High performance car design - Driving dynamics performance

The following document was written following a really formative engagement with Danisi Engineering S.r.l. in Nichelino (TO). This company is a well-known business in the automobile industry for its function as an engineering provider and supplier of prototype automotive solutions. The purpose of this thesis is to investigate the impact of typical tolerance chains in component manufacturing on the suspension's Kinematics & Compliance and then, the overall vehicle behaviour. The impact of positioning and assembly tolerances of frame and upright attachments, as well as the processing tolerances of suspension links, has been taken into account into this project. A sensitivity study was performed to determine how an individual tolerance in a single component impacts the suspension's elastokinematic metrics, by maintaining the location of other points constant. Then, methods for merging these limits were examined. Simulations are made feasible by using the Adams Car program, which is owned by Hexagon: it includes a robust multi-body analysis solver, designed exclusively for the automobile industry. The huge number of simulations necessary for the thesis aim needed the creation of a dedicated tool capable of automating the entire process. The document will provide a detailed description of the code created in MATLAB using the App Design toolkit. A step of analysing the combined impacts of tolerances has been completed, including the entire vehicle using objective measures in the VI - Car Real Time environment. The model was subjected to typical manoeuvres to investigate its dynamic behaviour, and objective metrics were evaluated using the Dynamic Simulator with professional drivers. Following that, a study was conducted to define the acceptable limits more clearly for the most essential kinematic measures, notably "Bump steer", "Camber Gain", and "Roll Centre Height Variation". It was suitable to adjust these metrics separately by using coefficients related to these kinematic measures. For every change it was created a single variation of the same car: all of these have been tested from Danisi Engineering professional drivers, in order to determine which of these vehicles has little or no difference from the baseline. In this way we discovered kinematic metric limits to identify potential future tolerance issues. So, if a metric will exceeds the project limit, there will be a high probability the driver will feel a different vehicle from the baseline. By doing so, a company methodology was derived to correlate the variations in the kinematic metrics parameters with the subjective marks of the various drivers. Furthermore, it was intended to establish a link between objective and subjective analysis, setting thresholds beyond which the driver would most likely begin to feel a difference in the vehicle.