Mold for fabricating composite articles having integrally bonded stiffening members

A composite mold for simultaneously co-curing at least one stiffening member formed of prepreg plies in combination with a main structural panel formed of prepreg laminates in a single cure process to form a composite article having the at least one stiffening member integrally bonded thereto, each at least one stiffening member having a leg and opposed flanges, comprising:

• a mold base;
• a stiffening member mold assembly mounted on said mold base, said stiffening member mold assembly including
• at least first and second complementary pressure blocks each having a forming face and a stepped shoulder for forming one stiffening member, said first and second complementary pressure blocks being mounted on said mold base with said forming faces and stepped shoulders thereof in opposed relation wherein prepreg plies layed up therebetween define the leg and opposed flanges of the one stiffening member, at least one of said first and second complementary pressure blocks having a pressure cavity formed therein, and
• a pressure pad formed from a thermally expansible material encapsulated in each said pressure cavity, each said pressure pad, pressure cavity combination being configured wherein each said pressure pad is operative to expand in volume to generate a predetermined pressure in response to elevated temperatures of the single cure process;
• and
• a rigid mold assembly disposed in combination with said mold base and said stiffening member mold assembly to define said composite mold, said rigid mold assembly including
• first and second members rigidly secured in combination with said mold base, said first member being disposed in abutting engagement with said first complementary pressure block and operative to act as a reactive surface therefor,
• a removable wedge member mounted on said mold base and disposed intermediate said second member and said second complementary pressure block in abutting engagement therewith, and
• end member means mounted on said mold base for facilitating assemblage of said stiffening member mold assembly in combination with said first member and said removable wedge member;
• exposed faces of aid stiffening member mold assembly and said rigid mold assembly distal said mold base providing a rigid lay-up surface for the prepreg laminates forming the main structural panel, the prepreg laminates contacting the prepreg plies forming the opposed flanges of the one stiffening member.