| abstract |
In a steel-polyolefin-steel structural laminate comprising a core of polyolefin having tightly adhered to each side thereof a steel skin layer each steel skin layer is from 50.8 µm to 508 pm thick, said laminate furhter having a ratio of core thickness to skin thickness of less than 9:1, and a total thickness of from 127 to 1651 µm; the materials of construction of said polyolefin core and steel skins and the geometry of the laminate being such that the laminate has (1) a flexural stiffness at least 40 percent that of the solid metal of the skin layer of the lower modulus having the same thickness as said laminate as measured by ASTM D790 on a 2.54 cm wide sample having a 10.16 cm span under three point loading conditions, (2) a density from 25 percent to 90 percent that of the average of two solid steel skin layers, (3) as a measure of stretch formability a limiting dome height of at least about 60 percent of the limiting dome height of the solid steel of the skin layer of the lower ultimate elongation having the same thickness as the laminate, (4) the capability of being subjected to a no load oven test, subsequent to forming of said laminate, at a temperature of at least 87,8°C for a period of 30 minutes without delaminating, and (5) the capability of being bent at room temperature to 90° to a critical radius without metal rupture, the critical radius defined as the distance from the pivot point to the inner skin surface of the laminate- being about equal to the total laminate thickness. |