Static properties and multiaxial strength criterion for design of composite automotive structures

The Durability of Lightweight Composite Structures Project was established at Oak Ridge National Laboratory (ORNL) by the US Department of Energy to provide the experimentally-based, durability-driven design guidelines necessary to assure long-term structural integrity of automotive composite components. The initial focus of the ORNL Durability Project was on one representative reference material -- an isocyanurate (polyurethane) reinforced with continuous strand, swirl-mat E-glass. The present paper describes tensile, compressive, flexure, and shear testing and results for the reference composite. Behavioral trends and proportional limit are established for both tension and compression. Damage development due to tensile loading, strain rate effects, and effects of temperature are discussed. Furthermore, effects on static properties of various fluids, including water at room and elevated temperatures, salt water, antifreeze, windshield washer fluid, used motor oil, battery acid, gasoline, and brake fluid, were investigated. Effects of prior loading were evaluated as well. Finally, the effect of multiaxial loading on strength was determined, and the maximum shear strength criterion was identified for design