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  • 1
    Electronic Resource
    Electronic Resource
    Theory for the rate of crack closure (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 212-216 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The theory for the constant rate of crack closure was investigated. The aim of this theory is to explain why the rate of crack closure is constant during the wetting stage of healing. Assuming that a surface crack in a material is treated by compression or with solvent, its crack closes up at a constant rate and its shape is independent of time. This approach was based on the Gibbs energy of an atom near the boundary between healed and unhealed zones. The results are in satisfactory agreement with experimental data in the literature. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360654
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of mold flow and microstructures of die casting in Al alloy/SiC(p) composites (1999)
    Springer
    Journal of materials science 34 (1999), S. 2229-2240 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The report involves a study of the microstructure of tensile, impact and three-point bending samples of aluminum alloy/SiC(p) composites produced by die casting. The results show that in impact samples, 80 μm SiC particulates cluster along the left and right edges of the section vertical plane with the notch plane, and near the notch. In tensile and three-point bending samples, they were distributed uniformly in the matrix. Furthermore, porosities occurred near the notch in the impact samples. The 80 μm SiC particulates will undergo settling in the shot biscuit. There exist arc and irregular shapes in the clustering section of the particulate. The dendrite arm spacing (DAS) is larger in this section. From the shot biscuit to the bending section of the sprue; the quantity of SiC particulate is less. The SiC particulate is clustered in the protrusive region where the injector pins are situated. We can decrease the porosity of die casting samples effectively by designing the overflow well in a wave shape. We can prevent the melt from adhering to the surface of the mold cavity, thermal cracking on the surface of die casting samples and wear on plungers using electroless nickel plating on the SiC particulate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004557103809
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of methanol on optical property of irradiated poly(methyl methacrylate) (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 2213-2224 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of methanol on optical property of irradiated poly(methyl methacrylate) (PMMA) has been investigated. The gamma irradiation enhances the methanol transport in PMMA. The activation energies of diffusivity for case I and velocity for case II decreases with increasing gamma ray dose. For the same wavelength, in the range 350-800 nm, the transmittance decreases with increasig gamma ray dose. The equation of transmittance I with gamma ray dose φ at the wavelength 405 nm is I = I0 exp(-0.06φ1/2), where I0 is the transmittance of virgin PMMA. When the irradiated PMMA is immersed into methanol bath, the yellow color fades out gradually. The recovery of transmittance increases with methanol content in irradiated PMMA. The boundary to separate the outer region (solvent affected zone) from the inner region (no solvent-affected zone) is also studied. The rate of boundary movement increases with gamma ray dose.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070441218
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  • 4
    Electronic Resource
    Electronic Resource
    Methanol-induced opacity in poly (methyl methacrylate) (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 1457-1466 
    Details
    ISSN: 0887-6266
    Keywords: poly (methyl methacrylate), methanol-induced opacity in ; sorption of methanol in PMMA ; transport of methanol in PMMA ; glassy polymers, solvent transport in ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Methanol-induced opacity in poly (methyl methacrylate) (PMMA) is investigated subject to two cooling processes; furnace cooling and air cooling. The glass transition temperature of PMMA decreases with increasing time of exposure to methanol at 40-60°C and then increases during cooling, due to progressive desorption. Voids form during cooling as long as specimen temperature remains above its glass transition temperature. Since furnace cooling affords enough time for holes to expand larger than the light wavelengths, the transmittance of furnace-cooled PMMA is independent of wavelength. The transmittance of PMMA subjected to rapid cooling in the air is wavelength dependent due to scattering by holes smaller than light wavelengths. The transmittance of PMMA bearing a given weight gain of methanol (measured at absorption temperature) prior to cooling for furance cooling is lower than that for the same material subjected to air cooling. A sharp front between outer and inner regions is found in specimens removed quickly from the thermostated water bath to air at ambient temperature.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090291202
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  • 5
    Electronic Resource
    Electronic Resource
    The fracture behavior of oriented poly(methyl methacrylate)This work was supported by the National Science Council, Taiwan, Republic of China. (1993)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 33 (1993), S. 431-436 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The fracture behavior of oriented poly (methyl methacrylate) (PMMA) has been investigated. The stress intensity factor KIC, characteristic distance a, and angle θ of switching propagation direction decrease with increasing draw ratio in the range of 1.25 and 3.25. The microstructures such as the plastic zone and the features of morphology are in good agreement with the variations of these three variables, i.e., KIC, a, and θ.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760330709
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  • 6
    Electronic Resource
    Electronic Resource
    Methanol-Induced crack healing in poly(methyl methacrylate)This work was supported by national science council, taiwan, republic of china (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1399-1406 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Crack healing in poly(methyl methacrylate) (PMMA) by methanol treatment at 40°C-60°C has been investigated. It is found that the methanol treatment reduces the glass transition temperature in PMMA. Crack healing only occurs at an operating temperature higher than the effective glass transition temperature. There are two distinctive stages for crack healing based on the recovery of mechanical strength. The first stage corresponds to the progressive healing due to wetting, which has a constant crack closure rate at a given temperature. Immediately following the first stage, the second stage corresponding to diffusion enhances the quality of healing behavior. The surface morphologies obtained during healing and after fracture tests confirm these two stages. By comparing the fracture stress with the fractography, the fracture surface for stage I of crack healing is coplanar to the original crack surface. On the other hand, the original crack surface is destroyed in stage II of crack healing. It occurs in the region incorporating the original healed surface and appears to be like the Virgin fracture surface. It is also found that the tensile fracture stress of PMMA treated by methanol can recover to that of the virgin material. In addition, it is interesting to find that after sustained methanol treatment, the “snake bone” phenomenon on the fracture surface emerges.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760302109
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