Abstract
High-temperature ceramic matrix composites (CMCs) are widely used in hot section components of aeroengine, and random loads have an important effect on their safety and reliability during aircraft operation. The current fatigue life prediction model of CMC is divided into macrophenomenon model and microdamage mechanism model. In this chapter, the fatigue life of fiber-reinforced ceramic matrix composites is investigated. The fatigue life of the fiber-reinforced ceramic matrix composites is predicted by micromechanical methods. The effect of random loading on fatigue life is analyzed and compared with constant peak stress fatigue life. The influence of composite constitutive properties on fatigue fracture is also discussed.
Highlights
Ceramic matrix composites (CMCs) have a great potential as high-temperature structural materials, especially as materials used in aerospace vehicles with special parts which need to bear a very high temperature
According to the fatigue fracture mechanism of composite under cyclic load, the life prediction model of composite is established, and an external load is applied to study the influence of random load on fatigue life prediction of hightemperature ceramic matrix composites
The addition of a random load at the Nth cycle can be considered to be the addition of a new peak stress higher than the original peak stress at the Nth cycle, which is approximately equivalent to cycling the random load as the constant peak stress, calculating the difference between its increased fiber failure probability at the Nth cycle relative to the fiber failure probability increased by the original peak stress at the Nth cycle k, and adding the k to the fiber failure rate after the first cycle
Summary
In the rapid progress and development of science and technology, the requirements of the use environment of the required materials are increasing. The main materials of aeroengine combustion chamber, turbine, and other high-temperature structures are still superalloys, cooling and thermal barrier coating technology is developing, but still cannot fully meet the requirements of engine hot-end components, so high-temperature ceramic-based composites are born. The application of ceramic matrix composite material structure to civil engine can reduce the amount of cooling air, increase the temperature and efficiency before turbine, and reduce the fuel consumption rate, so it can improve the economy of the engine. The new generation of military turboshaft GE3000 engine uses a ceramic matrix composite material, which reduces fuel consumption by 25% compared with T700 engine, reduces life cycle cost by 35%, prolongs life by 20%, and increases work-weight ratio by 65%. According to the fatigue fracture mechanism of composite under cyclic load, the life prediction model of composite is established, and an external load is applied to study the influence of random load on fatigue life prediction of hightemperature ceramic matrix composites
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