Crack formation and fracture under repeated tension-impact loads

1988 ◽  
Vol 9 (1) ◽  
pp. 39-44 ◽  
Author(s):  
A. Bhattacharya ◽  
T. Joseph ◽  
B. Kishor
Keyword(s):  
Crack Formation ◽  
Impact Loads

Determination of the metal toughness components in impact-bending test

2018 ◽  
Vol 84 (12) ◽  
pp. 68-72
Author(s):  
A. B. Maksimov ◽  
I. P. Shevchenko ◽  
I. S. Erokhina
Keyword(s):  
Crack Growth ◽  
Specific Energy ◽  
Crack Formation ◽  
Crack Nucleation ◽  
Scale Effects ◽  
Linear Equations ◽  
Bending Test ◽  
Cross Sectional ◽  
Two Samples ◽  
Sample Width

A method for separating the work of impact into two parts - the work of the crack nucleation and that of crack growth - which consists in testing two samples with the same stress concentrators and different cross-sectional dimensions at the notch site is developed. It is assumed that the work of crack nucleation is proportional to the width of the sample face on which the crack originates and the specific energy of crack formation, whereas the work of the crack growth is proportional to the length of crack development and the specific crack growth energy. In case of the sample fracture upon testing, the crack growth length is assumed equal to the sample width. Data on the work of fracture of two samples and their geometrical dimensions at the site of the notch are used to form a system of two linear equations in two unknowns, i.e., the specific energy of crack formation and specific energy of crack growth. The determined specific energy values are then used to calculate the work of crack nucleation and work of crack growth. The use of the analytical method improves the accuracy compared to graphical - extrapolative procedures. The novelty of the method consists in using one and the same form of the notch in test samples, thus providing the same conditions of the stress-strain state for crack nucleation and growth. Moreover, specimens with different cross-section dimensions are used to eliminate the scale effects. Since the specific energy of the crack nu-cleation and specific energy of the crack growth are independent of the scale factor, they are determined only by the properties of the metal. Introduction the specific energy of crack formation and growth makes possible to assign a specific physical meaning to the fracture energy.

Coupling Geometric and Microstructure Gradients in Fatigue Crack Formation

2020 ◽  
Author(s):  
Farhan Ashraf ◽  
Andrea Cini ◽  
Gustavo M. Castelluccio
Keyword(s):  
Fatigue Crack ◽  
Crack Formation

scholarly journals Effect of Zr content on crack formation and mechanical properties of IN738LC processed by selective laser melting

2021 ◽  
Vol 31 (5) ◽  
pp. 1350-1362
Author(s):  
Yong HU ◽  
Xiao-kang YANG ◽  
Wen-jiang KANG ◽  
Yu-tian DING ◽  
Jia-yu XU ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Selective Laser Melting ◽  
Crack Formation ◽  
Laser Melting

Enhanced stretchability of metal/interlayer/metal hybrid electrode

Nanoscale ◽  
2021 ◽  
Author(s):  
Seungseok Han ◽  
Ki-Won Seo ◽  
Wansun Kim ◽  
Taek-Soo Kim ◽  
Jung-Yong Lee
Keyword(s):  
Grain Size ◽  
Crack Formation ◽  
Hybrid Structure

Stretchable hybrid electrodes utilizing grain size engineering and hybridization with conductive interlayers are proposed. The conductive interlayers in the hybrid structure affect the crack formation and propagation significantly.

scholarly journals Influences of Residual Stress, Surface Roughness and Peak-Load on Micro-Cracking: Sensitivity Analysis

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 320
Author(s):  
Jairan Nafar Dastgerdi ◽  
Fariborz Sheibanian ◽  
Heikki Remes ◽  
Hossein Hosseini Toudeshky
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Crack Formation ◽  
Peak Load ◽  
Crack Size ◽  
Effective Parameters ◽  
Load Range ◽  
Load Effect ◽  
Damage Initiation ◽  
Load Conditions

This paper provides further understanding of the peak load effect on micro-crack formation and residual stress relaxation. Comprehensive numerical simulations using the finite element method are applied to simultaneously take into account the effect of the surface roughness and residual stresses on the crack formation in sandblasted S690 high-strength steel surface under peak load conditions. A ductile fracture criterion is introduced for the prediction of damage initiation and evolution. This study specifically investigates the influences of compressive peak load, effective parameters on fracture locus, surface roughness, and residual stress on damage mechanism and formed crack size. The results indicate that under peak load conditions, surface roughness has a far more important influence on micro-crack formation than residual stress. Moreover, it is shown that the effect of peak load range on damage formation and crack size is significantly higher than the influence of residual stress. It is found that the crack size develops exponentially with increasing peak load magnitudes.

scholarly journals Effect of Intermetallic Compound Bridging on the Cracking Resistance of Sn2.3Ag Microbumps with Different UBM Structures under Thermal Cycling

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1065
Author(s):  
Chun-Chieh Mo ◽  
Dinh-Phuc Tran ◽  
Jing-Ye Juang ◽  
Chih Chen
Keyword(s):  
Electron Microscope ◽  
Intermetallic Compound ◽  
Thermal Cycling ◽  
Thermal Cycle ◽  
Crack Formation ◽  
Thermal Cycling Test ◽  
Under Bump Metallization ◽  
Reflow Time ◽  
Cracking Resistance ◽  
Scanning Electron

In this study, the effect of intermetallic compound (IMC) bridging on the cracking resistance of microbumps with two different under bump metallization (UBM) systems, Cu/solder/Cu and Cu/solder/Ni, under a thermal cycling test (TCT) is investigated. The height of the Sn2.3Ag solders was ~10 µm, which resembles that of the most commonly used microbumps. We adjusted the reflow time to control the IMC bridging level. The samples with different bridging levels were tested under a TCT (−55–125 °C). After 1000 and 2000 TCT cycles (30 min/cycle), the samples were then polished and characterized using a scanning electron microscope (SEM). Before IMC bridging, various cracks in both systems were observed at the IMC/solder interfaces after the 1000-cycle tests. The cracks propagated as cyclic shapes from the sides to the center and became more severe as the thermal cycle was increased. With IMC bridging, we could not observe any further failure in all the samples even when the thermal cycle was up to 2000. We discovered that IMC bridging effectively suppressed crack formation in microbumps under TCTs.

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