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

In a process for forming composite laminate parts from reinforcing fibers and resin, a mold is selected which has a mold cavity having a part definition surface therein and a resin passageway leading to the cavity. An expansion member capable of expanding to a larger volume in response to heat is located in the cavity in conjunction reinforcing fibers which will form a part of the composite laminate part. The mold cavity is closed and resin is injected through the resin passageway to saturate the fibers. The expansion member is heated to expand the expansion member an amount sufficient to consolidate the resin and the reinforcing fibers between the expansion member and the part definition surface to shape the fibers and the resin into a component laminate part mimicking the shape of the part definition surface and to expel any excess resin from the cavity to the passageway. The resin is then cured within the mold for a time sufficient for the consolidated fibers and resin to maintain the shape of the part definition surface.