Abstract (Summary)
In vibrations testing, a structures response to a vibratory excitation is quantified and analyzed. A vibratory excitation is often generated by an electro-dynamic shaker, which is attached to the test structure. The attachment of the electro-dynamic shaker to the test structure usually requires the modification of the structures surface or the adhesive attachment of a threaded mounting base to the structure’s surface. Often in automotive applications, where an automobile’s dynamic characteristics are being analyzed, damage to the surface of the test structure is clearly undesirable. To address this, a pneumatic shaker attachment fixture was designed by test engineers that coupled a shaker to a test structure by vacuum. The design of the device was successful, but an in-depth analysis of its performance was not carried out.To augment the design of the device, its design was numerically optimized using a conventional gradient-based constrained minimization algorithm within MATLAB. In the optimization, the fixture’s mass was minimized while subject to performance and manufacturing constraints. Through design optimization, the fixture’s mass was reduced by 66%. To evaluate the performance of the attachment fixture, the frequency response of a structure was measured using a current method of shaker attachment and compared to a frequency response measurement of the same structure when using the pneumatic attachment fixture. The measured dynamics of the test setup using the attachment fixture were noted to be quite different than those of the test setup using a conventional shaker attachment method. The source of the difference was explored by varying design parameters and by finite element modeling, and was determined to be dependant on several different factors. The result of this work is a lightweight means of coupling a shaker to a test structure suitable for low frequency vibration testing. Surface damage to the test structure caused by shaker mounting is minimized and the test engineer is able to easily reposition the shaker during testing.
Bibliographical Information:


School:University of Cincinnati

School Location:USA - Ohio

Source Type:Master's Thesis



Date of Publication:01/01/2004

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