Composite construction members and method of making

An inflatable mold assembly for forming a hollow composite construction member suitable for use as a building material, the mold assembly having a longitudinal axis, and further having:

• a flexible, substantially tubular bladder wall defining an elongated inflatable cavity;
• a reinforcing fabric positioned concentrically around the flexible bladder wall;
• and
• a flexible air-impervious outer layer positioned concentrically around the fabric, with the bladder wall and the outer layer defining an elongated annular space, with the fabric being positioned within the space.

A system for making a rigid hollow composite construction member comprising:

• an inflatable mold assembly for a hollow composite construction member suitable for use as a building material, the inflatable mold assembly being elongated and having a longitudinal axis, and further having:
• a flexible, substantially tubular bladder wall defining an elongated inflatable cavity;
• a reinforcing fabric positioned concentrically around the flexible bladder wall;
• and
• a flexible air-impervious outer layer positioned concentrically around the fabric, with the bladder wall and the outer layer defining an elongated annular space, with the fabric being positioned within the space;
• apparatus for applying tension to the fabric in a longitudinal direction;
• apparatus for introducing a fluid into the cavity to inflate the tubular bladder wall;
• and
• apparatus for infusing the elongated annular space and the fabric with a rigidification material to form a rigid hollow composite construction member.

A method of forming a hollow composite construction member of the type suitable for use as a building material, the method comprising:

• providing an elongated inflatable mold assembly having a longitudinal axis, the mold having a braided reinforcing fabric extending along the mold assembly;
• applying tension in a longitudinal direction to the fabric and infusing the fabric with a rigidification material while shaping the mold assembly;
• and
• hardening the rigidification material while maintaining the fabric in tension to form a rigid hollow composite construction member.

A method of forming a hollow composite construction member of the type suitable for use as a building material, the method comprising:

• providing an elongated inflatable mold assembly having a longitudinal axis, and further having:
• a flexible, substantially tubular bladder wall defining an elongated inflatable cavity;
• a reinforcing fabric positioned concentrically around the flexible bladder wall, the fabric being preimpregnated with a resin material;
• and
• a flexible air-impervious outer layer positioned concentrically around the fabric, with the bladder wall and the outer layer defining an elongated annular space, with the fabric being positioned within the space;
• applying tension in a longitudinal direction to the fabric and introducing a fluid into the cavity to at least partially inflate the bladder wall and shape the fabric;
• shaping the mold assembly to a desired shape while maintaining the fabric under tension;
• and
• initiating rigidification of the resin material while maintaining the fabric in tension to form a rigid hollow composite construction member.