Detection of localized nonlinearity in dynamical systems using base excitation experimental results

Document Type : Research Article


1 College of Engineering, Swansea University, Bay Campus, Fabian Way, Crymlyn Burrows, Swansea, SA1 8EN, United Kingdom

2 Department of Mechanical Engineering, Arak University of Technology, Arak 38181-41167, Iran


Nonlinear localization approaches are used not only for detecting the exact location of
the nonlinear elements in mechanical structures, but they are also exploited in order to find any possible flaws such as cracks in Structural Health Monitoring (SHM) applications. This study aims to develop a localization method to determine the location of localized nonlinearities in dynamic structures utilizing the experimentally measured data obtained from the base excitation test. The nonlinear element in the experimental set-up is represented by a pair of permanent magnets placed on both sides on the free end of the cantilever, and a pair of electromagnets placed with equal distances on both sides of the
permanent magnets. The combination of permanent and electromagnets create and
apply nonlinear electromagnetic force on the free end of the cantilever beam.
Hence, stepped-sine vibration tests are carried out using constant acceleration
base excitation to measure the response of the nonlinear system. The linear
response of the system obtained from the low amplitude test is used to update
the Finite Element (FE) model of the underlying linear system of the structure.
Then, the developed approach utilizes the updated linear model along with the
measured nonlinear dynamics of the experimental set-up obtained using
high-amplitude excitation to determine the location of nonlinearity. The results of the experimental study are demonstrated to show the performance of
the presented method.


  • The nonlinear localization method is developed for base excited vibration tests.
  • Experimental results are obtained for linear and nonlinear response of the presented test rig.
  • Underlying linear model of the system is updated.
  • The exact location of nonlinear element of the system is detected


Main Subjects

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