High strength stainless steel sandwich panels for transport applications

All-metal sandwich panels of three different basic configurations were manufactured of various grades of austenitic stainless steels by laser welding. Once manufactured, the panels were subjected to exhaustive mechanical testing programme including constant load and four-point bending tests for full size panels of about 2.5 m², as well as fatigue and crash testing of smaller panel sections. Apart from laser welded constructions, reference panels were manufactured by adhesive bonding and by using insulating foam in a basic welded panel. The manufacture and resulting properties of such panels are described in this paper as well. It can be concluded from the results that all the panel types fulfilled the set requirements for the static, i.e. design loading, and fatigue loading situations – no requirements were preset for panel crash properties. Once the panel surface sheet thickness and total panel thickness are fixed, there are no significant differences in the practical applicability between panel types, material strength or manufacturing routes from the load bearing point of view. The reason is that the practical structural properties are stiffness, i.e. geometry dependent. Thus, the differences in panel type, material strength or assembly method only become evident at loads and resulting displacements that are way beyond acceptable service conditions for transport equipment structures – apart from perhaps exceptional impact load situations, such as crash or collision. The choice between panel details has to be based on other issues, such as weight optimisation, ease and cost of manufacture, or aesthetics