Papers by Author: V.F. Ruisi

Abstract: In this paper a development of clinching, called flat clinching, is presented. After a press clinching process, the joined sheets have been deformed by a punch with a lower diameter against a flat die. In this way a new configuration is created with a geometry that has no discontinuity on the external surface (bottom). A new procedure has also been tested: the second step is perfomed by pressing the joint between two flat dies. This second case has revealed itself to be very effective.Tensile tests have been done to compare the joints strength among the various joining techniques. Moreover some joints have been cut to analyse the changing of the contact line shape and how its characteristics parameters can influence the bonding performances. To optimise the process a finite element analysis has been performed.

Abstract: The efforts of new automotive industry are mainly directed towards the substitution of aluminum for steel in the body structure because the aluminum structures are lighter than traditional steel ones and meet the requirements, in terms of both vehicle design and manufacture. However, this substitution is not so automatic, but it is important to study the material properties and the structure design, focusing the attention on the methods of joining. Welding, typical technique to joint steel parts, is particularly difficult when applied on aluminum ones and then, in many cases, the adhesive bonding is preferred. To optimise the joint performances it is necessary to pre-treat the metal surface, not only to remove contaminants, but also to provide the intimate contact needed for the adhesive to successfully bond with the adherent surface. The mere cleaning of aluminum surfaces is not suitable for their bonding due to the oxide layer that naturally occurs on exposure to air so we need to apply a more effective treatment (mechanical or chemical etching) to increase the adhesion capability of the substrates. In this work different adhesive joint configurations (single lap) between aluminum substrates are studied. Two different resins are employed to evaluate the influence of the adhesive on the joint performances. Moreover the aluminum sheets are treated with a chemical etching with two different procedures.