Koark, F. and Beul, C., "Avoiding Safety Scandals by Controlling the Risk of Material Changes," SAE Technical Paper 2017-01-0373, 2017, doi:10.4271/2017-01-0373.
Achieving functional safety in mechatronic systems with growing product functionality is a major challenge in systems engineering. Following the current discussion, this challenge is mostly allocated to electronics and software development. For most of the scenarios this focus is feasible. Product design - the construction of the product - defines the properties and the appearance of the product by shape, material and assembly. So, the product design is often not under control of the safety management system. A hazardous deviation of part shape can be easily identified after the parts product or at least at its mounting. A wrong assembly is controlled by assembly documentation or data (e.g. screw torques) and identified at end of assembly line checks. The identification of a hazardous material choice depends on the product material class. Product materials can be separated into two classes: passive or active materials. Passive materials (e.g. car body) can be distinguished in as passive materials with constant shape (stiff) and variable shape (flexible) (e.g. damper, spring). The liability of those materials regarding their usage in the product is tested in labs in prototypes in prior. Active materials (e.g. fluids, gases), or functional materials fulfill, trigger or directly influence the functionality of the product. The choice of a functional material is not always made by the electronics engineering. Therefore, it is not under control of safety management processes. Never the less functional material, especially with radical behavior, underlie other safety regulation. Explosives for example, can be integrated in a product or system and are restricted by specific standards. This technology report reflects the verification methods of functional materials today. The responsibility of the product design engineer is discussed as well as the relevant standards. The challenge of achieving complete product compliance with functional materials is shown by the technology analysis of the Takata airbag recall. The required and available methods to control risks of functional materials choice and change are listed and rated. Gaps in existing engineering processes and regulations are identified. A strategy to close those gaps is explained.