| There is ever-increasing pressure on the manufacturers of Load-Haul-Dump (LHD) vehicles and similar mobile heavy equipment to produce machines that are strong and safe, yet of minimum weight. In the context of structural design, this has motivated a move away from standard stress-based assessments, to life-based calculations that require experimentally acquired load histories as input.; Unfortunately, acquiring the service history data of any machine is not always as simple as attaching an off-the-shelf transducer to the appropriate region of the structure. On occasion, the structure itself must be instrumented in a manner that effectively makes it its own load transducer. This thesis will present one such case, in which the load histories of the lift arms of an LHD are measured for a variety of operational tasks.; Using linear-static finite element analysis, the load histories are then converted to strain-time histories for a critical location on the lift arms. These computed strain-time histories are compared to the strain-time history registered by a rectangular strain gage mounted at that location. All strain-time histories are then converted to stress-time histories such that the stress-life based fatigue life of the boom can be determined for the various load histories.; Finally, the finite element analysis and fatigue life evaluation is repeated for a redesigned boom consisting of thinner steel plates in the region of interest. Comparisons are made between the predicted fatigue lives of the original and modified boom. |
