European Journal of Mechanics A-Solids最新文献

{"title":"Inverse-designed metastructures with customizable low dynamic stiffness characteristics for low-frequency vibration isolation","authors":"Changzhi Hu ,&nbsp;Zhishuai Wan ,&nbsp;Zonghan Li ,&nbsp;Ximing Tan ,&nbsp;Lichen Wang ,&nbsp;Mingji Chen","doi":"10.1016/j.euromechsol.2024.105515","DOIUrl":"10.1016/j.euromechsol.2024.105515","url":null,"abstract":"<div><div>The quasi-zero stiffness (QZS) vibration isolator is considered to be an effective way to address the contradiction between high load-bearing capacity and low-frequency vibration isolation. However, the design of traditional QZS isolators with multiple components, brings about complexity in structure integration, while designing a structure that is compact and lightweight is required for many engineering applications, especially for aerospace engineering. In this study, inverse design was employed to achieve QZS characteristics of the curved beam system. The trajectory of the cross-section center of a curved beam was optimized by using the genetic algorithm. The present design strategy has the advantage of achieving customizable stiffness and load-bearing capability, as well as constructing multiple QZS regions. The harmonic balance method was employed to analyze the dynamic response of the metatructure, and a parameter analysis was conducted to assess its isolation performance. Numerical simulations were also used to validate the theoretical model in the time and frequency domains, respectively. It is demonstrated by experiment that the proposed metastructure can effectively isolate vibrations above 4.67 Hz, with a mass of only 3.2% of the its load-bearing capacity. The presented design strategy provides a feasible solution for the compact and lightweight low-frequency vibration isolators, particularly benefiting miniature devices, precision instruments, and aerospace applications where space and weight constraints are critical.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"110 ","pages":"Article 105515"},"PeriodicalIF":4.4,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142756940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flexoelectric effect on bandgap properties of periodic bi-directional-graded curved nanoshells","authors":"Shanhong Lin,&nbsp;Qiang Han,&nbsp;Chunlei Li","doi":"10.1016/j.euromechsol.2024.105504","DOIUrl":"10.1016/j.euromechsol.2024.105504","url":null,"abstract":"<div><div>With the miniaturization of devices, the size effect of structures becomes increasingly apparent and it becomes crucial to consider flexoelectricity in MEMS/NEMS. Given that functionally graded materials (FGMs) can generate strain gradients that enhance flexoelectricity, it is both novel and crucial to investigate the synergistic effects of FGMs and flexoelectricity on bandgap characteristics. Understanding these interactions is essential for advancing materials science and could lead to significant innovations in nanotechnology. In this work, a theorectical model for the periodic flexoelectric doubly-curved nanoshells with bi-directional functionally graded (BDFG) and porosity considered are constructed. As the governing equations for longitudinal FG problems are more difficult to be solved analytically, their precise analysis is more challenging. Thus, an improved transfer matrix method based on state-space is proposed innovatively to obtain the complex band structures for longitudinal FG problems. Subsequently, the influences of the flexoelectric effect, strain gradient effect, BDFG indices, and porosity distributions on bandgaps are systematically discussed. The results indicate that the flexoelectric effect is non-negligible at small scales, which generally widens the bandgaps, with higher frequency ranges and larger attenuation capacity. Bandgaps are sensitive to the variation of functionally graded indices. Particularly, flexoelectricity brings about the appearance and disappearance of some bandgaps during the variation of FG index in the thickness direction <span><math><msub><mrow><mi>n</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span>, and complicates the bandgaps variation. Besides, the porosity distribution patterns and porosity coefficients enrich the regulation of bandgaps. Our investigation offers valuable insights into the application of flexoelectric electrical components combined with BDFG in MEMS/NEMS to the wave propagation domain.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"110 ","pages":"Article 105504"},"PeriodicalIF":4.4,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanical behaviour of rigid polyurethane foam under combined cutting and compression loads","authors":"Hongwei Luo,&nbsp;Ke Li,&nbsp;Yuwu Zhang,&nbsp;Minzu Liang,&nbsp;Xiangcheng Li,&nbsp;Yuliang Lin","doi":"10.1016/j.euromechsol.2024.105505","DOIUrl":"10.1016/j.euromechsol.2024.105505","url":null,"abstract":"<div><div>Rigid polyurethane foam (RPUF) is a porous material with good energy absorption characteristics, but it may suffer from the destructive effects of impact and cutting when used as a protective structure. Herein, the mechanical response characteristics of RPUF under combined cutting and compression loads is analysed. A cutting tool with a certain width is used to apply a load to the polyurethane foam under quasi-static conditions. The force and displacement are measured, and the influence of the geometric parameters of the cutting tool and the density of RPUF on the force are analysed. In addition, a theoretical model of the total force on RPUF under the combined action of cutting and compressive loads is established. Based on this model, the proportion of component force in the total force is calculated and the influence of size effect on the deformation mechanism of RPUF is analysed. Experimental results indicate that when the density of the RPUF is high, the amplitude of the increase in the total force improved after the increased cutting depth and tear length. Theoretical analysis results indicate that the proportion of crushing force increases with the increase of the foam's pore size, whereas the proportion of tearing force and friction decreases with the increase of the foam's pore size. When the width of the cutting tool is 0.5–20 times the pore size, the proportion of the crushing force decreased from 86.01% to 34.19%, and the proportion of tearing force is 0%–60.25%.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"110 ","pages":"Article 105505"},"PeriodicalIF":4.4,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanical regulation strategy for heterogeneous piezoelectric semiconductor thermoelectric structure based on energy conversion","authors":"Lingyun Guo,&nbsp;Yizhan Yang","doi":"10.1016/j.euromechsol.2024.105503","DOIUrl":"10.1016/j.euromechsol.2024.105503","url":null,"abstract":"<div><div>The piezoelectric properties inherent in piezoelectric semiconductors facilitate the manipulation of charge carrier redistribution, enabling the fabrication of electronic devices with adjustable characteristics. However, despite this capability, our understanding of the energy conversion and transfer mechanisms within such devices remains limited. By discarding the assumption of low injection and the approximation of depletion layer, a nonlinear model was developed on piezoelectric semiconductor thermoelectric structure (PS-TES), considering the penetration of hot electrons and regulation of mechanical loadings. The presented model reveals that the input electric energy is partitioned, with a portion being converted into electric potential energy stored (EPES) in non-equilibrium carriers and another portion being the energy dissipation (ED) due to the electrothermal action. Furthermore, from an energy conservation standpoint, a interesting competitive phenomenon between electric potential energy conversion and energy dissipation is obtained. The power of external electric energy input and internal electric energy conversion can be manipulated via mechanical loadings, thereby adjusting the energy conversion process of PS-TES. Finally, we found that the compressive loadings can increase EPES and reduce ED, thereby optimizing the cooling effect at cold end. While tensile loadings can reduce EPES and increase ED, thus causing the PS-TES to locally heat up and produce a heating effect. This study potentially offers a means to switch the performance of TES and provides fresh insights into energy conversion processes within piezoelectric semiconductors.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"110 ","pages":"Article 105503"},"PeriodicalIF":4.4,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative analysis of beam models for vertical rail vibrations under dynamic forces","authors":"Le-Hung Tran ,&nbsp;Tuan-Manh Duong ,&nbsp;Benjamin Claudet ,&nbsp;Khuong Le-Nguyen ,&nbsp;Anders Nordborg ,&nbsp;Franziska Schmidt","doi":"10.1016/j.euromechsol.2024.105497","DOIUrl":"10.1016/j.euromechsol.2024.105497","url":null,"abstract":"<div><div>An analytical model of the rails of ballasted railway track subjected to the dynamic loads are developed to study forced vertical vibration. In this work, the two rails are modelled as infinite uniform beams posed on a system of periodical supports with the help of Timoshenko beam theory. Besides, each support is considered as a beam posed on a visco-elastic foundation. A linear relation between the sleeper displacement at the crossing-points with two rails and the two reaction forces is established via the Green’s function in the frequency domain. In other words, the mechanical behaviour of the support can be written as a spring with an equivalent stiffness. By replacing this relation into the periodically supported rail models, the forced vertical vibrations of two rails are obtained analytically. This analytical model allows calculate rapidly the rail responses in different load, especially in the non-symmetric configuration. In addition, the comparison of rail responses calculated by two beam models are investigated. This work concerns the study of peaks resonances of the frequency responses functions which is useful to understand the excitations of rolling noise.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"110 ","pages":"Article 105497"},"PeriodicalIF":4.4,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Viscoelastic–viscoplastic model with ductile damage accounting for tension–compression asymmetry and hydrostatic pressure effect for polyamide 66","authors":"Soheil Satouri ,&nbsp;George Chatzigeorgiou ,&nbsp;Fodil Meraghni ,&nbsp;Gilles Robert","doi":"10.1016/j.euromechsol.2024.105491","DOIUrl":"10.1016/j.euromechsol.2024.105491","url":null,"abstract":"<div><div>This paper proposes a model for predicting the complex inelastic mechanical response of polyamide 66. Polyamide 66 is a semi-crystalline pressure-sensitive polymer that exhibits asymmetric yielding behavior, in which the yield strength is slightly higher in compression. With this in mind, an <span><math><msub><mrow><mi>I</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>-<span><math><msub><mrow><mi>J</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> yield function considering the asymmetric behavior and the hydrostatic pressure effect is presented and integrated into a phenomenological viscoelastic–viscoplastic model accounting for ductile damage. The corresponding thermodynamic framework and constitutive laws are discussed. Then, an experimental approach is presented to identify the model parameters through mechanical tests with different loading paths to capture the active mechanisms. The experimental findings obtained from uni-axial and multi-axial (tension-torsion) mechanical tests and the numerical model are used in an optimization algorithm to identify the model parameters. A parametric analysis is performed to study the effect of the asymmetric behavior on the state variables under different loading conditions using the identified parameters. The present model responses are in good agreement with the experimental data, and the combination of the experimental and numerical results demonstrates and states the asymmetric behavior of polyamide at relative humidity (RH) of 50%, which is captured by the suggested model. It is also worth pointing out that the parametric study conducted on a notched plate using finite element simulations showcases the structural computation capabilities of the proposed model.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"110 ","pages":"Article 105491"},"PeriodicalIF":4.4,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"The influence of bi-directional material gradation on a mode-III crack in functionally graded material via strain gradient elasticity theory","authors":"Rakesh Kumar Sharma ,&nbsp;Kamlesh Jangid ,&nbsp;Y. Eugene Pak","doi":"10.1016/j.euromechsol.2024.105496","DOIUrl":"10.1016/j.euromechsol.2024.105496","url":null,"abstract":"<div><div>In contrast to classical mechanics, which primarily relies on continuum assumptions and neglects micro-structural effects, the strain gradient elasticity (SGE) theory represents a paradigm shift in understanding the mechanical behavior of materials at small length scales. In this article, the influence of the bi-directional material gradation on a mode-III crack in functionally graded material via SGE theory is studied. The SGE theory uses two material characteristic lengths, <span><math><mi>ℓ</mi></math></span> and <span><math><msup><mrow><mi>ℓ</mi></mrow><mrow><mo>′</mo></mrow></msup></math></span>, to account for volumetric and surface strain-gradient factors, respectively. Our investigation is centered on a material gradation model assumed to vary exponentially, with the shear modulus represented as <span><math><mrow><mi>G</mi><mrow><mo>(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>)</mo></mrow><mo>=</mo><msub><mrow><mi>G</mi></mrow><mrow><mn>0</mn></mrow></msub><msup><mrow><mi>e</mi></mrow><mrow><mi>β</mi><mi>x</mi><mo>+</mo><mi>γ</mi><mi>y</mi></mrow></msup></mrow></math></span>, where <span><math><mi>β</mi></math></span> and <span><math><mi>γ</mi></math></span> are material gradation constants. To address the crack boundary value problem under consideration, we employ a methodology combining Fourier transforms and an innovative hyper-singular integro-differential equation approach. Using this approach, we systematically formulate a system of equations, which can be solved by selecting suitable collocation points. The closed-form analytical expressions are derived for the standard fracture parameters such as crack surface displacement (CSD), stress intensity factor (SIF), and energy release rate (ERR). Numerical studies are illustrated for the derived standard fractures, and the influence of these parameters <span><math><mi>β</mi></math></span>, <span><math><mi>γ</mi></math></span>, <span><math><mi>ℓ</mi></math></span>, <span><math><msup><mrow><mi>ℓ</mi></mrow><mrow><mo>′</mo></mrow></msup></math></span>, and applied shear load is graphically presented. Through comprehensive analysis, our aim is to provide insights into the complex interplay between material parameters, loading conditions, and crack behavior in functionally graded materials.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"110 ","pages":"Article 105496"},"PeriodicalIF":4.4,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved tangential interpolation-based multi-input multi-output modal analysis of a full aircraft","authors":"Gabriele Dessena ,&nbsp;Marco Civera","doi":"10.1016/j.euromechsol.2024.105495","DOIUrl":"10.1016/j.euromechsol.2024.105495","url":null,"abstract":"<div><div>In the field of Structural Dynamics, modal analysis is the foundation of System Identification and vibration-based inspection. However, despite their widespread use, current state-of-the-art methods for extracting modal parameters from multi-input multi-output (MIMO) frequency domain data are still affected by many technical limitations. Mainly, they can be computationally cumbersome and/or negatively affected by close-in-frequency modes. The Loewner Framework (LF) was recently proposed to alleviate these problems with the limitation of working with single-input data only. This work proposes a computationally improved version of the LF, or iLF, to extract modal parameters more efficiently. Also, the proposed implementation is extended in order to handle MIMO data in the frequency domain. This new implementation is compared to state-of-the-art methods such as the frequency domain implementations of the Least Square Complex Exponential method and the Numerical Algorithm for Subspace State Space System Identification on numerical and experimental datasets. More specifically, a finite element model of a 3D Euler–Bernoulli beam is used for the baseline comparison and the noise robustness verification of the proposed MIMO iLF algorithm. Then, an experimental dataset from MIMO ground vibration tests of a trainer jet aircraft with over 91 accelerometer channels is chosen for the algorithm validation on a real-life application. Its validation is carried out with known results from a single-input multi-output dataset of the starboard wing of the same aircraft. Excellent results are achieved in terms of accuracy, robustness to noise, and computational performance by the proposed improved MIMO method, both on the numerical and the experimental datasets. The MIMO iLF MATLAB implementation is shared in the work supplementary material.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"110 ","pages":"Article 105495"},"PeriodicalIF":4.4,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"The combination of random and controllable--- design strategy and mechanical properties of directional random porous structures inspired by Wolff's law","authors":"Xiaofei Ma,&nbsp;Ce Guo,&nbsp;Yu Wang,&nbsp;Hongqian Wang","doi":"10.1016/j.euromechsol.2024.105502","DOIUrl":"10.1016/j.euromechsol.2024.105502","url":null,"abstract":"<div><div>Porous structures have received extensive attention due to their excellent mechanical properties. Inspired by Wolff's law, a new design method for directional random porous structures (DRPS) that is based on principal stress lines is proposed. Considering three working conditions, namely, cantilever bending, shearing and compression, the mechanical properties and deformation modes of a directional random porous structure in the loading direction were studied via numerical simulation. The results show that the directional random porous structure significantly reduces both the maximum stress and deformation, as well as the stress concentration within the model. The design model was prepared via a light curing process with the photosensitive resin R4000 as the raw material, and its deformation pattern and mechanical behaviour under local and overall compression conditions were investigated. During local compression loading, the selection of different principal stress lines affects the mechanical properties of the structure. Selecting a dense area of principal stress lines with a large transfer stress as the directional growth design area can result in better strengthening efficiency. The experimental results under overall compressive loading conditions show that the design method proposed in this paper can substantially improve the mechanical properties of the structure in the strengthening direction while ensuring the mechanical properties in the non-strengthening direction, in which the modulus of elasticity, ultimate compressive strength and specific energy absorption (SEA) were improved by up to approximately 140.97%, 58.59 % and 51.32 %, respectively.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"110 ","pages":"Article 105502"},"PeriodicalIF":4.4,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Buckling-based topology optimization for underwater pressure hull with modified parameterized level-set method","authors":"Yuanteng Jiang ,&nbsp;Tengwu He ,&nbsp;Min Zhao","doi":"10.1016/j.euromechsol.2024.105499","DOIUrl":"10.1016/j.euromechsol.2024.105499","url":null,"abstract":"<div><div>Buckling is a common phenomenon in compression structures, and its occurrence will cause significant damage, especially in the application of underwater pressure hulls. In this paper, a new mathematical model based on an improved parameterized level-set method is developed to solve fundamental buckling load factor maximization and buckling-constraint topology optimization problems, and further the continuous descriptions of normal velocities are derived using the theory of the shape derivative and bifurcation analysis. In this model, a regularization term is introduced to ensure numerical stability, and an augmented Lagrange multiplier is presented to realize stable transitions of both optimization problems during the convergence process. Besides, Kreisslmeier–Steinhauser function is employed to aggregate multiple buckling load factors to a differentiable one. In this case, an easily implemented method is proposed to discretize normal velocities to every nodal point in the design area. By means of the developed method, the clear contours of the optimal structures are obtained, and the pseudo-buckling modes during optimization process is alleviated. To further prove the effectiveness, three-dimensional cases of underwater cylindrical pressure hull are extended, and corresponding buckling-based problems are solved, in which the optimal results with clearer contour and more details are approached. The current method can be used to deal with the similar buckling-based problems of underwater pressure hulls and the final structures are more easily manufactured in practical application.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"110 ","pages":"Article 105499"},"PeriodicalIF":4.4,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}