Define viscosity and elasticity7/25/2023 Viscosity is a measure of a fluid’s resistance to gradual deformation/ flow by shear stresses (forces) it describes the internal friction of a moving fluid and also explains its thickness. Phew!! There… this was the hardest part of this article. In purely elastic materials the applied energy/force for deformation is recovered & stored after each cycle without any loss (think of a thick steel spring). ![]() For the same amount of stress, the strain (deformation) experienced by rubber will be way higher than steel So, the stiffness of a material is used as a measure of the resistance to elastic deformationįrom the equation, it is clear that the lesser the strain experienced, the greater the elastic modulus (measure) of the material. That would make rubber more deformable but steel more elastic!! (that blew my mind again as I typed !!!) It is a measure of the stiffness or resistance the material inherently possesses to avoid deformation when forces are applied on it.Į.g., when the intrinsic stiffness/ resistance to stretch is greater than the force that is applied, no change is seen in the material (steel), but when the force applied is greater than the intrinsic resistance/ stiffness, the material deforms and takes time to resume its original form (rubber). Let me explain…Įlasticity is the material’s ability to stretch when a force is applied and also its ability to return to its original state when the force is removed. Isn’t elasticity the amount a material can be stretched? Well, Yes and No! Yes, because it is the amount a material can stretch before it can deform & no, only because it doesn’t give the complete information about the material. rubber/ steel WAIT…WHAT? Solids have higher elasticity? ![]() Materials with the highest elastic portion are called Elastic/Hookean solids & they show the same level of stiffness unless they are destroyed e.g. Materials with the highest viscous portion are called Viscous/Newtonian liquids & no matter how they are stressed, their viscosity never changes e.g water/ salad oil So, here goes…Īccording to Rheology (Greek: Rheos – flow/ logia – study of), most materials are viscoelastic & have both viscous & elastic components. I have also attached the links to a few of my favourite papers. ![]() I have tried to keep it to purely stringing facts together and less of any personal opinion (although there might be a few). So, here’s my attempt at making it simpler and easier for the rest of my fascia nerd family ? Most of you reading this are already aware that fascia is viscoelastic, but what amused me the most is what gives it that property, and while devouring at least 25-30 odd research papers (from physics to biochemistry to material science… (yeah, I am crazy like that), I realised how deviated my perception was about viscoelasticity.
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