Development of a test method for composite materials energy absorption: corrugated specimens Paolo Feraboli 1 , Francesca Garattoni 2 University of Washington, Seattle, WA 98195-2400 One of the key factors preventing the widespread adoption of composites in primary crash structures is the absence of specialized test methods for the characterization of specific energy absorption (SEA). Aside from thin-walled tubular specimens, a limited number of attempts have been made at using a plate specimen, which is easier to manufacture but requires complex anti-buckling fixtures. A new method, featuring a corrugated plate, which can be easily manufactured and is self-stabilizing and hence does not require a dedicated test fixture, is suggested here. A systematic investigation is performed to validate the possibility of using such specimen to screen candidate material systems and laminate designs, with the specific goal of isolating the sensitivity of the method to intrinsic specimen parameters. I. Introduction he four necessary conditions for survival during a vehicle collision are maintaining sufficient occupant space, providing adequate occupant restraint, employing energy-absorbing devices, and allowing for a safe post-crash egress from the craft [1]. Specifically, the energy-absorbing components, primary vehicle structure and secondary systems must all be designed to work together to absorb the vehicle kinetic energy and slow the occupants to rest without injurious loading. Vehicle impact events involve the simultaneous structural response of multiple components, and often the energy-absorbing devices experience combined loading, resulting from axial crushing and bending. However, the complexity of these events is such that often these processes need to be approached individually, and usually the energy-absorbing components are designed to dissipate energy under controlled collapse in simpler loading configurations. In general, while the total energy dissipated during a crash depends on the overall vehicle system deformation, the crash- oriented design of the individual structural subcomponents of simple geometry can provide a great increase in structural crashworthiness and survivability, with an acceptable increase in overall vehicle cost. For this reason, structural elements that provide energy absorption have received special attention in the literature [2-6]. T Energy absorbers can be found in the front end of all modern passenger cars, in the form of collapsible tubular rails [4, 5], or in the keel of modern aircraft (figure 1) as collapsible floor supports [6-9]. These elements have been traditionally made of steel or aluminum, which absorb energy through controlled collapse by folding and hinging, involving extensive local plastic deformation [2.]. However, the introduction of composites in the primary structure of modern air- and ground- vehicles presents special problems for the designer dealing with occupant safety and crashworthiness. The energy-absorbing behavior of composites is not easily predicted due to the complexity of the failure mechanisms that can occur within the material. Composite structures fail through a combination of fracture mechanisms. These involve a complex series of fiber fracture, matrix cracking, fiber-matrix debonding, and interlaminar damage (delamination) mechanisms. The brittle failure modes of many polymeric composite materials can 1 Assistant Professor, Department of Aeronautics and Astronautics, University of Washington, Box 352400, Seattle, WA, 98195-2400 USA. Tel: 206.543.2170, E-mail: feraboli@aa.washington.edu 2 Visiting post-graduate student, Facoltà di Ingegneria Aerospaziale, Università di Bologna (Sede di Forlì) American Institute of Aeronautics and Astronautics 1 48th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference 23 - 26 April 2007, Honolulu, Hawaii AIAA 2007-2011 Copyright © 2007 by Paolo Feraboli. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. COPY - NOT AN ORIGINAL COPY - NOT AN ORIGINAL