Meccanica最新文献_第7页

Closed-form equations for statically analyzing shaft-gear systems 用于静态分析轴齿轮系统的闭式方程

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-05-23 DOI: 10.1007/s11012-024-01803-4

Mahmoud-Reza Hosseini-Tabatabaei, Mahmoud Alfouneh

{"title":"Closed-form equations for statically analyzing shaft-gear systems","authors":"Mahmoud-Reza Hosseini-Tabatabaei, Mahmoud Alfouneh","doi":"10.1007/s11012-024-01803-4","DOIUrl":"10.1007/s11012-024-01803-4","url":null,"abstract":"<div><p>Shaft-gear systems are integral parts of industry. To analyze these systems using an existing classical method, one should first write the static equilibrium and compatibility equations and then solve these equations simultaneously, which is tedious for complex problems. This study proposes a novel method for analyzing shaft-gear systems. The systems are modeled as parallel or series arrangements using torsional springs. By introducing a concept of torque propagation, relationships of the stiffness/flexibility, torque, and twist angle are derived, resulting in closed-form equations with the unknown torques or the twist angles that can be directly found without concurrently solving the static equilibrium and compatibility equations. Illustrative examples are presented to validate and address the efficiency of the proposed method to quickly analyze the shaft-gear systems, even for a combination of parallel and series ones. The results are exact and portend that the technique requires cost-efficiency of computations compared to the existing method, especially when the systems are hybrid, or the number of unknowns is high. Also, a concise computer program can be provided by the proposed equations.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 6","pages":"921 - 938"},"PeriodicalIF":1.9,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141107701","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 low Mach number unsteady turbulent pipe flows 低马赫数非稳定湍流管道流动建模

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-05-21 DOI: 10.1007/s11012-024-01819-w

Carmine Di Nucci, Simone Michele, Marcello Di Risio

引用次数: 0

Nonlinear geometric decomposition of airfoils into the thickness and camber contributions 将机翼的非线性几何分解为厚度和凸度贡献

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-05-21 DOI: 10.1007/s11012-024-01801-6

George L. S. Torres, Flávio D. Marques

{"title":"Nonlinear geometric decomposition of airfoils into the thickness and camber contributions","authors":"George L. S. Torres, Flávio D. Marques","doi":"10.1007/s11012-024-01801-6","DOIUrl":"10.1007/s11012-024-01801-6","url":null,"abstract":"<div><p>In the thin airfoil theory, the camber line and the thickness distribution of general airfoils are mainly extracted by a linear combination of the upper and lower surfaces, giving rise to geometric distortions at the leading edge. Furthermore, despite the recent effort to obtain analytic expressions for the zero-lift angle of attack and quarter-chord moment coefficient, analytic generalizations are needed for the camber line component in the trigonometric series coefficients. In this sense, the present paper proposes a straightforward algorithm to extract the camber line and thickness distribution of general-shaped airfoils based on a finite difference method and the Bézier curve fitting. Integrals in the thin airfoil theory involving a Bernstein basis are performed, leading to series coefficients related to Gegenbauer polynomials. The algorithm is validated against analytical expressions of the NACA airfoils without introducing or adapting geometric parameters, and the results demonstrate good accuracy. In addition, the proposed algorithm indicated a significantly different geometric behavior for the SD7003 and E387 airfoils’ camber slope at the leading edge in contrast with the classical linear approximation. Moreover, the method can be coupled conveniently in recent unsteady aerodynamic models established on the thin airfoil theory to obtain closed-form expressions for general airfoils.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 6","pages":"889 - 907"},"PeriodicalIF":1.9,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141117936","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

Elasto-viscoplastic model for rayon yarns 人造丝纱线的弹塑性-粘弹性模型

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-05-21 DOI: 10.1007/s11012-024-01785-3

Marco Moscatelli, Lucas Pires da Costa, Paola Caracino, Simone Agresti, Giorgio Novati, Claudia Comi

引用次数: 0

Acoustoelastic and viscoelastic effects on guided wave characteristics in an incompressible plate 声弹性和粘弹性对不可压缩板中导波特性的影响

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-05-21 DOI: 10.1007/s11012-024-01805-2

B. Zhang, P. Liu, Y. W. Liu, J. G. Yu, C. X. Luo, K. Li, L. Elmaimouni

{"title":"Acoustoelastic and viscoelastic effects on guided wave characteristics in an incompressible plate","authors":"B. Zhang, P. Liu, Y. W. Liu, J. G. Yu, C. X. Luo, K. Li, L. Elmaimouni","doi":"10.1007/s11012-024-01805-2","DOIUrl":"10.1007/s11012-024-01805-2","url":null,"abstract":"<div><p>Owing to the high fluid content, most incompressible soft structures typically exhibit viscosity, which has a significant influence on wave characteristics, especially attenuation. Meanwhile, they are inevitably prestressed owing to the volume-preserving deformations. Therefore, it is essential to investigate acoustoelastic and viscoelastic effects to better understand guided wave characteristics in a pre-stressed soft plate. To this end, a hyperviscoelastic model concerning viscoelasticity, acoustoelasticity, and nonlinearity is established to deduce the governed equations. An analytical integration orthogonal polynomial method is employed to solve complex solutions of wave equations. The dispersion, attenuation, and wave shapes are illustrated. The acoustoelastic and viscoelastic effects are analyzed. Some new wave phenomena are revealed: The pre-stretching inhibits wave attenuation, and the pre-compression promotes attenuation; As the pre-stress increases, high-frequency phase velocity and incremental displacement amplitudes increase. The results lay a theoretical foundation for guided wave elastography, quantitative characterization, and disease diagnosis of biological soft tissue.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 6","pages":"875 - 887"},"PeriodicalIF":1.9,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141118047","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 existence of solutions to generalized Navier–Stokes–Fourier system with dissipative heating 论具有耗散加热的广义纳维-斯托克斯-傅里叶系统解的存在性

IF 2.7 3区工程技术

Meccanica Pub Date : 2024-05-21 DOI: 10.1007/s11012-024-01791-5

Anna Abbatiello, Miroslav Bulíček, Daniel Lear

引用次数: 0

Dynamics analysis of a nonlinear energy sink for passive suppression of a parametrically excited system 用于参数激励系统被动抑制的非线性能量汇的动力学分析

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-05-16 DOI: 10.1007/s11012-024-01812-3

Guilherme Rosa Franzini, Pierpaolo Belardinelli, Stefano Lenci

引用次数: 0

Generalized flutter reliability analysis with adjoint and direct approaches for aeroelastic eigen-pair derivatives computation 利用航空弹性特征对导数计算的辅助和直接方法进行广义扑翼可靠性分析

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-05-16 DOI: 10.1007/s11012-024-01807-0

Sandeep Kumar

{"title":"Generalized flutter reliability analysis with adjoint and direct approaches for aeroelastic eigen-pair derivatives computation","authors":"Sandeep Kumar","doi":"10.1007/s11012-024-01807-0","DOIUrl":"10.1007/s11012-024-01807-0","url":null,"abstract":"<div><p>The article presents physics based time invariant generalized flutter reliability approach for a wing in detail. For carrying flutter reliability analysis, a generalized first order reliability method (FORM) and a generalized second order reliability method (SORM) algorithms are developed. The FORM algorithm requires first derivative and the SORM algorithm requires both the first and second derivatives of a limit state function; and for these derivatives, an adjoint and a direct approaches for computing eigen-pair derivatives are proposed by ensuring uniqueness in eigenvector and its derivative. The stability parameter, damping ratio (real part of an eigenvalue), is considered as implicit type limit state function. To show occurrence of the flutter phenomenon, the limit state function is defined in conditional sense by imposing a condition on flow velocity. The aerodynamic parameter: slope of the lift coefficient curve (<span>(C_{L})</span>) and structural parameters: bending rigidity (<i>EI</i>) and torsional rigidity (<i>GJ</i>) of an aeroelastic system are considered as independent Gaussian random variables, and also the structural parameters are modeled as second-order constant mean stationary Gaussian random fields having exponential type covariance structures. To represent the random fields in finite dimensions, the fields are discretized using Karhunen–Loeve expansion. The analysis shows that the derivatives of an eigenvalue obtained from both the adjoint and direct approaches are the same. So the cumulative distribution functions (CDFs) of flutter velocity will be the same, irrespective of the approach chosen, and it is also reflected in CDFs obtained using various reliability methods based on adjoint and direct approaches: first order second moment method, generalized FORM, and generalized SORM.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 5","pages":"761 - 791"},"PeriodicalIF":1.9,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140967773","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

Numerical comparison of two methods for predicting the porous gas bearing pressure 预测多孔气体承载压力的两种方法的数值比较

IF 1.9 3区工程技术

Meccanica Pub Date : 2024-05-15 DOI: 10.1007/s11012-024-01820-3

Azael Duran-Castillo, Juan Carlos Jauregui-Correa, Oscar De Santiago

{"title":"Numerical comparison of two methods for predicting the porous gas bearing pressure","authors":"Azael Duran-Castillo, Juan Carlos Jauregui-Correa, Oscar De Santiago","doi":"10.1007/s11012-024-01820-3","DOIUrl":"10.1007/s11012-024-01820-3","url":null,"abstract":"<div><p>In this work, the numerical analysis of the modified Reynolds equation is compared. The difference between the two analyses is the porous media flow equation; the first considers the Darcy model, and the other the Darcy–Forchheimer model. The solution algorithms were developed using finite center differences for the geometric variable. This numerical scheme resulted in a non-linear set of equations solved with the Newton–Raphson method. Due to the nonlinearity of the problem, the relationship between the steps between axial and circumferential dimensions and the initial assumption is the main conditions for the solution to converge; the precision of the results obtained, in comparison with previous works, was acceptable; this contributes an additional effort in the development of the technology of the porous gas bearings. This work analyzed the differences in predicting the static behavior of a porous gas bearing using the Darcy model and the extended Darcy–Forchheimer model to determine the flow behavior through the porous medium. The solution algorithm of the modified Reynolds equation with the Darcy–Forchheimer model offers a broader range of solutions because it is capable of predicting both the linear and non-linear behavior of the flow through the porous medium and the influence in the lubricant film; this is essential for the design of porous gas bearings for industrial applications. The Finite Difference solutions are compared with a Finite Element and Finite Volume solution. The results show similar approximations with the advantage that the finite difference solution is more straightforward and can be coupled with a dynamic lump-mass model.</p></div>","PeriodicalId":695,"journal":{"name":"Meccanica","volume":"59 6","pages":"859 - 874"},"PeriodicalIF":1.9,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140973046","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

Model-based deep reinforcement learning for accelerated learning from flow simulations 基于模型的深度强化学习，从流动模拟中加速学习

IF 2.7 3区工程技术

Meccanica Pub Date : 2024-05-14 DOI: 10.1007/s11012-024-01808-z

Andre Weiner, Janis Geise

引用次数: 0