Development and validation of a mathematical model for a monotube automotive damper

Automotive dampers involve complex flow physics that cannot be fully described by analytical models derived from first principles. Therefore, the development of a mathematical model based on semi-empirical laws that accurately describe the influence of each of the many design features would greatly help the design and optimization of automotive dampers. This thesis aims to develop a computationally efficient mathematical model capable to predicting damper performance with reasonable accuracy. Lumped parameter mathematical models were developed and implemented using the MATLAB and Simulink environments. In order to solve for the structural dynamics of the shim stack, a force method based analytical model was developed. In order to solve for the internal flow field, fluid structure interaction simulations were necessitated due to the inherent coupling of fluid and structural dynamics. Fluid-Structure Interaction (FSI) simulations were attempted using an open source setup consisting of OpenFOAM and CalculiX coupled by the preCICE coupling library. Coupled simulations on a trial simplified geometry produced physically consistent results. FSI simulations could not be performed on the real geometry due to lack of time and computational resources. The discharge coefficients were modelled as a linear function on the basis of CFD simulations perfomed on outputs from the force method model. In order to validate the MATLAB mathematical model, experiments were carried out on a test automotive damper on a suspension dynamometer. The model showed good agreement in with experimental data at low bleed valve openings. The model accuracy was observed decrease for larger bleed valve openings due to unavailability of accurate model coefficients.