Papers by Keyword: Temperature Change

Abstract: A simple and efficient computational tool modeling the brittle thermal-cracking behavior of a spherical shell encapsulating a round inclusion is presented and compared to existing numerical techniques. Model applications to parametric studies and to particulate composite materials are proposed.

Abstract: Research thermal overload protection not only to protect the motor winding insulation damage due to temperature is too high, also can give full play to the overload capacity of the motor. This paper proposed overload protection model based on heat effects, and deduces the motor internal discrete recursive algorithm of temperature-rise calculation. Based on this algorithm, we constructed the motor internal temperature-rise model, which can calculate temperature-rise of the motor in real-time, and realized the intelligent control of the motor.

Abstract: In this paper there have been presented the results of low-cycle fatigue tests of steel P91 samples in the conditions of isothermal fixed amplitude loads as well as loads with a temperature change. Fixed amplitude isothermal loads were conducted on five levels of full strain and in two temperatures T1=20°C and T2=600°C. In the paper there has been found a significant influence of the sequence of temperature changes on the cyclic properties after the temperature change and on the fatigue life. The conducted experimental verification of the Palmgren-Miner hypothesis proved its influence on the temperature changes during the tests.

Abstract: With the constant improvement of the national economic level, the requirements on the building security are also increasing. The external temperature is a major factor leading to unsafe buildings. It is very necessary to research the civil engineering and architecture under the thermodynamic environment. The concrete will crack with the change of the temperature. According to this, the paper studies the reason and defensive measures of expansion caused by heat and contraction caused by cold based on thermodynamic principles. According to climatic characteristics, this article proposes the preservation and heat insulation of buildings, protection the buildings from icy frost damage and the ventilation of the buildings through the selection of building materials. It solves the cracking problem of the concrete very good with the change of the temperature. The research of this paper provides some reference for other research on the civil construction.

Abstract: The effects of temperature change on the pull-in behavior and on the capacitance of the RF MEMS clamped-clamped capacitive switch are quite heavy because of the larger slenderness ratio of the MEMS clamped-clamped switch beam. A one-dimensional three-stage static model with temperature change for analyzing the beam was presented based on the small displacement assumptions, in which the clamped-clamped beam was subjected to both the electrostatic forces and the temperature change. First, the model was used to calculate the capacitance of the RF MEMS clamped-clamped capacitive switch in different states. Then , the effects of temperature change on the capacitance of the clamped-clamped capacitive switch for some different geometry dimensions were analyzed. From the analysis the effect of some geometry dimensions, such as the length of the beam, the depth of the beam and so on, at different temperature changes on the capacitance can be understood and some conclusions may be useful to the design of the MEMS clamped-clamped capacitive switch with the temperature change.

Abstract: In this paper, the drop test on cotton and polyester fabrics were conducted when 0.5ml and 2ml water dropped on fabric at an ambient temperature of 20 ± 1 °C, relative humidity levels of 65 ± 2%, and an air velocity of 0 to 0.2m/s. The temperature changes on these fabrics were measured. The results showed that it cost much time of 2ml water than 0.5ml water dropped on two kinds of fabrics. As cotton fabric, when 0.5ml water dropped on fabric, the temperature at point 1 changes little than polyester fabric, this isbecause cotton absorbed much water than polyester, there is little water transport to the distance of 6cm. Either 0.5ml or 2ml water dropped on fabric, the time for polyester fabric is shorter than that of cotton fabric, this can be seen the property of drying-fast of polyester fabric.

Abstract: In this paper, the variational principle for the simply supported FGM plate is presented by the variational integral method. Then, the stationary value conditions are obtained with the derivation of the varitional principle. At last, the vibration governing equation is illustrated, which will be benefit for the numerical simulation with finite element method in further investigations. From the stationary value conditions deduced by the variational principle, it can be observed that the buckling characteristics of the simply supported FGM plate can be influenced by the temperature changes.

Abstract: In this paper, the CNTS are considered as the Euler-Bernoulli beams which have been used in many references about the CNTS. Taken the thermal-mechanical coupling and small scale effect into account, the variational principle for the CNTS is presented by the variational integral method. With the derivation of the varitional principle, the vibration governing equation is illustrated, which will be benefit for the numerical simulation with finite element method in further investigations. From the stationary value conditions deduced by the variational principle, the influences of the temperature changes and the thermal expansion coefficients based on nonlocal Euler-Bernoulli beam model are presented.

Abstract: This study deals with behaviour of bending deformation in CO2 laser forming process of titanium. CO2 laser forming technique was applied for a pure titanium plate with thickness of 1 mm to aim the development of new bending process. The experiments of laser forming were carried out with a CO2 laser machine. The bending angle and the temperature of workpiece were examined under the condition of various laser power, feed speed and laser spot diameter. Based on the experimental results, it was found that the bending deformation behaved greatly depending on the laser power and the laser spot diameter. The bending angle increased with an increase in the laser power. The bending direction tended to change from the laser irradiation side to its opposite side when the large laser spot diameter was applied.