scholarly journals Minimum Surface Formation Energy for Three-Dimensional Intergranular Fracture

1998 ◽  
Vol 539 ◽  
Author(s):  
E. A. Holm ◽  
G. N. McGovney
Keyword(s):  
Fracture Surface ◽  
Cross Section ◽  
Intergranular Fracture ◽  
Formation Energy ◽  
Boundary Energy ◽  
Surface Formation ◽  
Minimum Surface ◽  
Specimen Cross Section ◽  
Fracture Area ◽  
Surface Formation Energy

AbstractThe minimum expended energy for fracture is the free energy required to form two new surfaces. For intergranular fracture, the minimum surface formation energy is complicated by the rough fracture surface, with area greater than the specimen cross-section. We utilize network optimization algorithms (max-flow/min-cut) to determine the minimum surface formation energies and surfaces for intergranular fracture in 3D polycrystals. For equiaxed grains and uniform boundary strength, the minimum energy fracture area is independent of grain size and is 45% larger than the specimen cross-section, and intergranular fracture will occur when surface energy is less than 1.6 times the grain boundary energy. The 3D fracture area is larger than projected from 2D systems. In systems with microcracked boundaries, the fracture surface deviates to preferentially include microcracked boundaries, creating interlocking grain configurations. Two-dimensional percolation of microcracks occurs at about 80% microcracked boundaries.

scholarly journals The Ovalisation of Steel Circular Hollow Sections under Bending

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Manahel Sh. Khalaf ◽  
Amer M. Ibrahim
Keyword(s):  
Cross Section ◽  
Local Buckling ◽  
Bending Moment ◽  
Thickness Ratio ◽  
Experimental Results ◽  
Experimental Program ◽  
Specimen Length ◽  
Specimen Cross Section ◽  
The Cross

This paper investigates the ovalisation behavior of the Steel Circular Hollow Sections (CHSs) when subjected to bending moment. The experimental program included testing of ten specimens in four groups in order to examine the influence of changing the diameter, thickness, length and the presence of openings on the ovalisation phenomenon of these specimens.The experimental results showed that the ovalisation of the specimen cross-section appears clearly when the diameter to thickness ratio (D/t) is ranging from 17 to 50, while the ovalisation of the specimens that have D/t ratio greater than 50 is very little or unclear because the instability of these specimens are controlled by the local buckling. In addition, the change of the specimen length and the presence of openings didn’t cause the cross-section ovalisation

scholarly journals Urea Formaldehyde Resin Resultant Plywood with Rapid Formaldehyde Release Modified by Tunnel-Structured Sepiolite

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1286 ◽  
Author(s):  
Li ◽  
Gao ◽  
Xia ◽  
Li ◽  
Zhou
Keyword(s):  
Shear Strength ◽  
Fracture Surface ◽  
Cross Section ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Formaldehyde Resin ◽  
Tunnel Structure ◽  
Formaldehyde Release ◽  
Uf Resin ◽  
The Cost

In order to reduce the cost of plywood and save edible resources (wheat flour), a cheap and resourceful clay, sepiolite, was used to modify urea formaldehyde (UF) resin. The performances of filler-filled UF resins were characterized by measuring the thermal behavior, cross section, and functional groups. Results showed that cured UF resin with SEP (sepiolite) formed a toughened fracture surface, and the wet shear strength of the resultant plywood was maximum improved by 31.4%. The tunnel structure of SEP was beneficial to the releasing of formaldehyde, as a result, the formaldehyde emission of the plywood bonded by UF resin with SEP declined by 43.7% compared to that without SEP. This study provided a new idea to reduce the formaldehyde emission, i.e. accelerating formaldehyde release before the product is put into use.

Appearance of the Mechanical Plating Formed by Zn-Al Compounding Flake Powders and its Anticorrosion

2009 ◽  
Vol 79-82 ◽  
pp. 811-814 ◽  
Author(s):  
Jie Lu
Keyword(s):  
Corrosion Resistance ◽  
Fracture Surface ◽  
Cross Section ◽  
Corrosive Medium ◽  
Spherical Particles ◽  
Small Space ◽  
Matrix Metal ◽  
Aluminum Oxidation ◽  
The Matrix ◽  
Flake Structure

In this study, a comparison of appearance surface and fracture surface of mechanical plating was made, respectively formed by spherical Zn powders and Zn-Al compounding flake powders. It is found that the spherical particles are deposited and embedded on Zn plating. The deformation of granular Zn powders on coating superficial is relatively large, but there is little distortion of globe grain inside the coating, mainly with spheroidicity distorted. Besides, there are obvious gaps between the particles in Zn coating. In contrast, the flake structure granules of Zn-Al plating are densely and compactly laid out with small space. After contacting with air, the plating coat expands owing to aluminum oxidation, leading to the higher position of the plating coat on the cross section than the matrix metal. We then did salt mist test to verify the corrosion resistance of Zn-Al compounding flake coating. It was found that the Zn-Al compounding flake coating was superior to that formed by globe Zn powder. Results show that the addition of layers of flakes has a better shielding action resisting corrosive medium, leading to the decrease of the osmosis from corrosive medium to the coatings. And the coating can repair naturally after being damaged. We further passivate plating with molybdate to improve the anticorrosion of the coating.

The Effect of Cryogenic Treatment on the Microstructure and Properties of Ti-6Al-4V Titanium Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 899-903 ◽  
Author(s):  
Kai Xuan Gu ◽  
Zhi Qiang Li ◽  
Jun Jie Wang ◽  
Yuan Zhou ◽  
Hong Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Electron Microscope ◽  
Low Temperature ◽  
Fracture Surface ◽  
Cross Section ◽  
Cryogenic Treatment ◽  
Great Influence ◽  
Microstructure And Properties ◽  
Scanning Electron

The effect of cryogenic treatment on the microstructure and properties of Ti-6Al-4V has been studied in this paper. The program controlled SLX cryogenic box was used to conduct the cryogenic treatment and the subsequent low temperature temper. The scanning electron microscope was used to study the morphology of microstructure and fracture surface. As the results show that the cryogenic treatment increases the elongation of Ti-6Al-4V from 16.5 percent to 24.5 percent, at the same time, the strength increases slightly, this indicates that cryogenic treatment can improve the comprehensive mechanical properties. The microstructure measurement revealed that there is a tendency of reduction in the precipitated particles after cryogenic treatment. The cross section is flat and the size of dimples is more uniform. It is concluded that the change in the precipitation particle had a great influence in the mechanical properties.

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