Compressive and tensile structural elements having an enclosure with walls surrounding a cavity. A non-compressible material is disposed in the cavity. The walls are shaped such that a force tending to compress or elongate the element by a first deflection causes an amplified second deflection of the walls into the non-compressible material. The second deflection exerts a compressive force against the non-compressible material, resulting in a resistance to the first deflection and the force tending to compress or elongate the structural element. The walls of the elements are configured for optimum rigidity and/or optimum damping. Structural beams and motion impartation devices utilize the structural elements to provide lightweight rigidity and/or damping.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional application of co-pending application Ser. No. 09/992,460 filed Nov. 14, 2001, which is a divisional application of application Ser. No. 09/575,548 filed May 22, 2000, now U.S. Pat. No. 6,370,833 which is a divisional application of Ser. No. 09/177,137 filed Oct. 21, 1998, now U.S. Pat. No. 6,082,072 which is a divisional application of Ser. No. 08/934,402 filed Sep. 19, 1997 now U. S. Pat. No. 6,054,197.
A compound construction element formed of a composite material which composite material includes a matrix of thermoplastic synthetic material including wood particles or other cellulose-containing particles in a content on the order of 50% by weight or more, wherein also one or more continuous additional reinforcement elements are attached to the exterior or incorporated in the interior of the elements, that result in the reduction of length expansion due to moisture uptake.
A system and method of manufacture providing reinforced structurally functional load-bearing members, including but not limited to using thermoplastic materials, such as High Density Polyethylene (HDPE), reinforced such as with an aluminum alloy or carbon fiber core element. Among its possible uses, the present invention has application for provision of structural support members, such as an illustrative I-joist product having a vertical center member preferably comprising HDPE, and top and bottom flanges having structurally meaningful reinforcement. The center member and flanges preferably comprising HDPE provides a relatively hard, durable, substantially weather-resistant structure.
