Surface microcrack closure in fatigue: A comparison of compliance and crack sectioning data

1983 ◽  
Vol 22 (2) ◽  
pp. R69-R75 ◽  
Author(s):  
M. N. James ◽  
G. C. Smith
Keyword(s):  
Surface Microcrack

Effect of Cu on Surface Microcrack of Austenitic Stainless Cold Rolled Coil

2014 ◽  
Vol 21 ◽  
pp. 56-60
Author(s):  
Ji-xiang PAN ◽  
Guo-yu QIAN ◽  
Guo-guang CHENG ◽  
Yan LI ◽  
Wei PAN ◽  
...  
Keyword(s):  
Cold Rolled ◽  
Surface Microcrack

Detection of an axial surface microcrack in steel wire rods with noncontact ultrasonic reverberation spectroscopy

2017 ◽  
Vol 31 (12) ◽  
pp. 5921-5927
Author(s):  
Taehoon Heo ◽  
Seung Wan Cho ◽  
Seung Hyun Cho ◽  
Bongyoung Ahn ◽  
Zhong Soo Lim
Keyword(s):  
Steel Wire ◽  
Axial Surface ◽  
Surface Microcrack

Controlled Fracture of Nonmetallic Thin Wafers Using a Laser Thermal Shock Method

2004 ◽  
Vol 126 (1) ◽  
pp. 142-147 ◽  
Author(s):  
T. Elperin ◽  
G. Rudin
Keyword(s):  
Theoretical Model ◽  
Thermal Shock ◽  
Operating Parameters ◽  
Laser Shock ◽  
Suggested Model ◽  
Spontaneous Transition ◽  
Bending Stresses ◽  
Controlled Fracture ◽  
Two Stages ◽  
Surface Microcrack

We developed a theoretical model of a novel thermal laser shock method for separation of glass and glass-ceramic wafers into chips. The suggested model allowed us to determine the operating parameters of the device for wafer splitting. The investigated method involves two stages: 1) formation of a surface (blind) microcrack (or a grid of surface microcracks) using a double thermal shock method, and 2) splitting the cracked wafer into chips along the microcrack contour by applying small bending stresses. The emphasis was given to splitting of thin wafers with the thickness less than 1 mm. The latter process is more involved because of the undesirable spontaneous transition of a surface microcrack into a through crack.

Study on Surface Residual Stress of Nano-Zirconia Toughened Alumina Ceramics under Two-Dimentional Ultrasonic Vibration Assisted Grinding

2010 ◽  
Vol 126-128 ◽  
pp. 143-147
Author(s):  
Yan Yan Yan ◽  
Bo Zhao ◽  
Jun Li Liu
Keyword(s):  
Residual Stress ◽  
Surface Quality ◽  
Ultrasonic Vibration ◽  
Alumina Ceramics ◽  
Surface Residual Stress ◽  
Diamond Grinding ◽  
Ultrasonic Vibration Assisted Grinding ◽  
Zirconia Toughened Alumina ◽  
Surface Microcrack

Based on good processing property of two-dimentional ultrasonic vibration assisted grinding (TUVAG), the precision finishing of nano-zirconia toughened alumina ceramics (nano-ZTA) is carried out. According to theoretical analysis, TUVAG may obtain higher machining efficiency and better surface quality. Especially, experimental results show it may obtain the compressive stress in the finished surface of nano-ZTA that may restrain the expansion of surface microcrack, and surface residual stress of nano-ZTA under TUVAG differs from that under diamond grinding, and TUVAG may obtain the better surface quality of nano-ZTA than diamond grinding, as is characterized by scanning electronic microscope (SEM). As a result, it is good for TUVAG as a kind of processing method for nano-ZTA.

Formation of Surface Microcrack for Separation of Nonmetallic Wafers Into Chips

1999 ◽  
Vol 122 (4) ◽  
pp. 317-322 ◽  
Author(s):  
T. Elperin ◽  
A. Kornilov ◽  
G. Rudin
Keyword(s):  
Laser Beam ◽  
Thermal Stresses ◽  
Theoretical Modeling ◽  
Water Spray ◽  
Electronic Industry ◽  
High Quality ◽  
Thermal Elasticity ◽  
Subsurface Region ◽  
Surface Microcrack

In recent years a technology for a high quality separation of nonmetallic materials into chips using a surface (“blind”) microcrack attracted considerable attention in the electronic industry. In this method a wafer is positioned on the translated X-Y table and is heated by a laser beam up to a temperature of the order of 300–400°C. The wafer is then cooled by an air-water spray, and a surface microcrack is formed due to relaxation of the thermal stresses. The initial microcrack with a depth of the order of several hundred microns then propagates in a subsurface region of a wafer and follows the path of the laser beam. Theoretical modeling based on the solution of the equations of thermal elasticity was performed to determine the distributions of temperature and thermal stresses that cause formation of an “edge” microcrack (at the edge of a wafer) followed by its transformation into a surface microcrack. The results of thermal stresses analysis are in an agreement with experimental observations. [S1043-7398(00)00804-5]

The Growth of Surface Microcracks in Fatigue

1969 ◽  
Vol 91 (4) ◽  
pp. 770-779 ◽  
Author(s):  
P. H. Francis
Keyword(s):  
Crack Extension ◽  
Fatigue Loading ◽  
Test Results ◽  
Small Surface ◽  
Crack Extension Force ◽  
Micro Cracks ◽  
Theoretical Predictions ◽  
Extension Force ◽  
Elastic Fracture ◽  
Surface Microcrack

An analytical theory is proposed for describing the growth of a small surface “microcrack” under uniaxial fatigue loading. The theory is based upon dimensional analysis and uses the stress-intensity factor and crack extension force concepts of elastic fracture mechanics. Experimental measurements were made of the growth of surface micro-cracks, ranging from 0.0005–0.040 in. long, in polished specimens of 4340 steel. Good correlation was achieved in comparing the test results with the theoretical predictions. Finally, an approach is indicated for extending the analytical model to the prediction of fatigue failure.

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