That's interesting about the blades. Thanks for posting.
MIT STUDY ON THE REASON WHY HAIR DAMAGES RAZORS
- Thread starter nicepatina
- Start date
...but what happens if you shave the cat's tongue??I do think that it is cool to see this stuff up close. There was another study at MIT a few years back about how cat's drink milk. To the best of my knowledge, there were a number of theories out there, but no one had actually taken and studied high-speed video of the act.
The surprising physics of cats’ drinking
A new study reveals that even the way cats lap up liquid displays the perfect balance for which they’re known.news.mit.edu
There must be an app for that
So, if this is the main failure mechanism of a razor blade, it might explain why my razors with hard steel, like TI razors, don't have a much longer edge retention then something like a Böker or an old Sheffield steel razor, which is allot softer (59 vs 63-65).
The TI razor steel is almost as flexible, but the fracture toughness is lower then the a softer steel.
There is a really small difference is steel flexibility at different hardness values at the range from 59-65.
The TI razor steel is almost as flexible, but the fracture toughness is lower then the a softer steel.
There is a really small difference is steel flexibility at different hardness values at the range from 59-65.
I did an in-depth study in my Lavoratory that cost me two bucks of my retirement fund and a thousandth of an hours time to determine that I had read somewhere once upon a time back when the bears were bad that hair has the same tensile strength as copper wire of equal diameter and here endeth my lesson unto myself.
That is true, but it only applies to a bone dry hair.I did an in-depth study in my Lavoratory that cost me two bucks of my retirement fund and a thousandth of an hours time to determine that I had read somewhere once upon a time back when the bears were bad that hair has the same tensile strength as copper wire of equal diameter and here endeth my lesson unto myself.
I wish I were into wet-shaving when I was in 2nd/3rd year mineralogy classes, my profs had their own SEM in the lab. I would have annoyed them with things to scan for me.
Steve56
Ask me about shaving naked!
I haven’t seen any evidence that Federal funding was used, but it wouldn’t surprise me under a general grant or something similar.
What folks are missing is that knowing that something happens is different from knowing why it happens. That’s kind of a definition of science. People know that the sky is blue but not many people know why it is blue. Knowing why things are, or happen, advances science and technology.
What folks are missing is that knowing that something happens is different from knowing why it happens. That’s kind of a definition of science. People know that the sky is blue but not many people know why it is blue. Knowing why things are, or happen, advances science and technology.
It is all about fracture mechanics.
The edge is essentially cracks along the blade.
When you know the deformation mechanism, the rest is quite straight forward.
Fracture Mechanics | MechaniCalc
This page discusses fracture mechanics methods to predict failure of a cracked part. Topics include stress intensity factors, fracture toughness, Linear Elastic Fracture Mechanics (LEFM), and others.
They should do it again, but with a scything motion.
A kitchen knife dulls from cutting tomatoes, no one says boo.
A razor blade gets dull from cutting whiskers, and a team of 'scientists' arrive to save the day.
Gillette and their team of microscope weilding charlatans bamboozled the buying public with this stuff back in the 1930s and periodically it cycles back around.
A 4 micron edge slamming into a 75 micron whisker is enough of a deformation mechanism to disturb what is actually a flimsy apex. The edge is not a straight line, it's more like pinking shears at a microscopic level. Steel is an alloy, it's not pure, and it has a crystalline form. Damage to the 4 micron apex has to be expected.
Tensile strength is not important, it's a metric of how strong something can 'pull' hair is strong with pulling and compression. Shear strength is important enough here, and hair does not have tremendous shear strength. When wet, both shear and tensile strength diminish. It's enough to deform the apex of a razor though.
A razor blade gets dull from cutting whiskers, and a team of 'scientists' arrive to save the day.
Gillette and their team of microscope weilding charlatans bamboozled the buying public with this stuff back in the 1930s and periodically it cycles back around.
A 4 micron edge slamming into a 75 micron whisker is enough of a deformation mechanism to disturb what is actually a flimsy apex. The edge is not a straight line, it's more like pinking shears at a microscopic level. Steel is an alloy, it's not pure, and it has a crystalline form. Damage to the 4 micron apex has to be expected.
Tensile strength is not important, it's a metric of how strong something can 'pull' hair is strong with pulling and compression. Shear strength is important enough here, and hair does not have tremendous shear strength. When wet, both shear and tensile strength diminish. It's enough to deform the apex of a razor though.
Steel is in general a isotropic material. You can have a difference in the properties in different directions if it has a rolling direction.
Thus, the shear resistance is in general not different then the tensile/compression resistance.
Tensile strength of material is important.
Steel will fail when the stress at a given point reaches the ultimate tensile strength of the material.
The striations and most importantly the shape of the striations give rise to localised stress concentrations. So even if the global stress at the edge is below yield, a sharp notch will increase this significantly. A ductile material with a fine micro structure is able to redistribute the stress as plastic strain, which might avoid the formation of a failure mechanism. Here is where the strop comes into play. You allign the plastic deformation, but the damage is still present in the steel due to the plastic strain hardening effect.
If you are able to raise the tensile strength, and at the same time don't loose too much fracture thougnes, the edge retention will increase, but it's a balance.
Thus, the shear resistance is in general not different then the tensile/compression resistance.
Tensile strength of material is important.
Steel will fail when the stress at a given point reaches the ultimate tensile strength of the material.
The striations and most importantly the shape of the striations give rise to localised stress concentrations. So even if the global stress at the edge is below yield, a sharp notch will increase this significantly. A ductile material with a fine micro structure is able to redistribute the stress as plastic strain, which might avoid the formation of a failure mechanism. Here is where the strop comes into play. You allign the plastic deformation, but the damage is still present in the steel due to the plastic strain hardening effect.
If you are able to raise the tensile strength, and at the same time don't loose too much fracture thougnes, the edge retention will increase, but it's a balance.
Tensile strength of hair in this scenario isn't important at all.
Tensile strength and shear strength of hair are quite different.
Shear and tensile strength of steel wasn't/isn't a consideration.
My comment was in reference to an earlier comment about hair having the tensile strength of copper wire and that being the reason blades wear out. Human Hair has been compared to steel and copper in this regard but the copper wire thing started in an ad campaign long ago.
My point was that the copper wire hair nonsense sold to the general public by the microscope weilding bozos at Gillette back in the 30s was just marketing b/s. The 'copper wire' reference keeps popping up even though the edge would wear if it was cutting soggy paper. A straight razor's edge can/will ding really badly on some 40-44 gauge copper wire, makes cutting hair look like a walk in the park. Not all wire is the same though, which just adds to the pointlessness of the marketing scheme.
TLR
The copper wire whisker story from Gillette was a marketing ploy used to drive sales of moisturizing shave creams, soaps, etc. that's all.
Tensile strength and shear strength of hair are quite different.
Shear and tensile strength of steel wasn't/isn't a consideration.
My comment was in reference to an earlier comment about hair having the tensile strength of copper wire and that being the reason blades wear out. Human Hair has been compared to steel and copper in this regard but the copper wire thing started in an ad campaign long ago.
My point was that the copper wire hair nonsense sold to the general public by the microscope weilding bozos at Gillette back in the 30s was just marketing b/s. The 'copper wire' reference keeps popping up even though the edge would wear if it was cutting soggy paper. A straight razor's edge can/will ding really badly on some 40-44 gauge copper wire, makes cutting hair look like a walk in the park. Not all wire is the same though, which just adds to the pointlessness of the marketing scheme.
TL
RThe copper wire whisker story from Gillette was a marketing ploy used to drive sales of moisturizing shave creams, soaps, etc. that's all.
Similar threads
