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Multi-Domain Simulation Model of a Wheel Loader
Abstract:
Wheel loader subsystems are multi-domain in nature, including controls, mechanisms, hydraulics, and thermal. This paper describes the process of developing a multi-domain simulation of a wheel loader. Working hydraulics, kinematics of the working tool, driveline, engine, and cooling system are modeled in LMS Imagine.Lab Amesim. Contacts between boom/bucket and bucket/ground are defined to constrain the movement of the bucket and boom. The wheel loader has four heat exchangers: charge air cooler, radiator, transmission oil cooler, and hydraulic oil cooler. Heat rejection from engine, energy losses from driveline, and hydraulic subsystem are inputs to the heat exchangers. 3D CFD modeling was done to calibrate airflows through heat exchangers in LMS Amesim. CFD modeling was done in ANSYS FLUENT® using a standard k - ε model with detailed fan and underhood geometry.
Critical wheel loader drive cycle inputs into the model have been obtained from testing and have been used to validate the system response and cycle fuel consumption. Predicted engine speed, pump pressures, machine ground speed, and cycle fuel consumption were found to correlate with the test results. An energy distribution study shows energy losses in the respective subsystems. The model has been effectively used to identify improvements in system efficiency in terms of fuel consumption and productivity.