Simple Stresses And Strains.
1. Equilibrium:-
”Any system of forces which keeps the body at rest is said to be in equilibrium" or "when the condition of the body is unaffected even though it is acted upon by number of forces, it is said to be equilibrium".
2. Concept of stresses:-
"Stress is defined as the ratio
if applied force per unit cross-sectional area".
σ = P/A
where,
σ is the stress applied
F is the force applied
A is
the area of force application
Stress Units:-
Stress
can be expressed using multiple units. Refer to the table given below for
Stress units.
System of units |
Stress units |
Fundamental units |
Kg.m-1.s-2 |
SI (derived units) |
N.m2 |
SI (derived units) |
Pa or pascal |
SI (mm)(derived units) |
M.Pa or N/(mm)2 |
US unit (ft) |
lbf/ft2 |
US unit (inch) |
Psi (lbf/inch2) |
- Types of Stress:-
A stress acts on a body may be normal stress or shear
stress.
1.
Normal
Stress:
Normal stress is a stress that acts perpendicular to the area. The formula for the normal stress is given by
The normal stress is again subdivided into two parts.
I.
Tensile
Stress:-
The stress-induced in a body when it is subjected to two equal and opposite pulls as shown
in the figure given below
is called tensile stress.
![Tensile Stress](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLzmG_8Zx8ABxcVMeq0qgPN3vmYjZe9ZxD8ckyUNKqQ9G_W2ktW9wpfjl5Ox08xgX3lyAVGMDsbAEmqJC7LLE9kIwrgbmeqxqEImWgfXAFwIJyonKcYKqU5-d0K8gQ4i4v6L2nsW5ekc1F/w397-h170/image.png)
§
§ Due to the tensile stress there is
an increase in the length of the body and decrease in the cross section area of
the body.
§ Tensile stress is a type of normal
stress, so it acts at 90 degree to the area.
§ The strain which is induced due to
tensile stress is called tensile strain. It is equals to the ratio of increase
in the length to the original length.
I.
Compressive
Stress:-
The stress which induced in a body when it is subjected to two equal and opposite pushes as shown in the figure given below is called compressive stress.
![compressive stress](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1TrLQIXfbBxnnHuTOCjRV2mSPoSJDtLkurW2hyE7KPImPzaq10v_d_YPphnOlImolfS9U-8N9rLDFzpbrPhQlU-Tv4yABobiuHX4AwOl3IAno0FsQ2oVLs5dS-kcsgdfQYsN2tzghYIbL/w356-h128/image.png)
§ Due to the compressive stress, there
is a decrease in the length and increase in the cross section area of the body.
§ Compressive stress is also a type of
normal stress and so it also acts at 90 degree to the area.
§ The strain which is induced due to
compressive stress is called compressive strain. It is equals to the ratio of
decrease in the length to the original length.
2. Shear Stress:-
Shear stress induced in a body when it is subjected to two equal and opposite forces that acts tangential to the area.
§ The strain produced due to the shear
stress is called shear strain.
§ The shear stress is denoted by the
symbol τ (tau). It is a Greek letter.
§ It is defined as ratio of shear
resistance to the shear area.
§ The formula for the shear stress is
given below.
3. Concept of strain:-
Strain is defined a ratio of change in dimension
to original dimension of a body when it is deformed. It is a dimensionless
quantity as it is a ratio between two quantities of same dimension.
ϵ=δlL
where,
ϵ is the strain due to stress applied
- Strain Units:-
- Types of Strain:-
- Longitudinal Strain:-
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiBgJS4VHisnj086Z3gsBhX6GU6I8LprRGm4WWOoGKjeYDkUEzE0YbgBLDDS7m1VN3iK6V6QTwI3I6iW7CoHt50aJ37Hbny9270a1AY2FgLYqcXwAxElgqY5yYSluO3kTaLFx-RG2BVMbvA/w313-h43/image.png)
- Volumetric Strain:-
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgng_vutZfij2HgDYNj_LuWG_D8mxUGCGFAHBI9m_8SJa8JhP9gWtlW-l2HBa2Yf3JSH13yPArISn6ToZlCx5yr5lRvBNnJpvt-0v-AGI_wmLDKRuWsJuq4HJ86FUSm6FJ2iW82I2IzfRWG/w315-h51/image.png)
- Shear Strain:-
Shear strain is defined as the change in right
angle.
Subhan allah very nice for engineering knowledge
ReplyDeleteThanks :)
Delete