Meccanica最新文献_第8页

Crashworthiness capability comparison of a 3D Greek cross fractal structure additively manufactured with polyamide and thermoplastic polyurethane 用聚酰胺和热塑性聚氨酯加成制造的三维希腊十字分形结构的防撞性能比较

IF 2.7 3区工程技术

Meccanica Pub Date : 2024-05-14 DOI: 10.1007/s11012-024-01818-x

Marco Viccica, Gabriel Ferreira Serra, Ricardo Alves de Sousa, Manuela Galati

{"title":"Crashworthiness capability comparison of a 3D Greek cross fractal structure additively manufactured with polyamide and thermoplastic polyurethane","authors":"Marco Viccica, Gabriel Ferreira Serra, Ricardo Alves de Sousa, Manuela Galati","doi":"10.1007/s11012-024-01818-x","DOIUrl":"https://doi.org/10.1007/s11012-024-01818-x","url":null,"abstract":"Designers are continuously searching for materials or meta-structures, also inspired by nature, that exhibit favourable strength-to-weight ratios, substantial heat transfer capabilities, and efficient energy absorption. One particular example includes fractal geometries, which usually consist of intricate three-dimensional geometrical structures and are challenging to produce through traditional manufacturing methods. In this regard, this study analyses the performance of a three-dimensional cross-based fractal structure (3D-CFS) designed for energy absorption and manufactured using polymeric materials. Mathematically, the geometry is obtained using a 3D Greek cross repeated in the 3D space according to the fractal principle. Owing to the intricate final structure, samples are fabricated using an Additive Manufacturing system based on powder bed fusion with a laser beam and infrared light. The study is carried out using two polymeric materials, polyamide and thermoplastic polyurethane, and the mechanical response of the structure is analysed under dynamic compression tests. The tested geometries consisted of samples with a single 3D-CFS cell, various volume fractions and a configuration with multiple cells that emulated a possible layout for linear helmet application. The findings indicate that the 3D-CFS is a promising geometry for eventual implementation into shock absorption applications, specifically in personal protective equipment (PPE) usage.","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"118 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140938817","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

On the reliability of the dynamic terrain method to generate ABL winds for environmental applications 论动态地形法为环境应用生成 ABL 风的可靠性

IF 2.7 3区工程技术

Meccanica Pub Date : 2024-05-13 DOI: 10.1007/s11012-024-01810-5

Theodore Potsis, Alessio Ricci, Ted Stathopoulos

{"title":"On the reliability of the dynamic terrain method to generate ABL winds for environmental applications","authors":"Theodore Potsis, Alessio Ricci, Ted Stathopoulos","doi":"10.1007/s11012-024-01810-5","DOIUrl":"https://doi.org/10.1007/s11012-024-01810-5","url":null,"abstract":"Computational fluid dynamics (CFD) has been developing rapidly during the last decades for usage in wind engineering. OpenFOAM plays a big role in this respect since it is a reliable open-source tool frequently used in state-of-the-art applications. In the present research study, the focus is given to the analysis of wind flow, mean, and fluctuating properties of two environmental cases using a novel inflow generator method for Large-eddy simulation (LES) in OpenFOAM. This refers to the dynamic terrain (DT) method for the generation and propagation of turbulence in the computational domain. LES simulations are carried out with the DT method on two wind-tunnel (WT) benchmark case studies proposed by the Architectural Institute of Japan (AIJ) and widely adopted in the scientific literature: (1) an isolated building (2) a cluster of buildings. Then, the LES results are compared to the WT results of AIJ. A good agreement is found in terms of the mean and turbulence properties of the wind velocity for the two case studies. The level of accuracy achieved from the LES-DT results establishes its reliability for wind flow modeling for various environmental applications.","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"46 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140938806","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

Modeling of heat conduction through rate equations 通过速率方程建立热传导模型

IF 2.7 3区工程技术

Meccanica Pub Date : 2024-05-13 DOI: 10.1007/s11012-024-01788-0

Claudio Giorgi, Angelo Morro, Federico Zullo

{"title":"Modeling of heat conduction through rate equations","authors":"Claudio Giorgi, Angelo Morro, Federico Zullo","doi":"10.1007/s11012-024-01788-0","DOIUrl":"https://doi.org/10.1007/s11012-024-01788-0","url":null,"abstract":"Starting from a classical thermodynamic approach, we derive rate-type equations to describe the behavior of heat flow in deformable media. Constitutive equations are defined in the material (Lagrangian) description where the standard time derivative satisfies the principle of objectivity. The statement of the Second Law is formulated in the classical form and the thermodynamic restrictions are then developed following a variant of the Coleman-Noll procedure where the entropy production too is given by a non-negative constitutive equation. Both the free energy and the entropy production are assumed to depend on a common set of independent variables involving, in addition to temperature, both temperature gradient and heat-flux vector together with their time derivatives. This approach results in rate-type constitutive function for the heat flux that are intrinsically consistent with the Second Law and easily amenable to analysis. In addition to providing already known models (e.g., Maxwell-Cattaneo-Vernotte’s and Jeffreys-like heat conductors), this scheme allows the formulation of new models of heat transport that are likely to apply also in nanosystems. This is consistent with the fact that higher-order time derivatives of the heat flux are in order when high-rate regimes occur.","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"21 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140938645","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

On the entropy inequality and its exploitation in continuum physics 论熵不等式及其在连续物理学中的应用

IF 2.7 3区工程技术

Meccanica Pub Date : 2024-05-13 DOI: 10.1007/s11012-024-01804-3

Angelo Morro

引用次数: 0

Computational fluid–structure analysis of the impact of leaflet thickness and protrusion height on the flutter phenomenon in aortic valve bioprostheses 计算流体结构分析瓣叶厚度和突出高度对主动脉瓣生物修复体扑动现象的影响

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-05-13 DOI: 10.1007/s11012-024-01809-y

Matheus Carvalho Barbosa Costa, Saulo de Freitas Gonçalves, João Victor Curado Fleury, Mário Luis Ferreira da Silva, Rudolf Huebner, Artur Henrique de Freitas Avelar

{"title":"Computational fluid–structure analysis of the impact of leaflet thickness and protrusion height on the flutter phenomenon in aortic valve bioprostheses","authors":"Matheus Carvalho Barbosa Costa, Saulo de Freitas Gonçalves, João Victor Curado Fleury, Mário Luis Ferreira da Silva, Rudolf Huebner, Artur Henrique de Freitas Avelar","doi":"10.1007/s11012-024-01809-y","DOIUrl":"10.1007/s11012-024-01809-y","url":null,"abstract":"<div>Although it is associated with the low lifetime of aortic valve bioprostheses, flutter has little been studied in the dynamics of these valves. To improve the understanding of flutter in bioprosthetic leaflets, the present work evaluates the effect of leaflet thickness and protrusion height on flutter parameters through the computational fluid–structure interaction. A bioprosthesis geometry, based on a geometric model available in the literature, and a simplified fluid domain were developed. As a boundary condition, a parabolic velocity profile was applied at the inlet, outflow at the outlet, and fixed support at the sides of the leaflets. The valve cusps were considered with linear elastic and isotropic mechanical behavior, while the blood was modeled as a Newtonian fluid. Turbulence was modeled according to the k-(omega ) SST model. The numerical results showed that, due to the occurrence of leaflet oscillations, both fluid dynamic quantities, such as pressure, velocity, and turbulence intensity, and solid domain quantities, such as stress and strain, exhibited an irregular and oscillatory behavior. Furthermore, the radial displacements of the leaflets were asynchronous, and the phase difference between the leaflets increased with increasing thickness. The frequencies ranged from 28.3 to 36.7 Hz, while the amplitudes ranged from 5.34 to 6.53 mm, where the valve with the lowest protrusion height did not develop flutter</div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 5","pages":"685 - 701"},"PeriodicalIF":1.9,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140938821","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

A variational formulation for three-dimensional linear thermoelasticity with ‘thermal inertia’ 具有 "热惯性 "的三维线性热弹性的变分公式

IF 2.7 3区工程技术

Meccanica Pub Date : 2024-05-13 DOI: 10.1007/s11012-024-01796-0

Ivan Giorgio, Luca Placidi

{"title":"A variational formulation for three-dimensional linear thermoelasticity with ‘thermal inertia’","authors":"Ivan Giorgio, Luca Placidi","doi":"10.1007/s11012-024-01796-0","DOIUrl":"https://doi.org/10.1007/s11012-024-01796-0","url":null,"abstract":"A variational model has been developed to investigate the coupled thermo-mechanical response of a three-dimensional continuum. The linear Partial Differential Equations (PDEs) of this problem are already well-known in the literature. However, in this paper, we avoid the use of the second principle of thermodynamics, basing the formulation only on a proper definition (i) of kinematic descriptors (the displacement and the entropic displacement), (ii) of the action functional (with kinetic, internal and external energy functions) and (iii) of the Rayleigh dissipation function. Thus, a Hamilton–Rayleigh variational principle is formulated, and the cited PDEs have been derived with a set of proper Boundary Conditions (BCs). Besides, the Lagrangian variational perspective has been expanded to analyze linear irreversible processes by generalizing Biot’s formulation, namely, including thermal inertia in the kinetic energy definition. Specifically, this implies Cattaneo’s law for heat conduction, and the well-known Lord–Shulman model for thermo-elastic anisotropic bodies is then deduced. The developed variational framework is ideal for the perspective of analyzing the thermo-mechanical problems with micromorphic and/or higher-order gradient continuum models, where the deduction of a coherent system of PDEs and BCs is, on the one hand, not straightforward and, on the other hand, natural within the presented variational deduction.","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"38 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140938788","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

Experimental and numerical mechanical characterisation of additively manufactured polymeric lattice structures under uniaxial tensile load 单轴拉伸载荷下加成法制造聚合物晶格结构的实验和数值力学特性分析

IF 2.7 3区工程技术

Meccanica Pub Date : 2024-05-07 DOI: 10.1007/s11012-024-01813-2

Danilo Bruson, Luca Iuliano, Manuela Galati

{"title":"Experimental and numerical mechanical characterisation of additively manufactured polymeric lattice structures under uniaxial tensile load","authors":"Danilo Bruson, Luca Iuliano, Manuela Galati","doi":"10.1007/s11012-024-01813-2","DOIUrl":"https://doi.org/10.1007/s11012-024-01813-2","url":null,"abstract":"Additive manufacturing enables the production of lighter, more robust components with intricate features like lattice structures. However, since the mechanical behaviour of lattice structures is not fully characterized, the application of such potential is limited today. The challenge with lattice structures tensile tests is defining a suitable design that fits the standard requirements and process characteristics. In the polymeric powder bed fusion process, the problem is to produce powder-free geometries and to avoid stress concentrations zones, adapting the specimen accordingly. In this regard, numerical simulation may provide insightful information and support the analysis of the deformation mechanisms. This paper analyses a new tensile sample for lattice structures using finite element analysis. The sample is designed following the EN ISO 527 standard prescriptions. An area with a controlled gradation of the lattice relative density is designed to ensure both powder-free voids and fracture localization within the lattice specimen gauge length. Experimental tests are performed to validate the numerical results using a modified body cubic centred topology with two different strut diameters. The specimens are produced in polyamide by powder bed AM process. Due to the complexity of the lattice design, a digital image correlation is used to compute the full range of strains at the macroscopic level. Experimental and numerical strain maps results showed a good agreement. The recorded deviation was attributed to the process-induced defect, such as the geometrical accuracy that, if compensated, boosted the capability of the numerical model to predict the mechanical behaviour of the lattice structure.","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"109 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140885228","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

Correction to: Acceleration waves in thermoelastic complex media with temperature-dependent phase fields 更正：热弹性复合介质中的加速波与温度相关相场

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-05-06 DOI: 10.1007/s11012-024-01814-1

Pasquale Giovine, Paolo Maria Mariano, Federica Mugnaioni

引用次数: 0

Hybrid origami-linkage vaulted deployable structures: parametric development and form-finding 混合折纸-连杆拱顶式可展开结构：参数化开发和外形设计

IF 2.7 3区工程技术

Meccanica Pub Date : 2024-05-02 DOI: 10.1007/s11012-024-01802-5

Evangelia Vlachaki, Katherine A. Liapi

{"title":"Hybrid origami-linkage vaulted deployable structures: parametric development and form-finding","authors":"Evangelia Vlachaki, Katherine A. Liapi","doi":"10.1007/s11012-024-01802-5","DOIUrl":"https://doi.org/10.1007/s11012-024-01802-5","url":null,"abstract":"The demand for adaptable structures is steadily increasing in contemporary architectural practice. Deployable structures, characterized by their flexibility and versatility, offer innovative solutions across demanding engineering and architectural contexts. Among the various types of deployable structures, two main categories emerge: lattice deployable structures and continuous surface deployable structures. This paper explores the creation of hybrid deployable vaulted structures by incorporating kinetic elements from both deployable structure categories. A combination of rigid thick origami surfaces and retractable structural frames composed of four-bar and scissor-hinged linkages is examined, while both direct and inverse design methodologies are explored. To facilitate the parameterization and kinematic study of the proposed structures, an algorithm is developed within the Rhino Grasshopper visual programming environment, which is then utilized for form-finding and design optimization of the generated deployable vaults. The present study aims to contribute to the evolution of lightweight, kinetic elements for versatile architectural applications. The proposed hybrid deployable structures are designed to adjust to evolving spatial and functional requirements while maintaining structural integrity.","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"1 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140885265","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-shear-current modified nonlinear Schrödinger equation for gravity-capillary waves on deep water 深水重力-毛细管波的线性-剪切-电流修正非线性薛定谔方程

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-05-02 DOI: 10.1007/s11012-024-01800-7

Tanmoy Pal, Asoke Kumar Dhar

{"title":"Linear-shear-current modified nonlinear Schrödinger equation for gravity-capillary waves on deep water","authors":"Tanmoy Pal, Asoke Kumar Dhar","doi":"10.1007/s11012-024-01800-7","DOIUrl":"10.1007/s11012-024-01800-7","url":null,"abstract":"<div>Starting from Zakharov’s integral equation (ZIE) a modified nonlinear Schrödinger equation (NLSE) correct to fourth-order in wave steepness for deep water gravity-capillary waves (GCW) on linear shear currents (LSC) is derived under the assumption of narrow bandwidth. This equation is then used to examine the stability of uniform wave train. It is found that LSC change considerably the instability behaviors of weakly nonlinear GCW. At both third and fourth-orders, we have shown the significance of nonlinear coupling between the wave-induced mean flow and the vorticity. The key result is that the new fourth-order analysis shows notable deviations in the modulational instability properties from the third-order analysis and provides better results consistent with the exact results. The united effect of vorticity and surface tension is to increase the modulational growth rate of instability influenced by surface tension when the vorticity is negative. As it turns out, the most significant contribution appears from the mean flow response and in the absence of vorticity and depth uniform current the effect of mean flow for pure capillary waves is of opposite sign to that of pure gravity waves. As a consequence, it modifies significantly the modulational instability properties.</div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 5","pages":"743 - 759"},"PeriodicalIF":1.9,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140889779","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