Failed Connecting Rod

Connecting rods are used in many situations and are commonly found in road vehicle engines. They connect the pistons to the crackshaft and transmit force between these reciprocating and rotating parts. Connecting rods come in a range of specifications and materials (e.g. steel, aluminium and titanium).

Connecting rods are subject to a complex range of compressive and tensile forces during the combustion cycle with sudden changes in load direction. Failures can occur such as those in Figure 1. The Zencrack analysis shown here includes a simplified (i.e. constant amplitude) fatigue loading scenario in a steel rod of typical geometry (Figure 2). An initial crack of radius 1mm is defined in a location consistent with the failures shown in Figure 1.

An uncracked mesh is created with tet elements throughout (Figure 3). A deformed plot part way through the analysis is shown in Figure 4. Crack growth animations are shown in Figures 5, 6 and 7.