Wrought aluminum 7075 alloy is hardened by precipitation hardening heat treatment. This alloy is one of the AI-Zn-Mg series with high strength and mechanical properties which is used in military and aerospace industries. This alloy has a long time heat treatment process. Therefore decreasing the heat treatment time is an important factor from economical view. The main objective of the present work is to reduce heat treatment time by the process which is a combination of duplex ageing and deformation (rolling). This regime involves T-AHA type treatment which is called FTMT process. First and second stages of ageing temperatures are different in this process and rolling is carried out at room temperature. Effective parameters of the process have been studied. The experimental results showed that this kind of thermo-mechanical treatment has not increased the hardness of alloy 7075 compared with conventional T6 treatment but, this process has reduced the heat treatment time about 58%, increased yield strength about 9% and increased ultimate tensile strength about 5.5%. The elongation of the alloy has not been changed by using this kind of thermo mechanical process.

In this study, the microstructural evolutions, formed phases, micro-and macro-hardness changes and shear properties were evaluated in the as-cast, homogenized, cold-rolled and annealed AlCoCrFeNi2. 1 eutectic high-entropy alloy (EHEA). These studies were carried out using X-ray fluorescence (XRF), scanning electron microscopy (SEM), Rockwell C and Vickers hardness testing as well as shear punch testing (SPT). The microstructure after cold rolling followed by annealing was consisted of an elongated phases/grains in the direction of cold rolling and in almost equiaxed phases/grains. The homogenized specimen has the minimum amounts of hardness and yield/ultimate shear strength. Due to the presence of both elongated and equiaxed structures in the cold-rolled and annealed sample, the hardness and yield/ultimate shear strength of this specimen is between that of as-cast and homogenized cases.

Arbitrary Lagrangian Eulerian (ALE) finite element method is extensively used for numerical simulation of solid mechanics problem. The versatility of the mesh in ALE approach makes it particularly effective and efficient in solving large deformation problems. In this work, a complete treatment of fully coupled ALE formulation is presented incorporating inertial, rate and thermal effects. The formulation may be used in conjunction with thermo-elasto-viscoplactic material models. A consistent and efficient tangent operator is developed in closed form to handle stress integration. The applications of this formulation are given in the second part of this paper.

Thermal treatments and thermo-mechanical processing routes were applied on a conventional structural steel (st37 steel: 0. 12C-1. 11Mn-0. 16Si) for improvement of tensile properties and enhancement of work-hardening behavior. Full annealing resulted in a sheet with coarse ferrite grains and pearlite colonies arranged alternatively in distinct bands, which showed high ductility, low strength, and the presence of the yield point elongation at the beginning of the plastic flow. The cold-rolled sheet, however, showed poor ductility but much higher strength level. The dual phase (DP) sheet, resulted from intercritical annealing in the austenite plus ferrite region, showed a remarkable strength-ductility balance, which was related to the excellent work-hardening behavior. A bimodal-sized ferritic structure with the appearance of a poor strain hardening regime after experiencing a high yield stress was obtained from the subcritically annealed cold-rolled DP microstructure. The ultrafine-grained sheet was processed by applying the abovementioned route on a martensitic microstructure, which resulted in low ductility but high strength at ambient temperature. These results demonstrated the ability to control the properties of conventional steels by simple thermal and thermo-mechanical treatments.

In the first part of this paper series, a complete formulation for fully coupled ALE analysis of large deformation solid mechanic problems was developed. The formulation incorporated inertial, rate and thermal effects, and the treatment of rate and temperature dependent constitutive equations were presented. In this part, the ALE equations are discretized to form finite element equations. An algorithm for the treatment of mesh motion is described and example problems are presented to demonstrate the capability of the proposed formulation.

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.

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.

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.