The Method Based on Series Solution for Identifying an Unknown Source Coefficient on the Temperature Field in the Quasiperiodic Media

In this paper, we consider the reconstruction of heat field in one-dimensional quasiperiodic media with an unknown source from the interior measurement. The innovation of this paper is solving the inverse problem by means of two different homotopy iteration processes. The first kind of homotopy iteration process is not convergent. For the second kind of homotopy iteration process, a convergent result is proved. Based on the uniqueness of this inverse problem and convergence results of the second kind of homotopy iteration process with exact data, the results of two numerical examples show that the proposed method is efficient, and the error of the inversion solution r t is given.

Thermal strength of retention compartment interacting with exhaust gas

The thermal strength of the retention compartment is calculated to analyze the possibility of multiple use for a rocket start. The transient heat field of the retention compartment, which is induced by the interaction of the exhaust gas with the retention compartment, is analyzed. The part of the retention compartment undergoes significant heat action with a high-temperature gradient when the rocket is started. This heat action essentially changes in time. This leads to the generation of significant transient stress fields. The aim of the present paper is the calculation of the maximal values of stresses induced by the heat field. We analyze the stress state induced by the steady-state heat field. This field corresponds to the transient heat field at the time when the maximal temperature gradient is observed. The upper bound of stresses in the retention compartment is obtained by the suggested method.

Effect of Protective Coatings in Welded Constructions on Welding Stability and Electrode Metal Transfer into a Weld Pool in MMA

The paper presents data of experimental research into the importance of protective surface coatings in welded products for MMA stability; heat field distribution patterns on their surfaces, and structure and phase composition of the welded metal. The study has revealed that a protective surface coating in a welded item in MMA has a positive effect on shortcut duration, increasing it by 5-11 %, raising its formation and transformation time by 10-12 %; 15% dimensional increase of a welded metal grain is registered as well, and a heat impact zone expands by 25%.

Dynamic and Vibration Analysis of Nano-Composite Hollow Cylindrical with Piezoelectric Layers in thermal load by DQM Method

Cylindrical structures in many engineering constructions are used, so proper analysis of cylinder behavior under various conditions is important. In this paper we investigate the dynamic and vibrational response of carbon nanotube-reinforced carbon nanotube reinforced composite cylinder shell with two piezoelectric layers. The equations of motion are extracted by assuming Sanders shell theory using the Hamiltonian principle. The Quadrature Differential Method (DQM) is used to solve the equations of motion. Frequency changes and dynamic response (middle layer displacement) have been studied by varying geometric and piezoelectric parameters. Among piezoelectric parameters, the parameter of C11 has a lower effect than the effective transverse coefficient of e31 in the frequency response. Other piezoelectric parameters have very little effect on frequency. A mild initial heat field increases the displacement amplitude by decreasing the strength and brittle of the material. But the heat field reduces the hardness of the matrix to a greater extent and increases the frequency and amplitude of the displacement.

Analytical Investigation of the Vibrational and Dynamic Response of Nano-Composite Cylindrical Shell Under Thermal Shock and Mild Heat Field by DQM Method

In this paper, the vibrations and dynamic response of an orthotropic thin-walled composite cylindrical shell with epoxy graphite layers reinforced with carbon nanotubes under heat shock and heat field loading are investigated. the carbon nanotubes were uniformly distributed along the thickness of the composite layer. The problem is that at first there is a temperature change due to the thermal field in the cylinder and the cylinder is coincident with the thermal field, then the surface temperature of the cylinder rises abruptly. Partial derivative equations of motion are coupled to heat equations. The differential quadrature method (DQM) is used to solve the equations. In this study, the effects of length, temperature, thickness and radius parameters on the natural frequencies and mid-layer displacement are investigated. The results show that increasing the outside temperature reduces the natural frequency and increases the displacement of the system. Radial displacement results were also compared with previous studies and were found to be in good agreement with previous literature. Increasing the percentage of carbon nanotubes also increased the natural frequency of the system and decreased the mobility of the middle layer.