Topic
Indentation
About: Indentation is a research topic. Over the lifetime, 13002 publications have been published within this topic receiving 340476 citations.
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TL;DR: In this article, a systematic study of depth-sensing indentation was performed on nanocrystalline (nc) Ni-W alloys specially synthesized with controlled unidirectional gradients in plastic properties.
Abstract: A systematic study of depth-sensing indentation was performed on nanocrystalline (nc) Ni–W alloys specially synthesized with controlled unidirectional gradients in plastic properties. A yield strength gradient and a roughly constant Young's modulus were achieved in the nc alloys, using electrodeposition techniques. The force vs. displacement response from instrumented indentation experiments matched very well with that predicted from the analysis of Part I of this paper. The experiments also revealed that the pile-up of the graded alloy around the indenter is noticeably higher than that for the two homogeneous reference alloys that constitute the bounding conditions for the graded material. These trends are also consistent with the predictions of the indentation analysis.
74 citations
TL;DR: It was found that 'slow cooling' generated the least temperature difference between inner and outer surfaces of porcelain, and 'slow cool' significantly reduced the formation of residual stress for all pressed ceramics.
74 citations
TL;DR: In this paper, the strength and fracture of a directionally solidified Y3Al5O12/Al2O3 eutectic fiber was investigated using X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy.
Abstract: The strength and fracture of a directionally solidified Y3Al5O12/Al2O3 eutectic fiber were investigated. The fiber was grown continuously by an edge-defined film-fed growth technique. The microstructure was characterized using X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The tensile strength and Weibull's modulus of the eutectic fibers were determined in the as-fabricated state and after extended thermal exposure at 1460°C in air. Fractographic analysis was used to identify and classify the strength-limiting mechanisms. The fracture toughness and crack growth behavior were characterized by an indentation technique. A fracture mechanics analysis was also used to establish the relationships between surface flaw size, tensile strength, and fracture toughness of the fiber.
74 citations
TL;DR: In this article, a silicon microdevice is used for the in situ quantitative mechanical characterization of single 1-D nanomaterials within a scanning electron microscope equipped with a quantitative nanoindenter.
Abstract: We report on the development and application of a silicon microdevice for the in situ quantitative mechanical characterization of single 1-D nanomaterials within a scanning electron microscope equipped with a quantitative nanoindenter. The design makes it possible to convert a compressive nanoindentation force applied to a shuttle to uniaxial tension on a specimen attached to a sample stage. Finite-element analysis and experimental calibration have been employed to extract the specimen stress versus strain curve from the indentation load versus displacement curve. The stress versus strain curves for three 200-300-nm-diameter Ni nanowire specimens are presented and analyzed.
74 citations
TL;DR: In this paper, a closed form solution for cracking induced by expansion of a two-dimensional cavity is used to bring out essential features related to parametric dependence and scaling, and a three-dimensional axisymmetric problem for an annular crack driven by a rigid spherical or conical indenter is solved using numerical methods.
Abstract: The mechanics governing the lateral cracks that form when a hard object plastically penetrates a ceramic is presented. The roles of indentation load, penetration depth, and work of indentation are all highlighted, as are the influences of the mechanical properties of the material. A closed form solution for cracking induced by expansion of a two-dimensional cavity is used to bring out essential features related to parametric dependence and scaling. The three-dimensional axisymmetric problem for an annular crack driven by a rigid spherical or conical indenter is solved using numerical methods. The region of highest tensile stress is identified corresponding to the location where a crack is most likely to nucleate. This location coincides with the depth below the surface where the crack will expand parallel to the surface under mode I conditions. The solutions have been substantiated by comparison with measurements of the cracks that form upon Vickers indentation. The basic formula for the crack radius has been used to predict trends in cracking upon static penetration and impact by a projectile. In both cases, the extent of the cracking is substantially diminished by increasing the toughness of the material. The yield strength has a much smaller effect. The cracks caused by penetration and the volume removed per impact both decrease marginally at higher yield strength.
73 citations