Crack Opening Displacement as a Criterion for Crack Propagation in Thermal Barrier Coatings

2009 ◽  
Author(s):  
Bhavani Sankar ◽  
Prasanna Thiyagasundaram
Keyword(s):  
Crack Propagation ◽  
Crack Opening Displacement ◽  
Thermal Barrier Coatings ◽  
Crack Opening ◽  
Thermal Barrier ◽  
Opening Displacement ◽  
Barrier Coatings

A LIFE PREDICTION MODEL OF THERMAL BARRIER COATINGS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 3161-3166 ◽  
Author(s):  
LIYONG NI ◽  
CHAO LIU ◽  
CHUNGEN ZHOU
Keyword(s):  
Crack Propagation ◽  
Prediction Model ◽  
Thermal Barrier Coatings ◽  
Life Prediction ◽  
Crack Propagation Rate ◽  
Thermal Barrier ◽  
Critical Crack ◽  
Critical Crack Length ◽  
Barrier Coatings ◽  
Life Prediction Model

The durability and reliability of thermal barrier coatings(TBCs) have become a major concern of hot-section components due to lack of a reliable life prediction model. In this paper, it is found that the failure location of TBCs is at the TBC/TGO interface by a sequence of crack propagation and coalescence process. The critical crack length of failure samples is 8.8mm. The crack propagation rate is 3-10µm/cycle at the beginning and increases largely to 40µm/cycle near coating failure. A life prediction model based a simple fracture mechanics approach is proposed.

scholarly journals Effect of Thickness on Fatigue Crack Propagation in Injection Molded Short Carbon Fiber Reinforced Plastics

2018 ◽  
Vol 165 ◽  
pp. 07002 ◽  
Author(s):  
Kenichi Shimizu ◽  
Yuya Hasegawa ◽  
Keisuke Tanaka
Keyword(s):  
Carbon Fiber ◽  
Crack Propagation ◽  
Crack Opening Displacement ◽  
Crack Opening ◽  
Plate Thickness ◽  
Fiber Reinforced ◽  
Opening Displacement ◽  
Short Carbon Fiber ◽  
Carbon Fiber Reinforced ◽  
Short Carbon

The influence of plate thickness on the fatigue crack propagation behavior was studied by using center-notched specimens which were cut from injection-molded plates of short carbon-fiber reinforced polyphenylene sulfide (PPS) at two fiber angles relative to the molding flow direction (MFD), i. e. θ=0 deg. (MD), 90 deg. (TD). The short carbon-fiber reinforced plastics (SCFRP) plates have three-layer structure where the fiber orientation is parallel to MFD in the shell layer and is nearly perpendicular in the core layer. The fraction of the core layer increases with increase in the plate thickness. In the relation between the crack propagation rate, da/dN, and stress intensity factor, ΔK, da/dN increases with increase in thickness for MD specimen. Conversely, da/dN decreases for TD specimen. The crack opening displacement along the crack was measured by using the digital image correlation (DIC) method. The measured crack opening displacement become larger with increase in the plate thickness for MD specimens. Contrary, measured values become smaller with increase in the plate thickness for TD specimen. The crack-tip-opening radius, Δρ, was estimated from the parabolic approximation of the crack opening displacement distribution near the crack tip. The relationships between da/dN and Δρ for all specimens tend to merge into a unique relationship.

scholarly journals A Simulation Study on the Crack Propagation Behavior of Nanostructured Thermal Barrier Coatings with Tailored Microstructure

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 722
Author(s):  
Lei Zhang ◽  
Yu Wang ◽  
Wei Fan ◽  
Yuan Gao ◽  
Yiwen Sun ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Crack Propagation ◽  
Thermal Barrier Coatings ◽  
Element Model ◽  
Nano Particles ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Propagation Behavior ◽  
Stress Zone ◽  
Crack Propagation Behavior

The initiation and propagation of cracks are crucial to the reliability and stability of thermal barrier coatings (TBCs). It is important and necessary to develop an effective method for the prediction of the crack propagation behavior of TBCs. In this study, an extended finite element model (XFEM) based on the real microstructure of nanostructured TBCs was built and employed to elucidate the correlation between the microstructure and crack propagation behavior. Results showed that the unmelted nano-particles (UNPs) that were distributed in the nanostructured coating had an obvious “capture effect” on the cracks, which means that many cracks easily accumulated in the tensile stress zone of the adjacent UNPs and a complex microcrack network formed at their periphery. Arbitrarily oriented cracks mainly propagated parallel to the x-axis at the final stage of thermal cycles and the tensile stress was the main driving force for the spallation failure of TBCs. Correspondingly, I and I–II mixed types of cracks are the major cracking patterns.

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