A commercial hybrid-iron golf club fractured during normal use. The club fractured through its cast aluminum alloy hosel. Optical analysis revealed casting pores through 20% of the hosel thickness. Mechanical properties were determined from characterization results, then used to construct a finite element model to analyze material performance under failure conditions. In addition, a full scale structural test was conducted to determine failure strength. It was concluded that the club failed not from ground impact but from a force reversal at the bottom of the downswing. Large moments generated during the downswing aggravated by manufacturing defects and stress concentration combined to create an overload condition.

The head on a golf club driver developed multiple cracks during normal use. The head was a hollow shell construction made from a titanium alloy. Analysis and additional investigation revealed a progressive failure that initiated on the interior surface of the face plate along a deep, concentric groove created during a press forming operation. It was also determined that atmospheric contamination occurred during the welding of the head, causing embrittlement, which may have also contributed to the failure. Recommendations were made addressing the problems that were observed.