Yusuf Orcan

Elastic–plastic deformation of a rotating solid disk of exponentially varying thickness

Abstract The elastic–plastic deformation of a rotating solid disk of variable thickness in exponential form is investigated using Trescas yield criterion, its associated flow rule and linear strain hardening. An analytical solution is obtained and numerical results are presented for different values of the geometric parameters. In the limiting case of uniform thickness the solution reduces to Gamers solution.

On the rotating elastic–plastic solid disks of variable thickness having concave profiles

Abstract In this paper, an analytical solution for the elastic–plastic stress distribution in rotating variable thickness solid disks is presented. The analysis is based on Trescas yield criterion, its associated flow rule and linear strain hardening material behavior. It is shown that depending on the shape of the disk profile, the radial stress in the central region may exceed the circumferential stress. The plastic zone which develops away from the axis of the disk consists of three annular regions governed by different mathematical forms of the yield criterion. The propagation of these plastic regions with increasing angular velocity is obtained together with the distributions of stresses and deformations in nondimensional forms.

Elastic–plastic stresses in linearly hardening rotating solid disks of variable thickness

Abstract The distribution of stress, displacement and plastic strain in a rotating elastic–plastic solid disk of variable thickness in a power function form is investigated. The analysis is based on Trescas yield condition, its associated flow rule and linear strain hardening material behavior. An analytical solution is obtained and numerical results are presented for different values of the geometric parameters. The validity of the solution is demonstrated by comparing the results with those for a uniform thickness disk available in the literature.

Thermal stresses in a heat generating elastic-plastic cylinder with free ends

Abstract The exact solution of the distribution of stress and deformation in an elastic-perfectly plastic cylindrical rod with uniform internal heat generation under generalized plane strain condition is presented. The treatment is based on Trescas yield condition and the associated flow rule. The stress image points of the outer and inner plastic regions lie on two different edges of Tresca prism. With increasing heat generation parameter, the image points of the intermediate regions spread out through two side regimes and meet at another edge regime in the fully plastic state.

THERMAL STRESSES IN ELASTIC-PLASTIC TUBES WITH TEMPERATURE-DEPENDENT MECHANICAL AND THERMAL PROPERTIES

The thermoelastic-plastic deformations of internal heat-generating tubes are investigated by considering the temperature dependence of the thermal conductivity coefficient, Youngs modulus, the coefficient of thermal expansion, and the yield limit of the material. A model describing the elastic-plastic behavior of the tube is developed. The model consists of a system of two second-order ordinary differential equations and a first-order ordinary differential equation involving nonlinear temperature-dependent coefficients. The computer solution of the model is obtained, and the results are compared with the analytical solution that assumes constant thermomechanical properties. It is found that the difference between the two solutions becomes significant in the regions of high temperatures.

COMPUTATION OF TRANSIENT THERMAL STRESSES IN ELASTIC-PLASTIC TUBES: EFFECT OF COUPLING AND TEMPERATURE-DEPENDENT PHYSICAL PROPERTIES

The objective of this study is to obtain the transient solution of the thermoelastic-plastic deformation of internal heat-generating tubes by considering the thermomechanical coupling effect and the temperature-dependent physical properties of the material. The previously developed steady-state model describing the elastic-plastic behavior of the tubes is modified to obtain the transient solution. The propagation of the elastic-plastic interface for a given heat load is obtained; and the corresponding stress, displacement, and plastic strain components are computed. The effect of the coupling is investigated using three different engineering materials, namely, steel, aluminum, and magnesium; and it has been found to be negligible. On the other hand, the temperature dependence of the mechanical and thermal properties affects the computed profiles significantly.

Elastic-plastic deformation of a heat generating tube with temperature-dependent yield stress

The distribution of stress, plastic strain and displacement in an elastic-perfectly plastic tube with fixed ends in the presence of a uniform heat source is investigated analytically by taking into consideration the temperature dependence of the yield limit. The treatment is based on Trescas yield condition and its associated flow rule. Depending on the radius ratio of the tube, in general, five different plastic regions, two of them corresponding to an edge regime of Trescas prism, and an intermediate elastic region occur. Four different ranges of radius ratio of the tube can be distinguished which lead to different patterns of elastic-plastic deformation. In all cases the thermal load is increased up to the value for which the elastic region vanishes.

Thermoplastic Response of a Linearly Hardening Cylinder Subjected to Nonuniform Heat Source and Convective Boundary Condition

Abstract An analytical model based on Trescas yield criterion and its associated flow rule is developed to analyze the thermoelastoplastic response of a linearly hardening cylinder subjected to a nonuniform heat source and convective heat transfer condition at the external boundary. Closed form solutions are obtained for a state of generalized plane strain in different stages of elastic-plastic deformation. Considering a cylinder that is constrained axially, the plastic deformation commences at the axis and depending on the convective boundary condition, another plastic region may develop at the surface before the fully plastic state is reached. A calculation procedure is developed to determine the critical values of the heat-transfer coefficient, for which a third plastic region at the surface does not occur. The effect of various parameters on the critical heat-transfer coefficient is investigated. The residual stresses attained upon unloading are also determined and it is shown that the primary and secondary stresses fall within the shakedown regime.