Extreme Mechanics Letters最新文献

{"title":"Collision resistant study of spherical tensegrity structures for protective drone shells","authors":"Yaoyao Zhang ,&nbsp;Kexin Zheng ,&nbsp;Yi Zhao ,&nbsp;Zhiyuan Zheng ,&nbsp;Bingxing Chen ,&nbsp;Muhao Chen","doi":"10.1016/j.eml.2025.102312","DOIUrl":"10.1016/j.eml.2025.102312","url":null,"abstract":"<div><div>Due to its lightweight, impact resistance, and energy absorption, tensegrity is a good candidate for drone protection. Researching its collision resistance can significantly improve drone adaptability. This paper examines the structure–ground interaction and collision dynamics of 6-bar, 12-bar, and 30-bar tensegrity spheres through simulations and experiments. Results show consistency between simulations and experiments, confirming the collision dynamics model’s effectiveness. The 6-bar tensegrity structure demonstrates excellent collision resistance. Additionally, the influence of structural materials, pretension, and ground types on the 6-bar structure is analyzed, showing that increased cable pretension to certain values reduces peak acceleration during collisions. Drone collision tests with trees and high-altitude drops further confirm the tensegrity sphere’s good environmental adaptability and protective effect.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"76 ","pages":"Article 102312"},"PeriodicalIF":4.3,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629180","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 and control of coupled soft viscoelastic actuators based on sparse identification method","authors":"Jisen Li ,&nbsp;Anjing Cheng ,&nbsp;Hao Wang,&nbsp;Zhipeng Xu,&nbsp;Jian Zhu","doi":"10.1016/j.eml.2025.102309","DOIUrl":"10.1016/j.eml.2025.102309","url":null,"abstract":"<div><div>Dielectric elastomer actuators (DEAs) are extensively employed as artificial muscles in bioinspired soft robotics due to their large voltage-induced deformations and muscle-like characteristics. Achieving complex, multiple degree of freedom(DOF) motions often requires coupling multiple DEAs. However, modeling and controlling coupled DEAs pose significant challenges due to their inherently nonlinear response, driven by factors such as rate-dependent viscoelasticity, design irregularities, and complex interactions among adjacent actuators. This study presents a comprehensive framework for the modeling and control of multiple coupled DEAs, leveraging a sparse identification approach to derive explicit governing equations that effectively describe the viscoelastic and coupling effects from experimental data. Using these identified equations, we design a model predictive controller (MPC) that enables precise trajectory tracking across a range of motion profiles. The proposed framework is validated through tracking experiments on DEAs with two DOFs, demonstrating its effectiveness and robustness. This approach offers a novel pathway for uncovering the underlying physics of coupled DEAs, with the potential to enhance the functional capabilities of DEA-driven soft robotic systems.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"76 ","pages":"Article 102309"},"PeriodicalIF":4.3,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143641786","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":"DNN-based inverse design of line heating patterns for automated plate forming in shipbuilding using multi-start convex optimization","authors":"Hyeonbin Moon ,&nbsp;Kundo Park ,&nbsp;Jaemin Lee ,&nbsp;Donggi Lee ,&nbsp;Seunghwa Ryu","doi":"10.1016/j.eml.2025.102313","DOIUrl":"10.1016/j.eml.2025.102313","url":null,"abstract":"<div><div>Line heating is a widely used plate forming technique in the shipbuilding industry, where steel plates are heated along specified paths to achieve desired deformations. Traditionally, the design of these heating patterns relies on the expertise of skilled workers due to the complex and nonlinear relationship between the heating patterns and the resultant plate deformations. This reliance often results in inconsistent productivity and quality. This study presents a data-driven inverse design framework that automates the optimization of line heating patterns for specified plate deformations, addressing the need for rapid and systematic methodologies. A deep neural network (DNN) trained on finite element method (FEM) simulation data, which validated against experimental results, is employed to model the relationship between initial plate geometry, line heating patterns, and resultant deformations. This surrogate model enables rapid predictions of deformed plate shapes. Utilizing the trained DNN, a multi-start convex optimization process is employed to identify the optimal line heating patterns for any given initial plate geometry and desired deformation. The proposed framework demonstrates significant potential for various engineering inverse design applications requiring prompt and accurate results, as validated by designing line heating patterns for 800 different plate shapes, achieving desired deformations not included in the training data.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"76 ","pages":"Article 102313"},"PeriodicalIF":4.3,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620403","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":"Tiny scale defect contour recognition on curved structure based on electromagnetic thermography","authors":"Lihua Guo ,&nbsp;Wei Guo ,&nbsp;Ling He ,&nbsp;Liming Chen ,&nbsp;Yue Li ,&nbsp;Shunping Yan ,&nbsp;Qiang Wan ,&nbsp;Shejuan Xie ,&nbsp;Zhenmao Chen","doi":"10.1016/j.eml.2025.102311","DOIUrl":"10.1016/j.eml.2025.102311","url":null,"abstract":"<div><div>Precision spherical pressure vessels are used in critical pressure-bearing structures due to their excellent structural strength. The surface of the spherical shell may experience corrosion in long-term service, leading to the formation of tiny pitting defects, which cause a risk to the structural integrity. A high-precision, non-destructive method is required for tiny defects detecting and contour recognition. In this paper, firstly, a new sensor consisting of a rotatable yoke and spherical adaptive flexible material with high permeability (FMHP) is designed to improve the performance of the electromagnetic thermography, which achieves the detection of tiny scale defects in spherical shell surface with diameter of 40μm. Secondly, super-resolution algorithms based on machine learning and deep learning are developed to realize the contour recognition of tiny defects, indicating that the generative adversarial network has an optimum performance. Then, to address the distortion phenomenon in infrared imaging of spherical structures, a coordinate transformation-based image correction algorithm is developed, enabling the accurate reconstruction of defect contours.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"76 ","pages":"Article 102311"},"PeriodicalIF":4.3,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143600934","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":"Front cover CO1","authors":"","doi":"10.1016/S2352-4316(25)00018-5","DOIUrl":"10.1016/S2352-4316(25)00018-5","url":null,"abstract":"","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"75 ","pages":"Article 102306"},"PeriodicalIF":4.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A unified phonon-softening-based model to uncover processing history dependent strain hardening in metallic solids","authors":"Jinguo Lin ,&nbsp;Li Yu ,&nbsp;Cen Chen ,&nbsp;Tzu-Chiang Wang ,&nbsp;Feng Liu","doi":"10.1016/j.eml.2025.102310","DOIUrl":"10.1016/j.eml.2025.102310","url":null,"abstract":"<div><div>Recent years, microstructures are taken advantage to promote the improvement of both strength and ductility in metallic solids, or in other words to tailor the strain hardening behavior. Despite complicacy of microstructures, following the same processing protocol, it could guide as-cast samples all the way to the target structure and properties, which suggests that establishing a processing history dependent strain hardening model could be a way out for a better behavior description or even performance prediction. Based on a nonlinear transformation to strain, the common regularity of the processing history influence to metallic solids’ strain hardening behavior is uncovered, which helps us to model the processing history dependent strain hardening and its validity is confirmed by comparing with eighteen experimental data sets (66 stress-strain curves). Our theoretical model enables quantitatively describing the processing history dependence of strain hardening and even could be possibly used to characterize processing methods, which may provide insights into the strategy of evading strength–ductility trade-off.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"76 ","pages":"Article 102310"},"PeriodicalIF":4.3,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562486","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":"Structural effects of ply-level imperfections and extreme temperatures on bistable ultra-thin composite booms","authors":"Chloé Zarader,&nbsp;Xin Ning","doi":"10.1016/j.eml.2025.102305","DOIUrl":"10.1016/j.eml.2025.102305","url":null,"abstract":"<div><div>Bistable ultra-thin composite booms capable of self-deploying from coiled stable configuration to extended shape offer significant potential for lightweight deployable space structures. This paper explores the effects of ply-level thickness and angle defects on the bistable behavior of ultra-thin composite booms with circular cross-sections made from carbon fiber-reinforced epoxy (CF-Epoxy) and glass fiber-reinforced polypropylene (GF-PP) laminates. The results show that the curvatures and coiling angles are more sensitive to ply angle defects than to ply thickness imperfections. This work investigates the influence of uniform temperature variations on the bistability of the booms and the shapes of stable equilibrium states. The results suggest that the CF-Epoxy boom can maintain bistability with a wide range of temperatures, but the GF-PP boom would lose bistability in typical temperatures in space. The temperature variations have stronger effects on the coiled stable state than the extended stable shape. Furthermore, the paper investigates the combined effects of imperfections and temperature variations on the CF-Epoxy boom. Ply-level imperfections generally intensify the effects of temperature variations on the curvatures and angles of the stable states. Combined with temperature variations, ply angle imperfections still have greater effect on the curvatures than ply thickness imperfections.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"76 ","pages":"Article 102305"},"PeriodicalIF":4.3,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143548388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Artificial sunflower: Light-induced deformation of photoactive shells","authors":"Sathvik Sanagala,&nbsp;Kaushik Bhattacharya","doi":"10.1016/j.eml.2025.102302","DOIUrl":"10.1016/j.eml.2025.102302","url":null,"abstract":"<div><div>Photomechanically active materials undergo reversible deformation on illumination, making them ideal for remote, tether-free actuation. Much of the work on these materials has focused on one-dimensional structures, such as strips. In this paper, we explore photomechanically active two-dimensional structures such as sheets and shells. When illuminated, such structures undergo spontaneous bending due to the limited penetration of light. However, the geometry of the shell constrains possible deformation modes: changes in Gauss curvature lead to in-plane stretching, against which shells are very stiff. Therefore, there is a complex coupling between the photomechanical actuation and the mechanical behavior of a shell. We develop and implement a novel approach to study photomechanically active shells. This method is a discrete shell model which captures the interplay between actuation, stretching, bending, and geometric changes. Through a series of examples, we explore these complex interactions, demonstrating how one can design shells that deform to follow the source of illumination.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"76 ","pages":"Article 102302"},"PeriodicalIF":4.3,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562487","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":"Harmonically induced shape morphing of bistable buckled beam with static bias","authors":"Md Nahid Hasan ,&nbsp;Sharat Paul ,&nbsp;Taylor E. Greenwood ,&nbsp;Robert G. Parker ,&nbsp;Yong Lin Kong ,&nbsp;Pai Wang","doi":"10.1016/j.eml.2025.102299","DOIUrl":"10.1016/j.eml.2025.102299","url":null,"abstract":"<div><div>We investigate the effect of a constant static bias force on the dynamically induced shape morphing of a pre-buckled bistable beam, focusing on the beam’s ability to change its vibration to be near different stable states under harmonic excitation. Our study explores four categories of oscillatory motions: switching, reverting, vacillating, and intra-well in the parameter space. We aim to achieve transitions between stable states of the pre-buckled bistable beam with minimal excitation amplitude. Our findings demonstrate the synergistic effects between dynamic excitation and static bias force, showing a broadening of the non-fractal region for switching behavior (i.e., switching from the first stable state to the second stable state) in the parameter space. This study advances the understanding of the dynamics of key structural components for multi-stable mechanical metamaterials, offering new possibilities for novel designs in adaptive applications.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"76 ","pages":"Article 102299"},"PeriodicalIF":4.3,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529388","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":"Curling morphology of knitted fabrics: Structure and Mechanics","authors":"Kotone Tajiri ,&nbsp;Riki Murakami ,&nbsp;Shunsuke Kobayashi ,&nbsp;Ryuichi Tarumi ,&nbsp;Tomohiko G. Sano","doi":"10.1016/j.eml.2025.102300","DOIUrl":"10.1016/j.eml.2025.102300","url":null,"abstract":"<div><div>Knitted fabrics are two-dimensional-like structures formed by stitching one-dimensional yarn into three-dimensional curves. Plain stitch or stockinette stitch, one of the most fundamental knitting stitches, consists of periodic lattices of bent yarns, where three-dimensional (3D) curling behavior naturally emerges at the edges. The elasticity and geometry of knitted fabrics have been studied in previous studies, primarily based on 2D modeling. Still, the relation between 3D geometry and the mechanics of knitted fabrics has not been clarified so far. The curling behavior of knits is intricately related to the forces and moments acting on the yarns, geometry of the unit knitted loops, mechanical properties, and contacts, hence requiring a 3D analysis. Here, we show that the curling of plain knits emerges through the elasticity and geometry of the knitted loops, combining desktop-scale experiments and reduced elasticity-based simulations. We find that by changing the horizontal and vertical knitting numbers, three types of curl shapes emerge: side curl and top/bottom curl shapes, which are curled only horizontally and vertically, and double curl shape, in which both curl shapes appear together. We uncover that the knit is side-curled when the knitted loop is vertically elongated, while we observe double curl and then top/bottom curl as the loop becomes horizontally elongated. Furthermore, we find that this characteristic loop shape affects the mechanical properties of knitted fabrics. The fundamental mechanism of intricate shape deformation is clarified through the force and moment balance along yarn whose centerline shape is discretized through the B-spline curves, where elastic stretching, bending, and contact mechanics are taken into account. We reveal that the 3D structure of the single knitted loop plays a critical role in the curling behavior. Our results imply that the change in shape per a single knitted loop has the potential to control the 3D natural overall shape of knitted fabrics. The 3D curling behavior of knitted fabrics is useful for industrial applications such as composite materials, wearable devices, and actuators. Our findings could be applied in predicting or designing more complex 3D shapes made of knitted fabrics.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"76 ","pages":"Article 102300"},"PeriodicalIF":4.3,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143479815","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}