Composite laminate automotive structures

A laminate support beam comprising an elongated longitudinal outer structural member having an outer wall surface and an inner wall surface, portions of said inner wall surface being spaced from each other defining a channel therebetween;

• and a longitudinal rigid inner member having an outer wall surface and an inner wall surface, said outer wall surface of said inner member generally conforming in shape to said channel of said outer structural member and being slightly smaller in size whereby there is a gap between said outer wall surface of said inner member and said inner wall surface of said outer member;
• said outer wall surface of said inner member being precoated with a structural foam layer having a thickness of about 0.060 to about 0.50 inches, said foam being bonded to said outer wall surface of said inner member;
• said inner member and said structural foam comprising a drop-in insert unit for said channel to form a multilayer laminate having a layer of shape-retaining structural foam spread over said outer surface of said inner member whereby said foam is generally shape-retaining before said laminate is dropped into said channel with said layer of structural foam thereby disposed toward said inner surface of said outer member after said laminate is dropped into said channel;
• said structural foam being heat expandable whereby upon by application of heat and curing of said foam said foam is capable of filling said gap to intimately bond to said inner surface of said outer member and to provide a lightweight reinforcement for said outer structural member, said foam comprising from 35 to 95% by weight of a synthetic resin and 1-60% by weight of a cell forming agent and 1-55% by weight of a filler, and said foam having a density of about 15-40 pounds per cubic foot.