Failure Analysis

Windshield wipers are a vital component of any vehicle, and they have to withstand and function in a wide array of ambient conditions. In this project, I identified and analyzed all failure modes for a 2005 GMC Sierra 1500 4WD 6-cyl windshield wiper arm to determine if the arm is suitably constructed for the use cases it could encounter. To do this, experimental methods were developed to test physical properties, then a SOLIDWORKS model of the wiper arm was created for use in FEA. Specifically, the connection between the wiper arm and the wiper blade was tested as the most likely location for failure to occur. This location is the small hook at the end of the wiper arm in the images below.

The main failure modes analyzed were weather conditions, specifically extreme heat and cold, longevity and fatigue, and human mistreatment of the arm. Thermal properties of the bar were taken into account when investigating failure due to environmental conditions, such as thermal expansion and contraction, increases in ductility or brittleness, and the force required to break through a layer of ice on the windshield in the case of extreme cold. Fatigue calculations were carried out to attain a rough lifecycle estimate. For human mistreatment, I determined the force an average human could likely pull on the wiper arm for use in calculating stresses within the arm. Through this analysis, I determined that the only potential failure mode that could cause the arm to fail is human mistreatment, whether accidental or maliciously, at which point there is likely a larger problem than the broken windshield wiper arm!

If the project were to be redone, I would alter the physical testing slightly, as the method used, clamping the arm to workbench and using a tensile testing machine to pull on the hook, caused the hook to bend, imparting some torsion onto the arm which was not intended. Furthermore, experience I have gained in SOLIDWORKS since completing this project would allow me to create a higher fidelity model of the wiper arm in CAD, leading to more accurate FEA results and other calculations that utilized these values.

Below are pictures of the wiper arm during different stages of physical testing, after failing under a load of 870N in the final state, as well as a SOLIDWORKS static stress test on the CAD model windshield wiper arm.