Material properties are obvious different between aluminum matrix composites and iron and steel materials. After the brake disk braked at the same speed, the average temperature of the aluminum brake disk is 1.5 times...Material properties are obvious different between aluminum matrix composites and iron and steel materials. After the brake disk braked at the same speed, the average temperature of the aluminum brake disk is 1.5 times as high as one of iron and steel brake disk, the thermal expansion value of the aluminum brake disk is 2 times as big as one of iron and steel brake disk. Mechanical property of the material decreases with the temperature increasing generally during braking, on the other hand, the big thermal stress in the brake disk happens because the material expansion is constrained. Firstly, the reasons of the thermal stress generation and the fracture failure of brake disks during braking are analyzed qualitatively by virtue of three-bar stress frame and sandwich deformation principles in physic, and then the five constraints which cause the thermal stress are summarized. On the base of the experimental results on the 1：1 emergency brake test, the thermal stress and temperature fields are simulated; The behavior of the fracture failure is interpreted semi-quantitatively by finite element analysis, There is the coincident forecast for the fraction position in term of the two methods. In the end, in the light of the analysis and calculation results, it is the general principles observed by the structure design and assembly of the brake disk that are summarized.展开更多
The micro gas turbine propulsion systems represent a good choice for the unmanned aerial vehicles(UAVs). The present work monitors the engine parameters, correlating them with other important engine instrumentation da...The micro gas turbine propulsion systems represent a good choice for the unmanned aerial vehicles(UAVs). The present work monitors the engine parameters, correlating them with other important engine instrumentation data. The aim of this research was to study the operation of the Jet CAT using various types of fuels under various operating conditions: normal acceleration and sudden acceleration. The measured parameters were monitored under different conditions:(A) Engine operation at two different ambient temperatures – outdoor at 0oC and inside at 19oC; and(B) Using 4 fuel types: kerosene, diesel fuel, kerosene with 5% gasoline and kerosene with 10% gasoline. The relevance of this work is given by the fact that a detailed analysis is performed for the idle regime. The paper will present the detailed test plan used and the most relevant charts with the obtained results for: start time, force, temperature before turbine, fuel flow, depending on micro turbo engine speed.展开更多
基金This project is supported by National Hi-tech Research and Development Program of China(863 Program,No.2003AA331190).
文摘Material properties are obvious different between aluminum matrix composites and iron and steel materials. After the brake disk braked at the same speed, the average temperature of the aluminum brake disk is 1.5 times as high as one of iron and steel brake disk, the thermal expansion value of the aluminum brake disk is 2 times as big as one of iron and steel brake disk. Mechanical property of the material decreases with the temperature increasing generally during braking, on the other hand, the big thermal stress in the brake disk happens because the material expansion is constrained. Firstly, the reasons of the thermal stress generation and the fracture failure of brake disks during braking are analyzed qualitatively by virtue of three-bar stress frame and sandwich deformation principles in physic, and then the five constraints which cause the thermal stress are summarized. On the base of the experimental results on the 1：1 emergency brake test, the thermal stress and temperature fields are simulated; The behavior of the fracture failure is interpreted semi-quantitatively by finite element analysis, There is the coincident forecast for the fraction position in term of the two methods. In the end, in the light of the analysis and calculation results, it is the general principles observed by the structure design and assembly of the brake disk that are summarized.
文摘The micro gas turbine propulsion systems represent a good choice for the unmanned aerial vehicles(UAVs). The present work monitors the engine parameters, correlating them with other important engine instrumentation data. The aim of this research was to study the operation of the Jet CAT using various types of fuels under various operating conditions: normal acceleration and sudden acceleration. The measured parameters were monitored under different conditions:(A) Engine operation at two different ambient temperatures – outdoor at 0oC and inside at 19oC; and(B) Using 4 fuel types: kerosene, diesel fuel, kerosene with 5% gasoline and kerosene with 10% gasoline. The relevance of this work is given by the fact that a detailed analysis is performed for the idle regime. The paper will present the detailed test plan used and the most relevant charts with the obtained results for: start time, force, temperature before turbine, fuel flow, depending on micro turbo engine speed.
