MSE Projects – Spring 2021

After approximately one year of use, a garage door torsion spring fractured catastrophically from an unknown cause. The prematurely failed spring was an oil tempered steel wire that had an expected lifespan of around nine years. The fracture occurred in the middle of the 25-inch spring when an approximately 130- to 150-pound garage door was in use. To establish a testing plan, the fracture surface of the spring was examined and documented. For comparative analysis, non- destructive and destructive testing was then completed on the fractured component as well as on an exemplar spring to identify failure cause.

Quality control in the production of high-volume parts is crucial in sustaining an automotive supply business. A layered coil oil cooler produced by a heat exchanger company based in Wisconsin failed quality check at its manufacturing location in Shanghai, China. The oil cooler failed leak testing and was observed to be leaking through both welds of the coolant pipes. The cause of this manufacturing failure was determined through a series of tests and experiments, both destructive and non- destructive.

Cast iron has been used as cookware for centuries, dating back to the Han Dynasty (220 AD) in China, and has continued to be a mainstay in kitchens ever since. Because of their durability, consumers are able to keep the same cast iron skillet for decades without any decrease in quality or performance. With this in mind, it was quite confusing for a local home cook when his cast iron skillet formed a large crack during routine stovetop use. Using stereo and electron microscopy, and performing mechanical properties tests on both the sample and similar exemplars, the root cause of the failure was determined.

A turbocharger consists of a centrifugal compressor driven by an exhaust gas turbine. It is employed in engines to improve the overall performance and fuel efficiency. A turbocharger from a 2015 Ford Explorer failed, and the causes of failure were examined. In particular, the turbo’s forged steel shaft was investigated to determine the mechanisms behind the failure.
A series of non-destructive tests were carried out prior to cleaning. Fracture surfaces were examined using scanning electron microscopy. Metallographic examination of the microstructure was carried out following sectioning of the steel shaft. Additionally, uniaxial tensile testing and chemical analysis were performed.

The beer growler lost its life before the first use. When filled with beer, the neck of the growler broke upon the first pull of the closed metal clasp. A normal beer growler should sustain multiple uses before failing under similar circumstances. The topographic features of the fracture surface were analyzed under a stereo microscope and scanning electron microscope in order to determine the true nature of the failure. The strength of the growler was tested for its actual strength, in comparison to the theoretical strength, to provide an explanation for the fracture.

A sway bar link of unknown origin, possessing characteristics
of both ductile and brittle fracture, was acquired. Typically used
to help stabilize the steering and suspension of an automobile, a sway bar is incorporated into both the front and back end of an automobile. Accordingly, a sway bar link is used to attach the sway bar to the control arm, allowing it to support and help pivot the sway bar. This enables the vehicle to make smoother turns. A failure analysis was conducted using a variety of techniques including: non-destructive testing (NDT), microscopy techniques, material characterization techniques, stress analysis, dimensional analysis, and chemical analysis.

A torque bar is a specialized wrench that utilizes a long handle to exert increased torque to loosen bolts. Harbor Freight Tools is known for marketing low cost torque bars. Consequently, the materials used are more cost-effective rather than mechanically effective. A sample Harbor Freight torque bar failed on the opposing side of a repetitive applied force while being used to remove the shock absorber lower bolt on a 2010 Ford F150. This project sought to analyze the fracture surface, material makeup, and mode of failure of the torque bar in question in order to determine the technical cause of failure.

The Fusion D-Shaped Carabiner inspected was an exemplar of a subject carabiner which malfunctioned in an accident during a Ringling Brothers Circus performance. The part was analyzed and a failure mechanism was determined. The surface of the fracture was initially examined through multiple non-destructive tests, such as 3-dimensional replication system and scanning electron microscopy (SEM). Additionally, the carabiner also experienced various destructive testing methods. These tests were performed in order to compare the chemical, mechanical, and physical properties to an intact exemplar, as well as accessible manufacturer information to gain insight on the failure.

Failure analysis was performed on an exhaust heat shield from a 2011 Toyota Highlander. The part was located on the underside of the car near the front of the vehicle. A corrosive and high temperature service environment led to the premature failure of the part. Multiple non- destructive and destructive tests were performed on the component to determine the root cause of the failure, including chemical analysis and scanning electron microscopy (SEM).