Model Updating of Railway Car Body Using Operational Modal Testing Results

This paper represents finite element modeling and updating of a railway car body using two sets of operational modal measurements. The measurements are performed in two different car body speeds, namely 60 km/h and 80 km/h, in a straight track. The responses of the structure are measured using 20 accelerometers mounted on the body. Natural frequencies and mode shapes of the structure are extracted from the recorded responses using Frequency Domain Decomposition technique. A modified stability diagram is used for identification of stable modes of the structure within frequency range of 0-45 Hz. These stable modes are then used for updating of the car body finite element model. The finite element model of the car body is developed using NASTRANsoftware and the updating is performed by employing iterative linearized sensitivity based method available in MSC/NASTRAN Design Sensitivity & Optimization Module. The updated model reveals excellent agreement with measurement observations indicating successful operational modal identification practice and selecting appropriate updating parameters.