Analysis On Strength Of Clinching Connections For Metal Sheets And Tool Geometric Parameters Optimization

Recently, PM2.5and the weather of haze and mist are really concerned. Automobileexhaust is one of the pollution sources. It is an important way to reduce automobile exhaustby reducing fuel consumption through automobile mass reduction. Because of the trend ofdeveloping light-weight of car body, many light-weight materials like aluminium,magnesium alloy, are adopted. Traditional connecting techniques can not satisfy the needs ofconnecting different materials. The recent developed technique, mechanical clinching, whichis used for connecting metal sheets, is one of solutions. The present studies on sheetsmechanical clinching mainly focus on simulations of clinching process, the influence ofclinching tools’ geometric parameters on jointed connections’ geometric parameters andoptimization of clinching tools’ geometric parameters, etc. However, the studies of clinchingtools’ key geometric parameters optimization maximizing shear strength and tensile strengthbased on simulations of strength tests of joined connections are rarely published.To study theories and methods about simulating strength test of clinched connections forsteel and aluminium sheets, problems including quasi-static analysis, loading rate, loadingmethods, Element formulation and integration, adaptivity techniques were discussed. Withfinite element analysis software ABAQUS, the mechanical clinching process, unloadingprocess, shear test and peel test were stimulated. Based on the validity of the simulations,theories and methods about multi-objective optimization of key geometric parameters ofclinching tools were studied including design of experiments, construction methods ofapproximation model, error analysis and MOGA (Multi-Objective Genetic Algorithm)technique. With hyperstudy, approximation models were built, in which key geometricparameters of clinching tools are variables and strengths of shear and tensile are objectives.Errors of approximation models were compared and the solutions were obtained with MOGAtechnique.Through the study of this paper, the main conclusions are as follows. When dealing withquasi-static analysis, smooth amplitude curve for loading rate should be adopted to smooth the loading process. ALE technique can dramatically improve the performance of simulationof mechanical clinching by avoiding mesh distortion. It is effective to simulate quasi-staticproblems of metal deformation with3D linear reduced-integration elements (C3D8R) inABAQUS/explicit. Through comparing the results of simulation and test, it was proven thatsimulation method can be used to predict shear strength and tensile strength of clinchedconnections. With the approximation model of comparative high quality, the method ofclinching tools’ key geometric parameters optimization maximizing shear strength and tensilestrength was established.