Simulation Why Fewer Degrees of Freedom Means More Freedom

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Wuxi InfiMotion Technology Co., Ltd.

If only a small amount of information is relevant for FEM models with countless degrees of freedom, small reduced order models can save time. In this way, Wago has developed a tool with which customers can evaluate connectors themselves using thermoelectric simulations.

If only a little information is relevant for 3D FEM models with 1 million degrees of freedom, they can be exported in small Reduced Order Models (ROM). This saves a lot of time. An example from Wago shows how this works in Ansys—with benefits for many parties involved: both simulation engineers and sales at Wago are relieved because customers evaluate their connectors themselves using thermo-electrical simulations. The tool can be found on the product detail page of the relevant PCB connection technology in the Wago e-shop, where it is initially available for a selection of PCB terminal blocks and connectors.

We had the challenge that our small simulation department had to deal increasingly with inquiries from customers and colleagues from sales and product management in addition to product development.

Wilhelm Rust

"We were faced with the challenge that our small simulation department had to deal increasingly with inquiries from customers and colleagues from sales and product management in addition to product development," says Wilhelm Rust, simulation engineer at Wago, describing the trigger for the project. This is because internal Simulation-as-a-Service services are also based on large 3D FEM models and are correspondingly computationally intensive. A processing time of two weeks was not uncommon.

Three Steps from the Calculation to the E-Shop

The simulation team knew where to start: with the model sizes. Because it also knew which very similar issues many customers have, a reduced model with the customer-relevant electro-thermal properties is now exported from every finished 3D FEM model. This can easily be used for the thermo-electrical evaluation of connectors and terminals—by the product manager, technical support or the customer themselves. Existing simulation knowledge is thus used elsewhere in the product life cycle: at the interface to the individual customer application.

The Wago team thought one step further: the model was further automated, trained and integrated online in the e-shop. Today, customers can now check the suitability of the components completely autonomously, 24/7 and with just a few clicks.

As easy and intuitive as the Ansys models can be used online today, their path from the calculation department to the e-shop was a rocky one. Wago broke new ground with the project, both internally and in the industry. "We started out exploratively," says Wilhelm Rust, describing the approach, "we didn't really know at the beginning how everything would work."

Automated from 3D FEM Model to 1D ROM

For the simulation specialists, the main issue was how to export a suitable reduced model from the 3D FEM model. In an exchange with Cadfem, the special software "Model Reduction inside Ansys", including training, instruction and support, emerged as the solution that would help Wago. This is because Model Reduction inside Ansys ("MORiA") is particularly suitable for thermal, mechanical and thermomechanical issues:

• The solution, which was developed by Cadfem in cooperation with the Steinbeis Transferzentrum Niedersachsen, uses the highly efficient Krylov-based model order reduction in conjunction with a reduction approach from electrical engineering, which uses the inputs and outputs of the system and takes up their relationship, the transfer function.
• With MORiA, the usual 1 million degrees of freedom of thermomechanical, thermoelectric or piezoelectric models in Ansys Mechanical can be automatically reduced to the decisive 100 and used in system simulations.
• The user retains full control over the reduction via an APDL workflow.
• Since ROM models do not allow any conclusions to be drawn about the original complete models, there are no restrictions with regard to IP and data protection issues.

Full Concentration on Thermal Heating

Thanks to the workflow developed with Cadfem, the software now has a firm place in the development process for connectors and terminals at Wago. "The final export of the parameters relevant to the customer to a 1D-ROM allows us to share the results of our work with customers directly and with little effort," says Wilhelm Rust. The thermal heating of the electrical connectors and PCB terminals is important for Wago customers. It must be below defined limit values under the specific dynamic load profiles acting in their systems, i.e. current and ambient temperature, and this in the smallest possible installation space. Consequently, the respective ROM contains the decisive information for this.

An Intuitive Solution With Ansys Twin-Builder And Machine Learning

With Ansys Twin-Builder, the ROM is implemented in an overall context, i.e. a large number of dynamic load profiles are simulated in a short time. This means that many different current flows and changing ambient temperatures can already be considered manually.

It is even more convenient for customers if they can check the suitability of Wago products quickly and independently at any time. "All the more so," says Wilhelm Rust, "because these are components that don't play the main role in electrical systems. If you want to configure a wallbox or an inverter, you don't want to spend ages dealing with the conductor connection".

The models were trained using machine learning so that they can also be used by customers online in the e-shop to evaluate and identify suitable products. Wago started with 10 products. "We were able to generate a total of 20,000 data sets for these products in different variants. This is a very good basis for training the neural network, from which we have already been able to extract further variants," says Wilhelm Rust, explaining this supposedly final step.

Further Challenges for Implementation in the E-Shop

"Supposedly", because even with the trained models, they were not quite there yet. Wilhelm Rust: "If you have developed and trained the machine learning model for online use at great expense, it must of course also be made available. This means that IT has to check the whole thing and integrate it into their systems. And then comes the website: Design, data maintenance—as an engineer, you underestimate all of this."

In spring 2025, the portal finally went live with the 10 products from the first phase. More will follow quickly, as Wago now has a functioning workflow. Wago thus has a unique selling point in the industry and is looking forward to the response from the market.

It now has to be integrated into our customers' planning processes. They were used to data sheets, but we are very optimistic that the new option, which was ultimately initiated by us simulation engineers and also takes a lot of pressure off us, will become established.

Wilhelm Rust

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