b'How to Guide | Engineer InnovationHow toPredict realistic operational loads and assess fatigue lifeBy Sebastian FlockBusiness developer, Simcenter 3DOnce the structural design of the parts is consolidated the assembly can be analyzed in its entirety with multi-bodyFigure 3: Automated design space exploration based on simulation resultssimulation.Simulate the full transient mission cycleFrom that previous step, the loader unit is assembled within the context of the full vehicle. With simulations of characteristic operationsconsidering positions, velocities, accelerations realistic loads can be derived on the individual components, representing the real utilization of the Wheel Loader. Multi-body simulation considers the kinematics, hydraulic actuation, control system, as well as the relevant structural dynamics (figure 4). These analyses for operations such as lifting, digging or loading enableFigure 4: Multi-body simulation results of full duty cycleanswers to critical questions that improve the machines reliability, such as: What are the critical loading conditions? Which are the peak loads and where do they appear in a load cycle? How do controls and hydraulics influence these loads?Assess fatigue and derive representative component testsAfter having designed the component and understanding the systems interactions over real load cycles, a dedicated durability assessment can be performed. Sufficient analyses and dataFigure 5: Damage accumulation and transient strain curveexists to understand the likely fatigue for the main boom of the loader unit.In figure 5 we can see a typical damagewhich loads and in which direction are accumulation history for the highestcritical for the component. This helps to From the previous multi-body simulationloaded location on the main boom of thedefine test scenarios representative for scenario, information about damageLoader unit. This can be directly mappedall relevant loads and dynamics. For accumulation can be extracted andwith the transient load history from theexample, only a 2-second-long part of estimated remaining lifetime for variousmulti-Body simulation.the load cycle reflects all potential scenarios. A dedicated durability solverdamage accumulation. With this level of ensures that in the fatigue analyses theBecause we can assess the damageunderstanding, test durations can be correct local stresses are considered foraccumulation based on the transientreduced significantly and the setup the correct component and the correctresults, the identity of the critical loadsimplified. nexternal load. cycle sub-sections are clear. We know 65'