Coupled Flexible Multibody Dynamics and Hydraulic Simulation for a Load Device
Saarela, Ville-Pekka (2019)
2019
Konetekniikan DI-tutkinto-ohjelma
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2019-11-29
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-201911075793
https://urn.fi/URN:NBN:fi:tuni-201911075793
Tiivistelmä
A hydraulic driven load device is actuated by two hydraulic cylinders. The hydraulic cylinders are connected to opposite sides of the rotating frame of the load device. At the start of the work cycle cylinders receive half of the fluid flow generated by the flow source. After a while regenerative loading cycle is used. In regenerative loading one cylinder receives full fluid flow from the flow source and the other cylinder feeds itself. This causes cylinder forces that have different magnitude and opposite direction for each hydraulic cylinder. These forces affect the load devices structure with torsion.
To determine deformations for the structure a coupled flexible multibody dynamics and hydraulics simulation is done. Component Mode Synthesis (CMS) method is used for flexibility of a part of the structure for multibody simulation. CMS method is a linear modal analysis based method. Flexible multibody model is driven by a hydraulic system model. Due to contact nonlinearities in load devices structure, joint forces are imported to non-linear dynamic analysis to determine deformations caused by the load cycle.
Results of interest for the hydraulic system are the pressures in different places, cylinder forces and velocities and fluid flow rate in hydraulic pipes. Joint forces caused by the hydraulic system are the primary results which are transferred as boundary conditions for the second simulation that calculates deformations of the structure.
To determine deformations for the structure a coupled flexible multibody dynamics and hydraulics simulation is done. Component Mode Synthesis (CMS) method is used for flexibility of a part of the structure for multibody simulation. CMS method is a linear modal analysis based method. Flexible multibody model is driven by a hydraulic system model. Due to contact nonlinearities in load devices structure, joint forces are imported to non-linear dynamic analysis to determine deformations caused by the load cycle.
Results of interest for the hydraulic system are the pressures in different places, cylinder forces and velocities and fluid flow rate in hydraulic pipes. Joint forces caused by the hydraulic system are the primary results which are transferred as boundary conditions for the second simulation that calculates deformations of the structure.