Foreign Object Damage in an N720/Alumina Oxide/Oxide Ceramic Matrix Composite

Author(s):  
Sung R. Choi ◽  
David C. Faucett ◽  
Donald J. Alexander
Author(s):  
Nesredin Kedir ◽  
David Faucett ◽  
Luis Sanchez ◽  
Sung R. Choi

Foreign object damage (FOD) behavior of an N720/alumina oxide/oxide ceramic matrix composite (CMC) was characterized at ambient temperature by using spherical projectiles impacted at velocities ranging from 100 to 350 m/s. The CMC targets were subject to ballistic impact at a normal incidence angle while being loaded under different levels of tensile loading in order to simulate conditions of rotating aeroengine airfoils. The impact damage of frontal and back surfaces was assessed with respect to impact velocity and load factor. Subsequent post-impact residual strength was also estimated to determine quantitatively the severity of impact damage. Impact force was predicted based on the principles of energy conservation.


Author(s):  
Nesredin Kedir ◽  
David Faucett ◽  
Luis Sanchez ◽  
Sung R. Choi

Foreign object damage (FOD) behavior of an N720/alumina oxide/oxide ceramic matrix composite (CMC) was characterized at ambient temperature by using spherical projectiles impacted at velocities ranging from 100 to 350 m/s. The CMC targets were subject to ballistic impact at a normal incidence angle while being loaded under different levels of tensile loading in order to simulate conditions of rotating aeroengine airfoils. The impact damage of frontal and back surfaces was assessed with respect to impact velocity and load factor. Subsequent postimpact residual strength was also estimated to determine quantitatively the severity of impact damage. Impact force was predicted based on the principles of energy conservation.


Author(s):  
Michael J. Presby ◽  
Nesredin Kedir ◽  
Luis J. Sanchez ◽  
D. Calvin Faucett ◽  
Sung R. Choi ◽  
...  

The life-limiting behavior of an N720/alumina oxide/oxide ceramic matrix composite (CMC) was assessed in tension in air at 1200°C for unimpacted and impacted specimens. CMC targets were subjected to ballistic impact at ambient temperature with an impact velocity of 250 m/s under a full support configuration. Subsequent post-impact ultimate tensile strength was determined as a function of test rate in order to determine the susceptibility to delayed failure, or slow crack growth (SCG). Unimpacted and impacted specimens exhibited a significant dependency of ultimate tensile strength on test rate such that the ultimate tensile strength decreased with decreasing test rate. Damage was characterized using x-ray computed tomography (CT), and scanning electron microscopy (SEM). A phenomenological life prediction model was developed in order to predict life from one loading condition (constant stress-rate loading) to another (constant stress loading). The model was verified in part via a theoretical preloading analysis.


Author(s):  
Michael J. Presby ◽  
Nesredin Kedir ◽  
Luis J. Sanchez ◽  
D. Calvin Faucett ◽  
Sung R. Choi ◽  
...  

The life-limiting behavior of an N720/alumina oxide/oxide ceramic matrix composite (CMC) was assessed in tension in air at 1200 °C for unimpacted and impacted specimens. CMC targets were subjected to ballistic impact at ambient temperature with an impact velocity of 250 m/s under a full support configuration. Subsequent postimpact ultimate tensile strength was determined as a function of test rate in order to determine the susceptibility to delayed failure or slow crack growth (SCG). Unimpacted and impacted specimens exhibited a significant dependency of ultimate tensile strength on test rate such that the ultimate tensile strength decreased with decreasing test rate. Damage was characterized using X-ray computed tomography (CT) and scanning electron microscopy (SEM). A phenomenological life prediction model was developed in order to predict life from one loading condition (constant stress-rate loading) to another (constant stress loading). The model was verified in part via a theoretical preloading analysis.


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