Method of making composite laminate parts combining resin transfer molding and a trapped expansion member

A resin transfer molding process for forming a composite part from dry reinforcing fibers and resin comprising:

• providing a mold having a mold cavity, said mold having a resin passageway into said cavity, said cavity including a part definition surface for defining the shape of a composite part to be formed;
• providing an expansion member made of solid elastomeric material capable of expanding to a larger volume in response to being heated;
• providing a resin injector located in operative association with said passageway;
• said passageway means serving to conduct resin from said resin injector to said cavity,
• locating said expansion member in said mold cavity;
• locating reinforcing fibers in said mold cavity in association with said expansion member;
• closing said mold cavity;
• injecting resin into said closed mold cavity through said resin passageway to saturate said fibers;
• heating said expansion member to expand said expansion member an amount sufficient to consolidate said resin and said reinforcing fibers between said expansion member and said part definition surface to shape said fibers and said resin into a component part mimicking the shape of said part definition surface;
• curing said resin within said mold for a time sufficient for said consolidated fibers and resin to maintain the shape of said part definition surface;
• and
• cooling said mold, part, and said expansion member and removing said expansion member from said part and said part from said mold.