DYNAMIC EXPERIMENTAL TESTING SETUP AND EVALUATION FOR NON-LINEAR RESONANT DECAY METHOD (NLRDM

سال انتشار: 1391
محل انتشار: دومین کنفرانس بین المللی آکوستیک و ارتعاشات
کد COI اختصاصی: ISAV02_223
زبان مقاله: انگلیسی
تعداد مشاهده: 1330

نویسندگان

Mechanical Engineering Department, East Tehran Branch, Islamic Azad University

School of Engineering, The University of Manchester, Manchester, UK.

چکیده

The previous papers have discussed the theoretical and simulation behaviour of NL-RDM. In this paper preparations for the dynamic experimental testing and evaluation are explored. Any ex-perimental rig used to evaluate NL-RDM would be required to meet certain criteria. Any rig would have to be a multi-DOF setup in order to begin to evaluate the abilities of the method to analyse similar models. So, the rig is introduced and some information about instrumentation and data ac-quisition provided. Parts of the rig will be tested statically and dynamically. The system tested was a 2DOF lumped parameter linear system to which a nonlinear element was added, in the form of a clamped-clamped beam. The beam was evaluated for the degree of nonlinearity present and its suit-ability to be tested experimentally as a cubic stiffening spring.The system was tested using random excitation and FRFs were obtained for analysis. FRFs showed a clear shift in natural frequency for rising levels of excitation, demonstrating clear harden-ing stiffness non-linearity. The system was also tested using stepped sine excitation and FRFs again obtained. The results showed clear ‘jumps’ at higher levels of excitation, again demonstrating that non-linearity was present.The experimental rig is evaluated in relation to the degree of non-linearity present, linearity at low force vibration levels, degree of noise present and other variables that may affect the test re-sults, as discussed in other papers. Additionally other more general problems in testing are dis-cussed and where possible solutions proposed. Following this evaluation a final design is proposed for adoption in the testing phase.

کلیدواژه ها

Nonlinear System Identification; NL-RDM; FRF; Experimental Vibration

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