Vol. 19, No. 13

Dec. 2, 1999

Marine and aerospace industries
eye lightweight material

A building element made of lightweight honeycomb sandwiched between curved composite panels is getting the attention of companies making everything from storage containers to components for the space station, according to Jack R. Vinson, University's H. Fletcher Brown Professor of Mechanical Engineering. The marine and avionics industries are especially interested in the new material which, if improved, could contribute significantly to faster boats and fuel-efficient airliners, to meet consumer expectations and regulatory mandates, Vinson and others said. The advanced material is described as a sandwich structure and features an inner core of composite material designed like a honeycomb, wedged between two outer panels of aluminum or composite material. Vinson and other researchers involved in testing, analyzing and designing sandwich structures discussed their latest findings in November in Nashville, Tenn., as part of the 1999 International Mechanical Engineering Congress and Exposition, presented by the American Society of Mechanical Engineers (ASME). The key attribute of a sandwich structure is its light weight, which results from the honeycomb-like design of the inner core, researchers said. Wrapped around the inner core of the sandwich structure are the aluminum or composite panels, or facing sheets. These panels accept most of the moisture, pressure loads and weight-bearing forces exerted from external conditions. Although the panels of the sandwich structure take most of the pressure, researchers believe it's critical for the core material to withstand some external forces. Engineering approaches to improved designs include reinforcing the core material and creating more separation between the core and outer panels. The research community also is looking at the problem of breakage in sandwich structures. This occurs when the material that bonds the outer sheets to the core weakens from pressure or moisture. Stronger epoxy agents and improved curing methods can prevent such damage. According to Vinson, the sandwich structures have been used in Europe since the late 1980s, principally in navy ships. In the United States, manufacturers of passenger airliners and military aircraft systems have been the primary users. Joining Vinson on the conference program were leading researchers from the University of Cincinnati, University of Missouri at Rolla, the Georgia Institute of Technology, Purdue University and the U.S. Department of the Navy.