MODELING FOREIGN OBJECT DAMAGE TO CVI Ml SIC/IBN/SIC AND OXIDE/OXIDE CERAMIC COMPOSITE COMPONENTS IN GAS TURBINE ENGINES AT AMBIENT AND ELEVATED TEMPERATURES

摘要

The inherent toughness of ceramic matrix composites (CMCs) in advanced gas-turbine engines must be predictable under impact from small foreign objects to lower the amount of full scale testing needed to produce robust designs. Fiber/matrix/architecture properties of the composites, and a damage evolution based progressive failure code that can be used for a full range of composite architectures (GENOA) coupled with an explicit FEM impact code (LS-DYNA) were used to simulate impact and residual 4pt flexural strength of the ceramic engine components. This approach uses physics-based mechanics coupled at the micro and macro scale boundaries. The benefit of this technique is that the root cause of damage advancement at the micromechanical level could be understood and simulations could be performed to assess better damage tolerance structures. Steel projectiles with a diameter of 1.59 mm were used to impact the composites at speeds from 100-400 m/s (Mach 0.3-1.2) and the results shown to compare to prior test data for 2-D 5H Sylramic iBN CVI MI SiC at 25°C and 1316°C and for 2-D 8H N720/AS ceramic composites at 25 °C. Simulations also gave insight to the micromechanical damage progression and were comparable with test data.