Crack propagation speed

For glass, the speed of sound is about 4 to 5 kilometers per second , but the Slow Mo Guys recorded crack propagation speed at just under 1. Why do the cracks move so relatively slow? A wave moves in one of three ways : as a primary longitudinal compression wave, a secondary transverse shear wave, or a surface Rayleigh wave.

Primary waves are the fastest, followed by secondary waves, and finally surface waves. When a crack propagates, there are multiple different waves at work, each moving as one of these three wave types. In a perfectly brittle material stressed in tension, you could see crack propagation occurring at— or above —the speed of sound. But materials are rarely perfectly brittle and stressed in tension.

It is more likely you will see crack propagation ranging between 0. A major advantage of this method as compared to the established techniques is in the fact that it allows spatio-temporally resolved, full-field measurements rather than point-wise measurements. Furthermore, information on the crack width can be obtained simultaneously. To validate the experimentation, the authors processed image sequences of tests on four compact-tension specimens performed on a split-Hopkinson tension bar.

The images were taken by a high-speed camera at a frame rate of , images per second. Then, the crack tips are determined using principal component analysis.

The tips are tracked in the image sequence and the velocities between the time stamps of the images are derived. A major advantage of this method as compared to established techniques is in the fact of its allowing for spatio-temporally resolved, full-field measurements rather than point-wise measurements and that information on crack width can be obtained simultaneously.

To validate the experimentation, the authors processed image sequences of tests on four compact-tension specimens performed on a split-Hopkinson tension bar.

The images were taken by a high-speed camera at a frame rate of , images per second. Download PDF. Your full name. Your affiliation information e. Your Email address not made public. Importance: How significant is the paper to the field? Significant contribution. Incremental contribution. No contribution. I am not qualified to judge. Conclusions well supported. Most conclusions supported minor revision needed.

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