The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Eric M. Johnson - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Specimen Dimension on Residual Stress Relaxation of the Weldments
Advanced Materials Research, 2014Co-Authors: Zhongyuan Qian, L. Scott Chumbley, Eric M. JohnsonAbstract:The purpose of this study is to evaluate the residual stress relaxation behavior in weldments. The stress relaxation is studied while successively reducing the size of weld Specimens. Finite-element modeling was used to simulate the stress relaxation, and then an empirical model was derived based on the experimental and modeling results. The results of this study shall encourage industry users to utilize more plentiful conventional X-ray diffractometers for residual stress measurement of large weld components.
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The effect of Specimen Dimension on residual stress relaxation of carburized and quenched steels
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: Zhongyuan Qian, Scott Chumbley, Eric M. JohnsonAbstract:Abstract In this study X-ray diffraction was used to measure the redistribution of residual stress in carburized and heat treated AISI 8620 steel Specimens of different sizes during successive sectioning. Finite-element modeling was used to simulate the stress relaxation. Comparing the results of modeling to experimental results of ring-shaped Specimens shows that the residual stress relaxation associated with the size reduction was almost negligible. However, significant stress relaxation occurs while reducing the thickness of the Specimens. The results seen in ring-shaped test Specimens were verified by sectioning actual gear samples.
Zhongyuan Qian - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Specimen Dimension on Residual Stress Relaxation of the Weldments
Advanced Materials Research, 2014Co-Authors: Zhongyuan Qian, L. Scott Chumbley, Eric M. JohnsonAbstract:The purpose of this study is to evaluate the residual stress relaxation behavior in weldments. The stress relaxation is studied while successively reducing the size of weld Specimens. Finite-element modeling was used to simulate the stress relaxation, and then an empirical model was derived based on the experimental and modeling results. The results of this study shall encourage industry users to utilize more plentiful conventional X-ray diffractometers for residual stress measurement of large weld components.
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The effect of Specimen Dimension on residual stress relaxation of carburized and quenched steels
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: Zhongyuan Qian, Scott Chumbley, Eric M. JohnsonAbstract:Abstract In this study X-ray diffraction was used to measure the redistribution of residual stress in carburized and heat treated AISI 8620 steel Specimens of different sizes during successive sectioning. Finite-element modeling was used to simulate the stress relaxation. Comparing the results of modeling to experimental results of ring-shaped Specimens shows that the residual stress relaxation associated with the size reduction was almost negligible. However, significant stress relaxation occurs while reducing the thickness of the Specimens. The results seen in ring-shaped test Specimens were verified by sectioning actual gear samples.
Rainer Johe - One of the best experts on this subject based on the ideXlab platform.
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Tensile Testing of Nitinol Tubes and Wires with Higher Strain Rates
Journal of Materials Engineering and Performance, 2009Co-Authors: Rainer JoheAbstract:During tensile testing of superelastic Nitinol material, the Specimen temperature increases as result of the exothermic Austenite-to-Martensite phase transformation. The increase in Specimen temperature has great influence on the stress-strain response—in particular, upper and lower plateau values—and limits the strain rate of the tensile test, so that for larger Specimen Dimension, the strain rate has to be reduced. A special setup of the tensile testing equipment has been developed using a fan to improve the heat exchange between the Specimen and the ambiance to allow much higher strain rates as well as even gradient of the upper and lower plateau. It could be shown that the strain rate of the first loading and unloading cycle could be two to four times higher as recommended in ASTM F 2516-07 without any negative impact on the determined values. The needed time for tensile testing of Nitinol products could be reduced considerably. The improved heat exchange gives a better comparability and reproducibility of the tensile test data.
Scott Chumbley - One of the best experts on this subject based on the ideXlab platform.
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The effect of Specimen Dimension on residual stress relaxation of carburized and quenched steels
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: Zhongyuan Qian, Scott Chumbley, Eric M. JohnsonAbstract:Abstract In this study X-ray diffraction was used to measure the redistribution of residual stress in carburized and heat treated AISI 8620 steel Specimens of different sizes during successive sectioning. Finite-element modeling was used to simulate the stress relaxation. Comparing the results of modeling to experimental results of ring-shaped Specimens shows that the residual stress relaxation associated with the size reduction was almost negligible. However, significant stress relaxation occurs while reducing the thickness of the Specimens. The results seen in ring-shaped test Specimens were verified by sectioning actual gear samples.
R W Steinbrech - One of the best experts on this subject based on the ideXlab platform.
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threshold fracture stress of thin ceramic components
Journal of The European Ceramic Society, 2008Co-Authors: Jurgen Malzbender, R W SteinbrechAbstract:Strength is widely used as a design criterion to characterize the mechanical limits of brittle materials. However, depending on the flaw size distribution, measured strength values show considerable scatter. Statistically this spread can be represented for a specific Specimen Dimension using Weibull statistics with the characteristic strength, Weibull modulus and threshold strength. A comparison of three- and two-parameter Weibull approaches is exemplified using fracture stress results of thin bi-layer ceramic bending Specimens taken from solid oxide fuel cell (SOFC) components. Considering statistical parameters and the flaw size limiting thickness of the substrate layer in a SOFC, the three-parameter Weibull statistics is demonstrated to be more appropriate for the fracture characterization of thin ceramic components.