Case Study: Fracture of a Refrigerator Flow Sensor

This presentation covers a failure analysis case study that was done for a client in the insurance industry for subrogation. The part in question is a refrigerator flow meter. Its transparent polycarbonate body fractured and caused water damage to a home. The presentation consists of background info, initial non-destructive evaluation, followed by destructive testing which included optical and digital microscopy, teardown, sectioning, FTIR, and fracture imaging using SEM and a gelsight microscope. Then, the results were used to determine the origin, mechanism, and cause of failure. It was concluded that the flow meter failed due to fatigue, and that this fatigue initiated at a sharp corner on the inside of the device, which acted as a stress concentrator.