{"id":76325,"date":"2026-07-01T10:53:03","date_gmt":"2026-07-01T14:53:03","guid":{"rendered":"https:\/\/blogs.sw.siemens.com\/simcenter\/?p=76325"},"modified":"2026-07-01T10:53:22","modified_gmt":"2026-07-01T14:53:22","slug":"operational-deflection-shapes","status":"publish","type":"post","link":"https:\/\/blogs.sw.siemens.com\/simcenter\/operational-deflection-shapes\/","title":{"rendered":"Operational Deflection Shapes: From frequency peaks to understanding structural motion"},"content":{"rendered":"\n

In this blog it is described how operational deflection shapes can be used for a more profound NVH (Noise, Vibration and Harshness) analysis. Every NVH investigation often starts with the same question: a noise or vibration issue has been detected, but where does it come from? A peak in a frequency spectrum confirms that something is happening at a certain frequency, but it does not explain how the structure is moving, which component is mainly involved.<\/p>\n\n\n

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ODS helps to characterizes the component deformation pattern corresponding to operating points or peak values<\/figcaption><\/figure><\/div>\n\n\n

This is where Operational Deflection Shape analysis, or ODS, is useful. ODS visualizes the vibration pattern of a structure under real operating conditions. Instead of looking only at individual response curves, we can animate the motion of the measured component and evaluate relative amplitudes and phases at different locations.<\/p>\n\n\n

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CAD model for Virtual Instrumentation<\/figcaption><\/figure><\/div>\n\n\n

For test and simulation engineers, the method is practical because the required inputs are often already available: a geometry or model, a defined set of measurement points, and operating data. With a focused instrumentation plan, ODS can help identify whether a housing, bracket, gearbox, suspension component, or complete powertrain is moving in a way that is relevant to the observed NVH issue.<\/p>\n\n\n

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Investigate operating conditions<\/figcaption><\/figure><\/div>\n\n\n

ODS can give in some cases sufficient insight in the NVH issue or can be an early step in a broader troubleshooting workflow. Once the operational motion is understood, two follow-up analyses are particularly useful:<\/p>\n\n\n\n

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  1. Experimental or simulation-based modal analysis can help determine which structural mode shapes are related to the observed operational vibration, see case study below.<\/li>\n\n\n\n
  2. Transfer Path Analysis can help quantify how vibration energy travels from the source to the receiver. In this case, the objective is to identify which path contributes most and whether the target vibration is mainly driven by the source or by the receiver path. With in-situ TPA, the source can remain installed in the vehicle or assembly, enabling troubleshooting directly on the complete system.<\/li>\n<\/ol>\n\n\n\n

    In this blog, we focus on ODS itself: when to use it, how to prepare and execute the workflow with Simcenter<\/a> hardware and software, and how the method can be applied to an e-powertrain case study.<\/p>\n\n\n\n

    A practical workflow for Operational Deflection Shapes<\/h2>\n\n\n
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    ODS workflow<\/figcaption><\/figure><\/div>\n\n\n

    A reliable ODS analysis starts before the measurement. The objective is to select measurement locations that capture the expected vibration behavior of the component. Sensors should not all be placed in one zone but smartly spread over the evaluated component to cover its shape as good as possible. Previous experience, engineering judgment, simulation results, or a preliminary modal analysis can help to find the best measurement locations.<\/p>\n\n\n\n

    The ODS workflow can be structured into three main steps: measurement preparation and geometry creation, operating data acquisition, data processing and results visualization.<\/p>\n\n\n\n

    Measurement preparation and geometry creation<\/h2>\n\n\n
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    Measurement preparation and geometry creation<\/figcaption><\/figure><\/div>\n\n\n

    Geometry definition is the first step in ODS preparation. A wireframe model of the component is required for sensor placement and deformation visualization.<\/p>\n\n\n\n

    When CAD data is available, it should be used as the primary source. The CAD geometry enables virtual positioning of sensors at planned measurement locations prior to physical testing. This approach offers two advantages: it ensures correspondence between intended and actual sensor placement, and it streamlines wireframe model creation through direct CAD import rather than manual geometry reconstruction. When CAD data is not available, one can use either a CAD scanner or simply free of use applications on cell phones. Wireframes based on these CAD data can be still sufficiently precise and offer an efficient alternative.<\/p>\n\n\n\n

    Once the component geometry is defined and virtual sensors are positioned on the model, the model serves as a reference template for physical sensor positioning. This correspondence between virtual and physical instrumentation ensures that measured data directly correlates to the geometric model used for ODS visualization.<\/p>\n\n\n\n