Estimation of the Fatigue Strength of a Plate Traction Chain
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ESTIMATION OF THE FATIGUE STRENGTH OF A PLATE TRACTION CHAIN J. Wang,1 P. S. Kun,2, 3 T. M. Lenkovskyi,2,4 I. A. Vikovych,5 and V. M. Boiko2
UDC 539.37: 621.867
We present the results of simulations of the stress-strain state of a traction chain by the finite-element method with regard for the contact interaction and friction between the chain link and the roller. We propose an analytic relation for the approximate evaluation of the fatigue strength of the chain according to the distribution of stresses. We also establish conditions that should be imposed on the tensile forces acting upon the chain in order to guarantee its required service life under given operating conditions. Keywords: plate chain, stress distribution, contact interaction, fatigue strength.
Introduction In various branches of industry, the transportation of bulk cargos (ore, coal, cement, etc.) and cargos delivered in pieces (bricks, lumber, ingots, etc.) is carried on with the use of continuous-action machines. Plate chains play the role of the main load-bearing structural element of these machines. In the process of operation, the elements of a conveyer undergo the action of cyclic loads [1–3] both at the time of startup and in the course of steady motion, which often leads to the premature failures of chain links [3]. In the available standard methods used for the numerical analyses of the stress-strain state (SSS) of chain links, the distribution of stresses in the crosspiece (from the edge of plate to the hole) is regarded as homogeneous across the width [4, 5]. In [6], the SSS of traction chains was studied with the help of computer simulations by using special software. However, the variations of the SSS caused by the contact interaction of the roller with the plate and by the friction between them were not taken into account. The presence of contact interaction in the vicinity of the stress concentrator affects both the SSS and the fatigue strength. It was established that the role of the site of crack initiation, which may lead to subsequent failures of chain links, is played by the surface of the hole. In [7, 8], the authors studied the SSS and optimized the structure of chain links under static loading. However, neither its fatigue strength, nor the residual life was estimated. In order to predict the period of safe operation of driving chains, it is necessary to simulate the SSS with regard for the distribution of stresses in the contact zone and to estimate the fatigue strength. However, at present, the influence of contact interaction in the “roller–plate” system on the SSS and fatigue strength of elements of the chain is studied insufficiently. Therefore, in what follows, we focus our attention on this problem. 1 2 3 4 5
School of Mechanical Engineering, Northwestern Polytechnic University, Shaanxi, China.
Karpenko Physicomechanical Institute, National Academy of Sciences of Ukraine, Lviv, Ukraine. Corresponding author; e-mail: [email protected]. JSC “BIR Ukraina”, Odesa, Ukraine.
“Lviv Polytechnic Institute,” National Universit
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