The Altair GUI Toolkit is a resource tool for coding Tcl/Tk dialogs. It contains documentation of the HyperWorks commands, demo pages that illustrate our Altair GUI standards, and sample code for creating those examples.
The Model Identification Tool, known as HyperWorks, is a profile in HyperGraph for fitting test data from frequency- and amplitude-dependent bushings to analytical models. The HyperWorks operates in conjunction with HyperGraph, MotionView and MotionSolve to provide you with a comprehensive solution for modeling and analysis.
The Altair Bushing Model is a library of sophisticated, frequency- and amplitude-dependent bushing models that you can use for
accurate vehicle dynamics, durability and NVH simulations. The Altair Bushing Model supports both rubber bushings and hydromounts.
This section provides information about using the Altair Bushing Model, also known as AutoBushFD, with MotionView. The Altair Bushing Model is a sophisticated model that you can use to simulate the behavior of bushings in vehicle
dynamics, durability and NVH simulations.
The bodies connected by the bushing are flexible and may deflect under the load being transmitted. This phenomenon
is modeled with the Mount Stiffness feature. Mount stiffness models the structural stiffness of the bodies, thus mounting
the bushing as a linear spring and damper in series with the bushing in each direction.
The Altair Bushing Model includes a Mount Limits feature, which lets you model the material contact that occurs between
the bodies that a bushing connects. The bodies are flexible and may deflect under the load being transmitted. Given
enough bushing deflection, the bodies may contact one another for negative and positive deflections in each
direction.
This section describes how preloads, offsets and scales enter into bushing force computations. You use Preloads, Offsets
and Scales to alter the operating point of a bushing. You can offset the bushing displacement in any direction, and
scale the input displacement and velocity. You can also offset the bushing force in any direction by adding
a preload or scale-output force or moment in any direction.
Coupling refers to the forces and moments generated in a bushing to oppose the overall deformation of the bushing.
These forces and moments are independent of any coordinate system that might be used to measure the deformation or
deformation velocity. Coupling is an important factor when the bushing characteristics are non-linear.
The System Performance Data file, *.spd, contains the test data used for fitting a bushing. This data should be validated to ensure that it is physically
meaningful. One test for physical consistency is that the dynamic stiffness at any amplitude of vibration must always
be greater than the static stiffness at the same amplitude.
HgTrans translates solver results files from their native file format to Altair Binary Format (ABF). This can be done using
the HgTrans GUI or via the HgTrans batch mode.
The HyperWorks Automation Toolkit (HWAT) is a collection of functions and widgets that allows an application to quickly assemble
HyperWorks automations with minimal effort and maximum portability.
HyperWorks Verification and Validation Harness (HVVH) is a tool that can be used to verify and validate HyperWorks products. End users can use this tool to quickly evaluate the software quality, performance, reliability,
scalability, and robustness, and to gain more confidence in HyperWorks products.
Uninstall HyperWorks is a tool to launch the HyperWorks uninstallation program. This program contains two options that allow you to either remove the originally installed
files, or remove all the files that resides in the installation directory.
The Model Identification Tool, known as HyperWorks, is a profile in HyperGraph for fitting test data from frequency- and amplitude-dependent bushings to analytical models. The HyperWorks operates in conjunction with HyperGraph, MotionView and MotionSolve to provide you with a comprehensive solution for modeling and analysis.
The following image shows a cross-section of a typical hydromount:
At low displacement amplitudes, fluid in the upper chamber simply deflects the
decoupler. The hydromount behaves just like a rubber bushing. As the input
displacement increases, the fluid in the upper chamber flows into the lower chamber.
With increasing displacement, fluid effects start to dominate and the behavior of
the hydromount changes dramatically.
The hydromount model therefore consists of two components: a rubber model and a fluid
model. The total response of the hydromount is the sum of the rubber and the fluid
effects. A cubic step function gradually turns on the fluid effects, so that
transition from rubber behavior to full hydromount behavior is handled correctly.
The following figure shows an equivalent mechanical model for the hydromount:
The governing equations for the hydromount model are as follows:
Inputs
X is the input displacement provided to the bushing.
R is the cutoff frequency associated with a first order
filter.
The filter removes the steady state deformation of the bushing and passes
only the transient portion of the input, x, to the
dynamic models. The full input, X, is channeled to the
static model.
Outputs
The total force generated by the bushing is the sum of three forces:
The force due to the fluid behavior,
, which is turned on
gradually.
The force due to deformation in the rubber component,
.
The static force at the operating point, which is computed from the static
spline that is provided.
is a design parameter that defines the
deformation at which the fluid force transition begins.
is a design parameter that defines the
deformation at which the fluid force transition ends.
Quite often, the test data for a hydromount does not capture the transition from pure
rubber to full hydromount behavior. and are therefore not fitted, and are available for you
to modify in the .gbs. The default values of and are such that the STEP function always returns
1.0.
For the fluid equations in the center:
z is an internal state representing fluid motion.
represents the equivalent fluid
mass.
is the coupling stiffness between
rubber and fluid.
is the coupling damping between
rubber and fluid.
is the fluid damping.
and
model the amplitude dependence in the fluid equations.
is the effective fluid stiffness in
the bushing.
is the effective fluid damping in
the bushing.
For the rubber equations in the center:
y and w are the internal states of the
bushing.
and
represent the bushing stiffness.
is used to control the stiffness at
large velocities.
produces the roll-off observed in the experimental data at
low velocities.
accounts for the relaxation of the bushing impact force.
represents the viscous damping observed at large
velocities.
and
model the amplitude dependence in the rubber equations.
K is the effective stiffness of the bushing.
C is the effective damping of the bushing.
For the static equations on the right:
Spline (X) is the static force response of the bushing.
Filter implementation, multiple preload support, and the use of RMIN are exactly the
same as for the rubber bushing.