Foreign Object Impact Damage in Ceramic Matrix Composites: Experiments and Computational Predictions

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Rajesh S. Kumar ◽  
Matthew D. Mordasky

Abstract Foreign object impact of ceramic matrix composite (CMC) materials and components in a gas turbine engine environment could be detrimental to engine performance and hence must be accounted for in the design of such components. This paper is concerned with experiments and computational modeling of foreign object impact phenomenon in silicon carbide (SiC)-based CMC. Controlled impact experiments were conducted on the CMC material using a gas-gun apparatus with spherical hardened steel projectile. The internal damage state within the CMC specimens was assessed using X-ray computed tomography scan technique. The computational modeling involved explicit dynamic finite element (FE) simulation of the impact process wherein either delamination mechanism is modeled or both ply damage and delamination mechanisms are modeled in a coupled manner. The delamination mechanism is modeled explicitly using cohesive-zone (CZ) fracture mechanics approach, whereas, the ply-damage mechanisms are modeled implicitly using simplified continuum damage mechanics approach. The simulation results were found to be in reasonable qualitative and quantitative agreement with the experimental results. Furthermore, it is shown that modeling both the ply damage and delamination mechanisms are essential to predict the correct delamination pattern even for intermediate velocity impacts that leads to predominantly delamination damage. The predictive nature of the modeling approach is demonstrated and approaches to enhance the models are also discussed.

Author(s):  
Rajesh S. Kumar ◽  
Matthew M. Mordasky

Abstract Foreign object impact of Ceramic Matrix Composite (CMC) materials and components in a gas turbine engine environment could be detrimental to engine performance and hence must be accounted for in the design of such components. This paper is concerned with experiments and computational modeling of foreign object impact phenomenon in Silicon Carbide-based CMC. Controlled impact experiments were conducted on the CMC material using a gas-gun apparatus with spherical hardened steel projectile. The internal damage state within the CMC specimens was assessed using X-ray computed tomography scan technique. The computational modeling involved explicit dynamic finite element simulation of the impact process wherein either delamination mechanism is modeled or both ply damage and delamination mechanisms are modeled in a coupled manner. The delamination mechanism is modeled explicitly using cohesive-zone fracture mechanics approach, whereas, the ply damage mechanisms are modeled implicitly using simplified continuum damage mechanics approach. The simulation results were found to be in reasonable qualitative and quantitative agreement with the experimental results. Furthermore, it is shown that modeling both the ply damage and delamination mechanisms are essential to predict the correct delamination pattern even for intermediate velocity impacts that leads to predominantly delamination damage. The predictive nature of the modeling approach is demonstrated and approaches to enhance the models are also discussed.


Author(s):  
Peter H. Wilkins ◽  
Stephen P. Lynch ◽  
Karen A. Thole ◽  
San Quach ◽  
Tyler Vincent

Abstract Ceramic matrix composites (CMCs) are quickly becoming more prevalent in the design of gas turbines due to their advantageous weight and thermal properties. While there are many advantages, the CMC surface morphology differs from that of conventional cast airfoil components. Despite a great deal of research focused on the material properties of CMCs, little public work has been done to investigate the impact that the CMC surface morphology has on the boundary layer development and resulting heat transfer. In this study, a scaled-up CMC weave pattern was developed and tested in a low speed wind tunnel to evaluate both heat transfer and boundary layer characteristics. Results from these experiments indicate that the CMC weave pattern results in augmented heat transfer and flow field properties that significantly vary locally when compared to a smooth surface.


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.


1990 ◽  
Vol 112 (4) ◽  
pp. 492-501 ◽  
Author(s):  
D. E. Tripp ◽  
J. H. Hemann ◽  
J. P. Gyekenyesi

Ceramic matrix composites offer significant potential for improving the performance of turbine engines. In order to achieve their potential, however, improvements in design methodology are needed. In the past most components using structural ceramic matrix composites were designed by “trial and error” since the emphasis on feasibility demonstration minimized the development of mathematical models. To understand the key parameters controlling response and the mechanics of failure, the development of structural failure models is required. A review of short-term failure models with potential for ceramic matrix composite laminates under monotonic loads is presented. Phenomenological, semi-empirical, shear-lag, fracture mechanics, damage mechanics, and statistical models for the fast fracture analysis of continuous fiber unidirectional ceramic matrix composites under monotonic loads are surveyed.


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.


1994 ◽  
Vol 61 (2) ◽  
pp. 309-316 ◽  
Author(s):  
B. Audoin ◽  
S. Baste

After describing the crucial role of microcracking in the behavior of ceramic matrix composites, we introduce a phenomenological model in the framework of continuum damage mechanics, where damage is defined as the change of the tensor of elasticity. For damage identification, we have developed a specific ultrasonic device. This immersion set-up was connected to a suitable data processing system for an optimum recovery of the stiffness matrix coefficients from convenient sets of velocity measurements. Linked to a tensile machine, it enabled us to measure the stiffness changes and the anisotropic damage induced by a uniaxial tensile test.


Author(s):  
Sung R. Choi ◽  
D. Calvin Faucett

The combined effects of CMAS (calcium magnesium aluminosilicate) and FOD (foreign object damage) were determined in three different ceramic matrix composites (CMCs), two melt-infiltrated (MI) SiC/SiCs and one oxide/oxide. Foreign object damage was introduced at ambient temperature in CMC test targets using 1.6 mm steel ball projectiles at an impact velocity of 340 m/s utilizing a ballistic impact gun. One type of target support, partial support, was used. The impact-damaged test coupons were then CMAS-exposed at 1200°C for 10 hrs in air. Additional tests were also performed by exposing impact-damaged test coupons to a mixture of CMAS and salt (sodium sulfate) at 1200°C for 10 hrs in air. The combined effects of FOD and CMAS or CMAS/salt were quantified by determining the residual strengths of test coupons after exposures. Also, six different sands ingested into aeroengines were analyzed in their chemical compositions. The melt CMAS solid, melted at 1300°C and solidified, was assessed in its mechanical properties of microhardness and fracture toughness.


Author(s):  
Craig Iwano ◽  
Brian Sullivan ◽  
Michelle Hoo Fatt

Under a Phase II Navy SBIR program, Materials Research & Design (MR&D) performed an integrated analytical, fabrication and experimental program in order to develop foreign object damage (FOD) resistant silicon carbide (SiC) fiber-based ceramic matrix composites (CMCs), specifically 2D tape SiC/SiC. MR&D believes strongly that the most efficient approach towards the development of FOD-resistant CMCs is to develop a mathematical simulation of the impact event which can be correlated to measured responses and observed failures. Once correlated with available test data, the developed math model was used as part of an Integrated Computational Materials Engineering (ICME) approach to analytically investigate modifications to baseline CMC material in an attempt to identify which properties best influenced FOD resistance. The best candidate material modifications were then selected for fabrication and experimental validation. When considering all of the numerical and empirical data (visible damage, rebound velocity (energy absorption), strain data, NDE inspection and residual strength testing), all of the MR&D-proposed material modifications demonstrated improved FOD resistance when compared to the baseline CMC material.


2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Peter H. Wilkins ◽  
Stephen P. Lynch ◽  
Karen A. Thole ◽  
San Quach ◽  
Tyler Vincent

Abstract Ceramic matrix composites (CMCs) are quickly becoming more prevalent in the design of gas turbines due to their advantageous weight and thermal properties. While there are many advantages, the CMC surface morphology differs from that of conventional cast airfoil components. Despite a great deal of research focused on the material properties of CMCs, little public work has been done to investigate the impact that the CMC surface morphology has on the boundary layer development and resulting heat transfer. In this study, a scaled-up CMC weave pattern was developed and tested in a low-speed wind tunnel to evaluate both heat transfer and boundary layer characteristics. Results from these experiments indicate that the CMC weave pattern results in augmented heat transfer and flow field properties that significantly vary locally when compared with a smooth surface.


Author(s):  
David E. Tripp ◽  
John H. Hemann ◽  
John P. Gyekenyesi

Ceramic matrix composites offer significant potential for improving the performance of turbine engines. In order to achieve their potential, however, improvements in design methodology are needed. In the past most components using structural ceramic matrix composites were designed by “trial and error” since the emphasis on feasibility demonstration minimized the development of mathematical models. To understand the key parameters controlling response and the mechanics of failure, the development of structural failure models is required. A review of short term failure models with potential for ceramic matrix composite laminates under monotonic loads is presented. Phenomenological, semi-empirical, shear-lag, fracture mechanics, damage mechanics, and statistical models for the fast fracture analysis of continuous fiber unidirectional ceramic matrix composites under monotonic loads are surveyed.


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