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Hiroshi Yoshihara - One of the best experts on this subject based on the ideXlab platform.
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Effect of the Specimen Configuration on the accuracy in measuring the shear modulus of western hemlock by torsional vibration test
Wood Science and Technology, 2020Co-Authors: Hiroshi Yoshihara, Makoto MarutaAbstract:The shear moduli of solid wood in longitudinal–tangential and longitudinal–radial planes were obtained by conducting a torsional vibration test and subsequent numerical analyses on western hemlock Specimens by fixing the thickness as 10 mm and varying the width and length in the ranges of 20–80 mm and 100–400 mm, respectively. In the numerical analyses, the shear modulus in the tangential–radial planes was varied, and its effect was also examined as well as those of the width and length of the model. The results obtained indicated that the effect of the shear modulus in the tangential–radial plane was enhanced as the width increased and the length decreased. However, the shear modulus in the wider plane of the Specimen could be obtained accurately by reducing the effect of the shear modulus in the tangential–radial plane when appropriate ranges of the width and length were determined. From the numerical and experimental results, the shear moduli in the longitudinal–tangential and longitudinal–tangential planes were accurately obtained when the width was in the range of 20–40 mm and the length was in the range of 250–400 mm.
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Effect of Specimen Configuration and orthotropy on the Young’s modulus of solid wood obtained from a longitudinal vibration test
Holzforschung, 2020Co-Authors: Hiroshi Yoshihara, Makoto MarutaAbstract:AbstractYoung’s modulus in the longitudinal direction was measured by a longitudinal vibration (LV) test on western hemlock Specimens with various length/width ratios. The effects of the Configuration and orthotropy of the Specimen on the measurement of Young’s modulus was investigated through subsequent finite element (FE) calculations. The experimental results suggested that Young’s modulus could not be obtained accurately when the length/width ratio of the Specimen was in a certain range. The FE calculations revealed that Young’s modulus in the transverse direction and Poisson’s ratio in the length-width plane, as well as the length/width ratio, affected the Young’s modulus value. However, the results showed that when the length/width ratio of the Specimen was larger than 10, Young’s modulus could be measured accurately with the LV test with a reduction in the effect of orthotropy.
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Effect of Specimen Configuration on the measurement of off-axis logarithmic decrement of solid wood measured by longitudinal and flexural vibration tests
Holzforschung, 2014Co-Authors: Hiroshi Yoshihara, Masahiro YoshinobuAbstract:Douglas fir (Pseudotsuga menziesii) lumber was tested in terms of off-axis modulus of elasticity (MOEₒff₋ₐₓᵢₛ) and off-axis logarithmic decrement (λₒff₋ₐₓᵢₛ) by longitudinal and flexural vibration (VTₗₒₙg and VTfₗₑₓ) methods. Similar to the results obtained in a previous study, these results indicate that the values of MOEₒff₋ₐₓᵢₛ are dependent on the length-to-width ratio of Specimens when the value of off-axis angle (θ) is approximately 15°. Although the λₒff₋ₐₓᵢₛ values are also dependent on the length-to-width ratio, the dependence is not pronounced over a specific range of θ. To measure the λₒff₋ₐₓᵢₛ value accurately, as well as the MOEₒff₋ₐₓᵢₛ value, the Specimen should be sufficiently slender.
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Effects of Specimen Configuration and measurement method of strain on the characterization of tensile properties of paper
Journal of Wood Science, 2014Co-Authors: Hiroshi Yoshihara, Masahiro YoshinobuAbstract:Uniaxial-tension tests of copy paper were conducted to measure the tensile properties, including Young’s modulus, proportional limit stress, and tensile strength in the machine direction (MD) and cross direction (CD) using straight and dog-bone-shaped Specimens. In the tests using the straight Specimen, the distance between the grips was varied. Additionally, the tensile strain was obtained from the crosshead movement and elongation between the lines photographed by a CCD camera. When using a straight Specimen in the MD, the grip distance influenced the Young’s modulus value, and the tensile strength was markedly lower than that of the dog-bone-shaped Specimen. In contrast, the tensile properties in the CD could be obtained even when using the straight Specimen while reducing the influence of stress concentration at the grip.
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interlaminar shear strength of medium density fiberboard obtained from asymmetrical four point bending tests
Construction and Building Materials, 2012Co-Authors: Hiroshi YoshiharaAbstract:Abstract The interlaminar shear strength was obtained by conducting an asymmetrical four-point bending test. Four types of Specimens including rectangular, side-grooved, side-tapered, and notched Specimens, were prepared. In the test, the span lengths varied, and the influence of the span length with respect to the Specimen depth was examined. The Specimen Configuration was also examined. The interlaminar shear strength was effectively obtained, except for the notched Specimens, when the span length was appropriately determined. When considering convenience in the preparation of the Specimen, the rectangular Specimen is particularly recommended, although the effective span length is restricted. In contrast, the side-tapered Specimen is particularly recommended when considering a wide range of span lengths, although the fabrication of the Specimen is somewhat time-consuming.
Motozo Hayakawa - One of the best experts on this subject based on the ideXlab platform.
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Effect of loading velocity and testing temperature on the fracture toughness of a SiCw/6061Al alloy composite
Materials Science and Engineering: A, 2000Co-Authors: Lei Wang, Toshiro Kobayashi, Hiroyuki Toda, Motozo HayakawaAbstract:Abstract The effects of loading velocity and testing temperature on the fracture toughness of a SiC whisker reinforced 6061 aluminum alloy composite were investigated. A precracked three-point bend Specimen Configuration was selected for fracture toughness measurement, with tests being conducted at loading velocities of 10 −2 –10 m s −1 , and from room temperature to 473 K. The results showed that the fracture toughness increases with increasing loading velocity, but, the difference with respect to room temperature is small, because the fracture toughness decreases slowly with the increase of testing temperature. The composite material failed mainly by whisker pull-out and whisker breaking.
Makoto Maruta - One of the best experts on this subject based on the ideXlab platform.
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Effect of the Specimen Configuration on the accuracy in measuring the shear modulus of western hemlock by torsional vibration test
Wood Science and Technology, 2020Co-Authors: Hiroshi Yoshihara, Makoto MarutaAbstract:The shear moduli of solid wood in longitudinal–tangential and longitudinal–radial planes were obtained by conducting a torsional vibration test and subsequent numerical analyses on western hemlock Specimens by fixing the thickness as 10 mm and varying the width and length in the ranges of 20–80 mm and 100–400 mm, respectively. In the numerical analyses, the shear modulus in the tangential–radial planes was varied, and its effect was also examined as well as those of the width and length of the model. The results obtained indicated that the effect of the shear modulus in the tangential–radial plane was enhanced as the width increased and the length decreased. However, the shear modulus in the wider plane of the Specimen could be obtained accurately by reducing the effect of the shear modulus in the tangential–radial plane when appropriate ranges of the width and length were determined. From the numerical and experimental results, the shear moduli in the longitudinal–tangential and longitudinal–tangential planes were accurately obtained when the width was in the range of 20–40 mm and the length was in the range of 250–400 mm.
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Effect of Specimen Configuration and orthotropy on the Young’s modulus of solid wood obtained from a longitudinal vibration test
Holzforschung, 2020Co-Authors: Hiroshi Yoshihara, Makoto MarutaAbstract:AbstractYoung’s modulus in the longitudinal direction was measured by a longitudinal vibration (LV) test on western hemlock Specimens with various length/width ratios. The effects of the Configuration and orthotropy of the Specimen on the measurement of Young’s modulus was investigated through subsequent finite element (FE) calculations. The experimental results suggested that Young’s modulus could not be obtained accurately when the length/width ratio of the Specimen was in a certain range. The FE calculations revealed that Young’s modulus in the transverse direction and Poisson’s ratio in the length-width plane, as well as the length/width ratio, affected the Young’s modulus value. However, the results showed that when the length/width ratio of the Specimen was larger than 10, Young’s modulus could be measured accurately with the LV test with a reduction in the effect of orthotropy.
David N. Brewer - One of the best experts on this subject based on the ideXlab platform.
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Analytical stress intensity solution for the stable Poisson loaded Specimen
International Journal of Fracture, 1993Co-Authors: Louis J. Ghosn, Anthony M. Calomino, David N. BrewerAbstract:An analytical calibration of the Stable Poisson Loaded (SPL) Specimen is presented. The Specimen Configuration is similar to the ASTM E-561 compact-tension Specimen with displacement controlled wedge loading used for R -curve determination. The crack mouth opening displacements (CMOD's) are produced by the diametral expansion of an axially compressed cylindrical pin located in the wake of a machined notch. Due to the unusual loading Configuration, a three-dimensional finite element analysis was performed with gap elements simulating the contact between the pin and Specimen. In this report, stress intensity factors, CMOD's, and crack displacement profiles, are reported for different crack lengths and different contacting conditions. It was concluded that the computed stress intensity factor decreases sharply with increasing crack length thus making the SPL Specimen Configuration attractive for fracture testing of brittle, high modulus materials.
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Numerical calibration of the stable poisson loaded Specimen
1992Co-Authors: Louis J. Ghosn, Anthony M. Calomino, David N. BrewerAbstract:An analytical calibration of the Stable Poisson Loaded (SPL) Specimen is presented. The Specimen Configuration is similar to the ASTM E-561 compact-tension Specimen with displacement controlled wedge loading used for R-Curve determination. The crack mouth opening displacements (CMOD's) are produced by the diametral expansion of an axially compressed cylindrical pin located in the wake of a machined notch. Due to the unusual loading Configuration, a three-dimensional finite element analysis was performed with gap elements simulating the contact between the pin and Specimen. In this report, stress intensity factors, CMOD's, and crack displacement profiles are reported for different crack lengths and different contacting conditions. It was concluded that the computed stress intensity factor decreases sharply with increasing crack length, thus making the SPL Specimen Configuration attractive for fracture testing of brittle, high modulus materials.
R Sivakumar - One of the best experts on this subject based on the ideXlab platform.
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studies on short fatigue crack growth behavior of a plain carbon steel using a new Specimen Configuration
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: N Narasaiah, R SivakumarAbstract:A simple experimental technique has been developed to examine short crack growth behavior vis-a-vis microstructural features of a material. The procedure involves the use of a new Specimen Configuration, fatigue testing with the help of a rotating bending machine and optical microscopic examination of crack profiles and their associated microstructures using an image analyzer. The growth characteristics of several small fatigue cracks in a 0.25% carbon steel have been studied using this technique. The critical crack lengths above which linear elastic fracture mechanics may be applicable, the fatigue threshold values at the transition of short to long cracks and the influence of microstructure on the crack path have been examined. The estimated critical crack lengths are considered to be dependent on the nature of the short cracks; but the fatigue threshold values obtained from short crack growth experiments are found to lie in a narrow range. The cracks were found to have affinity to grow through interfaces, but the length of a crack passing through a specific phase was found to be approximately proportional to the amount of the latter.