Papers by Keyword: Temperature Effect

Abstract: Konjac glucomannan (KGM) belongs to pseudoplastic fluid. Remarkable non-linear change tendencies of shear rheological behavior of KGM were detected through analysis of the correlation of viscosity (η)-shear rates and shear stress-shear rates respectively, and its shear rheological curves conformed to the Power Law (τ=ＫDn). The change tendencies of viscosity factor (K) and flow index (n) correlated with concentration and temperature were also obtained, the curves can be fitted by power and quadratic polynomial equation respectively. The acquired non-linear correlation curves of K and n can provide reliable foundation for rational applications of KGM in food industry and its grade estimation.

Abstract: This paper describes the temperature effect on breakage behavior of cement clinker by single particle compression test. Portland cement clinker nodules, with mean diameter of 22 mm, were chosen as the test specimens. They were treated with heating to the temperatures of 300°C and 1000°C or cooling to -20°C and -88°C, respectively. The breakage behaviors were compared with the untreated nodules. The compression force-displacement profiles show that the treated nodules are easier to be broken because of the micro-cracks. Scanning electron microscope images illustrate that the clinker microstructures were changed after heating or cooling treatments. However, the main components are still the same according to the examination of X-ray diffraction. Comparing the heating with the cooling processes, it is more possible to use the waste heat of clinker sintering stage to reheat the clinker nodules, and these new reheating circuits may improve the energy efficiency of comminution.

Abstract: A new type steel and glass fiber reinforced polymer (GFRP) deck composite beam has been proposed. The relative slip and shear force on the interface of steel and GFRP deck composite beam appears to a certainty with the external loading, which induced internal force redistribution between GFRP deck and steel beam and shear connector, especially GFRP is a resin material, its physical and mechanical properties will change with temperature and time. According to the structure and bearing characteristics, the interface shear force differential equations that considering the temperature and creep effects were presented, the theoretical calculating formula of shear force were given under the uniform load. Results of calculation showed that the shear force of composite cross-section would increases with the increase of the connection stiffness, the increase of load, the change of temperature and the time. Loading effect and temperature changes creates a relatively larger impact on the shear force of the composite beam, while the stiffness of the connective interface and the creep effect of the GFRP material to composite beam shear force were much little.

Abstract: Since piezoelectric materials exhibit strong temperature dependency. The change of temperature results in marked variation of the PZT transducer’s electric impedance signals, which may lead to misjudgment of the structural health condition. A experiment was implemented on smart aggregates with embedded PZT transducers under 35°C, 45°C and 55°C three working conditions, and found that the temperature had significant influence on the electric admittance signals of embedded PZT transducers. The peak magnitudes of the admittance curves changed and the curves shifted leftward. Then a temperature compensation technique was used to minimize the temperature effects.

Abstract: The vibration features are affected by damage in structure and environmental conditions while the bridges are in the operation. Environment effects should not be ignored in making correct diagnoses of structures. Negative selection algorithm inspired by immune system has the capability for self-nonself discrimination. Temperature effect on natural frequency is analyzed in the paper, and the algorithm based on Euclidean distance is applied to natural frequencies of structures under temperature variations. The results indicate that negative selection algorithm using natural frequency passes the false-positive tests, and effectively detect the anomalous condition of structure under varying temperature.

Abstract: The steel-concrete hybrid structure is a new special industrial structure in large thermal power plants. It is composed of a spatial steel truss and steel-concrete tubular columns. Its stiffness and mass is highly non-uniform at vertical direction. Its temperature effect is obvious because its steel truss is a high order statically indeterminate structure. Types and characteristics of temperature load prescribed in codes are introduced. Temperature effect of the steel-concrete hybrid structure is calculated by FEM analysis software SAP2000 in four different supporting blocks. The structural internal force and distortion under temperature effect is analyzed. The influence of supporting blocks on the structual temperature effect is analyzed. The structural supporting block form to advantageously release its temperature effect is presented. Some advice is presented based on the analysis results.

Abstract: The Mg-Sn-Ca alloys have shown superior creep properties compared to the creep resistant alloy AE42. In the present study, the effects of small amounts of Al and Si additions on the mechanical properties have been investigated on a Mg-3Sn-2Ca (TX32) alloy. The Al content in the selected alloys was 0.4 wt% and the Si content was varied from 0–0.8 wt% in steps of 0.2 wt.%. The alloys were cast in pre-heated permanent molds. Cylindrical specimens machined from the cast billets were tested in compression in the temperature range 25–250 °C at a strain rate of 0.0001 s–1. The alloy with 0.4 wt% Al shows an increased strength at all test temperatures compared with the TX32 base alloy. This is attributed to a solid solution strengthening of Al in Mg. The alloy with 0.4 wt% Al and 0.2 wt% Si has compressive strength that is closer to that of the TX32 alloy. However, increased additions of Si (from 0.4–0.8 wt%) reduce the strength, more significantly at higher temperatures.

Abstract: Statistical damage detection in a structure operating under different temperatures via vibration testing is addressed by means of a stochastic global model based approach. The approach relies upon novel global models of the Functionally Pooled (FP) form, which are capable of describing the dynamics under any temperature, and statistical decision making. In its present form the approach utilizes response (output–only) vibration data, although excitation–response data may be also used. Its effectiveness is confirmed via a large number of experiments performed on a smart composite beam under different temperatures within the [¡20; +20]oC range.

Abstract: This paper researches on the temperature effects of a fully-symmetrical micromachined gyroscope. The Young’s modulus and thermal expansion coefficient of silicon vary with the environment temperature, which affects the modes’ resonant frequencies of micromachined gyroscopes. The effects of temperature fluctuation on the modes’ resonant frequencies is simulated by the FEM software ANSYS. The simulation results show that the fully-symmetrical gyroscope’s resonance frequencies decrease with the increase of temperature and the decrease degree nearly 0.256Hz/°C, but the two modes’ resonance frequencies matches well. The micromachined gyroscope’s dynamic characteristics are tested. The resonant frequencies and the quality factor are reduced with the increase of temperature and the decrease degree of the fit linear about the resonant frequencies is 0.276 Hz/°C. The test results are in good accordance with the simulation results.