آناليز شكست گيربكس قيچي برش ورق

چكيده انگليسي :

70 Fracture Analysis of Crop Shear Gear Box Amin Salimian Rizi a salimian@me iut ac ir Date of Submission 2014 09 02 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Mohammad Reza Forouzan forouzan@cc iut ac irAbstractStudy and prediction of fatigue fracture is an important subject to design the machines and structuralcomponents which are influenced by vibration or cyclic loading Some cracks are produced duringproduction process and the others can be created during the installation of components Due to cyclic loadsthese cracks propagate to a crirical length and after that the result is component fracture If an overloadtakes place during the cyclic loading so it will affect crack growth rate significantly Using the fracturemechanic science is one of the methods of studing the fatigue crack growth The fracture mechanicsinvestigate the components load capacity so it is possible to study the life of componetns which aresubjected to fatigue loads by using fracture mechanics Gears are the most important machine components that are used to transfer power and motion The fastgrowing industrial developments and economical considerations have led to the need for designing durablecomponents with minimum weight In order to achieve this goal designers need to understand the failuresmechanism of machine parts and do their calculations accordingly Gears may fail with several differentmechanisms One of the most important is fatigue crack growth in tooth root The tooth root is mostexposed to crack initiation and damage because of high bending stresses Since the gears are used in manymachines and the gears tooth fracture lead to machines work stop study and prediction of gears life can beso useful and efficient The goal of this study is to estimate the main gearbox life of Hallden flying shear in cold rolling mill area ofMSC First of all kinematic analyse was done on Hallden flying shear and after that the maximum shearingforce of cutting process was estimated At the next step dynamic analyse was done by using the maximumshearing force Dynamic modeling method was used the mass spring modeling in ABAQUS to model theshafts and gears The result of dynamic modeling was torques that was applied to gears and so the criticalgear was specified Then by using contact analysis the exact load distribution on critical gear teeth and thecrack initial location were obtained In order to obtain exact load distribution on the tooth face conjugateaction of the studied gear with its meshing gear has been analysed using contact elements Finally the extended finite element method XFEM has been used to simulate 3D fatigue crack growth andobtain growth path This method was introduced during recent years and modelling time has reducedconsiderably compared to previous works carried out on 3D crack growth in gears To estimate the fatiguelife of critical gear in main gearbox the Paris equation has been used Paris law is used to calculate lifecycles from the point when initial crack starts to grow until it reaches the critical length where fractureoccurs Also a code has been developed in ABAQUS environment taking advantage of this software scapability of modeling static cracks by XFEM The final results of analysis gave important and useful information about estimation of gears life andcrack s growth path and the final shape of the crack was found so by using these information it is possibleto prevent the sudden fracture of gear teeth in gearboxes of Hallden flying shear Keywords Fatigue Gear Fracture mechanic Finite element method Sheet metal shear

سليميان ريزي، امين

آناليز شكست گيربكس قيچي برش ورق

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