Study on Fracture Mechanism of Walnut Shell According to Brittle Fracture Area

2014 ◽  
Author(s):  
Zhang Hong ◽  
Lan Haipeng ◽  
Tang Yurong ◽  
Li Yong
Keyword(s):  
Brittle Fracture ◽  
Fracture Mechanism ◽  
Walnut Shell ◽  
Fracture Area

scholarly journals A New Fracture Analysis Technique for Charpy Impact Test Using Image Processing

2021 ◽  
Vol 59 (1) ◽  
pp. 61-66
Author(s):  
Tae Chang Park ◽  
Beom Suk Kim ◽  
Ji Hee Son ◽  
Yeong Koo Yeo
Keyword(s):  
Image Processing ◽  
Brittle Fracture ◽  
Ductile Fracture ◽  
Impact Test ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Fracture Analysis ◽  
Binary Image ◽  
Fracture Area ◽  
Brittle Fractures

The Charpy impact test is used to identify the transition between ductility and brittleness. The percentages of ductile and brittle fractures in steel can be evaluated based on each fracture area, which is presently determined by an analyzer with the naked eye. This method may lead to subjective judgement, and difficulty accurately quantifying the percentage. To resolve this problem, a new analysis method based on image processing is proposed in this study. A program that can automatically calculate the percentage of the ductile and brittle fractures has been developed. The analysis is performed after converting an RGB fracture image into a binary image using image processing techniques. The final binary image consists of 0 and 1 pixels. The parts with the pixel values of 1 correspond to the brittle fracture areas, and the pixel values of 0 represent the ductile fracture areas. As a result, by counting the number of 0 pixels in the entire area, it is possible to automatically calculate the percentage of ductile fracture. Using the proposed automatic fracture analysis program, it is possible to selectively distinguish only the brittle fracture from the entire fracture area, and to accurately and quantitatively calculate the percentages of ductile and brittle fractures.

Preliminary compression of a material as a factor in changing the brittle fracture mechanism for BCC metals

1996 ◽  
Vol 28 (4) ◽  
pp. 251-261 ◽  
Author(s):  
B. Z. Margolin ◽  
V. A. Shvetsova ◽  
A. Ya. Varovin
Keyword(s):  
Brittle Fracture ◽  
Fracture Mechanism ◽  
Bcc Metals

scholarly journals Vibration Fracture Mechanism and Optimization Design of Array Power Supply for Near-Space SAR

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Changrui Wang ◽  
Lina Tang ◽  
Henghai Wang
Keyword(s):  
Brittle Fracture ◽  
Yield Strength ◽  
Power Supply ◽  
Fracture Mechanism ◽  
Evaluation System ◽  
Random Vibration ◽  
Optimization Design ◽  
Electronic Components ◽  
Near Space ◽  
Welding Part

The random vibration failure of an array power supply for near-space SAR was analyzed. The fracture mechanism and the fracture reason of fracture formation in the specimen were investigated. The results show that antishock MOS pin breaks first, and the power supply is still in the working state during the process of random vibration. This caused dischargings at the tip of the fracture and melting of the tip of the broken pin which form a river-shaped fracture and granular tissue. The plastic fracture with typical dimple morphology of the pins for the resistor tube occurred during the random vibration. The intergranular fracture appeared at the welding part of the electronic components for array power supply, which presented a brittle fracture mechanism. The fracture was dominated by a ductile fracture for components when the stress produced by the vibration was close to the yield strength of the material. The fracture was dominated by a brittle fracture for components when the stress produced by the vibration was far beyond the yield strength of the material. A simulation evaluation system based on the high-confidence model was proposed. The stress of the electronic components for array power supply and its welding was much lower than the allowable strength of the material by the optimization of the structure and the form of the welding for the array power supply. The sample was successfully tested and verified without any further fracture problems.

Comparative studies of brittle fracture mechanism for standard and reconstructed CT specimens made of VVER-1000 RPV materials

2017 ◽  
Vol 8 (6) ◽  
pp. 927-935
Author(s):  
A. D. Erak ◽  
E. A. Kuleshova ◽  
S. A. Bubiakin ◽  
A. P. Bandura ◽  
D. A. Zhurko
Keyword(s):  
Brittle Fracture ◽  
Comparative Studies ◽  
Fracture Mechanism

The Fracture Research of Hexagonal Duralumin Nut

2010 ◽  
Vol 152-153 ◽  
pp. 1244-1247
Author(s):  
Bin Xu ◽  
Bai Yang Lou
Keyword(s):  
Brittle Fracture ◽  
Fracture Surface ◽  
Surface Topography ◽  
Fracture Mechanism ◽  
Fracture Behavior ◽  
Optical Microscope ◽  
Air Pressure ◽  
Brittle Mode ◽  
Electronic Microscope ◽  
Made In

The microstructure, fracture surface topography and mode of hexagonal nut cracked in assembling under air pressure were analyzed with optical microscope and scanning electronic microscope, which are made in contrast with that of hexagonal nut cracked in man-made. The research results show that the man-made fracture of nut was of dimple shape and cracked in toughness mode, which accorded with the fracture behavior of 2Al2 duralumin material. The air-pressure fracture of nut was of right shape and cracked in brittle mode. The fracture mechanism is concluded that crack fountain is formed in surface of nut because of scoring during assembling and then the crack expands rapidly, leading to brittle fracture of the nut.

scholarly journals Investigation on brittle fracture mechanism of a grade E cast steel knuckle

2014 ◽  
Vol 2 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Jin Huang ◽  
Lu Xia ◽  
Youshou Zhang ◽  
Sinian Li
Keyword(s):  
Brittle Fracture ◽  
Fracture Mechanism ◽  
Cast Steel

scholarly journals Study on Microstructure and Properties of Tailored Hot-Stamped U-shaped Parts Based on Temperature Field Control

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 593
Author(s):  
Xiangji Li ◽  
Limei Xiao ◽  
Qifeng Zheng ◽  
Huan Zhang ◽  
Yanjiao Gu
Keyword(s):  
Tensile Strength ◽  
Temperature Field ◽  
Brittle Fracture ◽  
Automotive Industry ◽  
Fracture Mechanism ◽  
High Speed ◽  
Fracture Behavior ◽  
Hot Stamping ◽  
Micro Hardness ◽  
Field Control

In order to meet the needs of the automotive industry, it is necessary to produce “tailored” parts. The U-shaped die equipped with a high-speed airflow device was designed to conduct the hot stamping experiments. The microstructure, micro-hardness, tensile properties, and fracture behavior of the parts were analyzed. The experimental results showed that the quenched phase of the hardened section was mainly martensite, and the micro-hardness and tensile strength could reach 445 HV and 1454 MPa, respectively. The fracture mechanism was brittle fracture. For the toughness section, as the tool temperature increased from 300 to 600 °C, both micro-hardness and tensile strength decreased. Meanwhile, the area fractions of bainite and ferrite increased, and the area fraction of martensite reduced. The fracture behavior was plastic fracture.

The fracture of glassy polymers

1972 ◽  
Vol 329 (1577) ◽  
pp. 137-151 ◽  
Keyword(s):  
Brittle Fracture ◽  
Viscous Flow ◽  
Fracture Mechanism ◽  
Glassy Polymers ◽  
Bulk Polymer ◽  
Fracture Front ◽  
Griffith Theory ◽  
Work Of Fracture ◽  
Viscous Mechanism

The fracture of glassy polymers starts with the separation of molecule bundles which then form a craze; this is followed by the fracture or rupture of the craze by sliding of the molecule bundles. The first process has the approximate characteristics of brittle fracture, the second those of viscous flow; at low velocities, therefore, the crack extends by the essentially viscous mechanism in the craze layer, whereas at higher velocity the stress required for this rises so high that either a quasi-brittle fracture occurs between the craze and the adjacent bulk polymer (for example, in polystyrene), or patches of craze arise in the bulk ahead of, and away from, the propagating fracture front, as in cast polymethylmethacrylate (PMMA). When the craze wedge ahead of the ‘ viscous ’ crack in the craze layer suddenly peels off the adjacent bulk polymer, either multiple crazes and cracks arise, radiating from its edge, or a new craze wedge is initiated. In either case only one craze wedge propagates, and it drops off the adjacent bulk when the rate of stretching of the craze (normal to its plane) reaches a critical magnitude. The repetition of this process results in the well known striation of the surface of fracture in polystyrene and other polymers. Since the fracture mechanism includes an essentially velocity-dependent viscous process, the Griffith theory cannot be applied to glassy polymers even as an approximation. The work of fracture oscillates by orders of magnitude within microseconds in the region of striations.

scholarly journals Microseismic characterization of brittle fracture mechanism in highly stressed surrounding rock mass

2016 ◽  
Vol 2016 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Chunchi Ma ◽  
Tianbin Li ◽  
Yupeng Jiang ◽  
Guoqing Chen
Keyword(s):  
Rock Mass ◽  
Brittle Fracture ◽  
Fracture Mechanism ◽  
Surrounding Rock

Fracture Properties of Mg-Alloys Assessed with Nanoindentation

2017 ◽  
Vol 891 ◽  
pp. 257-262 ◽  
Author(s):  
Jiří Němeček ◽  
Vladimír Hrbek ◽  
Veronika Petráňová ◽  
Petr Hlaváček
Keyword(s):  
Fracture Toughness ◽  
Optical Microscopy ◽  
Magnesium Alloys ◽  
Contact Area ◽  
Fracture Mechanism ◽  
Limit Values ◽  
Fracture Properties ◽  
Optical Images ◽  
Fracture Area

This paper deals with micromechanical properties of biocompatible magnesium alloys MgCa0.8 prepared by extrusion. At first, the microstructure, elastic and hardness properties are assessed at the scale of one micrometer by means of a nanoindenter. Further, determination of fracture mechanism, fracture area and fracture toughness of the alloy is studied with sharp indentation, optical microscopy and SEM and by means of energetic methods. Based on the examination of optical images it was concluded that the Mg matrix is not vulnerable to distinct cracking around indents even for high indentation loads. By computations, it was found the fracture area is very small, about 0.7-3% of the tip contact area based on the assumption of limit values of the target fracture toughness 10-20 MPa·m1/2.

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