Extreme Mechanics Letters最新文献_第6页

Crack-growth inhibition by designing dendritic pattern for soft adhesives 通过为软质粘合剂设计树枝状图案抑制裂纹生长

IF 4.3 3区工程技术

Extreme Mechanics Letters Pub Date : 2024-10-28 DOI: 10.1016/j.eml.2024.102254

Yifan Zhang , Danming Zhong , Qiuxuan Wang , Ping Rao , Shaoxing Qu

{"title":"Crack-growth inhibition by designing dendritic pattern for soft adhesives","authors":"Yifan Zhang , Danming Zhong , Qiuxuan Wang , Ping Rao , Shaoxing Qu","doi":"10.1016/j.eml.2024.102254","DOIUrl":"10.1016/j.eml.2024.102254","url":null,"abstract":"<div><div>Soft adhesive layers show promise in various engineering applications, including biomedicine, automotive, semiconductor, and aerospace industries. However, cavities trapped at the interface due to poor contact will significantly inhibit their adhesion capacity, leading to rapid crack-growth failure. Significant efforts in these applications within a confined contact area are focused on mitigating the effects and enhancing the debonding work of the interface without changing the materials, such as using bioinspired micropillars. However, soft adhesives with isolated contact elements face limitations due to manufacturing complexity and the collision of micropillars under large deformation. This study proposes a simple and effective method to reduce the hydrostatic pressure around the crack tips by designing a dendritic pattern within the confined area. This approach inhibited interface crack growth well and improved adhesive performance. As a result, the crack failure was delayed, with the stretch ratio enhanced by more than 36 %, while the debonding work increased by 85 % compared with the circular adhesive layer. This study demonstrates that adhesion capacity can be significantly improved while reducing material usage by designing dendritic patterns.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"73 ","pages":"Article 102254"},"PeriodicalIF":4.3,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578255","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}

引用次数: 0

Broadband elastic energy harvesting based on achromatic meta-grating 基于消色差元光栅的宽带弹性能量采集技术

IF 4.3 3区工程技术

Extreme Mechanics Letters Pub Date : 2024-10-25 DOI: 10.1016/j.eml.2024.102253

Yizhou Shen , Yanlong Xu , Feng Liu , Fanglong Wang , Guan Wang , Zhichun Yang

{"title":"Broadband elastic energy harvesting based on achromatic meta-grating","authors":"Yizhou Shen , Yanlong Xu , Feng Liu , Fanglong Wang , Guan Wang , Zhichun Yang","doi":"10.1016/j.eml.2024.102253","DOIUrl":"10.1016/j.eml.2024.102253","url":null,"abstract":"<div><div>Energy harvesting exploiting the inverse piezoelectric effect has been the subject of much attention and discussion in the field of elastic and structural dynamics. Recently, the ongoing development of elastic metamaterials and metasurfaces has opened up a new way to improve the quality of energy harvesting. Here, we proposed a new strategy for harvesting elastic energy in a plate, which is the use of the inverse piezoelectric effect to convert the elastic energy into electrical energy after the achromatic meta-grating has focused broadband flexural waves. A new theoretical method to design the achromatic meta-grating is proposed based on derived analytical expression of the phase shift of subunit. When a meta-grating, a thin plate and a piezoelectric patch are combined into an energy harvesting system, the elastic energy can be converted into electric energy by the system, and the output voltage can be amplified by twice that of the system without the meta-grating. A theoretical framework is built to analyze the performance of the energy harvesting system, and variational parametric analyses are carried out to obtain the optimal resistance, the optimal length, thickness and position of piezoelectric patch, which are <span><math><mrow><mn>870</mn><mi>Ω</mi></mrow></math></span>, 18 mm, 0.2 mm and 30 mm, respectively. For the optimized system, the power harvested rate of the system is close to 4 in the frequency band of 6–8 kHz. Finally, the design of the system based on the wave focusing principle is extended, and energy harvesters are designed for different frequency bands, which can all work under different excitation conditions (a local and a base excitations). Our work opens up a new route for elastic energy harvesting and may have broad application prospects in the development of self-powered sensors.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"72 ","pages":"Article 102253"},"PeriodicalIF":4.3,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535951","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}

引用次数: 0

Understanding the role of chain stiffness in the mechanical response of cross-linked polymer: Flexible vs. semi-flexible chains 了解链刚度在交联聚合物机械响应中的作用：柔性链与半柔性链

IF 4.3 3区工程技术

Extreme Mechanics Letters Pub Date : 2024-10-24 DOI: 10.1016/j.eml.2024.102252

Xiangrui Zheng , Wenjie Xia , Yao Zhang

{"title":"Understanding the role of chain stiffness in the mechanical response of cross-linked polymer: Flexible vs. semi-flexible chains","authors":"Xiangrui Zheng , Wenjie Xia , Yao Zhang","doi":"10.1016/j.eml.2024.102252","DOIUrl":"10.1016/j.eml.2024.102252","url":null,"abstract":"<div><div>Cross-linked polymers are widely used in structural, engineering, and biomedical applications due to their lightweight and superior properties. Although chain bending stiffness has been recognized to play an essential role in their thermodynamical and mechanical properties, how it influences these properties of cross-linked polymers with flexible or semi-flexible chains remains under debate. Here, we systematically explore its influences utilizing coarse-grained (CG) molecular dynamics (MD) simulations based on a bead-spring CG model. It is found that with chain bending stiffness increasing, both density and elastic moduli (i.e., shear modulus and tensile modulus) of cross-linked polymers first decrease slightly and then decrease significantly followed by a gradual increase, along with the polymer transition from a dense cross-linked thermoset to a highly porous fibrous network. The moduli of cross-linked polymers with flexible and semi-flexible chains exhibit distinct scaling laws with the density. For cross-linked polymers with flexible chains, their moduli increase significantly with increasing strain rate, which correlates to the change in potential energy of interchain interaction during deformation. However, the moduli display slight dependence on strain rate for porous cross-linked polymers with sufficiently stiff chains, where the intrachain interactions (i.e., bond stretching and angle bending energies) become dominant and independent of strain rate. Moreover, the elastic moduli exhibit scaling laws with Debye-Waller factor for both dense cross-linked thermosets with flexible chains and highly porous networks with stiff backbones. Our work facilitates a better understanding for mechanical properties and deformation mechanism of cross-linked polymers with variable chain bending stiffness at molecular level, shedding light on tailoring mechanical properties of cross-linked polymers via chain engineering.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"73 ","pages":"Article 102252"},"PeriodicalIF":4.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578256","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}

引用次数: 0

Linear strain gradient-regulated bifurcation of circular bilayer plates 圆双层板的线性应变梯度调节分叉

IF 4.3 3区工程技术

Extreme Mechanics Letters Pub Date : 2024-10-22 DOI: 10.1016/j.eml.2024.102250

Ben Cao , Yuanhang Yang , Mingchao Liu , Changjin Huang

{"title":"Linear strain gradient-regulated bifurcation of circular bilayer plates","authors":"Ben Cao , Yuanhang Yang , Mingchao Liu , Changjin Huang","doi":"10.1016/j.eml.2024.102250","DOIUrl":"10.1016/j.eml.2024.102250","url":null,"abstract":"<div><div>Bilayer structures with controllable self-folding capability have found applications in a variety of cutting-edge fields such as flexible electrics, wearable devices and soft robotics. The folding of bilayer structures occurs when the mismatch strain between the two layers exceeds the bifurcation threshold, resulting in a deformation transition from an axisymmetric to a folded state. Previous efforts have predominantly focused on bilayer structures with uniform and/or anisotropic strain distributions. However, the role of non-uniform in-plane strain distributions in regulating the bifurcation of bilayer structures has not been fully understood. In this study, the effects of linear in-plane strain gradients on the bifurcation of circular bilayer plates, both with and without geometric mismatch, are systematically investigated by combining theoretical analysis, finite element simulations and experiments. Our results reveal that both the mismatch strain gradient and the geometric mismatch between the two layers play crucial roles in regulating bifurcation. Notably, linear mismatch strain gradients with larger strain at the center delay bifurcation, while those with larger strain along the edge promote bifurcation. This work offers new insights into the design of controllable self-folding bilayer structures, which is of great significance for advanced applications.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"72 ","pages":"Article 102250"},"PeriodicalIF":4.3,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535949","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}

引用次数: 0

Multifunctional bistable ultrathin composite booms with flexible electronics 带柔性电子器件的多功能双稳态超薄复合材料吊杆

IF 4.3 3区工程技术

Extreme Mechanics Letters Pub Date : 2024-10-18 DOI: 10.1016/j.eml.2024.102247

Yao Yao , Juan M. Fernandez , Sven G. Bilén , Xin Ning

引用次数: 0

Strength characterization of ultrathin chips by using large deflection theory of multi-layer plate for three-point bending tests 利用多层板大挠度理论进行超薄芯片三点弯曲试验的强度表征

IF 4.3 3区工程技术

Extreme Mechanics Letters Pub Date : 2024-10-17 DOI: 10.1016/j.eml.2024.102249

Dao-Long Chen , Chien-Ming Chen , Chin-I. Tsai , Ryan Chen , Hsin-Chih Shih , Ian Hu , Sheng-Rui Jian

引用次数: 0

Optical penetration depth and periodic motion of a photomechanical strip 光电机械带的光学穿透深度和周期性运动

IF 4.3 3区工程技术

Extreme Mechanics Letters Pub Date : 2024-10-17 DOI: 10.1016/j.eml.2024.102244

Neda Maghsoodi , Kaushik Bhattacharya

{"title":"Optical penetration depth and periodic motion of a photomechanical strip","authors":"Neda Maghsoodi , Kaushik Bhattacharya","doi":"10.1016/j.eml.2024.102244","DOIUrl":"10.1016/j.eml.2024.102244","url":null,"abstract":"<div><div>Liquid crystal elastomers (LCEs) containing light-sensitive molecules exhibit large, reversible deformations when subjected to illumination. Here, we investigate the role of optical penetration depth on this photomechanical response. We present a model of the photomechanical behavior of photoactive LCE strips under illumination that goes beyond the common assumption of shallow penetration. This model reveals how the optical penetration depth and the consequent photomechanically induced deformation can depend on the concentration of photoactive molecules, their absorption cross-sections, and the intensity of illumination. Through a series of examples, we show that the penetration depth can quantitatively and qualitatively affect the photomechanical response of a strip. Shallow illumination leads to monotone curvature change while deep penetration can lead to non-monotone response with illumination duration. Further, the flapping behavior (a cyclic wave-like motion) of doubly clamped and buckled strips that has been proposed for locomotion can reverse direction with sufficiently large penetration depth. This opens the possibility of creating wireless light-driven photomechanical actuators and swimmers whose direction of motion can be controlled by light intensity and frequency.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"73 ","pages":"Article 102244"},"PeriodicalIF":4.3,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578257","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}

引用次数: 0

Interfacial fatigue fracture of pressure sensitive adhesives 压敏粘合剂的界面疲劳断裂

IF 4.3 3区工程技术

Extreme Mechanics Letters Pub Date : 2024-10-16 DOI: 10.1016/j.eml.2024.102248

Yichen Wan , Qianfeng Yin , Ping Zhang , Canhui Yang , Ruobing Bai

{"title":"Interfacial fatigue fracture of pressure sensitive adhesives","authors":"Yichen Wan , Qianfeng Yin , Ping Zhang , Canhui Yang , Ruobing Bai","doi":"10.1016/j.eml.2024.102248","DOIUrl":"10.1016/j.eml.2024.102248","url":null,"abstract":"<div><div>Pressure sensitive adhesives (PSAs) are viscoelastic polymers that can form fast and robust adhesion with various adherends under fingertip pressure. The rapidly expanding application domain of PSAs, such as healthcare, wearable electronics, and flexible displays, requires PSAs to sustain prolonged loads throughout their lifetime, calling for fundamental studies on their fatigue behaviors. However, fatigue of PSAs has remained poorly investigated. Here we study interfacial fatigue fracture of PSAs, focusing on the cyclic interfacial crack propagation due to the gradual rupture of noncovalent bonds between a PSA and an adherend. We fabricate a model PSA made of a hysteresis-free poly(butyl acrylate) bulk elastomer dip-coated with a viscoelastic poly(butyl acrylate-co-isobornyl acrylate) sticky surface, both crosslinked by poly(ethylene glycol) diacrylate. We adhere the fabricated PSA to a polyester strip to form a bilayer. The bilayer is covered by another polyester film as an inextensible backing layer. Using cyclic and monotonic peeling tests, we characterize the interfacial fatigue and fracture behaviors of the bilayer. From the experimental data, we obtain the interfacial fatigue threshold (4.6 J/m<sup>2</sup>) under cyclic peeling, the slow crack threshold (33.9 J/m<sup>2</sup>) under monotonic peeling, and the adhesion toughness (∼ 400 J/m<sup>2</sup>) at a finite peeling speed. We develop a modified Lake-Thomas model to describe the interfacial fatigue threshold due to noncovalent bond breaking. The theoretical prediction (2.6 J/m<sup>2</sup>) agrees well with the experimental measurement (4.6 J/m<sup>2</sup>). Finally, we discuss possible additional dissipation mechanisms involved in the larger slow crack threshold and much larger adhesion toughness. It is hoped that this study will provide new fundamental knowledge for fracture mechanics of PSAs, as well as guidance for future tough and durable PSAs.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"72 ","pages":"Article 102248"},"PeriodicalIF":4.3,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446085","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}

引用次数: 0

Orientation-dependent deformation and failure of micropillar shape memory ceramics: A 3D phase-field study 微柱形状记忆陶瓷的定向变形和失效：三维相场研究

IF 4.3 3区工程技术

Extreme Mechanics Letters Pub Date : 2024-10-11 DOI: 10.1016/j.eml.2024.102245

Amirreza Lotfolahpour, Mohsen Asle Zaeem

{"title":"Orientation-dependent deformation and failure of micropillar shape memory ceramics: A 3D phase-field study","authors":"Amirreza Lotfolahpour, Mohsen Asle Zaeem","doi":"10.1016/j.eml.2024.102245","DOIUrl":"10.1016/j.eml.2024.102245","url":null,"abstract":"<div><div>Some microscopic samples of zirconia-based shape memory ceramics (SMCs) have shown full martensitic phase transformation (MPT) over multiple loading cycles without cracking. However, the occurrence of MPT is strongly influenced by grain orientation. Depending on the specific grain orientation relative to the loading direction, alternative mechanisms such as plastic slip and fracture may emerge. This study introduces a phase-field (PF) based framework that integrates a PF-MPT model, a PF fracture model, and a crystal viscoplasticity model to investigate the effects of grain orientation on MPT, plastic slip, and fracture mechanisms in SMC micropillars. Single crystal micropillars are created to distinguish the orientations that facilitate each mechanism. A wide range of grain orientations are found to predominantly exhibit MPT. Micropillars with grain orientations close to the (100) and (001) directions primarily experience fracture, with minimal plastic slip. Additionally, samples oriented along the (110) direction show a significant amount of plastic slip. A pole figure is constructed to elucidate the interplay between MPT, cracking, and plastic slip under compressive loading conditions. This research provides valuable insights into the intricate behavior of SMCs under different loading scenarios, crucial for optimizing their performance in practical applications.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"73 ","pages":"Article 102245"},"PeriodicalIF":4.3,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659218","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}

引用次数: 0

Hopping potential wells and gait switching in a fish-like robot with a bistable tail 双稳态尾巴鱼形机器人的跳跃势阱和步态切换

IF 4.3 3区工程技术

Extreme Mechanics Letters Pub Date : 2024-10-11 DOI: 10.1016/j.eml.2024.102239

Prashanth Chivkula, Colin Rodwell, Phanindra Tallapragada

{"title":"Hopping potential wells and gait switching in a fish-like robot with a bistable tail","authors":"Prashanth Chivkula, Colin Rodwell, Phanindra Tallapragada","doi":"10.1016/j.eml.2024.102239","DOIUrl":"10.1016/j.eml.2024.102239","url":null,"abstract":"<div><div>Fish outperform current underwater robots in speed, agility, and efficiency of locomotion, in part due to their flexible appendages that are capable of rich combinations of modes of motion. In fish-like robots, actuating many different modes of oscillation of tails or fins can become a challenge. This paper presents a highly underactuated (with a single actuator) fish-like robot with a bistable tail that features a double-well elastic potential. Oscillations of such a tail depend on the frequency and amplitude of excitation, and tuning the frequency–amplitude can produce controllable oscillations in different modes leading to different gaits of the robot. This robot design is inspired by recent work on underactuated flexible swimming robots driven by a single rotor. The oscillations of the rotor can propel and steer the robot, but saturation of the rotor makes performing long turns challenging. This paper demonstrates that by adding geometric bistability to the flexible tail, turns can be performed by controllably exciting single-well oscillations in the tail, while exciting double-well oscillations of the tail produces average straight-line motion. The findings of this paper go beyond the application to a narrow class of fish-like robots. More broadly we have demonstrated the use of periodic excitation to produce bistable response that generate different gaits including a steering gait. The mechanics demonstrated here show the feasibility of applications to other mobile soft robots.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"72 ","pages":"Article 102239"},"PeriodicalIF":4.3,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535945","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}

引用次数: 0