Development of software that can predict damper curves on shock absorbers

Abstract: This thesis features the development of a software program with a plot function (a setting bank) for data curves, obtained when car dampers are tested in a dynamometer, which measures forces at given velocities. Advanced dampers have many different adjusting possibilities and it was desired to collect data about this for a number of damper types, in a software program that can be used to predict damper curves without having to perform actual tests. The goal was to make it easier for customers (mostly consisting of competitions teams) to test and evaluate different settings to a chosen damper in a fast and simple way, without having to use expensive testing equipment that also is a big time consumer. The project was performed at Öhlins USA Inc. in Hendersonville, North Carolina. It is a subsidiary to Öhlins Racing AB, that manufactures performance shock absorbers for cars, motorcycles, snowmobiles and ATVs for both competition and commercial use. The project was initiated by evaluating and deciding different measuring methods, to see what equipment would be used and how the data collection would be performed. A literature study was also performed to get a better understanding about dampers and their functioning and anatomy. Work began by collecting empirical data at different velocities for a number of different settings, with a dynamometer. Because of the number of possible settings and the time elapse when collecting data, all settings were not actually collected. Most of them were instead calculated mathematically from the collected data. This resulted in data consisting of forces and velocities for a great number of damper settings. Both internal (when hardware in the damper is changed) and external (when changes are made to the hardware). When the data collection and the calculations were done, the software program itself was created with Microsoft Excel and Microsoft Visual Basic. The software lets the user select a damper type and its settings and then plot a graph that corresponds to the damper curve that would be obtained in a real testing rig. The results of the project was a working setting bank that can plot damper curves for a number of Öhlins damper models, by using the collected and calculated data. To increase the accuracy of the curves towards reference data, future studies might need to be performed which uses even better mathematical models and considers flow resistance in the damper.