چكيده به لاتين
Modal analysis is always considered and employed as a powerful tool for detecting the dynamical properties of mechanical structurs. One of the most important dynamical parameters of this field is the mode shape of the structure. Modal tests are always coupled with measuring a number of dynamical parameters such as displacement, acceleration, force and etc. One of the most powerfull method involves using the measurement sensors such as accelerometers. In this method, the sensor must have a contact with the structure during the entire duration of the test, which is a disadvantage for this type of test. For this reason, in the last decade, non-contact testing methods have been majorly developed by researchers in this field. Our goal in this thesis is to extract a number of Mode shapes of a pre-designed structure with a practical test. First, a steel structure similar to the car body of passenger wagon was designed and made for testing. To conduct this test, two contact and non-contact methods, including measurements with accelerometer sensors and measurement by structural imaging, have been implemented. Then, with the image processing operation the results recorded from the imaging test was analysed, and then the modal analysis was performed on the results of both tests. Furthermore, the natural frequencies of the structure and the Mode shapes were extracted. At the end, among the extracted modes, two selected modes are shown are shown and their frequencies are compared.