Abstract: A method is provided for forming a complexly-shaped tubular structure such as a tapered pillar or other structure for a vehicle body. A sheet metal blank having a longitudinal axis is rolled about the longitudinal axis to form a tubular shape and the side edges of the blank are then welded together to form a tube. The tube is then enclosed in a hydroforming die and pressurized to conform the tube to the shape of the die and thereby form the desired complex shape. The sheet metal blank may be formed by the end-to-end welding together of a plurality of separate sheet metal blanks that differ from one another in characteristic including material thickness, material alloy composition, and/or coating. One or more of the blanks can have side edges that are non-parallel so that the tube will taper in diameter along its length.

Abstract: In an assembly of facing metal sheets separated by a polymer layer, welded metallurgical bonds are formed between the metal sheets by use of a friction stir weld tool. A rotating tool penetrates the first sheet, locally displaces the encountered portion of polymer film and penetrates into the second sheet. The affected metal of the two sheets is momentarily plasticized and stirred, and the plasticized metal of the two sheets combines to form a weld between the metal sheets. The interposed polymer film may be intended to serve as an adhesive or a vibration damping medium or the like. The facing metal sheets can be layers of facing laminated metal sheet structures that each comprise two metal sheets bonded by an adhesive interlayer.