The main objective of this study is to measure the torsional
stiffness of automotive transmissions. This activity is important
to provide data related to the elasticity of the vehicle powertrain
and contribute to create a national database for this
parameter.
The transmission torsional stiffness value is an input data of
the software Dyfasim that is used to predict (estimate) the
resonances of the vehicle powertrain. This analysis leads to a
better understanding of required design parameter of clutches.
Further, the statistical method Measurement System Evaluation -
MSE was applied in the planning and execution of tests. The MSE
methodology ensures that the bench is robust for variations common
to the usage, such as the influence of the operator, input force
and gear ratio. This step has an important hole in the Model
Verification and Validation '- MVV, methods, because is
possible to quantify the experimental uncertainties and indicate
the necessaries modifications to reach a considerable level of
acceptability.
The methodologies for MSE and MVV were performed in two
different test rigs, in the first setup the torque is applied
through a lever arm using standard weights. The second bench is
improved by the use of a pulley system which has a load cell to
controls the input torque. In both setups strain gages (45°) were
fixed in the input and output shafts to serve more details about
the behavior of the system and to guarantee that the correct load
is applied in the gearbox.
The results show that the second arrangement supplied high level
of precision and repeatability. Thus values found during the job
will be used to build a library and the parameters will be set in
the Dyfasim Software. The following steps should be: measure the
resonances during car operation and validate the software
results.