Visualize Results - Animation and Request Plots

MotionSolve provides you with simulation results in multiple file formats. These files can be plotted and animated to create rich visualizations of simulations results. This enables you to:
  1. Easily grasp the physical phenomena.
  2. Quickly detect errors.
  3. Create compelling presentations.

These images illustrate the Altair HyperWorks powerful tools for visualizing the results of multibody simulations in the form of 2D and 3D plots and animations.

Plots

Plots are essential for obtaining detailed information regarding system behavior as well as for subsequent engineering calculations, such as filtering.

MotionSolve creates the following three file types for plotting:
  1. Altair Binary Format (ABF): This binary file is optimized for fast plotting of very large data sets. This is the recommended format for plotting.
  2. Multibody Results File (MRF): The primary purpose of this binary file is to provide part displacement data to the post-processor module that creates the H3D file used for animation. The H3D file format is discussed later in this document. The MRF file can also be used to create plots. However, the performance may be slower than the ABF file.
  3. Plot File (PLT): This is an ASCII file that can be plotted using HyperGraph. The primary purpose of this file is to facilitate load transfers from MotionSolve to FEA software, such as Nastran and OptiStruct, for durability simulation, using the Load Summary utility available in MotionView.

The MRF and ABF files contain, by default, the displacement time histories of all parts and certain other information as shown in the table below:

Table 1. Default Contents in the ABF and MRF Files
Type Component Description
Rigid Body X, Y, Z Position
E0, E1, E2, E3 Orientation in Euler parameters.
VM, VX, VY, VZ Magnitude and X, Y, Z components of velocity.
WM, WX, WY, WZ Magnitude and X, Y, Z components of angular velocity of the principle inertia axes.
ACCM, ACCX, ACCY, ACCZ Magnitude and X, Y, Z components of acceleration.
WDTM, WDTX, WDTY, WDTZ Magnitude and X, Y, Z components of angular acceleration of the principle inertia axes.
Flex Body X, Y, Z Position
E0, E1, E2, E3 Orientation in Euler parameters.
Q/i, i = 1, 2, ..., n Modal participation factors.
QD/i, i = 1, 2, ..., n Modal velocities. These are written to the output file when the attribute FLEX_VEL_ACC_OUTPUT is set to TRUE in Output: Results
VM, VX, VY, VZ Magnitude and X, Y, Z components of velocity. These are written to the output file when the attribute FLEX_VEL_ACC_OUTPUT is set to TRUE in Output: Results
QDD/i, i = 1, 2, ..., n Modal accelerations. These are written to the output file when the attribute FLEX_VEL_ACC_OUTPUT is set to TRUE in Output: Results
  ACCM, ACCX, ACCY, ACCZ Magnitude and X, Y, Z components of acceleration. These are written to the output file when the attribute FLEX_VEL_ACC_OUTPUT is set to TRUE in Output: Results
  SE Strain Energy.
System KE Kinetic energy.
CPU Usage Total CPU time used.
CPU/Sim. Time Ratio The ratio between the total CPU time used and the simulation time.
Stepsize Actual step size used in the integration.
Integration Order Order of the integrator used in the integration.
Using the Post_Request element, you can request the solver to generate almost any signal from your system. Such requested signals are written to all three file formats: ABF, MRF, and PLT. You may use the Post_Request element in the following three ways:
  1. Using built-in types for commonly requested data, such as displacement, velocity, and acceleration, as well as forces on bodies and joints.
  2. Using the MotionSolve expressions. For example, DM(1, 2) returns the distance between the origins of two markers with identifiers 1 and 2.
  3. Using user-defined subroutines in C/C++, Fortran, or Python.

Refer to the Post: Output Request topic in the XML Format Reference Guide for details.

When one of these files is loaded in HyperGraph, the data is automatically organized under three separate categories: Type, Request, and Component. Valid types include Displacement, Velocity, Acceleration, Force and User-Defined. Your model may have one or more requests of each type. All of them are listed under the Request column. When you select a particular request from the list, all available components are displayed in the Component column, as shown in the image below. Please refer to the HyperGraph User's Guide for more details on HyperGraph usage.


Figure 1.

An example of organizing plot data into Type, Request and Component categories.

The following table displays the pre-defined components for each request type.

Table 2. Request Types Available in the ABF, MRF and PLT Files
Type Component Description
Marker Displacement DM, DX, DY, DZ Magnitude and X, Y, Z components of displacement.
E0, E1, E2, E3 Orientation in Euler parameters.
  PSI, THETA, PHI or YAW, PITCH, ROLL angles Orientation of the principle inertia axes expressed in either Euler Angles (B313) or YAW, PITCH, ROLL angles. The choice is made by specifying the ANGLE_TYPE attribute in the Output: Results command.
Marker Velocity VM, VX, VY, VZ Magnitude and X, Y, Z components of velocity.
WM, WX, WY, WZ Magnitude and X, Y, Z components of angular velocity of the principle inertia axes.
Marker Acceleration ACCM, ACCX, ACCY, ACCZ Magnitude and X, Y, Z components of acceleration.
WDTM, WDTX, WDTY, WDTZ Magnitude and X, Y, Z components of angular acceleration of the principle inertia axes.
Marker Force FM, FX, FY, FZ Magnitude and X, Y, Z components of force.
TM, TX, TY, TZ Magnitude and X, Y, Z components of torque.
Expressions F1, F2, ..., F8 Vectors containing evaluated expressions.

In addition to the above, when you request a linear analysis, MotionSolve writes out a *_linz.mrf file that contains results from the linear analysis. These are described below:

Type Component Description
Eigenvalue real part Real part of the eigenvalue
imag part Imaginary part of the eigenvalue
freq (cycle) Imaginary part of the eigenvalue (expressed in cycles per second).

freq = (imag part) / 2*PI

damping ratio Damping ratio for each eigenvalue
natural freq Natural frequency for each eigenvalue
Body Eigenvector dx.real, dy.real, dz.real Real part of the eigenvector for each body in the system
dx.imag, dy.imag, dz.imag Imaginary part of the eigenvector for each body in the system
% distribution of Kinetic Energy X, Y, Z Modal KE distribution in the translational directions for each supported part
RXX, RYY, RZZ Modal KE distribution in the rotational directions for each supported part
RXY, RXZ, RYZ Modal KE distribution in the cross-rotational directions for each supported part
% distribution of Strain Energy X, Y, Z Modal SE distribution in the translational directions for each supported part
RX, RY, RZ Modal SE distribution in the rotational directions for each supported part
% distribution of Dissipative Energy X, Y, Z Modal DE distribution in the translational directions for each supported part
RX, RY, RZ Modal DE distribution in the rotational directions for each supported part
The Frequency response analysis results, containing all output requests of type Marker_Displacement, Marker_Velocity, Marker_Acceleration, and Marker_Force for every FrequencyInput over the specified frequency, are saved to the file _frf.mrf.
Type Component Description
Body X mag, Y mag, Z mag, WX mag, WY mag, WZ mag Magnitude of frequency response in each direction.
X phase, Y phase, Z phase, WX phase, WY phase, WZ phase Phase of frequency response in each direction.
FlexBody X mag, Y mag, Z mag, WX mag, WY mag, WZ mag Magnitude of frequency response in each direction.
X phase, Y phase, Z phase, WX phase, WY phase, WZ phase Phase of frequency response in each direction.
Q/i mag, i = 1, 2, ..., n Magnitude of frequency response of each mode.
Q/i phase, i = 1, 2, ..., n Phase of frequency response of each mode.
Marker Displacement X mag, Y mag, Z mag, WX mag, WY mag, WZ mag Magnitude of frequency response in each direction.
X phase, Y phase, Z phase, WX phase, WY phase, WZ phase Phase of frequency response in each direction.
Marker Velocity X mag, Y mag, Z mag, WX mag, WY mag, WZ mag Magnitude of frequency response in each direction.
X phase, Y phase, Z phase, WX phase, WY phase, WZ phase Phase of frequency response in each direction.
Marker Acceleration X mag, Y mag, Z mag, WX mag, WY mag, WZ mag Magnitude of frequency response in each direction.
X phase, Y phase, Z phase, WX phase, WY phase, WZ phase Phase of frequency response in each direction.
Marker Force X mag, Y mag, Z mag, WX mag, WY mag, WZ mag Magnitude of frequency response in each direction.
X phase, Y phase, Z phase, WX phase, WY phase, WZ phase Phase of frequency response in each direction.


Figure 2. An example of organizing plot data into Type, Request, and Component categories.


Figure 3. Frequency response plot

Animation

Animations not only provide a quick way to check for errors, they also help create compelling presentations to communicate your results to a wide audience.

MotionSolve creates the following two file types for animation, based on your selected simulation type. The H3D file is used to animate static, quasi-static, linear, and transient simulation results. The H3D file contains both the graphics as well as the results information.

MotionSolve writes the complex nodal displacement to H3D in the _linz.h3d file, HyperView performs modal animation, and you can leverage the features of the NVH Director.

MotionSolve writes the frequency response analysis results to H3D in the _frf.h3d file.

The H3D file format provides the following benefits:
  1. Compact file size with additional compression options
  2. Fast animation
  3. Single format for sharing engineering animation results from finite element as well as multibody dynamics software
  4. H3D files may be animated using the stand alone HyperView Player

You may use the Post_Graphic modeling element to add graphics to visualize the elements in your models. Below is a summary of the different types of graphics available in MotionSolve. For details, see Post: Graphic in the MotionSolve XML Format Reference Guide.

Rigid Bodies

You can choose from the following types of graphics to visualize rigid bodies:

ArcFromRadius

ArcFromRM

BoxDefinedFromCenter

 BoxDefinedFromCorner

CircleFromRadius

CircleFromRM

 Cylinder

Ellipsoid

Frustum

 Plane

Sphere

TriaMesh

Parasolid

Note that these graphics are useful for visualization and contact only. They do not affect the mass and inertia properties. For example, when you use a box graphic to visualize a body, its mass and moments of inertia are not calculated based on the box geometry and material properties.

Forces and Moments

When your model includes a Post_Request element of type MARKER_FORCE asking for one or more forces and moments, MotionSolve automatically writes information to the H3D file that allows you to animate them as vectors as shown in the image below:


Figure 4. Animating Force Vectors

Outline

This graphic type draws an outline connecting the origins of markers that are attached to multiple bodies.


Figure 5. Outline Graphic Connecting Four Spherical Bodies

Flexible Bodies

All the information related to flexible bodies (both CMS linear flexible bodies and NLFE bodies) is written to the H3D file, which provides a compact format to store animation data. You may load the H3D file into HyperView to visualize the flexible body results using the following three approaches:
  1. Contour plots


    Figure 6. Result Contours for CMS Flexible Control Arms for a SLA Suspension Model


    Figure 7. Result Contours for an NLFE Stabilizer Bar in a Front Suspension Model

    You may contour results of various types including displacements, rotation (CMS only), velocity (CMS only), acceleration (CMS only), strain, and stress. For strain and stress, you must request the corresponding modes to be computed during the component mode synthesis solution for a CMS flexible component; for an NLFE body, these are written to the H3D by default.

    Note: The NLFE element results are always written in NODAL format whereas the CMS flexible results can be written in NODAL or MODAL format (this is controlled by the FORMAT_OPTION) attribute in the H3DOutput command statement.
  2. Vector plots


    Figure 8. Displacement Vectors for an NLFE Beam Superimposed on the Stress Contour Plot

    You may create vector plots of the following data types: displacement, velocity (CMS only), acceleration (CMS only), force (CMS only), and moment (torque, CMS only). The vectors may be resolved in a variety of coordinate systems. Scaling and querying are also supported. The vector plots can also be overlaid over the stress contour plots.

  3. Tensor plots


    Figure 9. Stress Tensors for a Control Arm in an SLA Suspension

    You may create tensor plots to visualize tensor quantities such as stress and strain. Two formats are available - Principal or Component. The tensors may be resolved in a variety of coordinates systems. Nodal averaging is also supported.

    For all these visualization approaches, displacements and deformations are available by default, while stresses and strains must be requested during the component mode synthesis (CMS) solution.

    For the NLFE bodies, displacements, stresses and strain information is written by default to the H3D.

3D Rigid Body Contact

During a simulation that contains rigid body contact elements, MotionSolve computes a number of contact related quantities like normal force, friction force, slip velocities etc. These are written to the H3D after the simulation so that they can be visualized in HyperView.

There are three types of contact-specific results that may be visualized in HyperView:
  1. Contact summary frame:
    The contact summary frame is a single frame in HyperView which allows you to visualize the maximum penetrations that occurred in your 3D geometries over the length of the entire simulation. A sample contact summary frame is shown below (in exploded view).


    Figure 10. Contact Summary Frame for Bevel Gears in Contact

    MotionSolve writes an additional load case, called “Contact Overview” to the animation H3D file when the model contains active 3D rigid body contact(s). Within this load case, you can create a contour plot defined by maximum penetration depth.

    The summary frame allows you to quickly check for excessive penetrations in your simulation before animating it. It can also be used to assess whether the areas where contact occurred are as expected. For more information on the contact summary frame, please see the Post-processing section in MV-1010: 3D Mesh-to-Mesh Contact Simulation.

  2. Vector plots:
    You may also use vector plots to display contact forces and velocities. In addition to the total contact force, you can visualize several other results including contact friction force:


    Figure 11. Contact Related Vector Plot Results


    Figure 12. Normal Contact Force for a Constant Velocity Joint Geometry

    You can plot these vectors for each triangular element on the rigid body or for a contact region.

  3. Contour plots:
    You may also use vector plots to display contact forces and velocities. In addition to the total contact force, you can visualize several other results including contact friction force:
    • Contact force (including normal and friction force)
    • Contact velocity (including normal and tangential velocities)
    • Contact penetration depth


    Figure 13. Total Contact Force Contour for a Constant Velocity Joint Geometry

Linear Modes

Linear modes animation is available in two formats that you can visualize in HyperView:
  1. MotionSolve computes and writes the displacements for each mode as transient results from 0 to 360 degrees from complex results in the *..h3d file.
  2. MotionSolve writes the complex nodal displacement to H3D in the _linz.h3d file, and HyperView performs the modal animation.
    Figure 14. Linear results from H3D results


    Figure 15. Linear results from Linz H3D