Skip to main content

What is stress? What is strain? What is the relation between them? What are the types of stress and strain?

  In physic, stress may be defined as the restoring force acting on a unit area of a material or object. In maximum cases, this restoring force is equal to the external force. So stress may also define as an external force per unit area of an object. 

If we consider a rod, which is tight on a wall as shown in the figure below



and apply stress or deforming force to it, then the rode opposes this deforming force by producing a restoring force because the rode is in static equilibrium that means the net force is zero. In this case,

Restoring force = Deforming force

It is a tensor quantity (in simple words, tensor quantity means we easily calculate its value by using simple mathematics.)

   The Formula of stress is Ïƒ = F/A

   Dimension of stress is [ML^-1T^-2] {Force=mass x acceleration = mass x (velocity/time)

    =kg x (meter/second/second) = kg x (meter/second^2) = kg meter second^-2= [MLT^-2]}

{Area = meter^2 = [L^2] }

{F/A = [MLT^-2]/ [L^2] = [ML^-1T^-2]}

Unit of stress is N/m^2 or Pascal (Pa).

Stress may be divided into the following types:

1)     1) Longitudinal stress: It is a force per unit area, which is related to the length of an object. It is further divided into two types-

 

a)     a) Tensile stress: It is the force applied per unit area, which results in an increase in length (or area) of a body. The object under tensile stress becomes thinner and longer.

 


b)     b) Compressive stress: It is the force applied per unit area, which results in a decrease in the length (or area) of a body. The object under compressive stress becomes thicker and shorter.

 


2)     2) Shear stress: The deforming force, which is applied tangentially on a crossectional area of an object, object shows some deformation or some minor changes can be obtained on that object, such deforming force is called shear stress.


3) Volumetric stress: If a solid object is present under the water, it experiences some deforming force due to liquid pressure, due to which the solid object starts to reduce its volume. As a result, the object becomes smaller than its original size and shape. This deforming force is called volumetric stress. In this case, the deforming force or stress is equal to the liquid pressure.



                                            Strain

Strain may be defined as the amount of deformation experienced by a body in the direction of applied force, divided by the initial dimension of the body.

The formula of strain in terms of length is ∂L/L (here ∂L = change in length and L = original length of the material

The strain has no dimension as well as the S.I. unit.

Depending on the stress application, strain experienced in a body can be of three types:

1)     1) Longitudinal strain: Longitudinal strain may be defined as the ratio of change in length of an object to the original length of that object due to longitudinal stress.

       2) Volumetric strain: Volumetric strain may be defined as the ratio of change in volume of an object to the original volume of that object due to volumetric stress.

       3) Shear strain: Shear strain may be defined as the ratio of total displacement or shifting to the length along which this shifting causes. This type of strain is obtained due to shear stress. 


that means, Strain = X/L

       Here, X = total displacement

                 L = the length along which this displacement occurs

     

     The relation between the stress and the strain: Up to elastic limit (It is a point in the stress-strain graph, from which object shows plastic deformation), the applied force or stress is directly proportional to the strain.

                        that means, stress ∝ strain

m                                         stress = E strain

                                            E = stress/strain, where E is a proportionality constant and it is called Modulus of Elasticity.


Comments

Post a Comment

Popular posts from this blog

What is Diastrophic and Non-diastrophic structure? What is the concept of Diastrophism?

 Before Know about the Diastrophic structure and non-Diastrophic structure we need to comprehend the Diastrophism interaction.  The Concept Of Diastrophism Diastrophism, likewise called tectonism, is the enormous scope misshapen of Earth's outside layer by regular cycles, which prompts the development of landmasses and sea bowls, mountain frameworks, levels, crack valleys, and different provisions by components, for example, lithospheric plate development (that is, plate tectonics), volcanic stacking, or collapsing.     The investigation of diastrophism incorporates the differing reactions of the covering to structural burdens. These reactions incorporate direct or torsional level developments (like mainland float) and vertical subsidence and elevate of the lithosphere (strain) because of normal weights on Earth's surface like the heaviness of mountains, lakes, and icy masses or glaciers.  Diastrophic Structure Any kind of movement of the Earth's crust, gen...
Post a Comment
Read more

What is Fault? How they are formed? What are the classifications of fault? Terminology of a Fault

  A fault may be defined as a well-defined crack along which the rock masses on either side have relative displacement. The displacement along a fault may be less than a meter, several meters, or many kilometers. Faults results from tensional as well as compressional forces TERMINOLOGY OF A FAULT Fault Plane : The fracture surface of a fault, along which relative movement has taken place, is called a “fault plane”. A fault plane is generally inclined but in some other cases, the fault plane may be markedly curved or undulating.    In a fault, there may be a number of parallel shear fractures along which the fault movement is distributed. Such a fracture zone is called a “shear Zone”. Hanging Wall and Foot Wall:  The block of rock lying above the fault plane such block of rock is called a hanging wall and if it is lying below the fault plane, then it is known as a footwall. Vertical faults have neither hanging wall nor footwall. Fault Scarp:  A fault scarp is a c...
Post a Comment
Read more

How does the moon cause ocean tide? What is the name of the coldest planet and green planet? and other some important questions and its answer

  How does the moon cause ocean tide? The moon's gravitational pull generates  something called the tidal force. The tidal force causes Earth—and its water—to bulge out on the side closest to the moon and the side farthest from the moon. These bulges of water are high tides. When the Sun and Moon are in line with the Earth (when a full moon or new moon occurs),  their combined gravity cause very high tides  (and very low tides), known as “spring tides.” So the Moon affects the tides because of gravity, but gravity from the Sun and the spinning of the Earth also change how the tides behave. The moon's gravitational pull on the Earth and the Earth's rotational force  are the two main factors that cause high and low tides. The side of the Earth closest to the Moon experiences the Moon's pull the strongest, and this causes the seas to rise, creating high tides. What is the name of the coldest planet and green planet? The lowest temperature recorded in Uranus's Tropo...
Post a Comment
Read more