Failure Analysis Expert Witness Examines Failed Rivet

A failure analysis expert witness performed a rivet fialure analysis of a rivet involved in a ladder failure. The failed rivet, which is a hollow end rivet, was found to be too short for the intended application. The photo on the upper left is a cross section of the failed rivet in question. The clinch allowance of this rivet was inadequate and over time the folded over portion failed from fatigue and allowed the joint to open. The center photograph is of a similar rivet. One can see that this rivet has very little left to grip on the hollow end. This rivet has not failed; however, it does show significant deterioration. Upper right is a rivet that has the proper clinch allowance. In additon, this rivet does not show any signs of deterioration.

Glass Failure AnalysisExpert Examines Cracked Automobile Windshield

Glass expert performs a glass failure analysis on a cracked automobile windshield. Records show that the windshields on this particular make and model of automobile are cracking at a very high rate. The windshield shown here is the third replacement in two years. In this case, glass failure analysis shows that the crack started at an impact point two inches below the top of the windshield. Initially the windshield crack was driven by bending stresses. Later it was driven by thermally generated stresses (caused the crack to curve). Factors that are of concern are the glass thickness, mounting (i.e. bending) stresses in the windshield, perpendicularity of the windshield and glass lamination stresses. Eventhough the failure was caused by an impact point; this damage should not have caused a large crack to form. The upper left photo is an overview of the crack. In the center is a close up of the impact point. Upper right is a 40X photomicrograph of the crack origon.

Failure Analysis Expert Discusses Metal Fatigue

Failure analysis was performed on a failed pin from a large tractor. The upper right gives an overview of the pin. Upper left is a close up of the fracture surface. The fatigue crack originated at the top of the photo and progressed downward until the final overload failure.

Glass Expert Analyses a Broken Bottle

Glass failure anlysis expert witness performs a root cause failure analysis on a broken bottle. This bottle broke into pieces (lowerleft figure). A failure analysis determined that the failure origin was in the bottle neck under the plastic cap (lower right figure). The glass expert removed the cap and the the residual polish (top left figure). The neck was cut open from the side opposite the visible crack, and the failure analysis revealed that the failure originated (arrow) at a damage site on the interior of the bottle neck (top right figure). Further study is required to determine the source of the damage.