The Effects of Cooling Holes on SiC/SiC CMC Tensile Strength

2020 ◽  
Author(s):  
Craig Smith ◽  
Michael Presby ◽  
Ramakrishna Bhatt ◽  
Sreeramesh Kalluri
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Film Cooling ◽  
Mechanical Test ◽  
Engine Performance ◽  
Ceramic Matrix Composites ◽  
Image Correlation ◽  
Matrix Composites ◽  
High Temperature Components ◽  
Multiple Holes

Abstract Silicon Carbide fiber-reinforced Silicon Carbide (SiC/SiC) Ceramic Matrix Composites (CMCs) are currently operating in select high temperature components of turbine engines. Primary benefits of CMCs compared to metals are improved temperature capability, reduced cooling requirements and reduced component weight. High temperature materials require less cooling air to be diverted from the compressor, resulting in improved engine performance. However, some amount of film cooling may be necessary when CMCs are implemented in higher temperature applications. Film cooling requires holes to be fabricated at appropriate locations and orientations within these components. It is important to understand how such holes will affect the material properties. While previous studies have shown that CMCs are notch insensitive, the effect of multiple holes and different hole orientations on SiC/SiC CMCs is not well documented. This study examines the effect of cooling holes on SiC/SiC tensile properties. Several hole geometries fabricated in SiC/SiC samples are explored. Mechanical test data on specimens with multiple holes is reported for tensile loading at room temperature. Tools such as Digital Image Correlation (DIC) and Acoustic Emission (AE) are used to monitor strain and cracking in the CMC upon loading.

scholarly journals Advances in Damage Monitoring Techniques for the Detection of Failure in SiCf/SiC Ceramic Matrix Composites

Ceramics ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 347-371 ◽  
Author(s):  
Martin R. Bache ◽  
Christopher D. Newton ◽  
John Paul Jones ◽  
Stephen Pattison ◽  
Louise Gale ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Fatigue Loading ◽  
Industrial Applications ◽  
Image Correlation ◽  
Full Potential ◽  
Matrix Composites ◽  
Monitoring Techniques ◽  
Macro Scale

From a disruptive perspective, silicon carbide (SiC)-based ceramic matrix composites (CMCs) provide a considerable temperature and weight advantage over existing material systems and are increasingly finding application in aerospace, power generation and high-end automotive industries. The complex structural architecture and inherent processing artefacts within CMCs combine to induce inhomogeneous deformation and damage prior to ultimate failure. Sophisticated mechanical characterisation is vital in support of a fundamental understanding of deformation in CMCs. On the component scale, “damage tolerant” design and lifing philosophies depend upon laboratory assessments of macro-scale specimens, incorporating typical fibre architectures and matrix under representative stress-strain states. This is important if CMCs are to be utilised to their full potential within industrial applications. Bulk measurements of strain via extensometry or even localised strain gauging would fail to characterise the ensuing inhomogeneity when performing conventional mechanical testing on laboratory scaled coupons. The current research has, therefore, applied digital image correlation (DIC), electrical resistance monitoring and acoustic emission techniques to the room and high-temperature assessment of ceramic matrix composites under axial tensile and fatigue loading, with particular attention afforded to a silicon carbide fibre-reinforced silicon carbide composite (SiCf/SiC) variant. Data from these separate monitoring techniques plus ancillary use of X-ray computed tomography, in-situ scanning electron microscopy and optical inspection were correlated to monitor the onset and progression of damage during mechanical loading. The benefits of employing a concurrent, multi-technique approach to monitoring damage in CMCs are demonstrated.

Detection of Strain and Damage Distribution in SiCf/SiC Mechanical Test Coupons

2018 ◽  
Author(s):  
Christopher D. Newton ◽  
J. Paul Jones ◽  
Louise Gale ◽  
Martin R. Bache
Keyword(s):  
Mechanical Test ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Fatigue Loading ◽  
Image Correlation ◽  
Matrix Composites ◽  
Macro Scale ◽  
Ultimate Failure ◽  
Complex Structural ◽  
Structural Architecture

The complex structural architecture and inherent processing artefacts within ceramic matrix composites combine to induce inhomogeneous deformation and damage prior to ultimate failure. Sophisticated mechanical characterisation is vital in support of a fundamental understanding of deformation in ceramic matrix composites. On the component scale, “damage tolerant” design and lifing philosophies depend upon laboratory assessments of macro-scale specimens, incorporating typical fibre architectures and matrix under representative stress-strain states. Bulk measurements of strain via extensometry or even localised strain gauging will fail to characterise such inhomogeneity when performing conventional mechanical testing on laboratory scaled coupons. The current research project has, therefore, applied digital image correlation (DIC), electrical resistance monitoring and acoustic emission techniques to the room and high temperature assessment of a SiCf/SiC composite under axial fatigue loading. Data from these separate monitoring techniques plus ancillary use of X-Ray computed tomography and optical inspection were correlated to monitor the onset and progression of damage during cyclic loading.

Rewiew of Fracture and Fatigue in Ceramic Matrix Composites

2000 ◽  
Vol 53 (6) ◽  
pp. 147-174 ◽  
Author(s):  
Victor Birman ◽  
Larry W. Byrd
Keyword(s):  
High Temperature ◽  
State Of The Art ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Review Article ◽  
Successful Implementation ◽  
Matrix Composites ◽  
Recent Developments ◽  
Hostile Environments

A review of recent developments and state-of-the-art in research and understanding of damage and fatigue of ceramic matrix composites is presented. Both laminated as well as woven configurations are considered. The work on the effects of high temperature on fracture and fatigue of ceramic matrix composites is emphasized, because these materials are usually designed to operate in hostile environments. Based on a detailed discussion of the mechanisms of failure, the problems that have to be addressed for a successful implementation of ceramic matrix composites in design and practical operational structures are outlined. This review article includes 317 references.

Influence of Anisotropic Thermal Conductivity on Overall Cooling Effectiveness on a Film Cooled Leading Edge

2021 ◽  
pp. 1-22
Author(s):  
Carol Bryant ◽  
James L. Rutledge
Keyword(s):  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Film Cooling ◽  
Leading Edge ◽  
Ceramic Matrix Composites ◽  
Internal Cooling ◽  
Matrix Composites ◽  
Edge Region ◽  
Turbine Engine ◽  
Anisotropic Thermal Conductivity

Abstract Increasing interest in the use of ceramic matrix composites (CMCs) for gas turbine engine hot gas path components requires a thorough examination of the thermal behavior one may expect of such components. Their highly anisotropic thermal conductivity is a substantial departure from traditional metallic components and can influence the temperature distribution in surprising ways. With the ultimate surface temperature dependent upon the internal cooling scheme, including cooling from within the film cooling holes themselves, as well as the external film cooling, the relative influence of these contributions to cooling can be affected by the directionality of the thermal conductivity. Conjugate heat transfer computational simulations were performed to evaluate the effect of anisotropy in the leading edge region of a turbine component. The leading edge region is modeled as a fully film-cooled half cylinder with a flat afterbody. The anisotropic directionality of the thermal conductivity is shown to have a significant effect on the temperature distribution over the surface of the leading edge. While structural considerations with CMC components are often paramount, designers should be aware of the thermal ramifications associated with the selection of the CMC layup.

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