Impact Force Identification by Using Modal Transformation Method for Automobile Test Rig

Abstract:

In the automobile industry, impact force is the main cause for material fatigue in lightweight vehicles. Bump-excited impact force is the most common case, which causes damage to vehicles and reduces the quality of the ride. Force identification is important to reflect the structure's health so that action such as structure modification can be taken before material fatigue. However, direct measurement by using force transducer is not practical due to difficulty in force sensor configuration. A methodology utilizing Operating Deflection Shape (ODS) analysis, Frequency Response Function (FRF) measurement and Modal Transformation Method (MTM) to evaluate the dynamic force is proposed here. This method is called indirect force measurement by using inverse technique. The performance of this approach was demonstrated via experiment. From the measured responses and measured dynamic characteristics of an automobile test rig, a real time mathematical manipulation can generate the systems input force. The force location is known in priori for impact excitation and therefore the inverse problem is well-posed. This method was tested using different force location with unique input force. It shows that high quality of curve fitting to extract the modal parameters such as damped natural frequency, modal damping and residue mode shape is essential to obtain a high accuracy force determination result.

• Periodical: Applied Mechanics and Materials (Volume 471)
• Pages: 102-106
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.471.102
• Online since: December 2013
• Authors: Abdul Ghaffar Abdul Rahman, Khoo Shin Yee, Zubaidah Ismail, Chong Wen Tong, Siamak Noroozi
• Keywords: Correlation, Frequency Response Function, Impact Force Identification, Lightweight Structure, Modal Transformation Method, Operating Deflection Shape

References

[1] D.M. Lilley, A. Kapoor, G. Gu, Calculation of dynamic impact loads for railway bridges using a direct integration method, Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit. 222 (2008) 385-398.

DOI: 10.1243/09544097jrrt189

[2] T. Lee, B. Kim, Vibration analysis of automobile tire due to bump impact, Applied Acoustics. 69 (2008) 473-478.

DOI: 10.1016/j.apacoust.2007.12.003

[3] J. -Y. Yoon, and R. Singh, Estimation of interfacial forces in a multi-degree of freedom isolation system using a dynamic load sensing mount and quasi-linear models, Journal of Sound and Vibration. 330 (2011) 4429-4446.

DOI: 10.1016/j.jsv.2011.04.033

[4] Z. Boukria, P. Perrotin, A. Bennani, Experimental impact force location and identification using inverse problems: application for a circular plate, International Journal of Mechanics. 5 (2011) 48-55.

[5] R.J. Hundhausen, D.E. Adams, M. Derriso, P. Kukuchek, R. Alloway, Transient loads identification for a standoff metallic thermal protection system panel, in: 23rd International Modal Analysis Conference (IMAC XXIII), Orlando, Florida (2005).

[6] B. Wang, Prediction of impact and harmonic forces acting on arbitrary structures: theoretical formulation, Mechanical Systems and Signal Processing. 16 (2002) 935-953.

DOI: 10.1006/mssp.2002.1505

[7] M. Richardson, C. Jamestown, Modal mass, stiffness and damping, Vibrant Technology. Inc., Jamestown, CA, (2000) 1-5.

[8] Vibrant Technology, Inc., Multiple reference curve fitting to find closely coupled modes, App. Note # 15, April, (2001).