Utilizing the Crushing Under Load Properties of Polypropylene and Polyethylene Honeycomb to Manage Crash Energy

Honeycomb absorbs energy by crushing under load. This characteristic has proven to be one of the most reliable and efficient methods of providing “G” limit protection. The action of crushing develops a uniform level of stress near the optimum response desired for energy absorption materials. Energy absorbing designs using honeycomb are presented in several forms. This paper presents a rapid method for calculating preliminary solutions for “G” limit protection. Honeycomb has had application as a calibrated “G” load limiter in test carts and in production steering columns and knee bolsters.

Recently a method for continuous production of honeycomb materials from polypropylene and polyethylene (DuPont Tyvek^®) called CECORE^™ has been developed. These materials are very lightweight with a range of crush strengths and applications. This allows designers to use recyclable base materials in configurations proven to manage energy. The paper discusses examples of how CECORE^™ can be used in a vehicle interior.

During the last several years the automotive industry has been increasingly concerned about the survivability of drivers and passengers in motor vehicles. Determination of the load conditions and crash mechanisms has been the basis for a large amount of research and broken automobiles. Honeycomb material continues to be used on the impacting faces to simulate the actual crash conditions without damaging the test fixtures. This protective mechanism of the test fixtures can be utilized within the interior to limit the loads on the occupants.

This paper explores crush properties of honeycomb and the basic calculations necessary for the preliminary design of a protective honeycomb interior. Some recent examples of how honeycomb was and can be used in certain applications are examined with a brief look at using a new low cost, recyclable honeycomb.