Using Adams Car to obtain transmission loads and Romax Enduro to perform component rating
A durability assessment case study
Since Romax became part of Hexagon’s Manufacturing Intelligence division, we have been exploring potential synergies with other products and technologies.
At present we are at the stage of exploration. Together with other teams in Hexagon we are collecting ideas and use cases for synergies, understanding each other’s technology deeply, exchanging industry knowledge, and testing workflows through worked examples and case studies.
This case study is a result of one of these investigations. It focuses on durability and one of the most important tools for us to consider – MSC Adams. The idea we explored was to run an Adams Car time domain simulation, obtain the transmission loads, use the ‘Generate Load Cases from Recorded Data’ function in Romax to convert the time history into binned load cases and perform some basic durability design and analysis tasks in Romax Enduro.
Adams Car model
A front-wheel driven vehicle is modelled in Adams Car to calculate the input torque to the transmission. The model includes a powertrain with a manual gearbox. The vehicle is operated by the built-in driver model in Adams that can follow a pre-defined path and speed profile. For this case, the vehicle is driving straight with a speed profile defined by the Worldwide Harmonised Light Vehicles Test Procedure (WLTP) – in total 30 minutes of driving. We chose the WLTP since it is a well-known drive cycle and the data is public, but this approach should be applicable to any drive cycle or other loading of the Adams Car model.
The WLTP speed profile was divided into 8 sections, to leave us the flexibility to process these later into multiple duty cycles or combine them together. Each section was simulated in Adams. Here are some results from the high speed section.
Processing the transmission loads
The initial test was to import 1 section of the data into Romax Enduro using the ‘Generate Load Cases from Recorded Data’ feature. This converts the time history data into load cases, binned by the input torque.
We were able to successfully import the data directly from Adams Car into Romax Enduro without any pre-processing and run the analysis. You can see this test in the video below.
Following this initial test, we decided to combine the data in Excel and scale it up inside Romax Enduro so the drive cycle covers 200,000 km to make it more realistic. We used 10 load cases per powerflow and uniform bin-widths. Further tests are planned to investigate the sensitivity to number of load cases per powerflow and bin width settings.
Romax Enduro durability analysis and design changes
With the updated load cases, we carried out some typical tasks in Romax Enduro.
The gear rating showed that the 5th Speed Pinion and Wheel and the Final Drive Pinion gears fail for this duty cycle. Further inspection reveals that the failure is for contact.
Diving deeper into the results for the 5th Speed gear set, we identified that the most damaging load case was ‘5 Load case 09’. Upon inspecting the tooth contact pattern, it was evident that it was not well optimised for this loading condition.
This meant that we could attempt to improve the contact pattern and check if this resolves the failing duty cycle rating. For demonstration purposes, we used simple trial and error, and were able to make the gears pass the duty cycle rating.
In a more realistic scenario, more in-depth optimisation of the gear micro-geometry can be carried out, e.g. using a generic algorithm optimisation, and more metrics can be considered, such as transmission error, micro-geometry based mesh losses, pressure-velocity, etc. However, in this case study we focused on demonstrating the basic workflow, so simple design changes were sufficient.
In addition to gear rating, we also checked the bearing rating and one of the bearings – Brg Input Shaft RH – showed excessive damage over 100%. In a similar fashion to gears, we could easily identify the most damaging load cases, and we could use the capability of Romax Spin to investigate advanced results for these such as raceway contact stress and footprints and try and optimise the bearing geometry.
As a simpler alternative, we replaced the failing bearing with a higher dynamic load capacity variant of the same size bearing from the supplier catalogues available in all Romax products and this significantly reduced the duty cycle damage to an acceptable level.
These were just a couple of examples of design changes we could decide to make based on more realistic duty cycle loads obtained from Adams Car.
Through this exercise we demonstrated that we can obtain transmission loads from Adams and successfully import them into Romax Enduro and convert them from time histories into load cases. We took this one step further to make the example more realistic and processed and scaled the data before performing durability analysis. The duty cycle analysis in Romax Enduro showed some failing components, and we were able to address those failures by changing the gear micro-geometry and selecting a different bearing from the built-in supplier catalogues.
Further work is needed to identify ways to streamline this workflow, investigate the sensitivity to different settings and levels of fidelity, establish best practices, and explore additional use cases for synergies between Adams and Romax for durability analysis such as shock loading.
Aside from durability and Adams, there are many similar parallel activities exploring synergies between Romax and other areas of Hexagon. We are excited by all the possibilities for technological advancements enabled by working closely alongside the broad range of industry-leading solutions within Hexagon.
If you are currently using a workflow between multiple Hexagon products, or if you have an idea of how a workflow between multiple Hexagon products could improve your processes, we’d love to hear from you.
To learn more about Romax and this case study please watch our on-demand presentation here.
Kristian Kouumdjieff joined Romax Technology in 2015 after graduating from the University of Nottingham with a Meng degree in Mechanical Engineering. Kristian is the Product Manager of the Durability and Structural Analysis (Romax Enduro), and Bearing Design and Analysis (Romax Spin) software products.