| Type 17 coupler is the latest model of heavy freight trains in China, which exists several weak areas of strength on its hook tongue and hook body part in working conditions. These weaknesses locally appeared as damages of cracks and plastic deformations. The main research of this article is based on Type 17 coupler to establish the CAD assembly model and to analyze the structural strength of the coupler using finite element method. The results precisely illustrate the regions of stress concentration under stretch and press conditions. These stress concentrations always distributed in contact surface between parts of the coupler. By applying Hertz theory, above phenomenon could be described reasonable. Finite element method with contact analysis was applied in order to estimate the detail of stress distribution on contact regions. Structural improvements were applied in hook tongue and hook body after data analysis and discussions, which significantly improved structural strength and safety for overall coupler.The main contents include the following:(1) Establishing the CAD model using the existing data of type 17 coupler, and based on the reference model of parts building its parameters and products in order to realize the rapid change of whole design;(2) Generating the mesh in local simplifies and local refinement and setting the contact size for grid in contact regions. The type of mesh was applied as Tetrahedrons.(3) By using Hertz theory to calculate the line contact stress between the inner side of S surface of hook tongues and indirectly measuring the value and distribution of contact stress between the inner side of S surface of hook tongues using a method of controlling a single variable in finite element calculations.(4) Proposing structural improvement designs for the S surface of hook tongue component and the upper ear region and traction boss of hook body component.These measures improved structural strength and operational safety of coupler effectively. |
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