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Case Study

TWI and InnoTecUK Replace Physical Testing with Virtual Simulation using Ansys


“By combining Ansys Granta and Ansys Maxwell tools, we were able to demonstrate that one week of virtual simulation was equivalent to 12 weeks of laboratory testing during the ATEX encoder project. This approach may lead to significant cost savings in future projects.”

— Dr. James H. Kern, Senior Project Leader/Non-Destructive Testing, NIS, TWI


For any application in an explosive environment, such as oil and gas or chemical plants, ATEX certification* is mandatory for all equipment to prevent explosions. Currently, there is no commercially available zero-torque encoder that’s certified for ATEX, which is required for accurate distance measurements. In a collaborative research and development project with Ansys, TWI together with InnoTecUK’s support, designed and developed an ATEX- compliant encoder to achieve accurate distance readings, safety, and life cycle requirements. InnoTecUK demonstrated the encoder on a submersible robot intended for in-service bottom plate thickness inspection of hazardous oil storage tanks.



Three material selection challenges were overcome in the design of the ATEX Encoder. The first was material selection for harsh environments to protect the sensor. The second challenge was meeting ATEX certification* for explosion protection. The third challenge was magnet selection to achieve measurement accuracy and flexibility during set-up after sensor system assembly to meet in-service requirements. This involved a systematic down-selection against key material properties and environmental durability, cost and supply chain availability for core components.


Engineering Solution

Ansys Granta Selector was initially used to choose materials and validate off-the-shelf ATEX rated components by trading off on key performance and business parameters. The data in MaterialUniverse™ filled in missing suppliers’ material information for durability in fluids, notably for the polymer-based jackets and cables. Granta Selector then helped select the magnet and casing by trading off performance, price and criticality. Material grades, geometry and motion were then consolidated into a parametric study using Ansys Maxwell with simulation-ready data available in Ansys MDS. The simulated and experimental results of the magnet selection, design and operational scenarios were comparable, which validated the results.



By combining Granta Selector and MDS with Ansys Maxwell magnetic flux simulation, the team demonstrated:

  • One week of virtual simulation equaled 12 weeks of laboratory testing.
  • A parametric study of design envelope by simulating various magnet grades, sizes, orientation lateral offsets, casing materials, and operational failure modes, required 5 days, saving an estimated 25 days of laboratory work with a physical setup.

The simulation approach can significantly reduce the time to market by replacing laboratory testing and simulation.

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