Abstract
The calculation of the dynamic stress of a large and complex welded carbody is the key to the fatigue design and the durability evaluation of the carbody. Adopting the advanced structural stress based on the finite element method, a new finite element transformation method between random loads and dynamic stresses is proposed to be applied in carbody for high-speed trains. The multi-axial random dynamic load spectrums of full-scale carbody are obtained by the vehicle system dynamics method, and the shell finite element model of a full-scale carbody is established. Adopting the concept of a surrogate model, the finite element transformation relationship between the random load and the dynamic structural stress at concerned points is constructed by using multidisciplinary methods to compute the dynamic stress spectrums of concerned points at the welding seam, and dynamic structural stresses are compared and validated through carbody rig-test. The analysis methods of dynamic structural stress are performed systematically for a full-scale welded structure, which provides reference methods for the fatigue durability evaluation of large-scale welded structures.
Highlights
The high-speed EMU (Electric Multiple Units) trains adopt a lightweight design and power distributed technology
Load spectrums of the carbody bearing positions are obtained by establishing a system dynamics model of the carbody, and a full-scale finite element shell model of the carbody is established
An aluminum alloy welded carbody for high-speed trains is taken as the research object, and the finite element transformation method of dynamic structural stress was proposed
Summary
The high-speed EMU (Electric Multiple Units) trains adopt a lightweight design and power distributed technology. The fatigue damage of the high-speed train is mainly caused by the stress cycle that the structure is subjected; the key to evaluate the fatigue reliability is to obtain accurate stress–time history. The random stress–time history of the carbody is obtained by a certain method, which provides the stress data for the fatigue reliability evaluation. Based on the fatigue failure characteristics of welded structures, Radaj et al.[16] and Hobbacher[17] adopted the hot spot stress analysis method and notch stress analysis method, which effectively eliminated the dispersion of the nominal stress of joints. Nominal stresses of welded joints were corrected by this method, and the dispersion of fatigue data was greatly eliminated, a unified master S-N curve was obtained This method has become a popular method for fatigue analysis of the carbody.
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