Magnetothermoelastic creep analysis of functionally graded cylinders

چکیده مقاله

This paper describes time-dependent creep stress redistribution analysis of a thick-walled FGM cylinder placed in uniform magnetic and temperature fields and subjected to an internal pressure. The material creep, magnetic and mechanical properties through the radial graded direction are assumed to obey the simple power lawvariation.Total strains are assumedto bethe sumof elastic, thermalandcreepstrains. Creepstrains are time, temperature and stress dependent. Using equations of equilibrium, stressestrain and strainedisplacement a differential equation, containing creep strains, for displacement is obtained. Ignoring creep strains in this differential equation a closed form solution for the displacement and initial magnetothermoelastic stresses at zero time is presented. Initial magnetothermoelastic stresses are illustrated for different material properties. Using PrandtleReuss relation in conjunction with the above differential equation and the Norton’s lawfor thematerial uniaxial creep constitutivemodel, the radial displacement rate is obtained and then the radial and circumferential creep stress rates are calculated. Creep stress rates are plotted against dimensionless radius for different material properties. Using creep stress rates, stress redistributions are calculated iteratively using magnetothermoelastic stresses as initial values for stress redistributions. It has been found that radial stress redistributions are not significant for differentmaterial properties, however major redistributions occur for circumferential and effective stresses.