Abstract: A multiple ply composite structure used to reinforce, seal and shape concrete structures has a first ply formed of unidirected continuous filament reinforcements which are bonded together by a thermosetting polymeric resin matrix. A second ply comprises a plurality of separately spaced protuberances, each of which is individually coated with a hardenable thermosetting polymeric resin. The hardenable thermosetting polymeric resin of the second ply bonds the first ply to the second ply by forming a concave resin meniscus which anchors each of the protuberances of the second ply to the first ply.

Abstract: A composite double-wall underground tank comprises an internal rotatable metal mandrel tank frame structure surmounted by two individual concentric corrugated cylindrical nonmetallic pressure vessels having hemispherical ends. The metal tank frame structure provides the buckling resistance and compression strength to resist soil loads when the tank is buried. The pressure vessels are made of identical materials and include an internal primary container enclosed by an external secondary container of equal tensile strength and corrosion-resistance. The composite double-wall underground tank is a substantial improvement over conventional steel and fiberglass tanks, and provides a more reliable method of protecting the environment by preventing the release of contaminating hazardous liquids stored in the tank. Each of the two pressure vessels is made from a multiple ply composite laminate having a unique arrangement of fabrics containing filament reinforcements impregnated with a thermosetting polymeric matrix.

Abstract: A composite double-wall underground tank comprises an internal rotatable metal mandrel tank frame structure surmounted by two individual concentric corrugated cylindrical nonmetallic pressure vessels having hemispherical ends. The metal tank frame structure provides the buckling resistance and compression strength to resist soil loads when the tank is buried. The pressure vessels are made of identical materials and include an internal primary container enclosed by an external secondary container of equal tensile strength and corrosion-resistance. The composite double-wall underground tank is a substantial improvement over conventional steel and fiberglass tanks, and provides a more reliable method of protecting the environment by preventing the release of contaminating hazardous liquids stored in the tank. Each of the two pressure vessels is made from a multiple ply composite laminate having a unique arrangement of fabrics containing filament reinforcements impregnated with a thermosetting polymeric matrix.

Abstract: A double-wall composite pipe comprises a permeable annulus structure separating impermeable inner and outer walls. The permeable annulus structure has micro-fractures formed therein that function to reduce the flow rate and pressure of fluids leaking through the inner wall to thus inhibit fluid leakage. The annulus structure resists the stresses produced by internal fluid pressures and other service loads. The inner and outer walls will remain permanently impermeable while the pipe annulus structure undergoes stress-induced dimensional changes. A coupler assembly mechanically connects each longitudinally adjacent pair of pipes together and comprises two semi-cylindrical half-couplers, a compressible seal ring, a cylindrical retaining sleeve, and a flexible boot that encloses and seals the assembled half-couplers. A leak detecting sensor may be located at the coupler assembly. A preferred method and apparatus for making the pipe and coupler assembly are also taught.

Abstract: A composite structure comprises at least one ply comprising approximately parallel unidirected twines comprising helically-configured matrix-impregnated continuous strands of filament reinforcements to provide a flanged composite cantilever spring which serves as the principal constituent of a coupling structure. An interior ply of a coupling structure body member comprises unidirected longitudinal twines configured at a body member extremity to provide a flange member connected to a cantilever spring. An exterior ply is disposed transversely of and superimposed upon the interior ply to provide the cantilever spring hinge line. The composite cantilever spring can be constructed to deflect about either a straight or curved hinge line. A preferred tubular form of the coupling structure comprises at least one end configured as a polygonal array of flanged cantilever springs which serve as the socket end of a spring-lock coupling used to connect mating flanged spigot-end structures.

Abstract: A composite structure comprises at least one ply comprising approximately parallel unidirected twines comprising helically-configured matrix-impregnated continuous strands of filament reinforcements to provide a flanged composite cantilever spring which serves as the principal constituent of a coupling structure. An interior ply of a coupling structure body member comprises unidirected longitudinal twines configured at a body member extremity to provide a flange member connected to a cantilever spring. An exterior ply is disposed transversely of and superimposed upon the interior ply to provide the cantilever spring hinge line. The composite cantilever spring can be constructed to deflect about either a straight or curved hinge line. A preferred tubular form of the coupling structure comprises at least one end configured as a polygonal array of flanged cantilever springs which serve as the socket end of a spring-lock coupling used to connect mating flanged spigot-end structures.

Abstract: A composite structure comprises at least one ply comprising approximately parallel unidirected twines comprising helically-configured matrix-impregnated continuous strands of filament reinforcements to provide a flanged composite cantilever spring which serves as the principal constituent of a coupling structure. An interior ply of a coupling structure body member comprises unidirected longitudinal twines configured at a body member extremity to provide a flange member connected to a cantilever spring. An exterior ply is disposed transversely of and superimposed upon the interior ply to provide the cantilever spring hinge line. The composite cantilever spring can be constructed to deflect about either a straight or curved hinge line. A preferred tubular form of the coupling structure comprises at least one end configured as a polygonal array of flanged cantilever springs which serve as the socket end of a spring-lock coupling used to connect mating flanged spigot-end structures.

Abstract: A composite structure comprises at least one ply comprising approximately parallel unidirected twines comprising helically-configured matrix-impregnated continuous strands of filament reinforcements to provide a flanged composite cantilever spring which serves as the principal constituent of a coupling structure. An interior ply of a coupling structure body member comprises unidirected longitudinal twines configured at a body member extremity to provide a flange member connected to a cantilever spring. An exterior ply is disposed transversely of and superimposed upon the interior ply to provide the cantilever spring hinge line. The composite cantilever spring can be constructed to deflect about either a straight or curved hinge line. A preferred tubular form of the coupling structure comprises at least one end configured as a polygonal array of flanged cantilever springs which serve as the socket end of a spring-lock coupling used to connect mating flanged spigot-end structures.

Abstract: A composite structure comprises at least one ply comprising approximately parallel unidirected twines comprising helically-configured matrix-impregnated continuous strands of filament reinforcements to provide a flanged composite cantilever spring which serves as the principal constituent of a coupling structure. An interior ply of a coupling structure body member comprises unidirected longitudinal twines configured at a body member extremity to provide a flange member connected to a cantilever spring. An exterior ply is disposed transversely of and superimposed upon the interior ply to provide the cantilever spring hinge line. The composite cantilever spring can be constructed to deflect about either a straight or curved hinge line. A preferred tubular form of the coupling structure comprises at least one end configured as a polygonal array of flanged cantilever springs which serve as the socket end of a spring-lock coupling used to connect mating flanged spigot-end structures.

Abstract: A composite structure comprises at least one ply comprising approximately parallel unidirected twines comprising helically-configured matrix-impregnated continuous strands of filament reinforcements to provide a flanged composite cantilever spring which serves as the principal constituent of a coupling structure. An interior ply of a coupling structure body member comprises unidirected longitudinal twines configured at a body member extremity to provide a flange member connected to a cantilever spring. An exterior ply is disposed transversely of and superimposed upon the interior ply to provide the cantilever spring hinge line. The composite cantilever spring can be constructed to deflect about either a straight or curved hinge line. A preferred tubular form of the coupling structure comprises at least one end configured as a polygonal array of flanged cantilever springs which serve as the socket end of a spring-lock coupling used to connect mating flanged spigot-end structures.

Abstract: A composite structure comprises at least one ply comprising approximately parallel unidirected twines comprising helically-configured matrix-impregnated continuous strands of filament reinforcements to provide a flanged composite cantilever spring which serves as the principal constituent of a coupling structure. An interior ply of a coupling structure body member comprises unidirected longitudinal twines configured at a body member extremity to provide a flange member connected to a cantilever spring. An exterior ply is disposed transversely of and superimposed upon the interior ply to provide the cantilever spring hinge line. The composite cantilever spring can be constructed to deflect about either a straight or curved hinge line. A preferred tubular form of the coupling structure comprises at least one end configured as a polygonal array of flanged cantilever springs which serve as the socket end of a spring-lock coupling used to connect mating flanged spigot-end structures.

Abstract: A multiple laminate comprises at least one laminate which is tapered at one or both ends to provide a laminate joint structure having a coupling tensile strength greater than the laminate interlaminar shear strength. The laminate joint structure contains at least one tapered laminate ply support structure containing continuous filament strands oriented parallel to the coupling load direction. The tubular laminate form of the tapered end laminate joint structure finds particular application to mechanically joined structures such as pipe and trusses.The method and apparatus for making the laminate in the form of a desired composite structure comprises winding a first ply of circumferentially oriented continuous filament strands upon a mandrel and forming the ends of the first ply to have sufficient thickness to provide an inwardly tapered conical shaped exterior surface.

Abstract: A corrugated laminate comprises at least two superimposed plies of continuous filament strands bonded together by a hardened plastic resin. The plies are biaxially pre-tensioned prior to hardening of the resin which impregnates and bonds the strands together in a generally concave parabolic configuration at each corrugation. The laminate finds particular application to tubular structures, such as sewer pipe liner and underground tanks, which contribute to the control and improvement in the quality of the nation's environment.The method and apparatus for making the laminate in the form of a desired composite structure comprises placing a first ply of unidirectional continuous filament strands upon one or more longitudinally spaced pairs of a gapped forming structure so that the ply bridges each forming gap.