b'Engineer Innovation | How to GuideHow toPredict realistic operational loads and assess fatigue lifeBy Sebastian FlockBusiness developer, Simcenter 3DHeavy equipment is a considerable investment, an excavator costs as much as a family home and even a small backhoe still matches the cost of a luxury car! An investment like this needs to be one that operators can rely on. Mechanical parts must be able to sustain many mission cycles and potentially unforeseen events, operating on a particularly challenging site or stretching the boundaries within which they were designed. Engineers designing this equipment therefore are seeking to guarantee sufficientFigure 1: Loader unit with main boom, bucket, and hydraulics cylindersoperating-life and ensure where possible the vehicle remains safe fromHere we will take a wheel-loader as structural load is clearly visible and damage that can accumulate over thean example to demonstrate the potential weak spots easily identifiable.many duty cycles. Consider theprocess, one of the main mechanical repetitive loads acting on the machineparts of a wheel loader that needs to beEvaluate your design- such as the weight lifted andefficiently engineered is the loader unitAfter the FEA, your next obvious step is vibrations from maneuvering on rough(figure 1).to take corrective actions in the CAD terrainchallenging conditions! design to try to optimize load capacity Providing modeling and design teamsand change the component geometry. Excavators can weigh up to 900 tonswith a single platform to access theThe simulation can be re-run without with a bucket load up to 80 tons for thesame data source for both CAD andadditional modifications and the results most extreme mining applications,CAE, enables efficient collaboration.compared to judge the design change. carrying these loads whilst oftenThis saves valuable time for both teamsEvaluating a variety of designs based on subjected to vibrations from maneuverswith less iteration cycles. Plus, switchingmodification can be time-consuming, on inclines or uneven ground. Thisfrom CAD to CAE modeling, enables thewhen done manually (figure 2). combination of loads and dynamicsengineer to refer to already existing imposes significant mechanical forces/ meshed components in the CAE libraryNow the design can be taken one step moments on the machines components.and automatically update the CADfurther as it is easy to define some Consequently, identifying weak spots inmodel. design degrees of freedom. Using a the structure during the machine designDesign Space Exploration tool helps ensures maximum resilience; durabilityOnce all the parameters, such as loadsengineers to systematically explore is a top priority for machine makers. and boundary conditions, have been setvariants in order to find the best one in the CAE 3D simulation environment,(figure 4).Pinpoint potential weak spotsThe engineering process typically involves different domains such as design, systems and mechanical engineering. Based on the initial CAD structure, finite element analysis (FEA) is performed. In order to refine the design and derive realistic operational loads, multi-body simulations of the entire machine are conducted. Finally, based on these loads, fatigue analyses certify the final design. Figure 2: FEM assembly of the loader unit with FEA results for the main boom64'