Structural Damping Analysis of a Vehicle Front Hood: Experimental Modal Parameters Extraction and Simulation Correlation

Structural damping is a type of energy dissipation that occurs within the structure of a mechanical system. Unlike other forms of damping that rely on external devices or materials, structural damping is intrinsic to the construction and assembly of the structure itself. This study focuses on the experimental determination of the structural damping ratios for a vehicle front hood fabricated from steel, with the main objective being to accurately identify these damping characteristics. To achieve this, the modal parameter extraction process utilized both the Least Squares Complex Exponential (LSCE) and PolyMAX methods, providing a robust and comprehensive approach to identifying dynamic properties of a hood structure. The hood was subjected to free vibration decay in a free-free condition, with dynamic properties—such as natural frequencies, mode shapes, and damping coefficients—extracted. Additionally, a correlation study was performed between numerical and experimental results, evaluating the Modal Assurance Criterion (MAC) and frequency differences to validate the numerical model’s accuracy. The findings underscore the damping capacity of a standard steel front hood structure and highlight the relationship between damping coefficients and mode shapes, resulting in a well-correlated model for frequency response functions that can be used in transient response calculations.