Topic
Stress concentration
About: Stress concentration is a research topic. Over the lifetime, 23250 publications have been published within this topic receiving 422911 citations.
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TL;DR: In this paper, the use of embedded optical fiber Bragg gratings to measure strain near a stress concentration within a solid structure was investigated, and it was shown that the form of the spectra in transmission varies between gages that are at different distances from the notch tip under given loading conditions.
Abstract: This paper investigates the use of embedded optical fiber Bragg gratings to measure strain near a stress concentration within a solid structure. Due to the nature of a stress concentration (i.e., the strong nonuniformity of the strain field), the assumption that the grating spectrum in reflection remains a single peak with a constant bandwidth is not valid. Compact tension specimens including a controlled notch shape are fabricated, and optical fiber Bragg gratings with different gage lengths are embedded near the notch tip. The form of the spectra in transmission varies between gages that are at different distances from the notch tip under given loading conditions. This variation is shown to be due to the difference in the distribution of strain along the gage length. By using the strain field measured using electronic speckle pattern interferometry on the specimen surface and a discretized model of the grating, the spectra in transmission are then calculated analytically. For a known strain distribution, it is then shown that one can determine the magnitude of the applied force on the specimen. Thus, by considering the nonuniformity of the strain field, the optical fiber Bragg gage functions well as an embedded strain gage near the stress concentration.
124 citations
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01 Jan 1986124 citations
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TL;DR: In this paper, the low cycle fatigue and fatigue crack propagation of Inconel 718 alloy and Waspaloy were investigated at 25, 550 and 650 °C and the qualitative observations indicate that there exists a close correspondence between the near-threshold regime and stage I crack initiation in low-cycle fatigue.
124 citations
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TL;DR: In this paper, structural properties of NCF cross-ply laminates have been tested in tension and the effects of damage on mechanical properties are modelled using modified micro mechanical models developed for analysis of conventional laminated composites.
124 citations
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TL;DR: In this article, the tensile properties of isotactic polypropylene filled with particulate kaolin fillers were evaluated in the composition range 0-60 wt % kaolin. And the authors attributed the restriction on the molecular mobility of the polymer imposed by kaolin particles.
Abstract: Tensile properties of isotactic polypropylene filled with particulate kaolin fillers were evaluated in the composition range 0–60 wt % kaolin. Tensile modulus increased with filler concentration while breaking elongation and tensile strength decreased. The modulus increase was attributed to the restriction on the molecular mobility of the polymer imposed by kaolin particles. The decrease in elongation was also an effect of this restriction coupled with interference to stress transfer by the filler particles. Generation of discontinuity in the composite structure through formation of stress concentration points accounted for the tensile strength decrease. Morphology studies by SEM also indicated the introduction of stress concentration points by the presence of bare and nonadherent kaolin particles and their agglomerates with sharp edges in these composites.
124 citations