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Chris Coker

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Everything posted by Chris Coker

  1. These are pretty basic operations in MotionView. If you have not already, I would recommend going through some of the basic tutorials. Other than that, I'm not sure what more detail you need. Chris
  2. Hi Flo- have you tried modifying the integrator settings? Usually when a solution values, you will find a lot of text that will point you in the direction of things to try. For example tighten (or loosen) integrator tolerance. Decrease the maximum step size. Chris
  3. Hi Lokesh- I took a look at your model, but there were not graphics included, so I couldn't test. However, your contact settings look a bit suspect to me. I would suggest looking over the section in our help "Best practices for contact modeling" Your stiffness value is likely too low, and you should use the Advanced option "find precise contact event" On the transient integrator settings, change the max step size from .01 to .001 Best, Chris
  4. 1. You need to type in the values for mass an inertia for each body. Also make sure you correctly define the cg location for each body. You can obtain these values from CAD data, from measuring the physical parts, or estimating them based on previous experience, or using historical data. 2. You can define a curve, that represents the displacement inputs from real world test data, and use that to define the motion, rather than using an expression.
  5. My background is mainly with MotionView. Now that you have successfully exported the loads, you may want to pose your question in the Hypermesh forums to get a better answer with that product. One tip when you export the loads using the Load export utility, you can specify the specific grid ID numbers you wish to apply the loads to. These should be ID's that already exist in the FE model. Kind regards, Chris
  6. Hi Flo- The short answer is yes. 1. First change you need to make is to your outputs. You need to create Force outputs on each Body of interest, not the joints. 2. When you run the your simulation a .meta file will be created (because you have a model with Force Outputs on Bodies) 3. Use the Load Export Utility (instructions in our help) to export the loads of interest. It will need to read in the .meta file created during the run. The utility will export loads in a tabular format, or in a format compatible with Optistruct Chris
  7. Here is a workaround that will override the Altair Driver, get a transient analysis to run, and at least get some results out of the model, to help you for debugging purposes. The process here will insert a Transient simulation command before the Altair Driver code takes over. Step 1, open the .xml solver file written out my MotionView, and scroll to the bottom of the file. Step 2, near the end of the file, you will find commands that look like this: <UserProgramControl usrsub_param_string = "user(6454, 10901010, 30101010,32802100,32802700)" usrsub_dll_name = "msautoutils" usrsub_fnc_name = "RUN_STANDARD_CAR_MODEL" /> Step 3 - Right above this command, insert the following commands: <Simulate analysis_type = "Transient" end_time = "4" print_interval = "0.01" /> <Stop/> Step 4 - Save the file, and run the .xml through motionsolve. To do this from MotionView, you can use the "run panel" but you have to change the option from "Save and run current model" to "Run MotionSolve file" You can then point to the .xml file you just edited. If you don't change this option, MotionView will overwrite the .xml file you just edited. Step 5 - you can then animate results, which can often be helpful in diagnosing the problem with the model.
  8. Two ways you can do this: 1. Create a displacement output on each Gear body. You will get displacements (and rotations) of the body, you could also request velocities, etc. 2. Create a displacement output for the joint that attaches the gear body.
  9. The model failed to reach a static solution, therefore it did not start the transient analysis, so, there are no results to plot. Will need to figure out the issues with the model itself. Chris
  10. Yes, they are Torques. They are resolved in the reference frame used when you created the Output to report that force. It will default to Global if you didn't create a reference frame
  11. I took a brief look at your model. There appear to be multiple fixed joints defined constraining the two parts. This creates and kinematically over-constrained model. The demo models provided previously show show good methods. I would recommend understanding those, and trying to replicate those. Another (simpler) approach would be to create a graphic that is attached to ground, and define 3D contact between the cube and ground. Then the cube will rest of the ground due to the contact. Then you avoid some of the complex things with the templates.
  12. Input the loads per the unit setting in MotionView. The documentation is likely written from a perspective of a "standard" units set that is commonly used traditionally in multibody dynamics (mm, kg, s, N) Note, if you are using the static loads event from the vehicle library task wizard, you may want to check your results carefully. I think this was developed with the assumption of using N as the units of force. Not sure if it will translate correctly if using a different units system for Force. It may, but again, check your results carefully. Chris Coker
  13. Hello Flo- Sequential simulation (like what was in MV-1051) is the normal approach to setting up something like this. Another approach (still using sequential simulation) would be to use forces, rather than joints. Our MotionSolve examples library has some examples that may be of use to you. Take a look at this link: https://altairhyperworks.com/motionsolve-models/ Model MV-04 Robot Arm is probably more complicated that what you are looking for, but should work as a good source for a starting point. Regards, Chris
  14. If you are trying to simulate the loading effects of a tire going through a pot-hole, a simple spring-damper approximation will not give you the correct loading into the suspension. You should be utilizing a proper tire model, or using physical test data collecting using wheel forces transducers, and applying those to the spindles. We have an extensive library of vehicle models built into MotionView. These can be a guide on how to properly set up a model like this. For your question about K&C coefficients for your trailer model....What values do you want to compare with? The purpose of measuring K&C is to evaluate a design vs. some target data, or evalute two different vehicles, etc. Our vehicle libraries are already setup to run K&C analysis. You can likely adapt your model to work with those. Note that starting from CAD data for building a vehicle model is not the most efficient approach. Typically, we encourage users to start with an existing suspension template. Then you can take advantage of the existing events (full vehicle, half-car, K&C, etc) that have already been created. Your existing model will not work with the existing event library without significant modification.
  15. Hi, You can modify your model under Tools -> Options -> Path Management. If you convert the model to use "Relative Path Names", and then keep your graphics, and .csv data in the same folder as the .mdl, then you will not have these issues. Also, you can convert the .csv data from type of "file" to "values", and the .csv will be converted to values that are stored internally. However this doesn't address the graphics, where are always externally referenced, unless you define them using graphic primitives inside MotionView.
  16. 1. You would want to use the Altair Driver for this. If you are using the 2019.1 release, there is a "Road Course Drive" event that should work for your application. I believe the setup/usage is well defined in our help 2. A. A road file developed in ADAMS/Car may not work with MV (actually this is a really a dependency on the tire model you are using, since MotionView (and MotionSolve) only reference the path names to the road files. 2. B. The road files are referenced in the AutoTire statements. These can all be managed in the gui in MotionView. Essentially the same area you define the tire data, you define the road data. By default, they point to a "flat road" file. Note, if you are using a 3D road profile, the tire models usually require additional software licencing. Note: Altair's modified Fiala tire can support the OpenCRG (.crg) format, as well as Polyline road surfaces. One clarification, HTIRE is depreciated and not installed by default with current versions of MotionView (2017 and forward). It does not require a license, but the cosin tools required to run it are not installed by default. We have migrated to MF-Tyre as the default "free" tire. Also, the fiala tire that is available is also free. Chris
  17. If you are using CAD data, and importing it into MotionView, the CG and MOI will be correctly read into MotionView. You can define it several ways, about the part CG, the vehicle CG, or the global CG, or any other location for that matter. Usually, people will define each part's mass, inertia, and CG location relative to the part, because that's how the data/CAD is defined. You don't have to calculate anything, assuming the CAD is correct. Just define your mass, CG, and inertia the way it is defined in your CAD. The tire forces should be described in our help. In general: f2 = Fx f3 = Fy f4 = Fz f6 = Tx .... It's also pretty easy to sort out the directions by plotting them, and observing the behavior of the forces using simple events.
  18. 1. I have changed the end time to 15, yet the simulation goes on only for 6 sec. You changed the end time, not the value in the template. There is likely a templex template (assuming you are not using the Altair Driver). You can change the end time in the template, or the end time inside the Driver event. 2. I have entered the values obtained from Tools>CG\Inertia Summary>Moment of inertia into Model>Data Summary>Bodies and getting this error. Also does adding these values lead to more accurate results? The values in the CG inertia summary are used to provide you a Total values of the overall CG and inertia of the vehicle. It's getting those values from your mass properties, which you are editing in the DataSummary. You are working in a loop, editing the same numbers. The normal process works like this: 1. Mass and CG location exists for each body in the model. Update the mass and CG location for each body to match this data. 2. The CG/inertia summary provides a method to allow to sum up all of the masses and CG locations entered in step 1, and check that the overall vehicle CG and inertias are correct. Usually you will need to only update the vehicle body mass, cg, and inertia, assuming step 1 is correct.
  19. 1. To change the end time of the simulation, you will need to edit the template. To increase the lateral acceleration, you can increase the speed of the vehicle. 2. The lane change is intended to be used with a flat road. If you need to run a non-flat road, you will need to change the road definition file. Note, some tire models are not compatible with non-flat roads, or require additional licensing depending on which tire model you are using. The Altair Driver has a path follower event that will work better for this kind of event, if you need to run something other than a lane change. 3. To change the reference frame to something other than global, when using the CG/Inertia summary, you need to be using HyperWorks version 2019 or later.
  20. The error indicates there is a problem of some sort (maybe incorrectly defined properties for the graphics) As a workaround, you can try deactivating that graphic (id # 90001) that's throwing the error. The removal of the graphic will not affect the physics of the solution.
  21. If the steering wheel is steering in the correct direction (it is unclear in the screen shot), but the road wheels are steering in the wrong direction, then the coupler that defines the steering gear needs to have it's sign changed. This sign convention is usually sorted out when you review the animation from your front suspension K&C analysis. Edit: Upon reviewing the screen shot more closely, it's clear that your steering rack is in front of the wheel centerline. In the default model, the steering rack is positioned behind the rear wheels. This explains why your vehicle is steering in the opposite direction (assuming you did not update the steering coupler sign when you updated hardpoints).
  22. "Collision Detection" is a feature that's only available in post-processing. It allows you to visualize penetrations between different bodies in the mode, AFTER your simulation is completed. When you need to stop (or change) the model as a result of some condition in the model during run time, we use an entity called Sensors. I would encourage you to read up on Sensors in our help, as they are quite powerful, but there are a few things to learn. A simple way to implement a sensor in your case would be for the sensor to monitor the displacement between two bodies (which you would define via an expression). When the displacement reaches some threshold value, you tell the sensor to halt the simulation. Another possible way (I haven't personally tried this), would be to monitor the contact forces between two bodies, assuming you are using 3D contacts in the model. When the contact force is generated, use that to trigger the sensor.
  23. Under Tools -> CG/Inertia summary, MotionView can calculate the overall CG and moment of inertia of your model. It is typically calculated about the origin, but you can calculate it with respect to another reference frame if you need to.
  24. In the screenshot your model, the Altair driver has been included in the model, but no events have been added. You can right click on "Model" in the project browser, and "Add events", then add a Altair Driver File event. The allows you to point to a file that contains the details for the maneuver. The specific details for maneuvers in the Altair Driver are defined via an .adf file. This event allows you to point to your own .adf file which you can customize. You can also search our documentation on the features of the .adf file. Chris
  25. Hi- There are no existing tutorials for this workflow, since it's not a workflow that is common with most users. Usually, CAD is exported with all parts correctly positioned relative to each other. It is possible to relocate CAD once you've imported into MotionView, but it is a manual process, and must be repeated for each part. It will be rather tedious. One way is to define a reference Marker for each part (this also means you need to define a point to define the position of the reference Marker). Then you can change the reference marker for each CAD part from Global, to the new reference marker. Then, each reference marker can be individually positioned manually to re-position the CAD. Others may have better ideas, but this is a method I have used in the past, when I had no other options. Chris
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