Best Of
Community Champion of the Month - June, 2025
The Community Team would like to introduce the June Champion of the Month, Andreas Altmann @AndreasAltmann.
Andreas works as a Senior Specialist Development CAE at thyssenkrupp Automotive Technology. His work covers a wide range of simulation topics, including NVH, stiffness, strength, crash, and optimization. “I’m particularly passionate about automating and standardizing simulation processes, and over time, I’ve extended this focus to include the automation and standardization of our CAE workflows - both using Altair products and other solutions.”
He primarily uses Altair HyperMesh, HyperView, and OptiStruct. “What I appreciate most about Altair products is how flexible and customizable they are – they adapt perfectly to our workflows, which makes them incredibly powerful and versatile.”
With the help of the Altair support team, Andreas and his team were able to develop a link between Altair’s mesh library and the encoded shapes functionality. This integration allows identification of identical parts even when they have different naming conventions, and to detect very similar geometries that can be used as a starting point for further shell meshing. This has significantly improved the efficiency and consistency of his team’s meshing workflows.
“I really value the fast and helpful support from Altair, and that’s why I’m happy to give back by helping others in the Community whenever I can. I know how challenging it can be when you’re stuck, and I’m glad to contribute where possible.”
In his free time, Andreas enjoys spending time with his family and hiking in the mountains.
Please join the Community team in congratulating Andreas @AndreasAltmann and thanking him for his willingness to collaborate with the Altair support team and share his knowledge and expertise with other members of the Community.
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Is there a fellow Community member you feel deserves to be recognized as next month's Community champion? Let us know who they are and why you feel they exhibit the qualities of a leader by emailing us at community@Altair .com. You can also learn more about the Community Champion of the Month program here Monthly Community Champion.
element normals directions reverse difficulty
Not a question.
Just an answer.
2D - Normals - reverse & adjust : difficulty.
When this function doesn't function, perhaps try to
copy-paste the tricky elements into a new empty component,
delete the tricky elements
reverse the normals of the new elements in the new component
organise the elements back into the original component
equivalence
check the element normal directions …

Re: Is it not possible to import SimLab mesh(.gda) in HyperMesh?
i beleive .gda is a binary file and for now cannot be imported directly. you should export solver deck from SimLab and then import it inside HM.
Re: Flow separation on Ahmed Body 25º slant
Hi Gabriel,
I was expecting the flow to be attached around the slant of the model like in this case https://help.sim-flow.com/validation/ahmed-body.
I did everything you said to improve my simulations, refined mesh upstream and aimed for an y+ below 5 with 25 layers (don't know if its too much, its what my calculations led me to).
Paused my simulation at 23 iterations to check if I already had the structures I seeked and the flow stays attached now.
Thank you for your help and apologies for taking me a month to respond :)

Re: Flow separation on Ahmed Body 25º slant
Hi @Arnau,
Just for my understanding, where you are not expecting flow to be attached and where to be separated?
Maybe to improve your model you can look into the following leads:
1) The Boundary layer on the ground in front of the Ahmed body seems weird. Are you sure it is slip condition? Can you also refined further upstream as well.
2) You are using K-Omega, and the surface Y+ is high wall y+, K-Omega is better with a low wall y+ treatment. Can you try to increase the number of boundary mesh layers to 12 layers with an aimed y+ below 5?
With those changes you might have a better resolved wall interaction.
Many thanks,
Gabriel

Optimizing Tractor-Implement Systems with MotionSolve and EDEM
Introduction
Effective tractor-implement systems are necessary for cultivating healthy crops. Traditionally, improving tractor-implement performance has relied on field testing – a process which is time-consuming, weather-dependent, and costly. In this article, we explore how MotionSolve (Multibody Dynamics) and EDEM (Discrete Element Method) enable engineers to simulate the performance of tractors and their implements, serving as a powerful alternative to field testing. Critical performance metrics such as drawbar pull, wheel slip, soil compaction, and tractive efficiency can all be predicted in a virtual environment allowing engineers to make informed decisions.
Draft Force – The force required to pull the implement (e.g. Disk harrow) through the soil. This directly informs engine power requirements and fuel consumption.
Drawbar Pull – The maximum force available to the tractor at the hitch for pulling implements and towing.
Wheel Slip – The ratio of ideal vehicle velocity to actual vehicle velocity resulting from a loss of traction. Wheel slip is related to efficiency and can indicate soil damage.
Soil Compaction – EDEM simulates the interaction of the tires and any implements with the soil, showing how the particles are compacted. Excess compaction degrades the soil making compaction an important indicator of performance.
Tractive Efficiency – A measure of the engine power converted to useful work calculated as the ratio of drawbar power to wheel input power. A valuable metric indicating the efficiency of the system with greater tractive efficiencies indicating a tractor requires less fuel for a given task.
Simulation is particularly valuable for performing virtual prototyping. The tractor or implement design can be modified and analyzed in a simulated environment to provide rapid insights without the cost and time associated with building prototypes. This allows engineers to tweak implement design, simulate performance, and measure outcomes leading to rapid iteration towards an optimal design that meets all requirements.
Beyond rapid prototyping, simulation allows engineers to simulate a wide range of conditions to understand performance in all situations. For example, new soil models can be tested to simulate different soil conditions like dry gravel or wet clay. Engineers can use these simulations to identify potential scenarios where the tractor does not meet requirements and then modify the design to improve performance. Finally, simulation has the added benefit of providing quantitative information in areas where it is difficult or impossible to measure in the field. This aids engineers as they make comparisons between different designs, allowing decisions to be based on data.
The Multibody Dynamics Model
The multibody dynamics model captures the dynamics of the system. The model is created following a standard process.
- CAD of the tractor and implements are imported into MotionView.
- Bodies are created for each of the CAD graphics.
- Points and joints are created to connect each of the bodies.
- Motions and forces are applied to joints to drive the system.
- Tire models are added where necessary to accurately simulate the interaction with the ground.
This model was built to be modular. The implement, a disc harrow, was built as its own system which can be enabled/disabled with a click. Users can import new implements and connect them to the tractor. This enables users to evaluate the performance of multiple implements with one tractor model.
Alternatively, the implement systems can be exported to new MBD models and hooked up to different tractors with a few clicks. This allows users to quickly explore the performance of an implement with different tractors.
The Discrete Element Method Model
The Discrete Element Model (DEM) handles the tractor/soil and implement/soil interactions. The first portion of the process requires defining material models based on the required application. EDEM includes the generic EDEM material model (GEMM) library which simplifies the material creation process. The library addresses one of the greatest challenges with bulk material simulations, defining an accurate material for realistic particle interactions. The library contains thousands of models for soils, rocks, and ores suited for applications at various scales in the construction, mining, and agricultural industries.
Once a material model is defined, the material can be created using a material factory. Then, the tractor and implement geometry can be imported into EDEM by enabling the coupling server in EDEM and using the EDEM tool in MotionView. After importing the geometry, materials should be defined for each component of the tractor which will interact with the bulk material. Materials which don’t interact can be set to virtual to speed up the simulation.
The Traction Controller
The tractor’s controls are modeled using Twin Activate, a tool for modeling and analyzing multidomain dynamic systems using a block diagram interface. The controller receives the error between the target velocity and actual velocity from the tractor MBD model. Then, feedforward and feedback PID controllers compute the engine torque which will minimize error. Additional features, including saturation limits to represent physical limitations in velocity of the engine, are incorporated in the model to increase fidelity.
Software Requirements
Model Files
Running the Model
Disk Harrow
- Open the Tractor_Model.mdl in MotionView.
- Open Tractor_Soil.dem in EDEM.
- Enable the coupling server in EDEM.
- Run the analysis in MotionView.
Results
Disk Harrow
The tractor requires a draft force of approximately 1500 N to pull the disk harrow through the soil. The draft force increases as the CG is moved rearward. This is expected as the vehicle has more traction on the rear, driven wheels allowing the velocity controller to apply more force to the implement throughout the vehicle’s acceleration.
The tractive efficiency of the tractor is the ratio of the drawbar power to the power produced by the engine at the drive axle. The simulation shows the tractor has a tractive efficiency of approximately 30%. The tractive efficiency or ratio of drawbar power to engine power increases as the CG is moved rearward. This is expected as the vehicle has lower slip and fewer losses with more traction on the driven wheels.
The wheel slip shown is the average slip of the rear wheels. As the center of gravity of the tractor body is shifted rearward, the initial wheel slip decreases. Once the tractor reaches a constant acceleration, the wheel slip is approximately equal between different CG locations. The tractor’s wheel slip is approximately 10%. Slip is a measure of the relative motion between the tire and the ground. High slip or lots of relative motion means the tire is sliding across the ground, which could potentially damage the soil. The low wheel slip is ideal, because it reduces the chance damage occurs to the soil.
Conclusion
Simulation is a powerful tool to complement field testing for understanding tractor-implement performance. A virtual environment enables quick design studies, a process which would be costly and time-consuming with physical prototyping. Key performance indicators including wheel slip, tractive efficiency, drawbar pull, and draft force can all be pulled from the model to understand the holistic performance of a tractor-implement system, allowing engineers to make informed design decisions.
Authors
John Dagg, Systems Engineering Intern
Original Model Authors
Stefanos Stathis, Systems Integration Team
Livio Mariano, Systems Integration Team
Re: "This license was already activated using different hostid"
Your previous license key activation is now deactivated in Altair one, you can now reactivate the student license with the same license key.
Deactivation and reactivation feature is only if a computer breaks down or reformatted and is only allowed a few times per user preprogrammed into the system.
You can deactivate the license from one machine and reactivate in another by yourself if you have access to both machines as per –
Thanks!

Re: Trouble with activation of Student Bundle
Also, Perhaps best to disconnect from the managed licensing,
Please set an environment variable with name ALM_HHWU and value F and let us know if you are able to activate,
You may have to reinstall with admin permissions, i.e. right click and run the exe as an administrator, and make sure you have read and write permissions in the location you are installing etc. and have admin permissions to your computer drives in general.
