Methods for Making Composite Parts from Stacked Partially Cured Sublaminate Units

A composite precursor comprising:

• a plurality of sublaminate units arranged in a stack, each sublaminate unit comprising a multiplicity of plies, each ply comprising fibers impregnated with resin which has been partially cured to a cure stage of 30% to 50% of full cure, and each ply having first and second holes which are aligned to form first and second longer holes that pass through the stack;
• first and second indexing pins disposed in the first and second longer holes respectively;
• and
• uncured adhesive disposed between each pair of adjacent sublaminate units arranged in the stack.

A method of forming a composite article, comprising:

• (a) arranging a plurality of sublaminate units in a stack with uncured adhesive between adjacent sublaminate units, each sublaminate unit comprising a multiplicity of plies, each ply comprising fibers impregnated with resin which has been initially cured to an initial cure stage of 30% to 50% of full cure;
• (b) heating the stack of sublaminate units to an intermediate temperature above a glass transition temperature of the resin for a time interval sufficient to intermediately cure the resin to an intermediate cure stage of 50% to 70% of full cure;
• (c) forming the heated stack of sublaminate units into a composite laminate having a surface defined by a surface of a forming tool;
• and
• (d) finally curing the resin in the composite laminate at a final temperature higher than the intermediate temperature to a final cure stage,