Aerospace engineer mode *activated*!
Mechanical strength is measured in several different ways:
Hardness/softness
Tortion/strain
Stiffness
Modulous of elasticity
Hardness is usally measured with a tool resemblng a cross between a drill stand, a vise, and a lancet. It's basically an electronic strain guage attached to a small conical diamond, with a hardened steel anvil below it. The diamond probe arm is attached to a geared handle, like a drill stand's. When the probe comes into contact with the tatget material, the strain gague's electrical resistance changes, letting the device know that force is being applied, and that the probe is in contact with the sample. Force is continually exerted until the target depth in the material is reached. The amount of travel of the probe, and the strain reading are used to derive the hardness of the sample.
A tortion test exerts mechanical twist on a sample. It also uses electronic strain sensors to dertermine the amount of tortional force in footpounds, until the sample starts to deform or shatters. A strain test places the sample in a vise with a fulcrum point, and exerts metered amounts of force until the sample deforms or shatters.
Stiffness is related to strain, but is not the same. Stiffness relates to the amount of force a sample is able to resist before mechanical failure (deformation or fracture) and still spring back.
The modulous of elasticity is the coefficient of the stiffness of a sample, and how far it deflects before stuctural failure. (Think a bow. You pull the string, the bow flexes. A good bow takes a lot of force to flex, and can flex a great deal before snapping. This means the material the bow is made of has a high modulous of elasticity. Its a kind of measurement of how much sustained load the material can handle before structural failure, and how much deformation it can handle and still return to its original shape. A bow that flexes, and then stays that way isn't very useful.| you see.)
Now.. its been several days since I posted anything, and I've been busy IRL doing fabric dye process experiments on tshirts with my new airbrush... so, if somebody wants to make a reader's digest breakdown for me, I'd be much abliged.
(To give the basic idea of what each of those kinds of strength represents in a material, we will compare say, steel to high quality ceramic.)
In the hardness gague, the steel will move out of the way of the probe as energy is exerted faster than will the ceramic. Steel has a moh hardness of around 5. High quality ceramic has a hardness of around 7 to 8. We don't use mos hardness in engineering, because its not particularly useful as a metric. We instead measure hardness as a value in footpounds per square inch before the probe begins to penetrate the material, and a resistance curve for how much force is required for the probe to continue its penetration. Due to steel being ductile, and ceramic not being so, the probe will crack the ceramic sample before it penetrates, and will require far more energy to do so than it would on the steel. As such, the ceramic is waaay harder.
In the tortional stress test, the steel wins out, hands down. The crystal structures that form in the ceramic have a stronger bond force, which is what makes it harder. It also makes the material fragile. Tortion stress will splinter the ceramic way sooner than the steel bar sample of identical diameter.
Similar story with strain. The springyness of the steel makes it stronger in a strain test than ceramic.
Same with the modulous of elasticity. Ceramic doesn't flex at all usually, while steel can flex a lot if properly formulated.
Ceramic is stronger than steel in regard only to blunt penetration, and sustained distributed static force. (A ceramic block under equal pressure will hold up more pressure per square inch than a steel block, before mechanical deformation. The low modulous of elasticity though means ceramic will have serious problems with fluctuating stresses, or uneven stresses. The strain forces would shatter the material.
Wierd's hazard suit is a composite material that tries to overcome material weaknesses with other materials that tae up the slack.
Glass fiber has a high tortion and strain rating, and a good hardness rating. This makes it flexible, and difficult to cut. it makes up for the inflexibility of the ceramic plates. The PVC rubber has a low hardness, (made up for by the ceramic plates, and the glass fiber running ) but a very high modulous of elasticity. The glass fiber and ceramic plates are not very elastic.
The result is a suit with puncture and scratch resistant plates, a glass fiber infrastructure that resists being cut and torn, and a rubber like plastic resin bonding material that resists mechanical straining. What the suit is weak against is high energy kinetic impact. The ceramic plates will shatter. This reduces the suits ability to resist projectile and slashing penetrations.
Proposed upgrade to the suit would be to plate the ceramic plates with about 2mm thick aluminum alloy (say, 2025.) This would make the suit more resistant to crushing/blunt attacks, but the 2025 is weak against chemical attacks, like strong alkaloids and acids. (7075 is better, but more fragile, which negates the reasoning behind plating.
Now.. somebody please tell me what I would be measuring the strength of?