Meccanica最新文献_第10页

Limit analysis of masonry arches and domes with finite strength: funicular analysis versus stability area method 具有有限强度的砌体拱和穹顶的极限分析：漏斗分析法与稳定面积法的比较

IF 2.7 3区工程技术

Meccanica Pub Date : 2024-04-07 DOI: 10.1007/s11012-024-01781-7

Danila Aita, Matteo Bruggi, Alberto Taliercio

{"title":"Limit analysis of masonry arches and domes with finite strength: funicular analysis versus stability area method","authors":"Danila Aita, Matteo Bruggi, Alberto Taliercio","doi":"10.1007/s11012-024-01781-7","DOIUrl":"https://doi.org/10.1007/s11012-024-01781-7","url":null,"abstract":"<p>This study, framed within the context of the lower bound theorem of limit analysis, aims to assess the anti-funicular equilibrium of masonry arches and domes using a computational approach based on the constrained force density method. In contrast to the commonly adopted classical Heyman’s assumptions, the approach proposed here considers the effects of finite compressive strength in the material. Assuming a fixed plan projection for a network with independent sets of branches, a suitable set of local constraints is enforced at each joint to account for the limit bending moment resulting from the material’s assumptions, including limited compressive strength and zero tensile strength. Additionally, the stereotomy of the voussoirs is considered by assigning a geometric law to the joint inclination. The collapse load is determined by formulating a multi-constrained maximization problem. The method is validated using a modern version of the semi-analytical Durand-Claye’s method. For benchmark case studies, such as symmetric masonry arches and domes with specific stereotomies subjected to axi-symmetrical load conditions, the set of statically admissible solutions compatible with equilibrium and strength requirements is graphically determined in terms of the horizontal thrust and its eccentricity at the crown, examining the shape of the stability area. Assuming an infinite value for the friction coefficient, the collapse condition is reached when the stability area shrinks to a single point. The results obtained from both of these methods are in excellent agreement. The influence of compressive strength on the bearing capacity of the structures is also discussed.</p>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"97 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140602693","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

XFEM analysis of cracked media under thermal shock considering Chandrasekharaiah–Tzou theory 考虑 Chandrasekharaiah-Tzou 理论的热冲击下裂纹介质 XFEM 分析

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-04-07 DOI: 10.1007/s11012-024-01787-1

Vahid Jafari, Mohammad Bagher Nazari, Masoud Mahdizadeh Rokhi

{"title":"XFEM analysis of cracked media under thermal shock considering Chandrasekharaiah–Tzou theory","authors":"Vahid Jafari, Mohammad Bagher Nazari, Masoud Mahdizadeh Rokhi","doi":"10.1007/s11012-024-01787-1","DOIUrl":"10.1007/s11012-024-01787-1","url":null,"abstract":"<div><p>In this paper, an isotropic environment with a static crack under thermal shock is studied using generalized thermoelasticity equations of Chandrasekharaiah–Tzou. The discretization of the governing equations in dimensionless space is done using the extended finite element method and the matrix form of the equations is extracted. Newmark’s method is used to solve the resulting system of nonlinear equations in the time domain. Some examples are solved using the numerical method and the temperature, displacements and stress fields along the length of the homogeneous layer are obtained. Also, the stress intensity factors under thermal shock are calculated using the interaction integral method and compared with the values obtained from the classical thermoelasticity theory. The results show that the speed of temperature, displacement and stress waves in the Chandrasekharaiah–Tzou theory are limited, unlike the classical thermoelasticity theory. Also, the maximum values of displacement and stress according to the theory of Chandrasekharaiah–Tzou occur at a smaller distance from the edge to which the thermal shock is applied.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 4","pages":"613 - 635"},"PeriodicalIF":1.9,"publicationDate":"2024-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140575226","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

Breaking the left-right symmetry in fluttering artificial cilia that perform nonreciprocal oscillations 打破进行非互惠振荡的人工纤毛的左右对称性

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-04-06 DOI: 10.1007/s11012-024-01765-7

Ariel Surya Boiardi, Roberto Marchello

{"title":"Breaking the left-right symmetry in fluttering artificial cilia that perform nonreciprocal oscillations","authors":"Ariel Surya Boiardi, Roberto Marchello","doi":"10.1007/s11012-024-01765-7","DOIUrl":"10.1007/s11012-024-01765-7","url":null,"abstract":"<div><p>Recent investigations on active materials have introduced a new paradigm for soft robotics by showing that a complex response can be obtained from simple stimuli by harnessing dynamic instabilities. In particular, polyelectrolyte hydrogel filaments actuated by a constant electric field have been shown to exhibit self-sustained oscillations as a consequence of flutter instability. Owing to the nonreciprocal nature of the emerging oscillations, these <i>artificial cilia</i> are able to generate flows along the stimulus. Building upon these findings, in this paper we propose a design strategy to break the left-right symmetry in the generated flows, by endowing the filament with a natural curvature at the fabrication stage. We develop a mathematical model based on morphoelastic rod theory to characterize the stability of the equilibrium configurations of the filament, proving the persistence of flutter instability. We show that the emerging oscillations are nonreciprocal and generate thrust at an angle with the stimulus. The results we find at the level of the single cilium open new perspectives on the possible applications of artificial ciliary arrays in soft robotics and microfluidics.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 8","pages":"1255 - 1268"},"PeriodicalIF":1.9,"publicationDate":"2024-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11012-024-01765-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140575311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Well-posedness and exponential stability in nonlocal theory of nonsimple porous thermoelasticity 非简单多孔热弹性非局域理论中的好拟性和指数稳定性

IF 2.7 3区工程技术

Meccanica Pub Date : 2024-04-05 DOI: 10.1007/s11012-024-01768-4

Moncef Aouadi, Michele Ciarletta, Vincenzo Tibullo

{"title":"Well-posedness and exponential stability in nonlocal theory of nonsimple porous thermoelasticity","authors":"Moncef Aouadi, Michele Ciarletta, Vincenzo Tibullo","doi":"10.1007/s11012-024-01768-4","DOIUrl":"https://doi.org/10.1007/s11012-024-01768-4","url":null,"abstract":"<p>In this paper, a nonlocal model for porous thermoelasticity is derived in the framework of the Mindlin’s strain gradient theory where the thermal behavior is based on the entropy balance postulated by Green–Naghdi models of type II or III. In this context, we add the second gradient of volume fraction field and the second gradient of deformation to the set of independent constituent variables. The elastic nonlocal parameter <span>(varpi)</span> and the strain gradient length scale parameter <i>l</i> are also considered in the derived model. New mathematical difficulties then appeared due to the higher gradient terms in the resulting system which is a coupling of three second order equations in time. By using the theories of monotone operators and the nonlinear semigroups, we prove the well-posedness of the derived model in the one dimensional setting. The exponential stability of the corresponding semigroup to type II and type III models is proved. The proof is essentially based on a characterization stated in the book of Liu and Zheng. This result of exponential stability of the type II model confirms the results of the classic theory for which the exponential decay cannot hold (for type II) without adding a dissipative mechanism.</p>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"31 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140575668","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: Optimized Gauss–Legendre–Hermite 2-point (O-GLH-2P) method for nonlinear time-history analysis of structures 更正：用于结构非线性时程分析的优化高斯-列根德-赫米特 2 点 (O-GLH-2P) 方法

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-04-03 DOI: 10.1007/s11012-024-01783-5

Mehdi Babaei

引用次数: 0

Continuous dependence in thermopiezoelectricity of nonsimple materials 非简单材料热压电性的连续依赖性

IF 2.7 3区工程技术

Meccanica Pub Date : 2024-04-03 DOI: 10.1007/s11012-024-01772-8

Martina Nunziata

引用次数: 0

Simplified inverse dynamic models of parallel robots based on a Lagrangian approach 基于拉格朗日方法的并联机器人简化逆动态模型

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-04-03 DOI: 10.1007/s11012-024-01782-6

Zhou Zhou, Clément Gosselin

引用次数: 0

Study on the rotordynamics of a high-speed motor supported by air foil bearings 由空气箔轴承支撑的高速电机的旋转动力学研究

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-04-02 DOI: 10.1007/s11012-024-01758-6

Yuqun Wei, Shuangmin Li, Haojie Xu, Q. An

{"title":"Study on the rotordynamics of a high-speed motor supported by air foil bearings","authors":"Yuqun Wei, Shuangmin Li, Haojie Xu, Q. An","doi":"10.1007/s11012-024-01758-6","DOIUrl":"10.1007/s11012-024-01758-6","url":null,"abstract":"<div><p>In order to adapt to the high speed of a high-speed permanent magnet synchronous motor (HSPMSM) used in hydrogen fuel cells, air foil bearings are applied to support the motor rotor. However, the stability of the motor rotor system supported by air foil bearings is relatively complex. In this article, the Castigliano’s second theorem and the theory of small deflection elastic thin plates are used to establish a deformation model of air foil bearings. Based on the generalized Reynolds equation, the stiffness and damping of the air foil bearings are calculated using perturbation methods and finite difference methods as the support model for the motor rotor. Subsequently, the transfer matrix of a typical disc-shaft unit is analyzed and obtained by using the transfer matrix method. On this basis, combined with Riccati transform, the natural frequencies and critical speeds of the motor rotor system in the spatial domain are calculated using MATLAB. And the unbalanced magnetic pull (UMP) is calculated by Maxwell stress tensor method, which is equivalent to the unbalanced mass and is applied to the disc it acts on to ascertain the unbalanced response, forming a theoretical model for calculating the dynamic performance of high-speed motor rotors. Then, the accuracy of the constructed model is verified by comparing the experimental results with a literature. Based on the estalished model, the effects of structural parameters and operating conditions on motor rotordynamics are studied, and the responses of the motor rotor system to unbalanced mass and unbalanced magnetic tension are compared. It is found that the critical speeds of the motor rotor system increase with the increase of the dynamic viscosity of air, and the motor can operate stably under the influence of the maximum UMP.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 4","pages":"637 - 655"},"PeriodicalIF":1.9,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140575227","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

Hydrodynamic and power conversion performance for linear and triangular dual-buoy wave energy converter array 线性和三角形双浮标波能转换器阵列的水动力和功率转换性能

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-04-01 DOI: 10.1007/s11012-024-01776-4

Yahui Zhou, Shuxu Liu, Yeqing Jin, Xiaoguo Zhou, Fankai Kong, Hengxu Liu

{"title":"Hydrodynamic and power conversion performance for linear and triangular dual-buoy wave energy converter array","authors":"Yahui Zhou, Shuxu Liu, Yeqing Jin, Xiaoguo Zhou, Fankai Kong, Hengxu Liu","doi":"10.1007/s11012-024-01776-4","DOIUrl":"10.1007/s11012-024-01776-4","url":null,"abstract":"<div><p>To address the issues concerning energy conversion efficiency and total energy in the propulsion process of wave energy conversion devices in deep water environments, this study examines the array layout of the existing dual-buoy point-absorption wave energy converter. Two array layouts, namely linear and triangular, are proposed. The coupling hydrodynamic coefficient between the dual-buoy wave energy converter array and the wave action is determined using the linear wave hydrodynamic theory. The optimal PTO damping coefficient of the dual-buoy wave energy converter array can be determined by combining the multi-degree-of-freedom vibration theory and optimization method. In this study, we introduce the array impact factor to conduct a comprehensive investigation into the energy conversion characteristics of dual-buoy wave energy converter arrays with linear and triangular configurations. We examine the effects of various factors such as wave angles, float spacing, and array layout on the wave energy conversion of dual-buoy wave energy converter arrays, as well as the causes of interference. Furthermore, the optimal wave energy capture impact factor of the linear array initially increases and then decreases with the wave direction angle and the distance between the buoys. This suggests that there is an ideal wave angle and spacing arrangement that can enhance the efficiency of the array system. The peak values of the optimal wave energy capture interference factors of the triangular array are all greater than 1, confirming that the array arrangement effectively improves the energy capture efficiency of the device. These research findings provide a theoretical basis for the engineering application of deep-water wave energy utilization and serve as a foundation for optimizing and designing the layout of oscillatory buoy wave energy generation converters.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 4","pages":"571 - 595"},"PeriodicalIF":1.9,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140602793","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

Thermal convection in reaction fronts confined between conductive walls 限制在导电墙之间的反应前沿的热对流

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-03-30 DOI: 10.1007/s11012-024-01775-5

Roberto Guzman, Desiderio A. Vasquez

引用次数: 0