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Over the last decade, on small- and medium-size passenger cars, a new class of front bumper - injection or blow molded from engineering thermoplastics - has been put into production use. These bumper systems provide full 8-km/hr federal pendulum and flat-barrier impact protection, as well as angled barrier protection. Thermoplastic bumpers, offering weight, cost, and manufacturing advantages over conventional steel bumper systems, also provide high surface finish and styling enhancements. However, there remain questions about the durability and engineering applicability of thermoplastic bumper systems to heavier vehicles. This paper presents results of a preliminary study that examines the durability of thermoplastic bumpers drawn from production lots for much lighter compact, and mid-size passenger cars against baseline steel bumper systems currently used on full-size pickup truck and sport-utility vehicles (SUVs). Bumpers were subjected to U.S.

The stiffness of randomly oriented, glass-mat thermoplastic (GMT) composites with a polypropylene matrix can be increased in a 3-point loading test through the selective use of a co-mingled E-glass and polypropylene filament thermoplastic prepreg. Bumper beams for a typical midsize vehicle made from combinations of these 2 materials were molded and tested using a static bumper test setup, with load being measured as a function of deflection. A design of experiments investigation based on the Taguchi methods [1, 2] was used to compare the effects of 4 glass-mat orientation variables on the measured static load response of the molded bumper beams. This led to follow-up tests of materials and design strategies for selectively increasing the stiffness of the GMT composites at select locations in the bumper beam. The details of the investigation and results will be discussed in this paper.

The I-Section bumper design has evolved over the past 10 years into a lightweight, low cost, high performance alternative to traditional bumper beams. Initial I-Section Bumpers were developed with 40% Chopped fiberglass GMT. Through the development of lower cost Mineral-Filled/Chopped fiberglass GMT, improved static load and dynamic impact performance results have been achieved in I-Section Bumper Designs.