Explanation Of Grain Boundries In Crystalline Materials
There can be stresses on materials and the strength of materials must be defined according to these stress values. So there are strength values are definef d for materials that generally used in engineering calculations. Two of them; tensile stress-strain, compression stress-strain characteristics of materials are explain in Mechanical Base. In this article we will explain the third one called as Shear Properties and Shear characteristics of materials.
Shear stress can be illutstrated as above that there is a opposite-sided forces that acting on stress element from above and below. This stress causes a deformation as shown by above called as torsion.
Formula of shear stress;
T = Shear stress(MPa)(lb/in^2)
F = Opposite force value(N)(lb)
A = Area(mm^2)(in^2)
Also we have a shear strain value as;
γ= Shear strain(mm/mm)(in/in)
δ= Deflection on element(mm)(in)
b = Orthogonal distance to deflection zone(mm)(in)
As other test methods, shear stress-strain also has an stress test called Torsion Test.
In torsion test, a torque is applied to the specimen. Shear stress-strain curve is obtained with this test.
If we take a look at the shear stress-strain curve above, there is a elastic region as in tensile stress-strain curves. After the yield point shear stress, plastic deformation occurs. The plastic region represents the plastic deformation of material that used as specimen in Torsion tests.
Formula that derived from Torsion tests;
τ= Shear stress at the specimen(MPa)(lb/in^2)
T = Applied torque(N.mm)(lb.in)
R = Radius of the specimen(mm)(in)
t = Thickness of the specimen(mm)
The shear strength can be obtained from this standardized tests. Shear strength generally lesser then tensile stresses of materials.
This is the general logic of shear stress-strain characteristics of materials in engineering.
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