Copyright © 2010 John Wiley & Sons, Ltd. Dynamic study of stacked packaging units by operational modal analysis By Carlos Bernad, Alberto Laspalas, David González, Elías Liarte and Miguel A. Jiménez Instituto Tecnológico de Aragón (ITA), Zaragoza, Spain SUMMARY Laboratory simulation of transport vibration has been the object of many studies in recent years due to the financial implications of potential customer claims in respect of damage caused during product distribution and the need for tools for packaging optimization. Most of these works concentrate on the special nature of transport vibrations and how to reproduce them: Power Spectral Density (PSD) profiles related to road and truck characteristics, the non-stationary aspects of the environment, the non-Gaussian characteristics of the recorded vibrations and the best procedures for meaningful laboratory testing. In the present work, a different point of view is applied to the issue. The paper deals with the dynamics of different corrugated stacked packaging units by means of operational modal analysis and a 6 degrees of freedom multi-axis shaker table. The results show the already known non-linear behaviour of the paperboard containers and the natural frequencies and modes likely to appear in the packaging. The relevance of bending-like modes in relation to laboratory testing is discussed. Copyright © 2010 John Wiley & Sons, Ltd. Received 03 August 2009; Revised 18 November 2009; Accepted 15 December 2009 KEY WORDS: packaging dynamics; transport vibration testing; operational modal analysis; corrugated container INTRODUCTION Laboratory testing of transport vibration is an active field of research due to the financial impact caused by possible product damage and over-packaging. The measurement and simulation of the vibrations suffered by packaging during distribution is the object of many research works, as is high- lighted by the numerous papers about this topic in the special edition of the Packaging Technology and Science journal 1 and in the conferences and symposiums organized by the International Safe Transit Association or International Association of Packaging Research Institutes. From the 1970s onwards, the improved capabilities of portable acceleration recorders have allowed an exponential increase in the environmental vibration data to be made available, mainly related to road transport, with deeper and more sophisticated analysis of the acquired data. Despite such efforts and the several standards available, 2–6 nowadays, there is no generally accepted approach when packaging optimization for vibration protection is the target. Discussion between the benefits and drawbacks of general simulation or focused simulation is still open, and the situation becomes more complex when acceleration of the test is sought. 7 PACKAGING TECHNOLOGY AND SCIENCE Packag. Technol. Sci. 2010; 23: 121–133 Published online 4 February 2010 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/pts.883 *Correspondence to: C. Bernad, Instituto Tecnológico de Aragón, C/María de Luna nº8, Zaragoza 50018, Spain. E-mail: cbernad@ita.es