{"id":32532,"date":"2021-11-22T09:36:22","date_gmt":"2021-11-22T14:36:22","guid":{"rendered":"https:\/\/blogs.sw.siemens.com\/simcenter\/?p=32532"},"modified":"2026-03-26T06:27:13","modified_gmt":"2026-03-26T10:27:13","slug":"frequency-response-function-measurements-on-permanent-magnet-rotors","status":"publish","type":"post","link":"https:\/\/blogs.sw.siemens.com\/simcenter\/frequency-response-function-measurements-on-permanent-magnet-rotors\/","title":{"rendered":"Frequency Response Function measurements on permanent magnet rotors"},"content":{"rendered":"\n

Simulation engineers are under constant pressure to increase modeling fidelity and efficiency. The ability to use a Digital Twin to simulate product behavior has become increasingly important. In recent years companies race to get products to market faster by reducing development time and costs.<\/p>\n\n\n\n

However, simulation alone does not always ensure a product will perform as expected once it is in service. Accurate data and correlation techniques will help engineers build better models with much higher accuracy<\/a>. In this blog post, we will explore how engineers can capture high-frequency FRF data on a permanent magnetic rotor. We will demonstrate a practical way to excite one, enabling accurate Frequency Response Function measurements and higher-fidelity, more efficient models.<\/p>\n\n\n\n

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Simcenter 3D allows you to improve simulation models to become more realistic or to make them accurate enough to quickly analyze a system using correlation and updating techniques.<\/em><\/figcaption><\/figure>\n\n\n\n

Solving sticky hammers using Frequency Response Function (FRF) measurements<\/h2>\n\n\n\n

Those who have tried it will know: Modal impact hammers tend to stick to magnetic parts of electric machines.<\/p>\n\n\n\n

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A sticky hammer.<\/em><\/figcaption><\/figure>\n\n\n\n

After you spend time getting accustomed to the progressive pull force the magnet is imposing on the hammer, you\u2019ll be able to hit the rotor. On inspecting your results though, you\u2019ll often find multiple points of impact from the hammer.<\/p>\n\n\n\n

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Multiple impacts when using the classic modal hammer shown in a time series in a local response.<\/em><\/figcaption><\/figure>\n\n\n\n

Next to that, you\u2019ll find it difficult to get sufficient force into the higher frequencies, even if you\u2019re using the hardest impact tip.<\/p>\n\n\n\n

Let\u2019s explore how we can excite the rotor without these measurement errors. For that, we will be using the High Frequency Shaker<\/a> to collect data up to frequencies exceeding classic excitation methods.<\/p>\n\n\n\n

The High Frequency Shaker<\/h2>\n\n\n\n

The Simcenter High Frequency Shaker is an electrodynamic inertia exciter. It is superglued to a part or inside an assembly and generates a well-defined, repeatable point force. This short video snapshot shows this in action.<\/p>\n\n\n\n