Service Life Aging and Heat Exposure Effects on Aluminum Sheet Alloy Properties and Structural Crashworthiness Under Dynamic Axial Loading

An investigation of the service life aging and heat exposure effects on sheet aluminum alloy properties and structural crashworthiness has been conducted. This research, part of a broader program, consists of investigating five aluminum sheet alloys each of which is subjected to four heat treatments. The aluminum sheet alloys investigated are 6111T4PD, 5754-O, 5182-O, 6022T4E29, and 6022T4. The four heat treatments are 177°C for 30 minutes, 200°C for 15 minutes, 200°C for 2 hours, and 200°C for 24 hours. The 200°C/24 hours treatment simulates the most severe thermal exposure i.e. components adjacent to exhaust pipes and manifolds. All 200°C heat treatments are in addition to the 177°C for 30 minutes. All specimens were subjected to the reference 177°C for 30 minutes treatment. Aluminum rails of hexagonal cross-section were formed for the twenty combinations of aluminum sheet alloys and heat exposures. These twenty formed aluminum rails were then bonded and riveted using Betamate 4601 adhesive and Henrob K50742 self-piercing rivets. Once assembled, these twenty rails were subjected to dynamic axial crushing at a speed of 40 kph (25 mph). Force-Time data was collected and responses were plotted for all tests. Force-Displacement responses were then integrated for the crush energy management and mean axial crush load for each of the aluminum sheet rails. Bar charts were generated to describe the crash loads and energy management behaviors of the various aluminum alloys and associated heat treatments. Service life simulated heat exposure was found to affect the mean crash load and crash energy management of the aluminum structural crash members. The heat exposure effects on the crashworthiness of the sheet aluminum members ranged from a reduction of [−21.6%] to an increase of [+6.8%] in the mean crash load and crash energy management with higher variation observed in the “T4” tempered aluminum alloys.Copyright © 2005 by ASME