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Volume 4, Number 3, September 2015

In this work we present a one-dimensional damage model capable of representing the dynamic fracture for elastodamage bar with combined hardening in fracture process zone - FPZ and softening with embedded strong discontinuities. This model is compared with another one we recently introduced (Do et al. 2015) and it shows a good agreement between two models. Namely, it is indicated that strain-softening leads to a sensitivity of results on the mesh discretization. Strain tends to localization in a single element which is the smallest possible area in the finite element simulations. The strain-softening element in the middle of the bar undergoes intense deformation. Strain increases with increasing mesh refinement. Strain in elements outside the strain-softening element gradually decreases to zero.

Key Words
dynamics; fracture process zone – FPZ; strain-softening; localization; finite element; embedded discontinuity

Adnan Ibrahimbegovic: Université de Technologie Compiègne / Sorbonne Universités, Laboratoire Roberval de Mécanique
Centre de Recherche Royallieu, Rue Personne de Roberval, 60200 Compiègne, France;
Chair for Computational Mechanics & IUF, France
Xuan Nam Do and Delphine Brancherie:Université de Technologie Compiègne / Sorbonne Universités, Laboratoire Roberval de Mécanique Centre de Recherche Royallieu, Rue Personne de Roberval, 60200 Compiègne, France

In the gear meshing process, gear temperature field concerns the meshing surface friction, the friction heat depends on the contact pressure, the contact pressure is affected by the elastic deformation of gears and the temperature field caused by the thermal deformation, so the temperature field, stress field and displacement field should be mutual coupling. It is necessary to consider in meshing gear pair in the operation process of thermodynamic coupling contact stress (TCCS) and thermodynamic coupling deformation (TCD), and based on thermodynamic coupling analysis (TCA) of gear teeth deformation.

Key Words
gear; temperature field; TCCS; TCD; TCA

Xigui Wang:Mechatronics school, Harbin Institute of Technology, Harbin 150001, China;
2703 Research of Institute, Harbin 150078, China
Yongmei Wang: Motorcar Engineering, Heilongjiang Institute of Technology, Harbin 150036, China
Xuezeng Zhao: Mechatronics school, Harbin Institute of Technology, Harbin 150001, China
Xinglin Li:Hangzhou Bearing Test and Research Center, Hangzhou 310022, China

The current paper aims at investigating the nonlinear dynamical behaviour of an electrically actuated microcantilever. The microcantilever is excited by a combination of AC and DC voltages. The nonlinear equation of motion of the microcantilever is obtained by means of force and moment balances. A high-dimensional Galerkin scheme is then applied to reduce the equation of motion to a discrete model. A numerical technique, based on the pseudo-arclength continuation method, is used to solve the discretized model. The electrostatic deflection of the microcantilever and static pull-in instabilities, due to the DC voltage, are analyzed by plotting the so-called DC voltage-deflection curves. At the simultaneous presence of the DC and AC voltages, the nonlinear dynamical behaviour of the microcantilever is analyzed by plotting frequency-response and force-response curves.

Key Words
microcantilevers; electrically actuated; pull-in instability; dynamical behaviour

Hamed Farokhi: Department of Mechanical Engineering, McGill University, Montreal, Quebec, Canada H3A 0C3
Mergen H. Ghayesh:School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong,
NSW 2522, Australia

This paper presents a coupled FEM-BEM strategy for the numerical analysis of elastodynamic problems where infinite-domain models and complex heterogeneous media are involved, rendering a configuration in which neither the Finite Element Method (FEM) nor the Boundary Element Method (BEM) is most appropriate for the numerical analysis. In this case, the coupling of these methodologies is recommended, allowing exploring their respective advantages. Here, frequency domain analyses are focused and an iterative FEM-BEM coupling technique is considered. In this iterative coupling, each sub-domain of the model is solved separately, and the variables at the common interfaces are iteratively updated, until convergence is achieved. A relaxation parameter is introduced into the coupling algorithm and an expression for its optimal value is deduced. The iterative FEM-BEM coupling technique allows independent discretizations to be efficiently employed for both finite and boundary element methods, without any requirement of matching nodes at the common interfaces. In addition, it leads to smaller and better-conditioned systems of equations (different solvers, suitable for each sub-domain, may be employed), which do not need to be treated (inverted, triangularized etc.) at each iterative step, providing an accurate and efficient methodology.

Key Words
elastodynamics; frequency domain; iterative coupling; relaxation parameter

Delfim Soares Jr.:Structural Engineering Department, Federal University of Juiz de Fora, CEP 36036-330, Juiz de Fora, Brazil
Kleber A. Gonçalves and José Claudio de Faria Telles: Department of Civil Engineering, Federal University of Rio de Janeiro, CEP 21945-970, Rio de Janeiro, Brazil

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