Scientia Iranica

Scientia Iranica

An investigation into the accelerometer mounting effects on signal transmissibility in modal measurements

Document Type : Research Article

Authors
Saeed Shokrollahi 1
Farhad Adel 1
Hamid Ahmadian 2
1 Malek Ashtar University of Technology, Space Research Institute, Modal Testing laboratory, Lavizan, Tehran 14665/143, Iran
2 Iran University of Science and Technology, School of Mechanical Engineering, Narmak, Tehran 16844, Iran
10.24200/sci.2017.4244
Abstract
The purpose of this study is to define a simple model and discuss the main effects due to the use of the sensors with imperfect mounting in experimental measurements. This paper presents a theoretical and experimental investigation for the effects of different mounting methods of accelerometers on signal transmissibility in modal testing. In the theoretical part, a two degree-of-freedom (2-DOF) model is used, where the first DOF accounts for the accelerometer seismic mass and Piezo-crystal and the second DOF represents the mounting interface dynamics. An experimental modal analysis is conducted on a simple steel free-free beam using impact hammer excitation. The time domain signals and frequency response functions (FRFs) are measured in the case of magnetic, wax and stud mounting. It is found that the method of mounting has a significant effect on damping rates of measured responses. Although natural frequencies have no important changes, but the quality of measured FRFs is degraded considerably.
Keywords
Accelerometer
Mounting dynamics
Signal transmissibility
Modal Testing
Subjects
Scientia Iranica
Volume 24, Issue 5
Transactions on Mechanical Engineering (B)
September and October 2017
Pages 2436-2444

  • Receive Date 10 February 2016
  • Revise Date 21 June 2016
  • Accept Date 08 October 2016