Abstract
Full- and semi-trailers are used in transportation since they require low operating cost per product weight. Moreover, the consequence of multi-axle conferred superior surface load distribution, traffic safety and reduced maintenance expenditure. Recently, full and semi-trailers in Thailand were designed base on two-dimensional information under the Department of Land Transport supervision. This research demonstrated the application of finite element method to study the three-dimensional models of full- and semi-trailers in both static and dynamic aspects. It was found that the structures examined have sufficient strength. For beam members, tridem axle semi-trailer was subjected to the highest stress of 184.8 MPa, whereas, the platform of full-trailer was exposed to the highest stress of 14.370 MPa. However, the major stress component on beam was a result of torsional moment and the normal stress exerted on the platform was a consequence of bent plate span, these were three-dimensional effects. The fundamental frequencies of full-trailer, tandem axle semi-trailer, and tridem axle semi-trailer were 73.16, 30.531, and 37.560 Hz, respectively. The tandem axle semi-trailer has the highest response amplitude to a specific excitation, considering large distance among wheel base supports. Obviously, three-dimensional structure analysis is essential to provide accurate and suitable guidelines to assist the economy and safety improvement.