The Uniaxial Tensile Response of Porous and Microcracked Ceramic Materials

Pandey, Amit Kumar; Shyam, Amit; Watkins, Thomas R.; Stafford, Randy; Hemker, Kevin J.

doi:10.1111/jace.12720

Cited by 31 publications

(23 citation statements)

References 37 publications

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“…Microcracking is responsible for hysteresis in the thermal expansion and stiffness versus temperature curves (see data on magnesium titanate, aluminum titanate, NZP ceramics, and cordierite) and has been directly observed in SEM studies (e.g., Shyam et al; Harada). Microcracking is also responsible for the nonlinearity of the stress–strain curves, especially in porous ceramics . In comparing the lattice and macroscopic thermal expansions, Ohya et al could only calculate the microcrack volume, whereas Kobayashi et al, estimated the fraction (and crystal orientation) of microcracked grains; none of them attempted at calculating stresses.…”

Section: Microstresses Due To Cooling Of Polycrystalline Ceramics: Dementioning

confidence: 99%

Microstructure–Property Connections for Porous Ceramics: The Possibilities Offered by Micromechanics

Bruno

Kachanov

2016

J. Am. Ceram. Soc.

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Microstructure of porous ceramics is highly “irregular”: it comprises pores and microcracks of diverse shapes and orientations. This makes their quantitative modeling challenging, and one often resorts to empirical relations containing fitting parameters and having somewhat uncertain range of applicability. We review the substantial progress made in modeling of “irregular” microstructures that does not seem to have been sufficiently utilized in the context of ceramics. We discuss the possibilities offered by micromechanics in developing microstructure–property relations for porous microcracked ceramics. After an overview of relevant micromechanics topics, we focus on several issues of specific interest for ceramics: nonlinear stress–strain behavior, effective elastic properties, and thermally induced microcracking. We discuss extraction of microscale parameters (such as strength of the intergranular cohesion, density of cracks and pores, etc.) from macroscopic data and identify the extent of uncertainty in this process. We also argue that there is no quantitative correlation between fracturing process and the loss of elastic stiffness.

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Section: Microstresses Due To Cooling Of Polycrystalline Ceramics: Dementioning

confidence: 99%

Microstructure–Property Connections for Porous Ceramics: The Possibilities Offered by Micromechanics

Bruno

Kachanov

2016

J. Am. Ceram. Soc.

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“…Microtensile tests were conducted using an experimental set-up, as described in detail elsewhere [36]. The main components were a stepper motor (NEMA 23, National Instruments), a 111.1 N (25 lbs) load cell and a custom slider linear air bearing.…”

Section: Tensile Testing Of Microspecimensmentioning

confidence: 99%

“…Tests were performed under a displacement rate of 0.005 mm s À1 , corresponding to a deformation rate of $0.003 s À1 , and specimen plan view images were captured every second using a complementary metal oxide semiconductor camera. These images were post processed to calculate the 2-D strain maps using a Matlab Ò -based digital image correlation (DIC) program, as described elsewhere [36,[38][39][40]. Each build configuration was tested twice in order to improve the statistical reliability.…”

Section: Tensile Testing Of Microspecimensmentioning

confidence: 99%

Mechanical response and deformation mechanisms of ferritic oxide dispersion strengthened steel structures produced by selective laser melting

et al. 2015

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Oxide dispersion strengthened (ODS) ferritic steels typically contain a fine dispersion of nanoscopic Y(Al, Ti) oxides, leading to an improvement in mechanical and physical properties. A rapid prototyping technique, selective laser melting (SLM), was successfully applied to consolidate as-mechanically alloyed ODS-PM2000 (Fe-19Cr-5.5Al-0.5Ti-0.5Y 2 O 3 ; all wt.%) powder to fabricate solid and thin-walled builds of different thickness. This work is intended to act as a first study to investigate the tensile response of such configurations at room temperature, using miniaturized test specimens along and perpendicular to the growth direction. The 0.2% offset yield strength of as-grown wall builds was inferior to conventional PM2000 alloy (recrystallized), but could be significantly increased by conducting post-build heat treatments. Young's modulus and yield strength showed anisotropy and were enhanced when testing perpendicular to the build growth direction. Electron backscatter diffraction revealed a strong [0 0 1] fibre texture along the growth direction, which explains the anisotropic behaviour. Additionally, studies on the morphology of the individual fracture surfaces, the grain structure of the cross-section near this region and the size distribution of ODS particles in such builds were conducted. A fine dispersion of precipitates was retained in all SLM builds, and findings suggest that a certain amount of Y is probably still in atomic solution in the as-grown condition and forms new small nanoscopic dispersoids during annealing, which lead to enhanced strengthening.

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“…The acicular mullite investigated in this study had needles with a diameter of 10‐20 μm and a length of 200‐400 μm, but these values can vary depending on the precursor composition and dopants chosen . Mechanically, acicular mullite is much stiffer than traditional porous ceramic systems, particularly those commonly used in DPFs …”

Section: Methodsmentioning

confidence: 99%

Out‐of‐plane mechanical characterization of acicular mullite and aluminum titanate diesel particulate filters

Brodnik

Faber

2018

Int J Applied Ceramic Tech

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This study characterizes the flexural and compressive behavior of two porous ceramic honeycombs commonly used in diesel particulate filtration, acicular mullite and aluminum titanate. Compression along the axis normal to the honeycomb cross‐section, referred to as out‐of‐plane compression, is compared to in‐plane flexure. The relationship between these loading modes is assessed using the failure strength and elastic modulus of the honeycomb structure and the constituent wall material. Weibull analyzes showed that flexure and out‐of‐plane compression exhibit similar behavior in cases where failure is governed by a single flaw, such as in acicular mullite. However, in heavily microcracked systems like aluminum titanate, compressive failure occurs by damage accumulation rather than growth of a single flaw, so compressive failure strengths are higher than flexural ones. Buckling was also shown to occur in both systems, but the geometries required are unlikely to be encountered in practical application. In the context of filter life assessment, failure in flexure occurs at much lower stresses for systems that rely on microcracking to accommodate thermal strains, so flexure is better suited as an estimate of filter strength.

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The Uniaxial Tensile Response of Porous and Microcracked Ceramic Materials

Cited by 31 publications

References 37 publications

Microstructure–Property Connections for Porous Ceramics: The Possibilities Offered by Micromechanics

Microstructure–Property Connections for Porous Ceramics: The Possibilities Offered by Micromechanics

Mechanical response and deformation mechanisms of ferritic oxide dispersion strengthened steel structures produced by selective laser melting

Out‐of‐plane mechanical characterization of acicular mullite and aluminum titanate diesel particulate filters

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