Tech Briefs
Plastics in automotive safety systems

First Technology Safety System's OCATD project will measure seat-load distribution patterns of a small adult female and a 6-year-old child.

Plastics played a major role in every safety advancement over the last 20 years, and plastics will play a key role during the next decade in solving many of the remaining auto safety problems," said Suzanne Cole, President of Cole & Associates and Chairperson of the Plastics in Automotive Safety conference in Troy, MI. The Society of Plastics Engineers sponsored the first-time event.

More than 37,000 people in the U.S. were killed in automobile accidents during 1998. Of that number, 7300 people died (and another 7800 people were seriously injured) from being partially or completely ejected through vehicle windows. Enhanced protective glass (EPG), a laminated glass used for side and rear windows and sunroofs, is making inroads as a vehicle safety feature that protects against occupant ejection.

"We see EPG not as a competitor of other safety features, such as side airbags, but as complementary," said Vicki Holt, Vice President and General Manager of Solutia's Saflex business. The Enhanced Protective Glass Automotive Association, spearheaded by DuPont and Solutia, functions as an information network (AEI February 2000).

"The objective of this effort will be to help the industry's value chain assist automakers as they seek a systems solution for added side-impact protection involving door redesign, side airbags, and curtain walls," said Dennis Reilley, Executive Vice President and Chief Operating Officer of DuPont Automotive. "An immediate benefit of these systems will be greater (vehicle) security."

Additional safety solutions involving plastics will be evident in future vehicle model years. "Accident avoidance systems that rely on sensors and micro-circuitry will be made possible through the use of engineering plastic and film substrates and plastic encapsulated components," said Reilley.

Bumper and side-door intrusion systems on future production vehicles are expected to utilize plastic reinforcements. "Ford's Equator concept truck features exposed DuPont Kevlar aramid fiber reinforcement for its bumpers, fenders, wheel wells, and lower trim panels," Reilley said.

Interior safety features continue to use plastics as a material solution. Lear Corp., the Southfield, MI-based interiors supplier, has been working on a knee bolster whose polypropylene structure is vibration-welded to a cover surface. "Lower extremity protection is an emerging area of safety emphasis," said Ash Galbreath, Lear's Vice President, Advanced Engineering and Validation. "Traditionally, a steel structure is spot welded. By using a polypropylene structure (the knee bolster) becomes lighter in weight and more cost effective." The product could launch in the 2004 model year.

Following two years of development work, another tier-1 supplier has modified the conventional knee bolster design. "Basically, it's a plastic (TPO or TPE) bag, and it stores in a flat mode (including inflator)—about 38-mm (1.5-in) thick," said Robert Jones, Staff Development Engineer with the Advanced Development Group of Delphi Automotive Systems. "It doesn't need a separate mounting bracket/plate or a separate show surface plate because it serves those functions as one-piece." The knee bolster can be done as a two-piece unit using materials such as polycarbonate and polyurethane.

First Technology Safety Systems' Occupant Classification Anthropomorphic Test Device (OCATD) program tapped plastic for a human surrogate's skeletal structure. For the OCATD project, the firm will design and manufacture an advanced test device to measure accurately seat-load distribution patterns of a small adult female and a 6-year-old child. "The plastic skeletal structure differs from traditional crash test dummies that use metal in the structural skeleton," said Gordon Morgan, Director Technical Marketing and Quality Systems. "The plastic spine bends, so it can take different postures and achieve a much more realistic shape."

All worldwide safety systems, regardless of the materials used in the design, undergo extensive testing. But major rule-making bodies in Europe, Japan, and the U.S. generally have differing test procedures, performance criteria, and certification systems. If regulations were the same globally, material benefits would transpire. "For the automotive industry, harmonization of regulations will allow more efficient development of vehicles, increase productivity, promote technological development, and allow a faster transfer of that technology to the consumer (as well as) remove redundant testing and certification requirements," said Helen Petrauskas, Ford Motor Co., Vice President, Environmental and Safety Engineering.

Kami Buchholz