Feasibility study of performing experimental modal analysis with oblique impact testing using various oblique impact directions

Abstract Oblique impact excitation has been introduced in Experimental Modal Analysis (EMA), with the great advantage of reducing the conventional EMA’s testing time by a factor of three. One major constraint of this technique is the investigation of the effect of various oblique impact directions towards its accuracy in determining the structural dynamic characteristic. This feasibility study is difficult to be achieved in practice, as it involves a lengthy amount of experimental works using various oblique impact directions. To solve this problem, a mathematical model has been developed to synthesize the FRF due to oblique impact (i.e. oblique FRF) in this study. The synthesized oblique FRFs show great agreement with the measured oblique FRFs in various oblique impact directions, which validate the reliability of the usage of the proposed synthesis method. The performance of the oblique impact testings using various impact angles is investigated. The results show that the oblique impact testing has a high success rate to extract directional modes in many impact directions, however wrong selection of the impact direction will lead to mode estimation failure. Good selection of impact direction based on force and modal strengths are demonstrated to ensure an accurate estimation of the structural dynamic characteristics.

[1]  S. M. Leonard,et al.  Increase reliability of reciprocating hydrogen compressors : Maintenance and reliability , 1996 .

[2]  D. L. Brown,et al.  A Complete Review of the Complex Mode Indicator Function ( CMIF ) with Applications , 2006 .

[3]  Tom Knechten,et al.  Improved Method for FRF Acquisition for Vehicle Body NVH Analysis , 2015 .

[4]  Peter J. G. van der Linden,et al.  Improved FRF Acquisition Method for Vehicle Body NVH Analysis , 2017 .

[5]  Peter Avitabile.  Experimental modal analysis : A simple non-mathematical presentation , 2001 .

[6]  Peng Qin,et al.  Multiple Reference Impact Testing for Bridge Assessment with Drop Hammer , 2012 .

[7]  Atef Eraky,et al.  Damage detection of flexural structural systems using damage index method - Experimental approach , 2015 .

[8]  Peter Avitabile,et al.  Improved Modal Characterization Using Hybrid Data , 2014 .

[9]  Peter Avitabile,et al.  Modal and operating characterization of an Optical telescope , 2001 .

[10]  Peter Avitabile,et al.  Comparison of Modal Parameters Extracted Using MIMO, SIMO, and Impact Hammer Tests on a Three-Bladed Wind Turbine , 2014 .

[11]  Hassan Elgamal,et al.  Modal analysis on tire with respect to different parameters , 2017 .

[12]  Martin Hagara,et al.  Experimental Investigation of Mode Shapes of Symmetric Structures , 2015 .

[13]  Zubaidah Ismail,et al.  Time Effective Structural Frequency Response Testing with Oblique Impact , 2018 .

[14]  Brian Schwarz,et al.  POST-PROCESSING AMBIENT AND FORCED RESPONSE BRIDGE DATA TO OBTAIN MODAL PARAMETERS , 2001 .

[15]  Peter Avitabile,et al.  FRF Measurements and Mode Shapes Determined Using Image-based 3D Point-tracking , 2011 .

[16]  Herman Van der Auweraer,et al.  Uncertain parameter numerical model updating according to variable modal test data in application of large composite fuselage panel , 2010 .

[17]  P ? ? ? ? ? ? ? % ? ? ? ? , 1991 .

[18]  Peter Avitabile,et al.  MODAL SPACE:Do you really need an accurate updated model? What are the effects if it is not perfect? , 2009 .

[19]  Lorenzo Scalise,et al.  Experimental and Numerical dynamic characterization of a human tibia , 2018, Journal of Physics: Conference Series.

[20]  Roslan Abdul Rahman,et al.  EFFECT OF ACCELEROMETER MASS ON THIN PLATE VIBRATION , 2009 .

[21]  Javad Baqersad,et al.  Effects of Boundary Conditions and Inflation Pressure on the Natural Frequencies and 3D Mode Shapes of a Tire , 2017 .

[22]  F. A. Moslehy,et al.  Stress reduction in a gear tooth using photoelasticity and finite element analysis , 2001 .

[23]  W. A. Crosby,et al.  Crack detection of cantilever beam by natural frequency tracking using experimental and finite element analysis , 2018, Alexandria Engineering Journal.

[24]  Anthony R. Barrett.  Dynamic Testing of In-Situ Composite Floors and Evaluation of Vibration Serviceability Using the Finite Element Method , 2006 .

[25]  H. Herlufsen.  Modal Analysis using Multi-reference and Multiple-Input Multiple-Output Techniques , .

[26]  Brian Schwarz,et al.  Modal Parameter Estimation from Operating Data , 2003 .

[27]  Peter Avitabile,et al.  Comparison of FRF measurements and mode shapes determined using optically image based, laser, and accelerometer measurements , 2011 .