Abstract: Sandwich panels and methods of making them, i.e., laminates which comprise two metal sheets with a filled resin core between a bonded metal sheets, which are useful for structural and other uses wherein the laminates utilize combinations of metal skins, metal surface preparation, resins, fillers, and reinforcement bonded together in the sandwich structure to provide a laminate having a flexural modulus of at least 1.7 million psi, a rigidity index of at least about 2,000 and other unique properties which enable the laminates to be particularly useful for thin wall trailer body construction, as well as other structural and non-structural uses. A rigidity index property for sandwich structures and panels and a falling ball impact test are disclosed and used to characterize the properties of sandwich laminates.

Abstract: Sandwich panels, i.e., laminates which comprise two metal sheets with a filled, reinforced resin core between and bonded to the metal sheets, are useful for structural and other uses. Combinations of metal sheets, resins, fillers, and reinforcement bonded together in the sandwich structure provided a laminate having a flexural modulus of at least 2.5 million psi, a rigidity index of at least about 2,000 and other unique properties which enable the laminates to be particularly useful for thin wall truck trailer body construction, as well as other uses. A rigidity index and a falling ball impact test for sandwich structures and panels are used to characterize the properties of these sandwich laminates. Methods of making the above sandwich laminates and means for joining the sandwich laminates and panels are disclosed, which provide for their particular usefulness in truck trailer body construction, as well as other structural and non-structural uses.