Dual expanding foam for closed mold composite manufacturing

A structure comprising:

• i) a fiber and resin matrix material layer at least partially forming a hollow section of the structure;
• and
• ii) a foamable material layer in direct planar contact with the fiber and resin matrix material layer, the foamable material layer at least partially filling the hollow section, wherein the foamable material layer has a first expansion upon exposure to a first temperature and a second expansion upon exposure to a second temperature.