Method of forming a prestressed article of fiber reinforced resin

Claim 1

A METHOD OF FABRICATING A FIBER REINFORCED RESIN TUBULAR MEMBER, COMPRISING WINDING A FIBROUS STRAND ON A FLEXIBLE SLEEVE IN A SUBSTANTIALLY HELICAL PATTERN WHILE COATING THE STRAND WITH AN UNPOLYMERIZED RESIN TO FORM A TUBULAR MEMBER OF GIVEN THICKNESS, INTRODUCING PRESSURE WITHIN THE SLEEVE TO EXPAND THE TUBULAR MEMBER TO A GIVEN INTERNAL DIAMETER AND PLACE THE STRAND UNDER TENSION WHILE MAINTAINING SAID MEMBER FREE OF EXTERNAL CONFINEMENT AND SUBSTANTIALLY MAINTAINING SAID GIVEN THICKNESS, APPLYING A POSITIVE PRESSURE OF LESSER MAGNITUDE THAN SAID FIRST NAMED PRESSURE ON THE OUTER SURFACE OF THE TUBULAR MEMMER TO REDUCE SAID THICKNESS WHILE MAINTAINING SAID GIVEN INTERNAL DIAMETER TO THEREBY DRIVE ENTRAPPED AIR FROM SAID TUBULAR MEMBER, AND POLYMERIZING THE RESIN WHILE MAINTAINING SAID PRESSURE ON SAID MEMBER TO MAINTAIN THE STRANDS UNDER TENSION DURING POLYMERIZATION.