European Journal of Mechanics A-Solids最新文献

英文中文

Fractional and memory effects on wave reflection in pre-stressed microstructured solids with dual porosity

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2025-01-11 DOI: 10.1016/j.euromechsol.2024.105565

Soumik Das , Rachaita Dutta , Vipin Gupta , Abhinav Singhal , M.S. Barak , Bandar Almohsen

The present work investigates the influence of fractional-order derivative and memory-dependent derivative on the behavior of various waves reflected at the free surface of a size-dependent, pre-stressed, microstructured thermoelastic solid with a dual porosity framework. A generalized Moore–Gibson–Thomson (MGT) model, incorporating higher-order terms and memory effects, is adopted to describe the complex heat transfer behavior within the material. A nonlocal framework based on Eringen’s theory is utilized to derive the basic relations of the considered medium. An examination of the non-dimensionalized governing equations is conducted employing the normal mode technique to provide accurate solutions. The research demonstrates the presence of six separate wave modes that travel at varying speeds within the medium. The energy and amplitude ratios of reflected waves are determined by applying suitable boundary conditions. The influence of varying incidence angles on the reflected wave energy distribution is investigated numerically and visualized using MATLAB software. The study reveals that the energy ratios of the reflected waves are sensitive to the fractional-order parameter, kernel functions, initial stress, and nonlocality parameter. The analysis suggests a conservative reflection process, indicating minimal energy loss during reflection. Key findings and their implications for relevant scenarios are presented in the conclusion. Comparisons with existing models for certain cases demonstrate good agreement, supporting the validity of the present model.

{"title":"Fractional and memory effects on wave reflection in pre-stressed microstructured solids with dual porosity","authors":"Soumik Das , Rachaita Dutta , Vipin Gupta , Abhinav Singhal , M.S. Barak , Bandar Almohsen","doi":"10.1016/j.euromechsol.2024.105565","DOIUrl":"10.1016/j.euromechsol.2024.105565","url":null,"abstract":"<div><div>The present work investigates the influence of fractional-order derivative and memory-dependent derivative on the behavior of various waves reflected at the free surface of a size-dependent, pre-stressed, microstructured thermoelastic solid with a dual porosity framework. A generalized Moore–Gibson–Thomson (MGT) model, incorporating higher-order terms and memory effects, is adopted to describe the complex heat transfer behavior within the material. A nonlocal framework based on Eringen’s theory is utilized to derive the basic relations of the considered medium. An examination of the non-dimensionalized governing equations is conducted employing the normal mode technique to provide accurate solutions. The research demonstrates the presence of six separate wave modes that travel at varying speeds within the medium. The energy and amplitude ratios of reflected waves are determined by applying suitable boundary conditions. The influence of varying incidence angles on the reflected wave energy distribution is investigated numerically and visualized using MATLAB software. The study reveals that the energy ratios of the reflected waves are sensitive to the fractional-order parameter, kernel functions, initial stress, and nonlocality parameter. The analysis suggests a conservative reflection process, indicating minimal energy loss during reflection. Key findings and their implications for relevant scenarios are presented in the conclusion. Comparisons with existing models for certain cases demonstrate good agreement, supporting the validity of the present model.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"111 ","pages":"Article 105565"},"PeriodicalIF":4.4,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136001","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}

引用次数: 0

Impact response and energy absorption mechanisms of polypropylene woven fabrics with varying mechanical properties in flexible protection systems

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2025-01-11 DOI: 10.1016/j.euromechsol.2025.105568

Tingting Zhuo , Jiacen Shi , Hao Luan , Yan Yu , Zexu Hu , Yinjun Chen , Kai Hou , Ruili Wang , Meifang Zhu

The mechanical properties of yarns are crucial for the energy absorption capabilities of fabrics during low-velocity impact (LVI). However, due to the trouble for obtaining materials with a wide range of mechanical properties, few studies have investigated their effects on impact response by experiments. This paper presents yarns with diverse mechanical properties, achieved by controlling the draw ratio during the molding process, which are subsequently used to fabricate polypropylene woven fabrics (PPFs) for LVI experiments. Additionally, finite element (FE) analysis using the elastic-plastic model is integrated with the LVI experiments to investigate the dynamic impact response and energy absorption mechanisms of PPFs. The experimental and numerical results demonstrate that PPF-3.0, characterized by superior mechanical properties, exhibits exceptional impact resistance. Moreover, elastic and plastic strain energies are critical components of PPFs during the LVI process, accounting for 9–14% and 76–79%, respectively. Notably, PPF-3.0, due to its high elastic modulus, exhibits significant strain energy. This study reveals the evolution of impact damage, energy absorption mechanisms, and stress wave distribution in PPFs during the process, offering valuable insights for designing flexible protective fabrics.

{"title":"Impact response and energy absorption mechanisms of polypropylene woven fabrics with varying mechanical properties in flexible protection systems","authors":"Tingting Zhuo , Jiacen Shi , Hao Luan , Yan Yu , Zexu Hu , Yinjun Chen , Kai Hou , Ruili Wang , Meifang Zhu","doi":"10.1016/j.euromechsol.2025.105568","DOIUrl":"10.1016/j.euromechsol.2025.105568","url":null,"abstract":"<div><div>The mechanical properties of yarns are crucial for the energy absorption capabilities of fabrics during low-velocity impact (LVI). However, due to the trouble for obtaining materials with a wide range of mechanical properties, few studies have investigated their effects on impact response by experiments. This paper presents yarns with diverse mechanical properties, achieved by controlling the draw ratio during the molding process, which are subsequently used to fabricate polypropylene woven fabrics (PPFs) for LVI experiments. Additionally, finite element (FE) analysis using the elastic-plastic model is integrated with the LVI experiments to investigate the dynamic impact response and energy absorption mechanisms of PPFs. The experimental and numerical results demonstrate that PPF-3.0, characterized by superior mechanical properties, exhibits exceptional impact resistance. Moreover, elastic and plastic strain energies are critical components of PPFs during the LVI process, accounting for 9–14% and 76–79%, respectively. Notably, PPF-3.0, due to its high elastic modulus, exhibits significant strain energy. This study reveals the evolution of impact damage, energy absorption mechanisms, and stress wave distribution in PPFs during the process, offering valuable insights for designing flexible protective fabrics.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"111 ","pages":"Article 105568"},"PeriodicalIF":4.4,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136293","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}

引用次数: 0

Magnetically tunable band gaps and defect states of longitudinal waves in hard magnetic soft phononic crystal beams

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2025-01-10 DOI: 10.1016/j.euromechsol.2025.105575

Shunzu Zhang, Ziqi Zhang

Phononic crystals consisting of hard magnetic soft materials have attracted extensive attention due to their finite deformation when subjected to magnetic loading. However, achieving effective control defect states remains a challenge. We propose a novel design of hard magnetic soft phononic crystal beams to achieve the tunability of band gaps and defect states for longitudinal waves when the defect is introduced by adjusting magnetic loading. The nonlinear deformation of the unit cell under varying magnetic loadings is discussed. Then, the magnetically controllable band gaps and defect states of longitudinal waves are successfully observed without changing the structure. The edges and widths of band gaps are significantly affected by magnetic induction intensity because of the large magnetic induced deformation. The frequency and location of defect states can be dynamically adjusted by changing the distribution of magnetic induction intensity in different unit cells, which is robust against the defect location. The magnetically tunable band gaps and defect states of longitudinal waves offer a novel approach for the development of adaptive programmable devices, such as wave switching and energy harvesting.

{"title":"Magnetically tunable band gaps and defect states of longitudinal waves in hard magnetic soft phononic crystal beams","authors":"Shunzu Zhang, Ziqi Zhang","doi":"10.1016/j.euromechsol.2025.105575","DOIUrl":"10.1016/j.euromechsol.2025.105575","url":null,"abstract":"<div><div>Phononic crystals consisting of hard magnetic soft materials have attracted extensive attention due to their finite deformation when subjected to magnetic loading. However, achieving effective control defect states remains a challenge. We propose a novel design of hard magnetic soft phononic crystal beams to achieve the tunability of band gaps and defect states for longitudinal waves when the defect is introduced by adjusting magnetic loading. The nonlinear deformation of the unit cell under varying magnetic loadings is discussed. Then, the magnetically controllable band gaps and defect states of longitudinal waves are successfully observed without changing the structure. The edges and widths of band gaps are significantly affected by magnetic induction intensity because of the large magnetic induced deformation. The frequency and location of defect states can be dynamically adjusted by changing the distribution of magnetic induction intensity in different unit cells, which is robust against the defect location. The magnetically tunable band gaps and defect states of longitudinal waves offer a novel approach for the development of adaptive programmable devices, such as wave switching and energy harvesting.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"111 ","pages":"Article 105575"},"PeriodicalIF":4.4,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136753","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}

引用次数: 0

A new method for solving parameter mutation analysis in periodic structure bandgap calculation

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2025-01-09 DOI: 10.1016/j.euromechsol.2025.105572

Wenjie Guo , Jiabao Li , Wenjun Luo , Jian Yang , Xiang Zhu , Jianwei Yan

This study introduces a bandgap solution method that combines the domain decomposition method with the linear expression method based on the principle of the energy method to solve problems related to detailed geometric construction, physical parameter mutation in multi-period structures, and high-frequency calculation from a new perspective. Moreover, it derives the vibration dispersion curve of the periodic structure using AB-type periodic beams and periodic row pile structures as examples by decomposing the calculation domain into multiple sub-domains for independent solutions. Subsequently, it proposed the linear expression method to manage boundary displacement constraints. The accuracy and effectiveness of the proposed method are confirmed by comparing the numerical results with those from the finite element method. The study results have shown that in contrast to traditional modeling methods and finite element methods, the proposed method can enhance computational efficiency by more than 30 times. Furthermore, as the parameter difference grows, the efficiency improvement becomes even more pronounced. By increasing the number of segmented structures within the cell, the challenges of function fitting in addressing high-frequency problems using traditional energy methods are effectively mitigated. Additionally, an optimal number of segments exists to maximize computational efficiency for varying computational frequency requirements.

{"title":"A new method for solving parameter mutation analysis in periodic structure bandgap calculation","authors":"Wenjie Guo , Jiabao Li , Wenjun Luo , Jian Yang , Xiang Zhu , Jianwei Yan","doi":"10.1016/j.euromechsol.2025.105572","DOIUrl":"10.1016/j.euromechsol.2025.105572","url":null,"abstract":"<div><div>This study introduces a bandgap solution method that combines the domain decomposition method with the linear expression method based on the principle of the energy method to solve problems related to detailed geometric construction, physical parameter mutation in multi-period structures, and high-frequency calculation from a new perspective. Moreover, it derives the vibration dispersion curve of the periodic structure using AB-type periodic beams and periodic row pile structures as examples by decomposing the calculation domain into multiple sub-domains for independent solutions. Subsequently, it proposed the linear expression method to manage boundary displacement constraints. The accuracy and effectiveness of the proposed method are confirmed by comparing the numerical results with those from the finite element method. The study results have shown that in contrast to traditional modeling methods and finite element methods, the proposed method can enhance computational efficiency by more than 30 times. Furthermore, as the parameter difference grows, the efficiency improvement becomes even more pronounced. By increasing the number of segmented structures within the cell, the challenges of function fitting in addressing high-frequency problems using traditional energy methods are effectively mitigated. Additionally, an optimal number of segments exists to maximize computational efficiency for varying computational frequency requirements.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"111 ","pages":"Article 105572"},"PeriodicalIF":4.4,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136325","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}

引用次数: 0

Noisy Kriging for robust shape optimization of mechanical systems with a nonlinear and gradient-free expensive black-box figure of merit

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2025-01-08 DOI: 10.1016/j.euromechsol.2025.105567

Achille Jacquemond , Frédéric Gillot , Sébastien Besset , Koji Shimoyama

We expose a way to deal with robust shape optimization of mechanical structures under a nonlinear and gradient-free expensive figure of merit. Driving parameters impact the geometry of the considered structures, and are subject to uncertainties. Considering that observations of an expensive black box representation of the figure of merit can be transferred to a noisy Kriging metamodel, the balance between the starting set of observations and enrichment cost is the key point to an enhanced way to reach the robust Pareto front. We present in this paper an applicative example, consisting of a disc-pad device exhibiting squeal-noise behavior, which exposes the benefits and drawbacks of the proposed approach for such complex figures of merit, as the squeal noise level is nonlinear and gradient-free. Pairing the noisy Kriging model with a relevant enrichment process for a limited additional cost shows potential for the ultimate purpose of finding robust optimal solutions.

引用次数: 0

Nanocluster-induced creep inhibition for nanocrystalline materials: A theoretical model

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2025-01-07 DOI: 10.1016/j.euromechsol.2025.105570

Hanlu Xie , Shilin Li , Long Yu , Xiazi Xiao

Nanocrystals have been well known for their high strength, but the comparatively poor creep properties have limited the application as engineering structural materials. Recently, it has been noticed that adding nanoclusters of alloying elements can effectively inhibit the creep behavior of nanocrystals. In order to fundamentally comprehend the creep inhibition mechanism, a theoretical model is proposed in this work that combines the crystal plasticity theory and viscoplastic self-consistent method. At the grain level, creep strain rate dominated by the grain boundary and grain interior is characterized, respectively. Nanoclusters result in the suppression of grain boundary creep from three aspects, including the influence on diffusion coefficient, dislocation glide area and movement resistance. For the grain interior, the average distance between dislocations is reduced by nanoclusters, thereby affecting the evolution of dislocation density. At the polycrystalline level, viscoplastic self-consistent method is applied to predict the creep behaviors of nanocluster-contained nanocrystals. To validate the developed creep model, experimental data of both nanocrystalline pure Cu and Cu–Ta alloys has been considered. A good agreement of the creep curves is achieved between the theoretical results and experimental data, which provides a basis for further analyzing the creep inhibition mechanisms from the perspective of microstructure evolution.

{"title":"Nanocluster-induced creep inhibition for nanocrystalline materials: A theoretical model","authors":"Hanlu Xie , Shilin Li , Long Yu , Xiazi Xiao","doi":"10.1016/j.euromechsol.2025.105570","DOIUrl":"10.1016/j.euromechsol.2025.105570","url":null,"abstract":"<div><div>Nanocrystals have been well known for their high strength, but the comparatively poor creep properties have limited the application as engineering structural materials. Recently, it has been noticed that adding nanoclusters of alloying elements can effectively inhibit the creep behavior of nanocrystals. In order to fundamentally comprehend the creep inhibition mechanism, a theoretical model is proposed in this work that combines the crystal plasticity theory and viscoplastic self-consistent method. At the grain level, creep strain rate dominated by the grain boundary and grain interior is characterized, respectively. Nanoclusters result in the suppression of grain boundary creep from three aspects, including the influence on diffusion coefficient, dislocation glide area and movement resistance. For the grain interior, the average distance between dislocations is reduced by nanoclusters, thereby affecting the evolution of dislocation density. At the polycrystalline level, viscoplastic self-consistent method is applied to predict the creep behaviors of nanocluster-contained nanocrystals. To validate the developed creep model, experimental data of both nanocrystalline pure Cu and Cu–Ta alloys has been considered. A good agreement of the creep curves is achieved between the theoretical results and experimental data, which provides a basis for further analyzing the creep inhibition mechanisms from the perspective of microstructure evolution.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"111 ","pages":"Article 105570"},"PeriodicalIF":4.4,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136324","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}

引用次数: 0

A novel methodology for affecting the strain paths during hydraulic bulge tests by means of laser heat treatments

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2025-01-07 DOI: 10.1016/j.euromechsol.2025.105569

A. Cusanno , D. Carty , G. Palumbo

Nowadays, the design of manufacturing processes is supported by numerical simulations, that require an understanding of the material forming limits under the process conditions. The hydraulic bulge test represents an effective and well-established experimental procedure to evaluate critical strains of a material. However, it relies on using different elliptical die geometries to vary strain paths, introducing limitations in experimental flexibility. This work aims to evaluate the feasibility of achieving different strain paths during hydraulic bulge tests only using a circular die, by pre-softening certain zones of the testing blank using laser heating. The laser heat treatments (LHTs) were designed using a numerical/experimental approach. Two LHT strategies using different laser power values were performed to locally modify the material properties. Then, hydraulic bulge tests were conducted on the LHTed specimens and the resulting strain paths were analysed. The strain paths acquired during hydraulic bulge tests confirmed the possibility to affect the slope of the strain path at the dome by changing the LHT strategy, designed with the proposed methodology.

{"title":"A novel methodology for affecting the strain paths during hydraulic bulge tests by means of laser heat treatments","authors":"A. Cusanno , D. Carty , G. Palumbo","doi":"10.1016/j.euromechsol.2025.105569","DOIUrl":"10.1016/j.euromechsol.2025.105569","url":null,"abstract":"<div><div>Nowadays, the design of manufacturing processes is supported by numerical simulations, that require an understanding of the material forming limits under the process conditions. The hydraulic bulge test represents an effective and well-established experimental procedure to evaluate critical strains of a material. However, it relies on using different elliptical die geometries to vary strain paths, introducing limitations in experimental flexibility. This work aims to evaluate the feasibility of achieving different strain paths during hydraulic bulge tests only using a circular die, by pre-softening certain zones of the testing blank using laser heating. The laser heat treatments (LHTs) were designed using a numerical/experimental approach. Two LHT strategies using different laser power values were performed to locally modify the material properties. Then, hydraulic bulge tests were conducted on the LHTed specimens and the resulting strain paths were analysed. The strain paths acquired during hydraulic bulge tests confirmed the possibility to affect the slope of the strain path at the dome by changing the LHT strategy, designed with the proposed methodology.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"111 ","pages":"Article 105569"},"PeriodicalIF":4.4,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136292","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}

引用次数: 0

Is the decoupling into plane and antiplane singular eigensolutions always possible in corners with frictional contact?

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2025-01-03 DOI: 10.1016/j.euromechsol.2024.105559

María A. Herrera-Garrido , Vladislav Mantič , Roman Vodička

Consider stress singularities in semiinfinite linear elastic corners under generalized plane strain (GPS), where elastic variables do not change along the longitudinal direction

x_{3}

. It is commonly assumed that if the material in the corner has an elastic symmetry plane

x_{3} = 0

, the singular eigensolutions can be decomposed into plane and antiplane solutions. This has traditionally been assumed regardless of the boundary and interface conditions applied on the corner faces. The present work shows that this assumption should not be made if there is sliding friction contact, even with a low coefficient of friction, on the interface between the materials or on the boundary of the corner because some eigensolutions might be overlooked. It is shown that unexpected asymmetric eigensolutions may exist in which the plane and antiplane modes cannot be decoupled despite the elastic symmetry in the corner. Examples of such unexpected asymmetric eigensolutions are computed and analyzed for isotropic and orthotropic single- and bi-material corners. The key is to perform the corner singularity analysis under GPS without assuming the sliding angle on the friction faces. In some corner configurations, these unexpected strange coupled eigensolutions are the most singular of all eigensolutions satisfying the friction energy dissipation condition, thus, they could govern damage initiation at these corners.

{"title":"Is the decoupling into plane and antiplane singular eigensolutions always possible in corners with frictional contact?","authors":"María A. Herrera-Garrido , Vladislav Mantič , Roman Vodička","doi":"10.1016/j.euromechsol.2024.105559","DOIUrl":"10.1016/j.euromechsol.2024.105559","url":null,"abstract":"<div><div>Consider stress singularities in semiinfinite linear elastic corners under generalized plane strain (GPS), where elastic variables do not change along the longitudinal direction <span><math><msub><mrow><mi>x</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span>. It is commonly assumed that if the material in the corner has an elastic symmetry plane <span><math><mrow><msub><mrow><mi>x</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>=</mo><mn>0</mn></mrow></math></span>, the singular eigensolutions can be decomposed into plane and antiplane solutions. This has traditionally been assumed regardless of the boundary and interface conditions applied on the corner faces. The present work shows that this assumption should not be made if there is sliding friction contact, even with a low coefficient of friction, on the interface between the materials or on the boundary of the corner because some eigensolutions might be overlooked. It is shown that unexpected asymmetric eigensolutions may exist in which the plane and antiplane modes cannot be decoupled despite the elastic symmetry in the corner. Examples of such unexpected asymmetric eigensolutions are computed and analyzed for isotropic and orthotropic single- and bi-material corners. The key is to perform the corner singularity analysis under GPS without assuming the sliding angle on the friction faces. In some corner configurations, these unexpected strange coupled eigensolutions are the most singular of all eigensolutions satisfying the friction energy dissipation condition, thus, they could govern damage initiation at these corners.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"111 ","pages":"Article 105559"},"PeriodicalIF":4.4,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136004","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}

引用次数: 0

Mechanical modeling of plantar pressure during human walking in different terrains: Experiments and analysis

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2025-01-03 DOI: 10.1016/j.euromechsol.2024.105566

Jiaqi Liu , Hongbin Fang , Mingfei Feng , Qiwei Zhang , Jian Xu

Accurate plantar pressure models play a pivotal in predicting human gait dynamics and have broad applications, including the development of exoskeletons, prosthetics, and legged robots. However, existing models often overlook the influence of varying terrains on plantar pressures. In this study, we conducted a comprehensive modeling analysis of plantar pressure using experimental walking data collected from 12 subjects (6 males and 6 females). Statistical analysis reveals significant variations in vertical ground reaction forces across different plantar regions and terrains. In response to these findings, we develop a novel viscoelastic ellipsoid model capable of describing the complex mechanical behavior of foot-ground contact. The plantar tissue is divided into five distinct regions, each represented by an ellipsoid with viscoelastic material properties. Our model also expresses the plantar deformation by the contact area, which can be measured by in-shoe pressure sensors, thus addressing the challenge of measuring plantar tissue deformation in walking experiments. Additionally, we employ a quasi-static contact model to estimate the equivalent contact area, overcoming the challenge of contact area saturation during walking and improving the model's accuracy. Based on this foundation, we apply an intelligent optimization algorithm to identify the optimal geometric and material parameters of the ellipsoid models. Comparison of model outputs and experimental results demonstrate that the ellipsoid model can accurately render the vertical ground reaction forces of different plantar regions under various terrains, providing valuable insights into foot-ground interaction. Moreover, by comparing the results of parameter optimization in different terrain contexts, we unveil the critical relationships between terrain factors and model parameters, thereby deepening our understanding of foot-ground contact mechanics.

{"title":"Mechanical modeling of plantar pressure during human walking in different terrains: Experiments and analysis","authors":"Jiaqi Liu , Hongbin Fang , Mingfei Feng , Qiwei Zhang , Jian Xu","doi":"10.1016/j.euromechsol.2024.105566","DOIUrl":"10.1016/j.euromechsol.2024.105566","url":null,"abstract":"<div><div>Accurate plantar pressure models play a pivotal in predicting human gait dynamics and have broad applications, including the development of exoskeletons, prosthetics, and legged robots. However, existing models often overlook the influence of varying terrains on plantar pressures. In this study, we conducted a comprehensive modeling analysis of plantar pressure using experimental walking data collected from 12 subjects (6 males and 6 females). Statistical analysis reveals significant variations in vertical ground reaction forces across different plantar regions and terrains. In response to these findings, we develop a novel viscoelastic ellipsoid model capable of describing the complex mechanical behavior of foot-ground contact. The plantar tissue is divided into five distinct regions, each represented by an ellipsoid with viscoelastic material properties. Our model also expresses the plantar deformation by the contact area, which can be measured by in-shoe pressure sensors, thus addressing the challenge of measuring plantar tissue deformation in walking experiments. Additionally, we employ a quasi-static contact model to estimate the equivalent contact area, overcoming the challenge of contact area saturation during walking and improving the model's accuracy. Based on this foundation, we apply an intelligent optimization algorithm to identify the optimal geometric and material parameters of the ellipsoid models. Comparison of model outputs and experimental results demonstrate that the ellipsoid model can accurately render the vertical ground reaction forces of different plantar regions under various terrains, providing valuable insights into foot-ground interaction. Moreover, by comparing the results of parameter optimization in different terrain contexts, we unveil the critical relationships between terrain factors and model parameters, thereby deepening our understanding of foot-ground contact mechanics.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"111 ","pages":"Article 105566"},"PeriodicalIF":4.4,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143136005","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}

引用次数: 0

Contribution of microscale stochastic truss models to investigate the macroscale elasticity constants of porous ceramics

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2025-01-03 DOI: 10.1016/j.euromechsol.2024.105561

Thierry Canet, Gilles Dusserre, Thierry Cutard

This paper deals with modelling the mechanical behaviour of silica-alumina open-cell porous ceramics obtained by viscous flow sintering. The modelling approach is based on the similarity of the material microstructure to a truss of sintering bridges connecting alumina particles. This makes it possible to use two-node elements, leading to a low computational cost. The method includes the building of a random packing of spheres (alumina particles) and the setup of connections between their centres (silica sintering bridges). An equivalent stiffness is then assigned to each bridge, based on the material parameters. The macroscale elasticity constants have been derived from the natural frequencies of such micrometric cylindrical volume elements made of thousands of particles. The reliability of the underlying assumptions is discussed and the dependence to the material parameters is emphasized. The method is suitable to handle more complex behaviours, which opens the door to fracture modelling.

引用次数: 0

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