Characterisation of SiCf/SiC Specimens Using an In-Situ Tensile Stage Within a Scanning Electron Microscope

Jordan, Steven P.; Bache, M.R.; Newton, Christopher D.; Gale, Louise

doi:10.1115/gt2019-90356

Cited by 2 publications

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“…On occasion, the early onset of localised strain concentration in notched coupons can be significantly displaced away from the plane of the notch root and is controlled by local architecture and/or processing artefacts. Such behaviour has even been detected in samples with relatively high K t factor [17].…”

Section: Discussionmentioning

confidence: 84%

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

et al. 2019

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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.

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Section: Discussionmentioning

confidence: 84%

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

et al. 2019

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“…While the resolution of the in situ XCT technique here was insufficient to identify interfacial cracks and de-bond lengths, the quantified measure of crack opening space may aid the validation of analytical shear-lag models [17,18]. Such 2-D crack opening measurements have previously been achieved through surface SEM imaging [13], and XCT imaging of mini-composite specimens [19]. Since the damage volume measured here is a function of crack length, width and opening displacement, further manual segmentation would be required in order to extract relevant data.…”

Section: Discussionmentioning

confidence: 99%

“…It is acknowledged that crack widths below the voxel size cannot be detected and therefore the full extent of cracking may not been visualised. In future it may be necessary to explore correlations between the measured volumetric crack content via XCT and crack density measured via SEM imaging, and this is an active area of investigation within our labs [13]. Since crack density has a good correlation with tensile stress (and also with cumulative AE energy) [14], further investigations 2mm have been planned to assess the degree of accuracy and reliability of these volumetric crack quantifications, and also to investigate mechanical properties and remnant life predictions.…”

Section: Conventional Imagingmentioning

confidence: 99%

Volumetric assessment of fatigue damage in a SiCf/SiC ceramic matrix composite via in situ X-ray computed tomography

Quiney

Weston

Nicholson

et al. 2020

Journal of the European Ceramic Society

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To enhance the understanding of matrix cracking and damage progression on the macroscopic scale, within a 0/90º fibre reinforced SiCf/SiC ceramic matrix composite (CMC), X-ray computed tomography (XCT) imaging and analysis have been performed in conjunction with a commercially available in-situ mechanical loading device.CMC test coupons were subjected to tensile cyclic loads and inspected using XCT without removal from the tensile loading device. Attempts to measure and quantify the resulting damage using volumetric image analysis techniques are presented, by characterising the crack network from XCT images acquired at both the maximum and minimum load condition during selected fatigue cycles. The XCT detection of significant crack development within the first loading half-cycle shows good agreement with cumulative acoustic emission energy data recorded under similar test conditions. The results are seen as an important step towards correlating the damage behaviour detected via different NDE and health monitoring techniques.

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Characterisation of SiCf/SiC Specimens Using an In-Situ Tensile Stage Within a Scanning Electron Microscope

Cited by 2 publications

References 0 publications

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

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

Volumetric assessment of fatigue damage in a SiCf/SiC ceramic matrix composite via in situ X-ray computed tomography

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