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KOBAYASHI, Toshiro

doi:10.2464/jilm.54.333

Cited by 6 publications

(5 citation statements)

References 33 publications

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“…Concerning the three-point bending tests for the accurate determination of fracture toughness of brittle materials such as bone, no specifications regarding the size of a test specimen are established at present; there are also few reports on the effects of test specimen configuration, loading rate or related parameters on fracture toughness values. Kobayashi et al 14,15) have performed fracture toughness evaluation of ceramics (test specimen width: W ¼ 8 mm) and indicated that fracture toughness values increase with a plate thickness of B ¼ 4 mm or below and with increasing radius of the notch tip, where the process zone tends to also increase. Regarding cortical bone, American Society for Testing and Materials (ASTM)-compliant research was conducted by Niinomi et al 4) using a specimen with W ¼ 8 mm.…”

Section: Preparation and Preservation Of Fracture Toughnessmentioning

confidence: 99%

Effect of Different Preservative Methods on Fracture Behavior of Bovine Cortical Bone

et al. 2009

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Bone specimens used for evaluating the mechanical properties of bone may not have been necessarily preserved by the same method before they become available. To this end, the mechanical properties of bone may be affected by freezing, a common preservation method, as well as by formalin and other preservation solutions. In this study, bone specimens were preserved by different methods (i.e., freezing, preservation in saline, preservation in ethanol, and preservation in formalin) to examine the effects of each preservation method on the fracture characteristics of bovine femoral cortical bone. Regarding the crack extension behavior in the fracture toughness test, microcracks accumulated at the top of the slit in the low-load region before the maximum load was reached. When such accumulated microcracks grew to a visible size, a crack was formed from the top of the slit, and then grew with subsequent expansion of the processing zone. The fracture toughness values of the bone groups preserved in formalin and neutral buffered formalin were significantly lower than those of the bone groups preserved by other methods. As the fracture surface by scanning electron microscopic observations was smoother with a loading rate of 20 mm/min than with 1 mm/min, cracks were considered to develop easily, resulting in a lower fracture toughness value. Scanning electron microscopic observations of a test section subjected to a low loading rate showed that the fracture surface of the bone groups preserved in formalin or neutral buffered formalin was flat and smooth. In the other preservation groups, the lamellae adjacent to the top of the slit had undulating contours with plastic deformation. [

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Section: Preparation and Preservation Of Fracture Toughnessmentioning

confidence: 99%

Effect of Different Preservative Methods on Fracture Behavior of Bovine Cortical Bone

et al. 2009

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“…(2) The J-integral parameters (J x and J y ) are computed by automatically activating a specially created internal macro file; the crack-growth angle is then predicted according to the J-integral-based criterion (Eq. [1]), and one step of crack increment is read in by the software. (3) The old crack tip is moved to a new position, and, thus, a new crack is generated.…”

Section: Crack-growth Simulationmentioning

confidence: 99%

“…[25] The J-integral criterion, an extension of the maximum strain energy release rate criterion, states that the crack extends along the direction of the vector J, and fracture occurs when J reaches its critical value (J IC ). [26,27] The crack-growth angle is decided by [1] where J x and J y are the components in the directions parallel and perpendicular to the crack, respectively, and are evaluated numerically along a contour ⌫ surrounding the crack tip ( Figure 1) as follows: [28] [2] The origin of the coordinate system is set at the crack tip, x-axis on the crack line, and y-axis vertical to the crack line. The term w is the strain-energy density, n i is the Cartesian component of the unit outward normal vector to the contour, and ij and u j are the Cartesian components of the stress tensor and the displacement vector, respectively.…”

Section: Fracture Criteriamentioning

confidence: 99%

“…As a result, much research has been conducted in an attempt to improve their fracture properties. [1][2][3][4][5] Fracture resistance has been found to be largely dependent upon the alloy's microstructure, especially the size, shape, and distribution of its constituents. Ductile materials can be studied with elastic-plastic fracture mechanics, provided that appropriate specimen dimensions are employed.…”

Section: Introductionmentioning

confidence: 99%

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Numerical simulation of fracture of model Al-Si alloys

Qian

Toda

Nishido

et al. 2005

Metall Mater Trans A

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HIROYUKI TODA, SEISHI NISHIDO, TOSHIKAZU AKAHORI, MITSUO NIINOMI, and TOSHIRO KOBAYASHI Hypoeutectic Al-Si alloys consist of primary ␣-Al and Al-Si eutectic phases and show typical elasticplastic fracture. To understand their fracture behavior, fracture processes were simulated using an elastic-plastic finite-element method. The validity of the J-integral-based criterion was verified and applied to the simulations. A complicated model was used to simulate the fracture in an idealized dendritic microstructure, and four simplified models were intended to more clearly understand the interaction between a crack and individual ␣ phases. Results show that the crack is attracted to the soft ␣ phase when passing by the ␣ phase, whereas it is repelled when the ␣ phase is close in front of or behind the crack tip. The presence of ␣ phase close in front of or behind the crack tip leads to an amplification of the driving force. However, the ␣ phase beside the tip reduces the driving force. Furthermore, the fracture behavior is mainly affected by the adjacent ␣ phase on one side around the crack tip, while the remote ␣ phase on the opposite side has an offsetting effect. The local stress-strain fields were examined to analyze the simulated behavior. The simulated crack-growth path in the dendritic model was compared and verified with the experimentally observed path.

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“…However, in order to expand the use of aluminum alloys, some believe it will be necessary to find alloys stronger than AlMgSi alloys. Al ZnMg alloys have excellent strength of 600650 MPa, 4) which is greater than that of high-strength AlMgSi alloys. Thus, they are expected to be used widely, not just in cars but in airplanes as well.…”

Section: Introductionmentioning

confidence: 95%

Formation of Corrosion-Resistant Films on Al–Zn–Mg Alloy by Steam Coating Using Acidic Zn(NO<sub>3</sub>)<sub>2</sub> Aqueous Solutions

et al. 2018

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Corrosion-resistant films were fabricated on AlZnMg alloy by steam coating using an acidic aqueous solution of Zn(NO 3) 2 at different concentrations. X-ray diffraction patterns and Fourier transform-infrared spectrometer spectra demonstrated that nitrate-type ZnAl layered double hydroxide (LDH) and ZnO films were formed on the AlZnMg surface by steam coating at temperatures of 373, 433, and 473 K, using Zn(NO 3) 2 aqueous solution at 1000 mM. At 513 K, £-AlO(OH) films were formed on the AlZnMg surface by steam coating using 1 to 100 mM Zn(NO 3) 2 aqueous solution. The corrosion resistance of the films was investigated by potentiodynamic polarization curve measurements, which revealed that the £-AlO(OH) films prepared by steam coating at 513 K using 1 mM of Zn(NO 3) 2 aqueous solution was the most effective treatment for suppression of pitting corrosion and anodic current density.

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Untitled

Cited by 6 publications

References 33 publications

Effect of Different Preservative Methods on Fracture Behavior of Bovine Cortical Bone

Effect of Different Preservative Methods on Fracture Behavior of Bovine Cortical Bone

Numerical simulation of fracture of model Al-Si alloys

Formation of Corrosion-Resistant Films on Al–Zn–Mg Alloy by Steam Coating Using Acidic Zn(NO<sub>3</sub>)<sub>2</sub> Aqueous Solutions

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