A novel approach to modelling and simulating the contact behaviour between a human hand model and a deformable object

A deeper understanding of biomechanical behaviour of human hands becomes fundamental for any human hand-operated Q2 activities. The integration of biomechanical knowledge of human hands into product design process starts to play an increasingly important role in developing an ergonomic product-to-user interface for products and systems requiring high level of comfortable and responsive interactions. Generation of such precise and dynamic models can provide scientific evaluation tools to support product and system development through simulation. This type of support is urgently required in many applications such as hand skill training for surgical operations, ergonomic study of a product or system developed and so forth. The aim of this work is to study the contact behaviour between the operators’ hand and a hand-held tool or other similar contacts, by developing a novel and precise nonlinear 3D finite element model of the hand and by investigating the contact behaviour through simulation. The contact behaviour is externalised by solving the problem using the bi-potential method. The human body’s biomechanical characteristics, such as hand deformity and structural behaviour, have been fully modelled by implementing anisotropic hyperelastic laws. A case study is given to illustrate the effectiveness of the approac

A new hybrid PSO algorithm based on a stochastic Markov chain model

International audienceBased on the recent research concerning the PageRank Algorithm used in the famous search engine Google, a new Inverse-PageRank-Particle Swarm Optimizer (I-PR-PSO) is presented in order to improve the performances of classic PSO. The resulted algorithm uses a stochastic Markov chain model to define an intelligent topological structure of the swarm's population, in which the better particles have an important influence on the others. In the presented experiments, calculations on some benchmark functions classically used to test optimization methods are performed, and the results are compared to different versions of the standard PSO, that is using different topological structures of the population. The experimental results show that I-PR-PSO can converge quicker on the tested functions, and can find better results in the solution domain than its tested peers

New smoothing procedures in contact mechanics

AbstractThis paper presents recent methods to improve numerical simulation of contact problems by smoothing. The main idea is to combine contact surfaces regularization with an automatic adjustment of both penalty parameter and load step. The underlying goal is to provide handle situations frequently met in an industrial context

Topology Optimization Considering Additive Manufacturing Constraints In An Industrial Context

Manufacturing-oriented Topology Optimization (TO) is an active field of research both in academic and in industrial world. On one hand, the potential offered by topology optimization as a powerful design method is undeniable in improving the structural performance in different areas of engineering. On the other hand, Additive Manufacturing (AM) technology provides numerous industrial mechanisms of manufacturing and producing complex structure where classical methods fail to deliver an outcome. Merging both branches of TO and AM together introduces encouraging results in terms of designing optimized structures showing an acceptable mechanical response. In our contribution, we present a topology optimization model developed for additive manufacturing design. Using an innovative meshing algorithm, we particularly showed how the topology optimization could be implemented in order to consider the constraints of additive manufacturing specifically the printability of the parts with overhang angle. The design of the self-supporting structures is a challenging part of the additive manufacturing process, without which the process becomes tedious in terms of time, efficiency and financial resources. Therefore, a continuous effort for a better understanding of such issue is justified. In this paper, we suggest an improvement on the work carried out by Langelaar in this context. The model used in this study is a more complicated geometry compared t

Computational design for 4D printing of topology optimized multi-material active composites

Recent efforts on design for four-dimensional (4D) printing have considered the spatial arrangement of smart materials and energy stimuli. The development of multifunctional structures and their desired mechanical/actuation performances require tackling 4D printing from a multi-material design perspective. With the materials distributions there is an opportunity to increase the spectrum of design concepts with computational approaches. The main goal being to achieve the “best” distribution of material properties in a voxelized structure, a computational framework that consists of a finite element analysis-based evolutionary algorithm is presented. It fuses the advantages of optimizing both the materials distribution and material layout within a design space via topology optimization to solve the inverse design problem of finding an optimal design to achieve a target shape change by integrating void voxels. The results demonstrate the efficacy of the proposed method in providing a highly capable tool for the design of 4D-printed active composites

A new smooth contact element: 3D diffuse contact element

Many difficulties due to geometrical and material non-linearities arise when dealing with numerical simulation of contact problems. Within a finite element context, the contact interface is usually represented by a piecewise differentiable surface. Numerical problems due to the non-smoothness of the contact surface may occur especially when large slips are considered. Major changes of normal and tangential vectors may impede both convergence and precision. In order to smooth the contact interface and to release constraints due to the mesh, we propose a technique in which diffuse approximation is combined with a determination of neighboring nodes by a convex hull strategy. The formulation is developed for three-dimensional applications with frictionless contact and a 3D diffuse contact element has been developed. The efficiency of the approach has been validated with industrial frictionless contact problems

Thermal aspects in friction stir process of AISI 316L: Numerical and experimental investigation

International audienc

Optimization of grillages using genetic algorithms for integrating MatLab and Fortran environments / Matlab ir Fortran aplinkų sujungimas rostverkams optimizuoti genetiniais algoritmais

The purpose of the paper is to present technology applied for the global optimization of grillage-type pile foundations (further grillages). The goal of optimization is to obtain the optimal layout of pile placement in the grillages. The problem can be categorized as a topology optimization problem. The objective function is comprised of maximum reactive force emerging in a pile. The reactive force is minimized during the procedure of optimization during which variables enclose the positions of piles beneath connecting beams. Reactive forces in all piles are computed utilizing an original algorithm implemented in the Fortran programming language. The algorithm is integrated into the MatLab environment where the optimization procedure is executed utilizing a genetic algorithm. The article also describes technology enabling the integration of MatLab and Fortran environments. The authors seek to evaluate the quality of a solution to the problem analyzing experimental results obtained applying the proposed technology. Santrauka Straipsnyje pateikiama sijynų tipo pamatų (toliau sijynų) globalaus optimizavimo technologija. Optimizavimo tikslas – nustatyti optimalų polių išdėstymą sijynuose. Šis uždavinys priskiriamas topologijos optimizavimo uždavinių grupei. Tikslo funkciją sudaro maksimali poliuje kylanti atraminė reakcijos jėga, kuri minimizuojama optimizavimo procese. Šio uždavinio projektavimo kintamieji - polių padėtys po jungiančiosiomis sijyno sijomis. Tiesioginis reakcijų poliuose skaičiavimo uždavinys sprendžiamas originaliu algoritmu, sukurtu Fortran programavimo kalba. Šis algoritmas juodosios dėžės principu jungiamas prie MatLab aplinkos, kurioje genetiniu algoritmu sprendžiamas optimizavimo uždavinys. Straipsnyje taip pat aprašyta technologija, kuri leidžia sujungti Matlab ir Fortran aplinkas, t. y. iš Matlab aplinkos iškviesti Fortran paprogramį. Analizuodami eksperimentinius duomenis autoriai bando įvertinti gaunamų sprendinių kokybę. Raktiniai žodžiai: globalusis optimizavimas; genetiniai algoritmai; rostverkų optimizavimas; baigtinių elementų metodas; MatLab; Fortra