scholarly journals Investigation of mode II crack growth following a very high speed impact

2008 ◽  
Vol 3 (2) ◽  
pp. 271-290
Author(s):  
Wei Ma ◽  
Zhuping Duan
Keyword(s):  
Crack Growth ◽  
High Speed ◽  
Mode Ii ◽  
High Speed Impact ◽  
Mode Ii Crack ◽  
Very High

Estimation of Dynamic Forces in Very High-Speed Impact Forging

1966 ◽  
Vol 88 (4) ◽  
pp. 369-372 ◽  
Author(s):  
M. J. Hillier
Keyword(s):  
Approximate Solution ◽  
Velocity Field ◽  
Plane Strain ◽  
Energy Method ◽  
Coulomb Friction ◽  
High Speed ◽  
Admissible Velocity ◽  
High Speed Impact ◽  
Dynamic Forces ◽  
Very High

A study is made of three methods of estimating die loads in impact forging: By approximate solution of the equations of equilibrium; by an energy method, assuming plane sections remain plane; and using the energy method in association with a kinematically admissible velocity field. Results are given for die pressures and die loads for axisymmetric and plane-strain forging of disks and slabs with smooth dies, perfectly rough dies, and for the case of Coulomb friction.

CMC Mode II Crack Growth Resistance Prediction of ASTM Specimen and Test Validation

2019 ◽  
Author(s):  
Frank Abdi ◽  
Cody Godines ◽  
Michael J. Presby ◽  
Amir Eftekharian ◽  
Jalees Ahmad ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Standardized Test ◽  
Crack Tip ◽  
Test Methods ◽  
Crack Growth Resistance ◽  
Mode Ii ◽  
Mode Ii Fracture ◽  
Mode Ii Fracture Toughness ◽  
Mode Ii Crack

Abstract The objective of this effort is to predict ceramic matrix composites (CMC) interlaminar Mode II Crack Growth Resistance (CGR), and the design of ASTM test specimen. Currently, there are a number of test standards and American Society for Testing and Materials (ASTM) for CMC’s at both ambient and elevated temperatures; however, there are no standardized test methods for determination of interlaminar shear (Mode II) fracture toughness in CMC’s. Although research work exists on interlaminar Mode II fracture toughness of CMC’s, the test methods applied showed definite drawbacks and limitations. Delamination Crack Growth (CGR) tests of CMC Mode II may exhibit zig-zag pattern, wavy cracks, fiber bridging, and premature specimen failure under bending load. The experimental parameters that may contribute to the difficulty can be summarized as specimen width and thickness, interface coating thickness, mixed mode failure evolution, and interlaminar defects. Modes II crack growth resistances, GII, were analytically and numerically determined at ambient temperature using end notched flexure (ENF) and the end-loaded split (ELS). Finite Element (FE) based. Multi-scale progressive failure analysis (MS-PFA) a combined Micro-mechanical damage and fracture mechanics Virtual Crack Closure Technique (VCCT) algorithms. Modeling of melt-infiltrated SiC/SiC CMC of ENF specimen (Laminate: with initial crack length was accomplished using a MS-PFA and VCCT approach. Test data were compared with MS-PFA prediction: a) Force vs. Crack Opening Displacement; and b) Mode II crack tip energy release rate vs. crack extension length for both edge and center line due to formation of Micro Crack Density Contribution, Crack Tip Stiffness Reduction; and c) zig-zag crack growth behavior (adhesive/cohesive). Next the ASTM Standard Proposed linear SGR equation was developed based on interpretation compliance technique from both MS-PFA Analysis and Test.

The driving force for mode II crack growth under rolling contact

Wear ◽  
1985 ◽  
Vol 101 (4) ◽  
pp. 333-346 ◽  
Author(s):  
S.D. O'regan ◽  
G.T. Hahn ◽  
C.A. Rubin
Keyword(s):  
Crack Growth ◽  
Driving Force ◽  
Rolling Contact ◽  
Mode Ii ◽  
Mode Ii Crack

scholarly journals Discontinuous Growth Mechanisms of Mode II Crack under High-Speed Impact Conditions

2008 ◽  
Vol 41-42 ◽  
pp. 169-173
Author(s):  
Wei Ma
Keyword(s):  
Crack Growth ◽  
Main Crack ◽  
Wave Speed ◽  
Impact Testing ◽  
Growth Speed ◽  
Mode Ii ◽  
Growth Mechanisms ◽  
Shear Wave Speed ◽  
Mode Ii Crack ◽  
Crack Growth Model

A recoverable plate impact testing technology has been used for studying the growth mechanisms of mode II crack. The results show that interactions of microcracks ahead of a crack tip cause the crack growth unsteadily. Failure mode transitions of materials were observed. Based on the observations, a discontinuous crack growth model was established. Analysis shows that the shear crack grows unsteady as the growth speed is between the Rayleigh wave speed cR and the shear wave speed cs; however, when the growth speed approaches 2cs, the crack grows steadily. The transient microcrack growth makes the main crack speed to jump from subsonic to intersonic and the steady growth of all the sub-cracks leads the main crack to grow stably at an intersonic speed.

Analysis of very high speed impact

1987 ◽  
Vol 25 (4) ◽  
pp. 473-482 ◽  
Author(s):  
M. Ravid ◽  
S.R. Bodner ◽  
I. Holcman
Keyword(s):  
High Speed ◽  
High Speed Impact ◽  
Very High
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