Process for forming a monolithic composite plate

A process for forming a solid, monolithic composite structural plate, said plate when formed comprising a reinforcement sheet having first and second parallel, spaced-apart sides, a corrugation between said sides having alternating crests and troughs, each of said crests defining a void thereunder, and buttresses filling said troughs and said voids, said buttresses being bonded to said corrugation and said sheet, said process comprising:

• adhering a sequence of said crests of said corrugation to said first side, the material of said corrugation being initially flexible;
• placing said second side of said sheet in spaced-apart, parallel relation with said corrugation and said first side such that said corrugation is situated between said first and second sides;
• inserting a flexible strand in each trough, and moving said strands to engage the corrugation material and move said troughs toward said second side;
• placing an initially fluid, foam-forming material in said troughs and said voids;
• and
• curing said foam-forming material to form a solid foam buttress in each of said troughs and said voids, which bonds to said corrugation and to a respective side.