Load Sensitive Control Arm based on Martensitic Phase Transformation

In this paper, a new technology for a novel material inherent load sensor for sheet metal components of metastable austenitic steel is presented. The new technology is based on load induced martensite formation and is investigated in the Collaborative Research Centre (CRC) 653. The sensors are small areas in the sheet metal material, which have been plastically deformed by means of stamping. Due to this, residual stress remains within the material assisting the formation of martensite if mechanical load is applied to the component. The martensite content correlates with the magnitude of the load and can be measured by means of eddy-current testing. The aim is to expand the possibilities of load and damage detection especially for security-relevant components. For demonstration, a control arm made of metastable austenitic stainless steel EN 1.4301 (X5CrNi8-10) is being investigated. In the frame of this paper, the results of numerical analyses to determine adequate positions for implementing the load sensors are presented. Therefore, a mathematical model was developed that considers formation of martensite in the FE-simulation and allows for computer-aided design of the sensors. The basic idea of the CRC 653, the principle of the load sensor, the development of the mathematical model and results of the numerical investigations are presented.