An 8.8” differential failed during use in a Jeep when the driver abruptly shifted from reverse to drive. The differential was disassembled and examined to determine the method of failure. Analysis of the failed part included evaluation of fracture surfaces, macroscopic defects, failure modes, mechanical properties, and microstructures. The investigation was carried out using a variety of testing methods including stereomicroscopy, scanning electron microscopy, chemical testing, metallography, and others. The root cause of failure was determined and recommendations were made to avoid future failure.

Team Members (L-R): Christina Casali, Kegan McKinnon, Sam Schab

Two acetabular cup reamers were submitted to DePuy Synthes after failure and were loaned to MSU for failure analysis. Acetabular cup reamers are used to strip the excess bone from the acetabulum to prepare the socket for a total hip replacement. These parts failed within the ‘cutting teeth’ features of the reamers. Through various investigative techniques, data was collected and analyzed to determine the root cause of the failures.

In the Michigan State University Physics machine shop, Rob Bennett (MSU Employee) was CNC milling an artifact using a titanium carbide end mill with the trochoidal machining technique. Amidst the milling, the titanium carbide bit fractured in a very unique and peculiar way, which raised the question as to manufacturing flaws in the bit. “Thrill of the Mill” has examined the cause of this failure through Scanning Electron Microscopy (SEM), microstructural analysis, and several other material analysis techniques. This research was done to prevent this failure from happening again. The results will be used to advise future CNC operators and refine the manufacturing process used.

The bearing cage inside a constant velocity axle failed during use in a 2008 GMC Sierra 1500 pickup truck. The vehicle had been driven for 135,000 miles when failure occurred, a shorter lifetime than typically expected. The cage was shattered into 13 pieces and was possibly driven on for a month before being replaced. Analysis was performed on the bearing cage to conclude the reasons for its failure. This was done through various methods of testing such as non-destructive analysis regarding surface replication, optical microscopy and imaging of the subject and various destructive techniques such as hardness tests, scanning electron microscopy, and other metallographic techniques.

Team Members (L-R): Lia Hetherington, Darwin Warga Kane, Mike Zuker

The middle of an ice hockey blade fractured after five years of use. The blade was struck by a puck traveling at high velocity, which may have led to the catastrophic failure of the blade. The fracture is unusual as ice skates are often struck by pucks but rarely fracture. This is problematic as a broken blade can be hazardous, leading to injury or damage of equipment. An analysis of the failed specimen was carried out using various testing methods in order to determine the method of fracture and the root cause of failure.

The main goal of this project was to perform a failure analysis on a chosen part for Michigan State University’s MSE 466 course. The chosen component was a screen door latch that fractured during normal usage. The component is approximately 3” x 3” and made out of die cast zinc. The failure occurred during the summer of 2015 in Dewitt, Michigan, while the door was being opened. The part was purchased around 1998, and was manufactured between 1985-2000 by Wartian Lock Company. Our hypothesis for the cause of failure was that based on how the forces were applied to the handle and the poor design of the handle, there were areas that had high stress concentrations, eventually leading to fracture. To prove this, we performed non-destructive and destructive testing procedures on our component.

A nickel heat shield from a ULVAC ZEM-3 failed when it was handled by an operator under normal use conditions. The walls of the heat shield were punctured and suspected to be embrittled after the part was subjected to thermal cycles at 600 ̊C on the order of hundreds of cycles. Theoretical calculations were performed to predict chemical changes due to diffusion and stresses associated with thermal cycling and fatigue. Physical and chemical analyses were performed to evaluate the cause of the failure.