The Forms Of Unbalanced Loads And Its Influence To The Coupler Knuckle Fatigue Life

With the railway transport continuously develops in the direction of high speed and overload,the demand for safety of locomotive vehicles’ components and parts is higher and higher.The coupler is one of the most important connection parts of the locomotive vehicles,it is directly related with the train operation safety and reliability.The function of a coupler is to connect vehicles and haulage motors,and make sure there are certain distances,so that traction and compression loads can be delivered.The coupler knuckle will bear exchanging traction and compression loads in its working conditions.So its working conditions are very serious.Along with the effect of its material、manufacturing technique and structure,the use of the coupler knuckle shows that thecoupler knuckles appeared a lot of fatigue cracks.And during the coupler knuckle’s working time,there may be kinds of working conditions,in which the coupler knuckles suffer unbalanced loads that will influencethe coupler knuckles’ fatigue life.So it’s important to do research of unbalanced loads’ influence to the coupler knuckle’s fatigue life.The research object of this topic is No.16 coupler knucklewhich is used generally in Chinese heavy truck,and I mainly do the following several researches:1.Summarize the coupler knuckle’s working conditions of unbalanced loads,introduce the possible reasons of unbalanced working conditions,and classify the unbalanced conditions’ forms as linear loads、loads acting on the top or bottom of the coupler knuckle、take-off unbalanced loads and so on;2.Analyze possible forms of unbalanced conditions with the method of geometry analysis,turns out there are two-parts contact state and three-parts contact state in the head-decline condition and head-uplift condition;°3.Assemble the coupler body and coupler knuckle in Abaqus and analyze the contact states,compare the coupler knuckle’ s contact distribution with the results of geometry analysis,so that the finite element model’s rationalization can be confirmed;4.Compare the coupler knuckle’s stress distribution in unbalanced conditions,dangerous points are in the root of upper traction flange and bottom of S-surface in head-decline conditions,and in the root of bottom traction flange and bottom of S-surface in the head-uplift conditions,according to the variation of stress amplitude in various unbalanced working conditions,make sure the typical unbalanced working conditions are the take-off coupler knuckle’s bottom-uplift condition and bottom-uplift condition,of which the dangerous points lies in the root of upper traction flange and bottom of S-surface;5.Along with the three improved schemes came up by our team,simulate improved schemes’ condition in the two typical unbalanced conditions,and analyze the dangerous points’ stress amplitude variation and fatigue life,it comes out the third improved scheme is the best solution.