Viktor Keric & Abdullah Tekcan presenterar sitt examensarbete.
Examinator: Lennart Josefson, IMS
Handledare: Mikael Almqvist, Alten
Opponent: Dejan Lolic, Mehmet Esat Özel
The Durability Department of Volvo Cars (Gothenburg) is interested in modifying its approach to the finite element (FE) analysis of the door seal system. The seal system is a complex and important component in a door closing event. Volvo Cars currently uses an implicit FE solver in a model in which nonlinear spring elements describe the relationship between the forces and displacements in the seal system. Volvo Cars has proposed to switch to using LS-Dyna which has an explicit solver. Explicit solvers are more computationally effective than implicit solvers and it enables Volvo Cars to use a similar FE-solver to several different car body analyses.
The development of a working explicit model of a Volvo car door that captures the static and dynamic behaviour of the seal system during a door closing event is presented. It is developed for LS-Dyna based on existing knowledge from the implicit solution and data received from the implicit model. To model the rubber seal system in an explicit solver, both the static and dynamic behavior of the seal system are needed.
The static behaviour for the rubber seal is estimated using hyper¬elastic material with the Yeoh material model. Three material constants in the Yeoh material model (C10, C20 and C30) that affect the stiffness of the seal system are determined using a quasi-static simulation of a section of the seal with a prescribed motion of the door closing event. The constants are selected using a curve fit analysis.
To capture the dynamic behaviour of the seal system an existing LS-Dyna airbag model is used. With the airbag model it was possible to estimate the evacuation of the airflow out from the seal system during the closing event. The unknown parameter that had to be established in the airbag model was a shape factor. This shape factor s is found by comparing the measured acceleration signals provided by Volvo Cars to the simulated acceleration signals recorded at a door closing event. By comparison of the acceleration signals it is possible to determine which values of the shape factors gives the best signal correlation.
Finally, it is concluded that evacuation of air from the seal system during a door closing event can be estimated by the working explicit model of a Volvo car door. It is recommended that additional studies be carried to determine the applicability of the model to a variety of door and seal geometries.
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