art design of strengthening and toughening strategies. The analysis commences with crystal-chemical principles and progresses through salient microstructural and mesostructural characteristics, followed by an exploration of thermally induced deformation and structural evolution at elevated temperatures. The dominated factors in mechanical degradation and corresponding strengthening and toughening mechanisms across nanoscale, microscale, and mesoscale levels are systematically dissected. Furthermore, we highlight recent advances in high-throughput screening within materials genome engineering and the integration of machine learning (ML) for rapid property prediction and structural optimization of UHTCs. Finally, prospective multiscale design strategies are proposed to synergistically optimize the balance of strength and toughness in UHTCs.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"79 ","pages":"Article 102392"},"PeriodicalIF":4.3,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704219","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":"Band gap analysis and prediction for phononic metamaterials with different spiral shapes based on transfer learning","authors":"Majid Kheybari, Hongyi Xu","doi":"10.1016/j.eml.2025.102379","DOIUrl":"10.1016/j.eml.2025.102379","url":null,"abstract":"<div><div>This study presents a comprehensive computational investigation of band gap characteristics in spiral-based phononic metamaterials, including Archimedean, Octagon, Hexagon, and Square spiral configurations. It offers a quantitative understanding of the similarities in Bloch wave properties across these spiral types and demonstrates the feasibility of using data from known spiral patterns to facilitate the property prediction of new types. Based on the spiral datasets that vary in the number of turns, cutting width, and inner radius, we observed strong correlations in band gap counts among patterns (e.g., Rotated Octagon and Octagon, Archimedean and Rotated Octagon), indicating similar behaviors in band gap occurrence across different geometries. It was also found that the rotation of geometric shapes had a minor impact on band gap counts. However, we observed that the distribution of band gap width varies significantly across different types of spirals, with weak correlations. Furthermore, we demonstrate that transfer learning (TL) enhances prediction accuracy for new spiral types compared to traditional neural network approaches. TL model demonstrated superior performance, effectively capturing complex band gap details and improving overall prediction accuracy, without requiring extensive training data.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"79 ","pages":"Article 102379"},"PeriodicalIF":4.3,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703631","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":"Modeling the dynamics of sub-millisecond electroadhesive engagement and release times","authors":"Ahad M. Rauf, Sean Follmer","doi":"10.1016/j.eml.2025.102382","DOIUrl":"10.1016/j.eml.2025.102382","url":null,"abstract":"<div><div>Electroadhesive clutches are electrically controllable switchable adhesives commonly used in soft robots and haptic user interfaces. They can form strong bonds to a wide variety of surfaces at low power consumption. However, electroadhesive clutches in the literature engage to and release from substrates several orders of magnitude slower than a traditional electrostatic model would predict. Large release times, in particular, can limit electroadhesion’s usefulness in high-bandwidth applications. We develop a novel electromechanical model for electroadhesion, factoring in polarization dynamics, the drive circuitry’s rise and fall times, and contact mechanics between the dielectric and substrate. We show in simulation and experimentally how different design parameters affect the engagement and release times of centimeter-scale electroadhesive clutches to metallic substrates, and we find that the model accurately captures the magnitude and trends of our experimental results. In particular, we find that higher drive frequencies, narrower substrate aspect ratios, and faster drive circuitry output stages enable significantly faster release times. The fastest clutches have engagement times less than <span><math><mrow><mn>15</mn><mspace></mspace><mi>μ</mi></mrow></math></span>s and release times less than <span><math><mrow><mn>875</mn><mspace></mspace><mi>μ</mi></mrow></math></span>s, which are 10<span><math><mo>×</mo></math></span> and 17.1<span><math><mo>×</mo></math></span> faster, respectively, than the best times found in prior literature on centimeter-scale electroadhesive clutches.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"79 ","pages":"Article 102382"},"PeriodicalIF":4.3,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694475","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}
Shah Khalid , Jiyu Li , Han Chen , Longyu Pan , Lidan Tan , Ke Wu , Mingchao Liu , Liu Wang
{"title":"Modeling of magnetic soft catheters in contact with aneurysms","authors":"Shah Khalid , Jiyu Li , Han Chen , Longyu Pan , Lidan Tan , Ke Wu , Mingchao Liu , Liu Wang","doi":"10.1016/j.eml.2025.102385","DOIUrl":"10.1016/j.eml.2025.102385","url":null,"abstract":"<div><div>Magnetic soft catheters (MSCs) represent a breakthrough for remote navigation in minimally invasive endovascular procedures, especially in the coil embolization of cerebral aneurysms. However, current MSC models often neglect the contact interaction between the catheter and the aneurysm boundary during navigation, which limits their real-world use. To address this issue, this paper introduces a detailed theoretical model that considers the magneto-mechanical behavior of MSCs and the contact with aneurysms in endovascular environments. The navigation of MSCs through aneurysms of different shapes, such as circular, elliptic, and rounded-elliptic, is investigated to simulate the various anatomical constraints in clinical practice. We present a numerical framework based on polynomial approximations and weighted residuals to analyze the deflections of MSCs in contact with aneurysms under varying magnetic fields. A parametric analysis further explores the impact of magnetic field strength, magnetic field direction, catheter flexibility, and aneurysm wall shape, allowing adjustments to ensure safe navigation. We also examine how these factors affect MSC’s ability to navigate different aneurysm shapes, offering insights for optimizing design strategies for practical use. The proposed model is validated through finite element method (FEM) simulations and experiments, accurately predicting large deformations of MSCs in contact with aneurysms in endovascular environments. The results provide key guidelines for safely navigating MSCs, thus reducing the risk of incorrect coil placement during embolization and laying a solid foundation for the clinical application of MSCs in endovascular procedures.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"79 ","pages":"Article 102385"},"PeriodicalIF":4.3,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703633","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}
Yilong Chang , Guansheng Li , Jay Sim , George Em Karniadakis , Ruike Renee Zhao
{"title":"Clot treatment via spinning-induced fibrin microstructure densification and clot volume reduction","authors":"Yilong Chang , Guansheng Li , Jay Sim , George Em Karniadakis , Ruike Renee Zhao","doi":"10.1016/j.eml.2025.102391","DOIUrl":"10.1016/j.eml.2025.102391","url":null,"abstract":"<div><div>Blood clots, composed of red blood cells (RBCs) embedded within a fibrin network, can cause life-threatening conditions such as strokes and heart attacks. However, conventional thrombectomy techniques, such as aspiration or stent retrievers, often struggle with large or tough clots, limiting their clinical efficacy. The recently developed milli-spinner thrombectomy offers a breakthrough approach that fundamentally departs from these traditional methods. Instead of extracting the clot intact, the milli-spinner mechanically shrinks the clot by densifying its microstructure through the combined action of compression and shear forces, achieving up to 95 % volume reduction. This novel clot debulking strategy enables more effective clot removal and holds strong potential for significantly improved clinical outcomes in thrombectomy procedures. To uncover the underlying mechanisms and optimize performance, we combine in vitro experiments with dissipative particle dynamics (DPD) simulations for multiscale analysis of clot volume reduction and microstructural densification under integrated compression and shear. Experiments quantify macroscopic clot volume reduction under controlled loading, while simulations reveal microscale fibrin network densification and RBC release. This systematic study provides a quantitative understanding of how different loading modes alter clot microstructure across clot types. These findings lay the foundation for the rational design of next-generation thrombectomy systems, capable of mechanically reconfiguring clot microstructure in situ, offering enhanced efficacy and broader clinical applicability.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"79 ","pages":"Article 102391"},"PeriodicalIF":4.3,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704218","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}
Brianna MacNider , Dana M. Dattelbaum , Nicholas Boechler , Carl Cady , Benjamin K. Derby , Saryu Fensin , Kwan-Soo Lee , Jihyeon Kim , Sushan Nakarmi , Nitin Daphalapurkar
{"title":"Influence of strain-rate on the response of elastomeric architected materials","authors":"Brianna MacNider , Dana M. Dattelbaum , Nicholas Boechler , Carl Cady , Benjamin K. Derby , Saryu Fensin , Kwan-Soo Lee , Jihyeon Kim , Sushan Nakarmi , Nitin Daphalapurkar","doi":"10.1016/j.eml.2025.102389","DOIUrl":"10.1016/j.eml.2025.102389","url":null,"abstract":"<div><div>Architected materials have shown substantial promise in impact mitigation and protective applications, and there has accordingly been great interest in better characterizing their response at elevated strain rates due to impact. There remains ambiguity regarding the contribution of inertial and material responses to strain rate sensitivity, and, in particular, when these effects begin to gain dominance in the impact response of an architected material. The response of soft polymer architected materials as a function of strain rate, in particular, has been little investigated. We characterize the experimental impact response of four soft polymer architected lattice geometries across varying strain rates in the intermediate strain rate regime (∼10<sup>3</sup> s<sup>−1</sup>) using split-Hopkinson pressure bar loading and high speed video characterization of the resulting deformation fields. Our results highlight the interplay of influence between constituent material, lattice geometry, length scale, and strain rate in determining the onset of significant inertia effects.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"79 ","pages":"Article 102389"},"PeriodicalIF":4.3,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144670476","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}