Failure probability of ceramic coil springs

Ceramic springs are commercially available and a detailed reliability analysis of these components would be useful for their introduction in new applications. In this paper an analytical and a numerical analyses of the failure probability for coil springs under compression is presented. Based on analytically derived relationships and numerically calculated results, fitting functions for volume and surface flaws will be introduced which provide the prediction of the failure probability of ceramic coil springs with different spring- and material-parameters. As an example, typical mechanical properties for Si3N4 are chosen. It is shown that surface flaws control the strength of the investigated springs.