Abstract:
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Competition among automotive manufacturers has increased a lot in the recent years. One
of the main concerns regarding the suspension design of a vehicle is its ride comfort and
handling performance characteristics. This thesis aims to create new methodologies for
comfort and handling evaluation as well as to make a brief study regarding the influence that
the characteristics of a damper have over the vehicle behaviour. The thesis is divided into
two parts.
In its first part, this thesis proposes new virtual road scenarios, some of which allow
evaluating simultaneously ride comfort and handling performance during a vehicle dynamics
simulation. These roads are created as a standard CRG format which can be used by
different software in the field of vehicle dynamics.
In its second part, a total of five different scenarios are chosen in order to study the
differences that two different software and two different tyre models have over the results.
Three models are used: Adams Car with FTire, Adams Car with MF-Tyre and CarMaker with
MF-Tyre. Also, some metrics are defined for each scenario in order to compare quantitatively
the results between these three models. Results have shown important differences regarding
the tyre model in the impact scenarios and minor differences regarding the software in all
scenarios except for the primary ride, which provides good accuracy using the simplest
model: CarMaker with MF-Tyre. This configuration also presents much shorter running
simulation time. Basically, the best configuration to carry out the simulation would be Adams
Car with FTire model for all scenarios except for the primary ride, in which CarMaker with
MF-Tyre model could be used too.
Also within the second part, a sensitivity analysis is done. The original spline of the front
damper is converted into a bilinear spline defined by six different parameters, which are
modified at two different levels: 40% lower and higher than baseline. Then, the five scenarios
previously defined are used to study how a certain parameter of the damper spline affects
each metric. Apart from confirming the expected results (a low level of damping is needed to
improve comfort while a high level of damping is needed to improve handling or road
holding), this methodology quantifies and helps finding the optimum compromise between
ride comfort and handling performance of a damper. |