International Journal of Engineering Science最新文献

{"title":"Elasticity solutions of inhomogeneous and anisotropic nano-circular rings","authors":"Teoman Özer ,&nbsp;Martin Kröger","doi":"10.1016/j.ijengsci.2025.104293","DOIUrl":"10.1016/j.ijengsci.2025.104293","url":null,"abstract":"<div><div>This study extends classical elasticity to gradient elasticity by investigating the analytical solutions for inhomogeneous and anisotropic curvilinear nano-beams with axial symmetry. For this purpose, we consider two variations for the elastic material coefficients along the thickness of the curvilinear beam. First, the coefficients are assumed to be proportional to the radial coordinate as <span><math><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>i</mi><mi>j</mi></mrow></msub><mrow><mo>(</mo><mi>r</mi><mo>)</mo></mrow><mo>=</mo><msub><mrow><mi>s</mi></mrow><mrow><mi>i</mi><mi>j</mi></mrow></msub><mi>r</mi></mrow></math></span>. Secondly, it is assumed that the coefficients are linear functions of the radial coordinate with two coefficients of the material coefficients such as <span><math><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>i</mi><mi>j</mi></mrow></msub><mrow><mo>(</mo><mi>r</mi><mo>)</mo></mrow><mo>=</mo><msub><mrow><mi>s</mi></mrow><mrow><mi>i</mi><mi>j</mi><mi>c</mi></mrow></msub><mo>+</mo><msub><mrow><mi>s</mi></mrow><mrow><mi>i</mi><mi>j</mi><mi>g</mi></mrow></msub><mi>r</mi></mrow></math></span>. For both cases of variation of the elastic coefficients, the analytical solutions of stress fields for both classical and nano-curvilinear beams are obtained by using the definition of the gradient Airy stress function introduced for the gradient elasticity theory, similar to the Airy stress function notation defined in the classical elasticity theory. Then, analytical solutions of displacement fields are given similarly for classical and nano-curvilinear beams. As a special application of this general case, circular rings’ stress and displacement fields subjected to internal and external pressures are examined for the classical and nano-beam cases. Furthermore, the initial stress fields, depending on the initial pressure, are examined in the classical and gradient elasticity theory using the notation of the initial gradient pressure and initial gradient stress fields. Lastly, an expansion for the small gradient coefficient <span><math><mrow><mi>c</mi><mo>≪</mo><mn>1</mn></mrow></math></span> is performed analytically, as the solutions presented are otherwise numerically difficult to evaluate within this regime. The expansion allows us to show analytically that for all derived stress and displacement fields, including the gradient Airy stress functions, the gradient elasticity solutions converge to the classical elasticity as the gradient coefficient <span><math><mi>c</mi></math></span> goes to zero.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"214 ","pages":"Article 104293"},"PeriodicalIF":5.7,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144069243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unequal-biaxial taut states of functionally graded dielectric elastomers","authors":"Sankalp Gour ,&nbsp;Deepak Kumar ,&nbsp;Aman Khurana","doi":"10.1016/j.ijengsci.2025.104291","DOIUrl":"10.1016/j.ijengsci.2025.104291","url":null,"abstract":"<div><div>A thin dielectric elastomeric (DE) plate with thickness gradients deforms and wrinkles under applied voltages. Such wrinkling, with regular periodic patterns in thin functionally graded DEs, occurs to relax in-plane compressive stresses through out-of-plane deformations. These functionally graded DE-based soft actuators, primarily used in soft robotic applications, exhibit highly localized point loads compared to non-graded soft actuators. DE-based soft actuators frequently exhibit a variety of instabilities, which may adversely affect their functioning and trigger device failure. Conversely, fine-tuned wrinkles can be utilized proactively in specific applications, necessitating an intentional transformation with directional gradients and the truncation of biaxial deformations. This paper presents an experimentally verified continuum physics-based model under a special case for unequal-biaxial deformation in functionally graded DEs. The proposed model integrates classical tension field theory to predict thresholds in taut domains within the plane of principal stretches. The model solutions provide insight into the deviations of taut domains influenced by the graded parameter and the biaxiality ratio in unequal-biaxial deformations of wrinkle formations in this material class.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"214 ","pages":"Article 104291"},"PeriodicalIF":5.7,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143942361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polarization estimates for longitudinal elastic moduli of unidirectional multi-component materials","authors":"Duc-Chinh Pham","doi":"10.1016/j.ijengsci.2025.104279","DOIUrl":"10.1016/j.ijengsci.2025.104279","url":null,"abstract":"<div><div>We consider the elastic unidirectional composite composed of <span><math><mi>n</mi></math></span> transversely-isotropic components, all of which are distributed statistically-isotropic in the transverse plane. Based on the minimum energy or complementary energy principles, the polarization (extended Hashin–Shtrikman-type) strain and stress trial fields are constructed to derive new direct upper or lower polarization estimates for some macroscopic (effective) longitudinal elastic moduli of the <span><math><mi>n</mi></math></span>-component materials. The more-refined non-trivial polarization trial fields can utilize the statistical isotropy assumption in the transverse plane of the composite to give definitely better estimates from above or below on the effective moduli than those obtained earlier using only the much simpler basic constant strain and piece-wise constant stress trial ones effective for the unidirectional composites which are macroscopically isotropic in the transverse plane (<span><span>Pham, 2020</span></span>). The primary upper or lower bounds appear optimal in the two-component case (attained by the coated cylinder assemblage model). The new and other available estimates, and/or exact models are compared in a number of two- and three-component illustrating numerical examples.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"214 ","pages":"Article 104279"},"PeriodicalIF":5.7,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143934949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rectangular finite elements for modeling the mechanical behavior of auxetic materials","authors":"Alexey V. Mazaev","doi":"10.1016/j.ijengsci.2025.104290","DOIUrl":"10.1016/j.ijengsci.2025.104290","url":null,"abstract":"<div><div>This paper is devoted to the exploration of rectangular finite elements’ ability to model the stress-strain state of isotropic and orthotropic materials with a negative Poisson’s ratio, known as auxetic materials. By employing linear elasticity in the plane stress formulation, the research evaluates the linear compatible and the quadratic incompatible shape functions in describing the mechanical behavior of auxetic materials within a displacement-based finite element method under static shear and indentation. Additionally, the analytical expression of an incompatible rectangular finite element is adapted to accommodate an orthotropic case. Hexachiral and re-entrant honeycomb structures, characterized by auxetic behavior, are modeled as continuous media with homogenized properties using analytical expressions for their effective material constants. The findings reveal that while the classical shape functions may be sufficient for displacement modeling, they are ineffective in accurately predicting the characteristic auxetic behavior and stress distributions in auxetic materials. In contrast, the incompatible shape functions prove to be effective in providing appropriate stress modeling in both cases. This work underscores the relevance of the incompatible rectangular finite elements in the analysis of advanced materials with a negative Poisson’s ratio. It provides computationally efficient approaches for the calculation of auxetic honeycomb structures and multilayer composites based on them.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"213 ","pages":"Article 104290"},"PeriodicalIF":5.7,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143942580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear elastic response of 2D materials under simultaneous in-plane strains and flexural deformations","authors":"Serge R. Maalouf ,&nbsp;Senthil S. Vel","doi":"10.1016/j.ijengsci.2025.104270","DOIUrl":"10.1016/j.ijengsci.2025.104270","url":null,"abstract":"<div><div>In this paper, we study the elastic response of 2D materials that are subjected to simultaneous in-plane strains and flexural deformations. A nonlinear elastic constitutive model is proposed for the in-plane and flexural deformations of 2D materials of arbitrary symmetries. The constitutive model consists of a series expansion of the strain energy density in terms of the strain and curvature components. The influence of in-plane symmetry and out-of-plane reflective symmetry on the number of linearly independent elastic constants is discussed. A methodology is presented for the evaluation of the elastic constants based on the proposed model. The strain energy is evaluated along rays in strain and curvature space to simulate different strain and curvature states of the materials. Subsequently, the elastic constants are systematically evaluated by curve fitting the proposed constitutive model to the sampled strain energy densities. The approach proposed to obtain the elastic constants is independent of the method used for calculating the strain energy density, e.g., classical interatomic potentials or density functional theory, as the curve fitting process is decoupled from the energy calculations. In the present work, the strain energies are evaluated using classical interatomic potentials. The atomic coordinates of the 2D materials are relaxed in a unit cell while preserving the applied strains and curvatures in order to evaluate the strain energy and, subsequently, the elastic constants. We analyze the nonlinear response of graphene to simultaneous strains and curvatures. Furthermore, we analyze black phosphorus which serves as a representative orthorhombic 2D material. The in-plane, flexural and coupling elastic constants are evaluated for both materials, and the effects of bending and twisting on the in-plane strains are studied. We investigate the effect of the in-plane strains on the effective flexural rigidities of the materials. It is found that a tensile strain causes a decrease in the bending rigidity of graphene. The flexural rigidities of black phosphorus are found to be less sensitive to in-plane strains than that of graphene.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"214 ","pages":"Article 104270"},"PeriodicalIF":5.7,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143922325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrokinetic energy conversion efficiency in carbon nanotubes","authors":"Yongbo Liu ,&nbsp;Yongjun Jian","doi":"10.1016/j.ijengsci.2025.104263","DOIUrl":"10.1016/j.ijengsci.2025.104263","url":null,"abstract":"<div><div>The electrokinetic energy conversion (EKEC) of pressure driven flow in carbon nanotubes (CNTs) is of great interest due to its potential high conversion efficiency. The existing EKEC theories had made many simplified assumptions for this problem, such as the surface charge is fixed on the surface and can not move, the slip length is independent of pipe diameter and the surface charge density is decoupled from the solution concentration. In order to get more accurate conversion efficiency, the prior theoretical models of EKEC in CNTs are revised in this paper by focusing on the combined influence of surface charge mobility and tube diameter on slip length and conversion efficiency. In addition, the surface charge density is no longer viewed as a constant, but a function of solution concentration of the electrolyte solution inside the CNTs. Results show that considering the surface charge mobility will reduce the EKEC efficiency. However, the decrease of tube diameter could enhance the EKEC efficiency. In order to maximize the EKEC efficiency, we give the optimal values of corresponding parameters. The maximum EKEC efficiency obtained in this paper is 18.8 %, which is obtained for the pressure driven flow of a LiCl solution with a concentration of 2 mM through a CNT with a radius of 15 nm.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"213 ","pages":"Article 104263"},"PeriodicalIF":5.7,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143859748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Utilization of the quadratic Hill yield function to model Ti-6Al-4V within multiplicative finite strain kinematics","authors":"Jakob Platen,&nbsp;Johannes Storm,&nbsp;Michael Kaliske","doi":"10.1016/j.ijengsci.2025.104268","DOIUrl":"10.1016/j.ijengsci.2025.104268","url":null,"abstract":"<div><div>In the contribution at hand, the quadratic Hill yield function is extended to a finite strain, multiplicative kinematic framework. Furthermore, it is expanded by a novel combination of linear and exponential hardening. The formulation is derived in a consistent manner. Subsequently, the capabilities to model Ti-6Al-4V in a realistic manner are demonstrated, considering the anisotropy in plastic material behavior, which is induced by additive manufacturing. Therefore, different tensile tests from the literature are simulated, and a validation is carried out. Finally, the significance of the anisotropy is demonstrated in a numerical example. The maximal force obtained in the simulation is shown to be significantly different, if the building direction is considered.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"213 ","pages":"Article 104268"},"PeriodicalIF":5.7,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143864748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"General shape transformations of thin hyperelastic shells through stress-free differential growth","authors":"Zhanfeng Li ,&nbsp;Jiong Wang","doi":"10.1016/j.ijengsci.2025.104266","DOIUrl":"10.1016/j.ijengsci.2025.104266","url":null,"abstract":"<div><div>To address the needs of engineering applications, researchers often wish that the shapes of samples can be precisely controlled. The current work aims to propose a promising approach, i.e., through stress-free differential growth, to realize general shape transformations of thin hyperelastic shells. First, within the finite-strain regime, we formulate the 3D governing equations system for modeling the growth behavior of hyperelastic shells. To facilitate the derivations, it is assumed that the shell sample attains the stress-free state in its current configuration. Subsequently, through series expansions of the unknown variables, we derive the explicit analytical formulas that elucidate the intricate relationships between growth functions and the geometric quantities of general 3D target surfaces. Based on these analytical formulas, we propose a theoretical framework for controlling the shape changes of the shell sample from the reference configuration to a desired target configuration. Notably, our framework accommodates a wide array of geometric mappings, including topology transformation, conformal mapping, and isometry mapping. To promote applications of the theoretical framework, a numerical scheme is further proposed to achieve shape transformations of shell samples between complex surfaces without explicit parametric equations. Both the theoretical framework and the numerical scheme are validated through 3D finite element simulations. The results of the current work can be applied for the design of novel intelligent soft devices, which also reveal the connections between solid mechanics and differential geometry.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"213 ","pages":"Article 104266"},"PeriodicalIF":5.7,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143835175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and control of multi-branch and multi-segment-based dielectric elastomer actuator and biomimetic applications","authors":"Haihao Ci,&nbsp;Zhan-Sheng Guo","doi":"10.1016/j.ijengsci.2025.104271","DOIUrl":"10.1016/j.ijengsci.2025.104271","url":null,"abstract":"<div><div>Dielectric elastomer actuators (DEAs) based on the dielectric elastomer minimum energy structure (DEMES) exhibit excellent dynamic shape deformation and fast response characteristics, making them widely applicable in flexible actuators, smart grippers, and biomimetic devices. While existing studies have explored the fundamental mechanisms of DEMES, most focus on simple structural types or single application scenarios. However, a systematic approach for designing, modeling, and computing versatile, complex DEAs remains underexplored. In this work, the nonlinear motion equations for an electroelastic cantilever plate are derived based on Hamilton's principle to capture the nonlinear behavior of DEAs. Multi-structured single-segment DEAs are designed to investigate the influence of the driven shape and geometric configuration of the frame on actuator performance. Additionally, complex deformations and grasping strategies for four-branch single-segment and six-segment DEAs are analyzed in detail, considering the actuation of individual branches and parts of each segment. An octopus-inspired variable-stiffness DEA is designed to grasp polygonal objects of varying sizes and shapes using diverse voltage control strategies. Different hand gestures are mimicked by independently controlling each segment and finger of a human hand-based DEA. The accuracy of the three-segment and six-segment DEMES is validated by comparison with rotary joint experiments and a microsatellite gripper, respectively. Additionally, a duty cycle voltage strategy that enables the variation of the flapping angle of a rotary joint to closely match real flight conditions is proposed. The results confirm the independence and controllability of multi-branch and multi-segment DEAs in complex tasks. This research offers new insights and methodologies to advance the field of flexible actuators, highlighting the vast application potential of DEAs in multi-task and multi-objective operations.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"212 ","pages":"Article 104271"},"PeriodicalIF":5.7,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143820575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 large-deformation investigation into the electromechanically coupled sensing performances of flexible nanoparticle-reinforced composite stretch sensors","authors":"Xiaodong Xia ,&nbsp;Yu Su ,&nbsp;Chuang Feng ,&nbsp;George J. Weng","doi":"10.1016/j.ijengsci.2025.104265","DOIUrl":"10.1016/j.ijengsci.2025.104265","url":null,"abstract":"<div><div>In contrast to the conventional strain sensors under the small-deformation condition, the large-deformation analysis on the flexible nanocomposite-reinforced stretch sensors remains to be investigated. In this research, an extended multi-field coupled homogenization model has been developed to illustrate the nonlinear stretch sensing capacities of flexible nanoparticle-reinforced composite sensors. In this analysis, the stretch-dependent pseudo-moduli and conductivity are chosen as the dual homogenization parameters of current stretch sensing analysis. The predicted resistance change ratio and stretch sensitivity factor are consistent with the experimental data of silver nanoparticle/PDMS nanocomposite sensors over a broad range of stretch loading. The nonlinear stretch sensing performance is attributed to the shape deformation of nanoparticles and significant variation of tunneling distance. The uncovered stretch sensing capacities can provide the directions to optimize flexible nanoparticle-reinforced composite sensors in the area of electronic skin.</div></div>","PeriodicalId":14053,"journal":{"name":"International Journal of Engineering Science","volume":"212 ","pages":"Article 104265"},"PeriodicalIF":5.7,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143820576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}