Aditya Kumar
@adityakr.bsky.social
Assistant Professor at Georgia Tech studying fracture mechanics and mechanics of soft solids.
https://sites.gatech.edu/adityakumar/
https://sites.gatech.edu/adityakumar/
This also clarifies confusion about whether cavitation should be treated as elastic cavity growth or fracture growth.
Based on the results of this paper and our previous work, cavitation, as observed experimentally in elastomers, is understood to be a fracture process!
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Based on the results of this paper and our previous work, cavitation, as observed experimentally in elastomers, is understood to be a fracture process!
[12/n]
October 27, 2025 at 2:44 AM
This also clarifies confusion about whether cavitation should be treated as elastic cavity growth or fracture growth.
Based on the results of this paper and our previous work, cavitation, as observed experimentally in elastomers, is understood to be a fracture process!
[12/n]
Based on the results of this paper and our previous work, cavitation, as observed experimentally in elastomers, is understood to be a fracture process!
[12/n]
This analysis provides insight into when this mode of failure may be expected. It is relevant not only to thin films. Cavitation failure is observed in many other geometries. It is particularly applicable to understanding fracture nucleation in elastomeric composites.
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October 27, 2025 at 2:44 AM
This analysis provides insight into when this mode of failure may be expected. It is relevant not only to thin films. Cavitation failure is observed in many other geometries. It is particularly applicable to understanding fracture nucleation in elastomeric composites.
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Other factors such as the material's fracture toughness and the aspect ratio of the thin layer also plays a role:
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October 27, 2025 at 2:44 AM
Other factors such as the material's fracture toughness and the aspect ratio of the thin layer also plays a role:
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The main culprit is the material's Poisson's ratio. As the Poisson's ratio approaches 0.5, load-parallel crack growth becomes preferable over horizontal crack growth in thin confined layers. The material seeks to release the large buildup of stress in the horizontal direction.
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October 27, 2025 at 2:44 AM
The main culprit is the material's Poisson's ratio. As the Poisson's ratio approaches 0.5, load-parallel crack growth becomes preferable over horizontal crack growth in thin confined layers. The material seeks to release the large buildup of stress in the horizontal direction.
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Vertical crack growth occurs parallel to the loading direction. This is highly unusual and typically not observed in most materials. In this paper, we discuss the conditions that promote vertical crack growth.
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October 27, 2025 at 2:44 AM
Vertical crack growth occurs parallel to the loading direction. This is highly unusual and typically not observed in most materials. In this paper, we discuss the conditions that promote vertical crack growth.
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Because the rubber is highly compliant, the simultaneous growth in two directions makes it appear as if a spherical cavity is elastically growing. See this figure, which shows how a crack geometry with two perpendicular crack fronts appear in the deformed configuration.
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October 27, 2025 at 2:44 AM
Because the rubber is highly compliant, the simultaneous growth in two directions makes it appear as if a spherical cavity is elastically growing. See this figure, which shows how a crack geometry with two perpendicular crack fronts appear in the deformed configuration.
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Building on our past theoretical work and experimental work from other groups, we show in this new paper that cavitation growth is actually due to simultaneous vertical and horizontal crack growth in the elastomer.
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October 27, 2025 at 2:44 AM
Building on our past theoretical work and experimental work from other groups, we show in this new paper that cavitation growth is actually due to simultaneous vertical and horizontal crack growth in the elastomer.
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This second mode has been named "cavitation" growth in the literature. First observed in 1930s, but analyzed more rigorously in 1950s, the prevailing theory had been these cavities are forming due to uncontrolled elastic growth of very small pre-existing defects in the rubber.
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October 27, 2025 at 2:44 AM
This second mode has been named "cavitation" growth in the literature. First observed in 1930s, but analyzed more rigorously in 1950s, the prevailing theory had been these cavities are forming due to uncontrolled elastic growth of very small pre-existing defects in the rubber.
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The second mode is more unusual. Instead of a penny-shaped crack, cavities of nearly spherical shape are observed to form!
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October 27, 2025 at 2:44 AM
The second mode is more unusual. Instead of a penny-shaped crack, cavities of nearly spherical shape are observed to form!
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First mode resembles the usual way a rubber band would have failed. Cracks nucleate internally or on the surface and grow perpendicular to the load.
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October 27, 2025 at 2:44 AM
First mode resembles the usual way a rubber band would have failed. Cracks nucleate internally or on the surface and grow perpendicular to the load.
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If one pulls a rubber band, cracks nucleate perpendicular to the applied load.
If the length of the rubber band becomes extremely small (such that it resembles a disk), two different modes of crack growth are observed.
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If the length of the rubber band becomes extremely small (such that it resembles a disk), two different modes of crack growth are observed.
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October 27, 2025 at 2:44 AM
If one pulls a rubber band, cracks nucleate perpendicular to the applied load.
If the length of the rubber band becomes extremely small (such that it resembles a disk), two different modes of crack growth are observed.
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If the length of the rubber band becomes extremely small (such that it resembles a disk), two different modes of crack growth are observed.
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Very well written. I suppose things have been so good for so long that we are not quite ready to face the grim reality.
May 2, 2025 at 11:02 AM
Very well written. I suppose things have been so good for so long that we are not quite ready to face the grim reality.
Reposted by Aditya Kumar
I wrote this a little while ago, because I felt like too many scientists were treating this as something to ride out, rather than looking at how authoritarianism has played out for science elsewhere.
laurenkuehne.wordpress.com/2025/03/25/v...
laurenkuehne.wordpress.com/2025/03/25/v...
Vengeance of the Stinking Old Ninth
In 2018, during Trump’s first regime, I had the opportunity to hang out with a visiting scientist from China (nameless, for obvious reasons) at a conference. We talked a lot about the “era of the s…
laurenkuehne.wordpress.com
May 2, 2025 at 2:14 AM
I wrote this a little while ago, because I felt like too many scientists were treating this as something to ride out, rather than looking at how authoritarianism has played out for science elsewhere.
laurenkuehne.wordpress.com/2025/03/25/v...
laurenkuehne.wordpress.com/2025/03/25/v...
It has happened in India and many other democracies around the world. The time for resistance is now or never!
April 15, 2025 at 2:56 AM
It has happened in India and many other democracies around the world. The time for resistance is now or never!
Once institutions start giving up and getting scared, there is no coming up even if the government changes in 4 years. The damage done is irreversible for what is considered acceptable.
April 15, 2025 at 2:54 AM
Once institutions start giving up and getting scared, there is no coming up even if the government changes in 4 years. The damage done is irreversible for what is considered acceptable.
Wow how did she get hired? Somebody should do an investigation
May 4, 2024 at 3:03 AM
Wow how did she get hired? Somebody should do an investigation
He is also the son of a professor and a long term Berkeley Professor. So definitely expected him to be more sensitive with the handling of the protest.
April 26, 2024 at 4:46 PM
He is also the son of a professor and a long term Berkeley Professor. So definitely expected him to be more sensitive with the handling of the protest.
Why would outside protestors even go to Emory which is located in a rich suburb when there are more centrally located universities in Atlanta? Just shameless lying.
April 26, 2024 at 4:34 PM
Why would outside protestors even go to Emory which is located in a rich suburb when there are more centrally located universities in Atlanta? Just shameless lying.
Exactly. Georgia State and Georgia Tech will be much better places for outsiders to protest at because of their central location and closeness to the golden dome.
April 26, 2024 at 4:33 PM
Exactly. Georgia State and Georgia Tech will be much better places for outsiders to protest at because of their central location and closeness to the golden dome.
Yeah they are absolutely feeling the pressure from the donors and lack the capability/will/incentive to think through the long term consequences of their actions
April 26, 2024 at 4:12 PM
Yeah they are absolutely feeling the pressure from the donors and lack the capability/will/incentive to think through the long term consequences of their actions