Plastic bending of adhesive-bonded sheet metals

Adhesive bonding is becoming one of the popular joining techniques in sheet metal industries, since it has some advantages over other techniques such as welding and diffusion bonding, e.g., any dissimilar metals are easily ad hesive-bonded together, and the adhesive layer existing between the two she et metals can play the role of vibration damping. Usually, press-formed she et metal elements are jointed together at the final stage of assembly. Howe ver, if it could be possible to press-form adhesive-bonded flat sheet metal s into the final products, this would be an excellent technique from the vi ewpoint of high productivity. In the present work, the plastic bending of adhesive-bonded sheet metals wa s investigated by performing V-bending experiments. A serious problem encou ntered in the V-bending was bending-induced large transverse shear deformat ion of the adhesive layer, which leads to geometrical imperfection of the b ent sheets (so-called 'gull-wing' bend), and in some extreme cases, it caus es the delamination of the sheet. It was found both from experimental obser vations and from elasto-plastic stress analysis that the large shear deform ation progresses rapidly only at the final stage of V-bending. Consequently , the air-bending operation for adhesive-bonded sheet metals is recommended for suppressing the shear deformation of the adhesive layer to within an a cceptable limit. (C) 2001 Elsevier Science B.V. All rights reserved.