Experimental Modal Analysis of High-Speed EMU Carbody Structure

摘要

Modal is the natural characteristic of structural vibration, each mode has a specific frequencies, damping and modal shape. Modal parameters reflect the dynamic properties of the structure. The dynamic characteristics of car-body structure play an important role to the stability and comfort of the High-speed EMU (Electric Multiple Unit). Experimental Modal Analysis (EMA) is the common method to study the structural dynamic characteristics. This paper adopts the EMA technology to analyse the high-speed EMU car-body structure. The car-body structure is supported by coil springs, which simulates the operational condition. The system uses two electromagnetic exciters to produce the excitation force, and the burst random signal is used. Two piezoelectric transducer are applied to measure the force, 285 piezoelectric acceleration sensors are used to pick up the vibration response, and the LMS-SCADA III is used to acquire data. Based on multiple-input multiple-output (MIMO) method, modal testing is performed. The PolyMAX method is utilised for extracting the modal parameters: frequencies, damping and modal shape. The vibration characteristics of the car-body structure have been further understood through the modal parameters, which also can be used for the vibration and noise reduction design.