EDITORIAL

Abstract

It is a great pleasure for me to be involved with the August issue of Strain. The current issue contains two full papers and three technical notes covering strain gauge techniques, structural health monitoring, vibration-buckling testing, and finite-element modelling and validation. The first paper by Ajovalasit discusses the effect of a stress normal to the grid on the output of the embedded strain gauge. Usually such a stress has a negligible effect. He derives the theory of the effect of pressure on the strain gauges to apply to the embedded strain gauges. The analysis indicates that the strain gauge output is affected by the coupled effect of transverse sensitivity and pressure sensitivity, which fully explains the experimental data in the literature. The second paper by Mustapha, Manson, Pierce and Worden is concerned with the structural health monitoring of an annular component using a statistical approach. Such annular components are widely used in the aerospace industry. They use the effect of the scattering of an ultrasonic guided wave. They conclude that the technique is good for simple geometries, but that data acquisition needs to be improved for more realistic structures. The first technical note by Brandon and Featherston deals with the bifurcation behaviour in an experimental vibration-buckling test. The aim is to use vibration testing to predict buckling failure. They find that the resonance properties under random load conditions contradict the expectation from elementary theory. The second technical note, by McCarthy, Lawlor, O'Donnell, Harris, Kelly and Cunningham, describes two different experiments to measure axial (pre-load) load caused by torquing of bolts in composite joints. They examine the effect of relaxation of load over time when joining composite (graphite/epoxy) plates and other plates, as well as the influences of washers. It is found that the drop-off in pre-load over time, when using steel plates, was about half that when using composite plates. Tests are conducted with and without washers, and very little difference in the results is observed. The final technical note by Sun, Howard and Moatamedi considers the issue of footwear and ground interaction as a traditional stability problem. The authors aim to establish a methodology to predict the traction performance for a particular tread pattern. They use the ANSYS finite-element program to evaluate the traction forces, soil deformation, and failure distances for the five typical tread patterns. The finite-element modelling provides a good agreement with the experimental results for soil failure patterns and the forward soil failure distance, as well as the maximum upward soil movements. This work will be useful for the optimum design of military boots. Taking this opportunity, I would like to introduce the research activities in Experimental Mechanics in Japan as well as in the Asian countries. In Japan, the Mechanics and Materials Division (MMD) of the Japan Society of Mechanical Engineers (JSME, nearly 40 000 members) has been holding the Annual Conference, providing a forum for the exchange of ideas and knowledge related to Experimental Mechanics. The JSME–MMD has hosted the International Conference on Advanced Technology in Experimental Mechanics (ATEM) every 2 years from 1993 until 2003. The next International Conference on ATEM is to be held in Fukuoka, Japan, in 2007. The Japan Society for Photoelasticity was reorganised to establish the Japanese Society for Experimental Mechanics (JSEM) in 2000. Since then, the JSEM has been playing an important role in the development of Experimental Mechanics. The JSEM publishes the Japanese Journal for Experimental Mechanics quarterly, which welcomes papers on experimental techniques in the field of Fluid Mechanics as well as Solid Mechanics. The JSEM concluded a cooperative agreement for the promotion of technical and scientific progress in the field of Experimental Mechanics with the Society for Experimental Mechanics, Inc., USA, in 2002. Furthermore, the JSEM cosponsors the SEM and BSSM Conferences regularly, and the International Conferences on Experimental Mechanics under the auspices of the European Association for Experimental Mechanics (EURASEM). In order to promote international collaboration on Experimental Mechanics, especially in Asia including the Western Pacific, and to contribute to the advance in Experimental Mechanics, the Asian Committee for Experimental Mechanics (ACEM) was founded in 1997. The Steering Committee has people from 14 countries (Australia, China, Hong Kong, India, Indonesia, Japan, Korea, New Zealand, Philippines, Singapore, Taiwan, Thailand, Vietnam, Malaysia). The Steering Committee decided to avoid holding more than two Conferences on Experimental Mechanics in the Asian countries in the year. For further information on the ACEM, please visit the website http://jsem.jp/acem. Finally, I would very much like to thank Dr R. Mines, Editor-in-Chief, for providing me an opportunity to write this Editorial.