Multi-Factor Influence Mechanism and Test Method Optimization for Modal Parameters of Railway Freight Car Body

The railway industry currently lacks unified testing standards for modal parameter acquisition of freight cars, and the influence mechanisms of different test methods, support conditions, and loading states on modal parameters remain unclear, resulting in significant variations in test results that hinder effective vehicle structural optimization design, fatigue life assessment, and vibration control. This study aims to establish a comprehensive understanding of how different testing methodologies affect modal parameter identification of railway freight cars and to develop systematic criteria for test method selection and support condition assessment. A hierarchical progressive experimental approach was implemented on a C70E general-purpose gondola car using five distinct excitation methods (impact hammer, electromagnetic exciter, hydraulic exciter, shaking table, and track testing), with progressive boundary conditions and four loading states designed based on orthogonal experimental principles, utilizing optimized placement of 56 measurement points to identify modal characteristics. The shaking table method demonstrated superior identification capability with 100