Improved Laminated Windshield with Reduced Laceration Properties

Abstract

A new laminated automobile windshield called Triplex Ten-Twenty, fabricated from two thermally stressed glass plies of 2.3 mm soda-lime float glass laminated with a 0.76 mm HPR polyvinyl butyral interlayer, has been biomechanically evaluated by Triplex Safety Glass Co., Ltd., using a dropping headform and a skull impactor, and by Wayne State University, using a 50th percentile anthropomorphic dummy on the WHAM III sled test facility. The results of these evaluations at velocities up to 60km/h are expressed in terms of Gadd index, head injury criterion, and various laceration scales including the new Triplex laceration index (TLI). Some details are also given of other properties of the windshield. The results of the evaluations indicate that the Ten-Twenty windshield offers a reduction of about two units on the TLI scale equivalent to one of the following: 1. A 99% reduction in the number of cuts when the length and depth of cuts remain unaltered. 2. A 90% reduction in the length of cuts when the number and depth of cuts remain unaltered. 3. A change in depth of cuts from one layer of skin simulation to another, but in particular a 78.5% reduction in the depth of cuts into the polyvinyl chloride base layer when the number and length of cuts remain unaltered. In practice, the length, number, and depth of cuts all change together so that one typical example taken from the test program of a two-unit reduction in TLI is: 1. A 62% reduction in the average depth of cuts into the polyvinyl chloride base. 2. A 27% reduction in the average length of cuts. 3. No increase in the total number of cuts. On the basis of these results, Ten-Twenty is a much safer laminated automobile windshield than those now commercially available due to decreased laceration to the occupants during a collision.