426
A. Prokop et al.
conditions. Also, at transmission, the gear shift significantly affects the passenger’s
comfort. This phenomenon is also solved for electric vehicles [1], where the overall
sound pressure level of the key sources is significantly lower. At manual transmission,
the driver is responsible for the shifting smoothness, in case of automatic transmission this role is moved to gearbox development team. The setting of clutch activation
and deactivation at direct shift gearbox can be modelled and debugged by using
numerical simulation and afterward by testing at test rig or at whole car prototype.
During the developing phase, several modifications are investigated, but the prototype
parts are very expensive; thus the experimental approach is dominantly used only
for final modification to verify the required parameters. This leads to placing high
demands on used numerical simulations. On the other side, the numerical approach
and the numerical model have to be validated to be able to use it several times.
For that reason, it is appropriate to use the simplified structure first to minimize
possibilities of inaccuracies, decrease time and costs demands. The used numerical
approach for prediction of dynamic behaviour is developed and validated on the
single-stage gearbox, the detail about the whole development process and validation of this numerical approach is described in [2]. Several sensitivity studies were
performed afterward.
2 Methods
The determination of dynamic behaviour can be done by three different levels of
modelling. The modal analysis is widely used at concept design to find all potential critical operation modes. The second level, the harmonic analysis, is mostly
used when the character of excitation is known. Based on the excitation in a given
frequency range the optimization of design can be performed. To determine the
dynamic behaviour of gearboxes at transition state can be simulated by multibody
simulation. Because the accuracy of this simulation depends on the accuracy of all
inputs data, the modal analysis and harmonic analysis should be also performed.
2.1 Modal Analysis
The modal analysis of gearbox was performed in frequency range 0 ÷ 3000 Hz,
which is typical for such applications, the similar frequency range is used for truck
transmission in [3]. The results of numerical simulations and technical experiments
were compared. The difference in eigen frequency is up to 4%. The results are shown
in Fig. 1.
The highest level of numerical model consists of gearbox with other surrounding
components, which can affect modal properties. For that reason, the modal analysis
of whole complex structure was performed, and the Craig Bampton modal reduction
was used to create flexible bodies for the next analysis.
A. Prokop et al.
conditions. Also, at transmission, the gear shift significantly affects the passenger’s
comfort. This phenomenon is also solved for electric vehicles [1], where the overall
sound pressure level of the key sources is significantly lower. At manual transmission,
the driver is responsible for the shifting smoothness, in case of automatic transmission this role is moved to gearbox development team. The setting of clutch activation
and deactivation at direct shift gearbox can be modelled and debugged by using
numerical simulation and afterward by testing at test rig or at whole car prototype.
During the developing phase, several modifications are investigated, but the prototype
parts are very expensive; thus the experimental approach is dominantly used only
for final modification to verify the required parameters. This leads to placing high
demands on used numerical simulations. On the other side, the numerical approach
and the numerical model have to be validated to be able to use it several times.
For that reason, it is appropriate to use the simplified structure first to minimize
possibilities of inaccuracies, decrease time and costs demands. The used numerical
approach for prediction of dynamic behaviour is developed and validated on the
single-stage gearbox, the detail about the whole development process and validation of this numerical approach is described in [2]. Several sensitivity studies were
performed afterward.
2 Methods
The determination of dynamic behaviour can be done by three different levels of
modelling. The modal analysis is widely used at concept design to find all potential critical operation modes. The second level, the harmonic analysis, is mostly
used when the character of excitation is known. Based on the excitation in a given
frequency range the optimization of design can be performed. To determine the
dynamic behaviour of gearboxes at transition state can be simulated by multibody
simulation. Because the accuracy of this simulation depends on the accuracy of all
inputs data, the modal analysis and harmonic analysis should be also performed.
2.1 Modal Analysis
The modal analysis of gearbox was performed in frequency range 0 ÷ 3000 Hz,
which is typical for such applications, the similar frequency range is used for truck
transmission in [3]. The results of numerical simulations and technical experiments
were compared. The difference in eigen frequency is up to 4%. The results are shown
in Fig. 1.
The highest level of numerical model consists of gearbox with other surrounding
components, which can affect modal properties. For that reason, the modal analysis
of whole complex structure was performed, and the Craig Bampton modal reduction
was used to create flexible bodies for the next analysis.