Experimental Investigation on the Residual Stresses Induced by a Plastic Forming Process

Abstract

The extrusion of a space frame must be followed by forming operations of some kind to obtain the desired shape/curvature, for example a stretch bending process. Therefore, one has to face with problems as production tolerances and cross-sectional distortions of the curved product. In house experience combined with trial–and–error procedures have been traditionally used to cope with the said problems. Aircraft frames show significant residual stresses as a consequence of plastic forming processes. A great number of variables, such as initial frame length and/or final additional stretch, can influence the stress state of frames determining their life and efficiency under operating loading conditions. In the present paper, we refer about the experimental evaluations of the residual stress state of aircraft frames which have carried out taking into account different process parameters. The experimental results obtained and discussed show some interesting trends: they demonstrate that the residual stresses of the formed component can be controlled and reduced.

Evaluation by FEM of the Influence of the Preheating and Post-Heating Treatments on Residual Stresses in Welding

“…Several experimental destructive and non destructive techniques like X-ray diffraction [1], neutron diffraction [2], layer-removal, and hole drilling [3]. for directly measuring residual stress have been developed.…”

Mechanical Characterization of Sheet Moulding Composites for the Automotive Industry

“…The SMCs under study may be exposed in service to hostile conditions, e.g. service temperature, Tg near glass transition, cyclic loadings, or aggressive environments [15][16][17][18][19][20][21][22][23][24][25][26]. In particular the viscoelastic behaviour of the polymer matrix and its long-term behaviour can be altered by the vicinity of the glass transition temperature of the polymer itself [27][28][29][30][31][32][33][34][35][36][37].…”