Technological Aspects of Manufacturing and Numerical Modelling of Clinch-Adhesive Joints

The analysis of technological factors that influence the plastic forming of the clinch joint and its strength is described. Basing on literature date and authors’ studies, it was found that quality and strength of the joint are mainly related to plastic deformation of joined sheets and sheets’ adhesion on the joint interface. These conclusions determined the subsequent investigations of the clinching process. The clinch joints made of one or two different materials with diversified plastic and strength properties were experimentally tested. The basic samples were single overlap clinch joints with one clinch bulge. The joints mechanical response was analysed in the pull and peer tests. The obtained results showed the relation of the clinch joinability to the exponent of materials strain hardening curves. The good quality and good strength joints were obtained for materials with low value of strain hardening curve exponent ‘n’ in the range of about 0,14–0,22. The book includes also experimental results and numerical calculations of clinch joint forming process with different sheets’ interface preparation (degreased, greased and separated by thin PTFE film). The investigations covered the effect of the above specified contact conditions on the clinch joint geometrical parameters and the shear strength. The obtained results showed crucial role of interface friction conditions, apart from geometrical parameters, on the joint shear strength. The hybrid joints combining clinching and adhesive bonding techniques were also investigated. Application of the hybrid clinch-bonded joints lead to the significant increase of the joint quality and strength. It was found that an adhesive plays the role of grease when the joint is clinched and then, after curing it causes great and advantages adhesion between sheets, stopping their displacement and bending. The book includes: (a) very wide experimental testing program with analysis of the obtained results, (b) advanced finite element numerical model of the hybrid joints behavior with application of 2 degradation processes: in the adhesive layer and the plastic adherends.