Similarities of Fatigue Failures in Various Materials

A California materials expert has performed hundreds of materials failure analysis on a wide variety of materials. Surprisingly fatigue failures have the same appearance regardless of type of material. Above are three examples of fatigue. Upper left is a sample of a rubber fatigue failure. This is very similar in appearance to the CPVC pipe plastic fatigue failure (center) and the metal fatigue failure (right). All these fatigue failures start at one point and "progressively" spread out leaving redily distinguishable fatigue "beach marks" indicating the direction of travel.

California Failure Analysis Expert Witness Examines Failed Glass Pool Tiles

California glass expert performed a failure analysis on several broken glass tiles. These tiles were above the water line in a swimming pool. The failed tiles were removed and submitted for failure analysis. It was impossible to open the tiles to examine the fracture surface. The thin set mortar had "squeezed" into the crack and was firmly holding the tile pieces together. The tiles were soaked overnight in muriatic acid to allow separation. They could then be pulled apart to expose the fracture surface for failure analysis. The figure above is an 8X photomicrograph of a representative fracture surface. All the failures initiated on the backside of the tile. It appears that the glass tile backside was forced against a small hard particle during mounting in the thin set mortar. The failure initiated at a point on the glass tile backside and srpead into the tile (indicated by the arrows). The root cause of the glass fracture was inpact against a hard particle, The fact that the mortar had squeezed into the crack indicated that the glass tile failure occured during mounting. Perhaps the tile setter was using a mallet to align the glass tiles.