Modal testing of Buick sub-frame structure
Project name: Buick sub-frame structure modal test
Brief introduction：In modern automotive engineering, vibration management and noise control are essential for both performance and driver comfort. One critical component that significantly influences these aspects is the sub-frame structure, which serves as the primary mounting point for the engine and suspension systems.
To enhance the NVH (Noise, Vibration, and Harshness) characteristics of a new Buick model, engineers performed a modal analysis on the vehicle’s sub-frame structure. The goal of the project was to understand the sub-frame's natural vibration modes and optimize its dynamic behavior to reduce unwanted resonance during engine operation.
Using high-precision sensors and a dynamic signal acquisition system, the team conducted a series of modal experiments. By exciting the sub-frame through controlled force inputs (such as modal hammers or shakers) and measuring its dynamic response at multiple points, they were able to identify key modal parameters:
Natural frequencies
Mode shapes
Damping ratios
With this data, engineers gained valuable insight into how the sub-frame deforms under various dynamic loads. More importantly, the detailed modal test revealed critical vibration nodes—specific points where movement is minimized—enabling the strategic positioning of engine mounts to enhance overall structural stability and reduce unwanted vibrations.
By aligning the engine-mounting locations with these nodes, the design minimizes the transmission of engine vibrations into the vehicle chassis. This not only helps protect engine components from stress-induced fatigue but also reduces cabin noise and structural vibration, significantly improving ride comfort and vehicle durability.
The modal analysis of the Buick sub-frame structure represents a practical example of how advanced testing and engineering design come together to refine vehicle performance. Through data-driven development processes, manufacturers are able to deliver cars that are significantly quieter, smoother in operation, and more enjoyable to drive—all while consistently maintaining structural integrity and ensuring long-term mechanical reliability.
