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Modulus of rigidity 
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#1
Jun605, 06:30 AM

P: 139

what is modulus of rigidity and shear modulus? What do they define?



#2
Jun605, 07:40 AM

P: 541

There are three moduli of rigidity:
1. Young's Modulus 2.Bulk Modulus 3.Shear Modulus Modulus is generally defined as Stress/Strain 1.Young's Modulus is generally used for solid materials( In problems, for wires..) [itex]Y= \frac{Longitudinal Stress}{Longitudinal Strain}[/itex] 2. Bulk Modulus is generally used for Liquids and Gases [itex]B= \frac{Volumetric Stress}{Volumetric Strain}[/itex] 3. Shear Modulus is used where tangential stress is applied and the object bends or tangentially bends making some angle with vertical. I assume you know what stress and strain is. 


#3
Jun605, 08:39 AM

HW Helper
P: 2,277

Rigidity is the required force to produce a unit incrementum of length.
In prismatic beams, the product of EA is known as axial rigidity. [tex] \delta = \frac{PL}{EA} [/tex] where [itex] \delta [/itex] is the change in length, P is the force applied at the centroid, L is the original length, E is the modulus of elasticity (assuming the material is at the elasticlinear region) and A is the cross sectional area. Of course this is for Homogenous materials. In general the rigidity will be a measure of a structural member "opposing the change in length", with rigidity it's often used flexibility, which is inverse to the rigidity. 


#4
Jun605, 11:28 AM

HW Helper
P: 2,277

Modulus of rigidity
Maybe you are refering to the modulus of elasticity in shear stress, also know as modulus of rigidity.
According to Hooke's Law in shear (elasticlinear region) [tex] \tau = G \gamma [/tex] where [itex] \tau [/itex] is the shear stress, G is the modulus of rigidity or elasticity in shear and [itex] \gamma [/itex] is the angle of distorsion or the unit deformation. The rigidity here is about measuring the structural element resistance to the "change of its shape". 


#5
Aug1209, 02:07 AM

P: 1

what does the product of rigidity modulus and moment of inertia of a beam mean??



#6
Oct2809, 09:55 AM

P: 5

can some one please tell me the derivation of modulus of rigidity or shear modulus i stuck
i need to finish with this equation: G=E/2(1+U) please help out if you can thanks 


#7
Oct2809, 12:24 PM

Sci Advisor
P: 5,095

They are not derived quantities. They have specific definitions:
http://www.engineeringtoolbox.com/mo...ityd_946.html http://en.wikipedia.org/wiki/Shear_modulus http://www.efunda.com/formulae/solid..._constants.cfm http://geophysics.ou.edu/geomechanic...ast_const.html For the proof you are doing, you'll need to look at the definition of shear strain and how shear strain is related to shear stress in multiple dimensions. 


#8
Jul2310, 10:45 AM

P: 1

[QUOTE=rotin089;2414500]can someone tell me in brief about modulas of elasticiy along with pictures



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