The defect in work rolls directly influence the forming cost and the final shape of the product. The researchers tend to investigate the Thermo-mechanical stress in work roll of rolling machines. These stresses may reduce the roll life. Since the investigation of the Thermo-mechanical stress in work roll with real-conditions is complex, comprehensive studies by means of numerical methods are available in numerous literature. However, simulating the Thermo-mechanical stress is time-consuming. So, most researchers desire to simplify the geometry and boundary conditions in order to reduce simulation cost. This paper proposes an integrated finite element model to study the Thermo-mechanical behavior of work rolls during hot ring rolling process. Various methods were simulated and advantages and disadvantages of each method were discussed. Due to complexities of ring rolling process, the presented model was used in flat rolling in order to verify model integrity. After that work rolls of ring rolling mill subjected to partial boundary conditions are investigated. The results of thermal and Thermo-mechanical simulations show stresses in the contact region of work rolls are rather different. However, they expressed the same results in other regions. Based on the obtained results, it is revealed that the effect of mechanical loads in the equivalent stresses should be considered and the location of equivalent maximum stress is below the surface.

Piston has to withstands Thermo-mechanical cyclic stresses in a wide range of engine operating conditions. The Thermo-mechanical stresses distribution enables us to optimize the piston design at lower cost Thermo-mechanical stress analyses of an engine piston used in a gasoline engine was studied. The boundary conditions of thermal loads of piston obtained by thermal resistance circuit model and GT-POWER and MATLAB software products. The thermal analysis results showed that the piston crown center withstands the maximum temperature. The results of finite element analysis (FEA) indicated that the stress has the most critical values at the upper portion of piston pin and piston compression grooves. The numerical results showed that the stress maximum occurred at the upper region of piston pin. The results of the Von-Mises and Tresca criterions proved that the upper region of piston pin and ring grooves are critical areas. The distribution of the safety factor demonstrated no critical point in the piston, and the minimum safety factor of 1. 1061 occurred in the upper area of piston pin. The results of the FEA are match with experimental damaged piston in these regions.

Coupling effects of stress, temperature, pore pressure and damage on hydraulic parameters of hydrocarbon and geothermal reservoirs and their production wells show that the realistic design of the production process from these reservoirs requires a comprehensive stress-strain behavioral model. In this study, through presenting a novel definition of total damage due to the effects of high temperature fluid in porous medium, a coupled stress-strain Thermo-hydro-mechanical-damage behavioral model of rock in three-axial loading condition is performed based on the effective medium theory, the concept of Biot effective stress, power probability density function and convection and conduction heat transfer. Results show that: A) Increasing Biot effective stress coefficients, rock permeability, pore pressure and temperature leads to the augmentation of the coupled Thermo-hydro-mechanical damage while the increase in confining pressure reduces damage thus improves rock bearing capacity. B) As temperature increases, total Thermohydro-mechanical damage rate decreases and its peak occurs at larger strains, C) Modified Lade failure criterion provides a more realistic prediction from coupled Thermo-hydro-mechanical-damage behavior compared with Mohr-Coulomb and Dragger-Prager failure criteria. Generally, it is concluded that taking into account the concept of Biots effective stress and convection heat transfer along with power distribution function will lead to more accurate predictions of the coupled Thermo-hydro-mechanical-damage model.

In this research, static stresses analysis of boron nitride nano - tube reinforced composite (BNNTRC) cylinder made of poly - vinylidene fluoride (PVDF) subjected to non - axisymmetric Thermo - mechanical loads and applied voltage is developed. The surrounded elastic medium is modelled by Pasternak foundation. Composite structure is modeled based on piezoelectric fiber reinforced composite (PFRC) theory and a representative volume element has been considered for predicting the elastic, piezoelectric and dielectric properties of the cylinder. Higher order governing equations were solved analytically by Fourier series. The results demonstrated that the fatigue life of BNNTRC cylinder will be significantly dependent on the angle orientation and volume fraction of BNNTs. Results of this investigation can be used for the optimum design of thick - walled cylinders under the multi - physical fields.

Prediction of the Thermo-mechanical behavior of machine-tool spindles is essential in the reliable operation of high speed machine tools. In particular, the performance of these high speed spindles is dependent on their thermal behavior. The main source of heat generation in the spindle is the friction torque in angular contact ball bearings. This paper presents an effort to develop a comprehensive model of high speed spindles that includes viable models for the mechanical and thermal behavior of its major components, i.e., bearings, shaft and housing. Spindle housing and shaft are treated as six-degree-of-freedom Timoshenko beam elements. Bearings are modeled as two-node elements with five displacements and a thermal load component at each node. Mutual interaction between the thermal and structural behavior of both spindle shaft/housing and bearings is characterized through thermal expansion and the rate of heat generation/transfer. Components are combined to form a finite element model for the Thermo-mechanical analysis of spindle-bearing systems.The results of simulation for a typical spindle system are presented.

This paper presents finite element analysis (FEA) of a coated and uncoated cylinder heads of a diesel engine to examine the distribution of temperature and stress. A thermal barrier coating system was applied on the combustion chamber of the cylinder heads, consists of two-layer systems: a ceramic top coat (TC), made of yttria stabilized zirconia (YSZ), ZrO2-8%Y2O3 and also a metallic bond coat (BC), made of Ni-Cr-Al-Y. The coating system in this research comprises 300 μm zirconium oxide TC and 150 mm BC. The three-dimensional model of the cylinder heads was simulated in abaqus software and a two-layer viscoplasticity model was utilized to investigate the elastic, plastic and viscous behavior of the cylinder heads. The elastic and plastic properties of BC and TC layers were considered and the effect of thermal barrier coatings on distribution of temperature and stress was investigated. The aim of this study is to compare the distribution of temperature and stress in the coated and uncoated cylinder heads under Thermo-mechanical loads. The results of FEA showed that the thermal barrier coating system reduces the temperature about 53°C because of its lower thermal conductivity. As a result, the cylinder heads tolerates lower temperature and fatigue life will increase. The results of Thermo-mechanical analysis indicated that the stress in the coated cylinder heads decreased approximately 24 MPa for the sake of depletion of temperature gradient which can lead to higher fatigue lifetime.

A functionally graded material beam with generalized boundary conditions is contemplated in the present study in order to examine the deformation and stress behavior under thermal and Thermo-mechanical load. Three discrete combinations of functionally graded materials have been deliberate in including a wide range of materials and material properties. The variation of material properties has been taken along the height of the beam cross-section as per power law formulation. The formulation has been derived, applying the principle of virtual work in order to acquire governing equations for FG Timoshenko beams. The development of governing equations is made through applying a unique method of unified formulation (Li [16]) in which the displacement variables are arranged in the form of aindependent variable that subsequently reduces the equations to a single fourth order differential equation similar to the equation given by classical beam theoryand is been extended to Thermo-mechanical loading in the present work. The transverse shear stress/ strain for Timoshenko beams have been taken care of within this unified formulation. The formulation employed in this research has been generalized for various loading conditions, and in the present work, thermal and Thermo-mechanical load has been pondered where temperature has been varied in accordance with the beam height. Exact solutions of the fourth order differential equation for the deformation and stress have been obtained for three types of boundary conditions viz.-Clamped-Free (C-F), Simply Supported (S-S), and Propped Cantilever (C-S). The study has been extended to cover wide range of temperature distribution so as to include uniform, linear and non-linear temperature profiles. Deformation and stresses, axial stresses, and transverse (shear) stresses have been reported for different power law index values.

In this research, thermal variation and internal pressure effects on stresses and strains of the creep behavior of composite laminates are investigated. Schapery's viscoelastic approach as a nonlinear model is used by Prandtl‐Reuss theory and Mendelson's approximation to explain the stress/strains creep treatment. History of the radial, circumferential, and axial creep stresses and strains of a laminated composite cylindrical shell made of the E-glass/Vinylester laminated composites are studied and examined. Different laminated sequences of lay-ups, linear variation of thermal loading, various composite materials accomplished with internal pressure loading are investigated. For this purpose, two laminated lay-ups as [[010/4510/010/4510 ] and [010/9010/010/9010 ] are selected, and Schapery integral nonlinear viscoelastic model of creep stress and strain approach for the constitutive equation is used. It was believed that the circumferential creep strain and absolute values of axial and radial creep strains are increasing with time and Also, creep stresses/strains in the multilayer composite cross-ply [010/9010/010/9010 ] is more than the [010/4510/010/4510] laminated composite cylindrical shells.