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Civil - Mechanics Of Solids - Stress, Strain And Deformation Of Solids

*STRESS,
STRAIN AND DEFORMATION OF SOLIDS*

*1. What is strength of Material?*

*When an external force acts on a body, it
undergoes deformation. At the same time the body resists deformation. This
resistance by which materials of the body opposes the deformation is known as
strength of material.*

*2. What is Rigid body?*

*A rigid body consists of innumerable particles. If
the distance between any two or its particles remains constant, it is known as
solid body.*

*3. What is deformable solids?*

*A body which undergoes
deformation due to application of external forces.*

*4. Define stiffness.*

*The stiffness may be
defined as an ability of a material to with stand high load without major
deformation.*

*5. What
is stability? Explain*

*It is the over all property of a member made out a
material to maintain the overall equilibrium preventing complete collapse.*

*6. **What are
the types of stress? *

*i. **Tensile
stress *

*ii. **Compressive
stress *

*Shear stress.*

*7. Define Stress*

*The force of resistance per unit
area offered by a body against deformation is known as stress.*

*8. Define tensile stress?*

*It may be defined as the tensile
force per unit area.*

*9. Define compressive stress?*

*It may be defined as the
compressive force per unit area.*

*10.
Define shear stress stress?*

*It may be defined as the
shear force per unit area.*

*11.
Define crushing stress?*

*It may be defined as the crushing
force per unit area.*

*12. What
is simple stress?*

*When a body is subjected to an external force in
one direction only, the stress developed in the body is called simple stress.*

*13. What
is Compound stress?*

*When a body is subjected to an external force more
than one direction only, the stress developed in the body is called Compound
stress.*

*14.
Define Strain.*

*The ratio of change of dimension of
the body to the original dimension is known as strain.*

*15.
What is meant by Poisson's ratio?*

*It is the ratio between lateral
strain and linear strain.*

*16. What are the three main types of strain? **i).
Tensile strain*

*ii).
Compressive strain iii). Shear strain*

*17.
Define factor of safety.*

*It is the ratio of
ultimate tensile stress to the permissible stress.*

*18. Define lateral strain.*

*A direct stress is always accompanied by a strain
its own direction and the opposite kinds of strain in every direction at right
angles to it. Such a strain is known as secondary strain or lateral strain.*

*19. What
is meant by elastic limit?*

*Whenever a system of external forces, causing
deformation of a body, is removed the body springs back to its original
position. For a given section, there is always a limiting value of force, up to
and within which, the deformation entirely disappears on the removal of the
force. The intensity of stress, corresponding to the limiting force is called
elastic limit.*

*20. What
are the types of elastic constants?*

*There are three types of elastic
constants*

*They are, a) Young's
Modulus (E), b) Bulk Modulus (K) and c) Shear Modulus(C)*

*21.
Define Bulk modulus (K)*

*The ratio of direct stress to the corresponding
volumetric strain is constant within its elastic limit. The ratio is known as
Bulk modulus.*

*Bulk modulus (K) = Direct
stress/Volumetric strain*

*22.
Define Poisson's ratio.*

*It is ratio of the lateral strain
and longitudinal strain.*

*23.
Define volumetric strain.*

*It is ratio of the change in
volume and original volume.*

*24.
State clearly the Hooke's **law.*

*Hooke's law states, 'Whenever a material
is loaded within its elastic limit, the stress induced is directly proportional
to strain'. It holds good equally for tension and compression.*

*25.
**What are the three elastic
constants? *

*i. **Modulus
of Elasticity *

*ii. **Bulk
Modulus *

*iii. **Shear
modulus *

*26.
**Define Modulus of rigidity. *

*Within elastic limit, the ratio
of shear stress to the shear strain is known as modulus of rigidity.*

*Modulus of Rigidity (G) = Shearing stress/Shear
strain = q/e _{s}*

*Where,*

*q=Shearing stress*

*e _{s} =Shear strain*

*27.**What is
composite bar? How will you find the stresses and load carried by each members
of a composite bar? *

*A composite member is composed of two or more
different materials, joined together in such a way that the system is elongated
or compressed as a single unit. In such a case, the following two governing
principles are to be followed.*

*i) Change on length in the bar (1) = Change on
length in bar (2) P _{1}L_{1}/A_{1} E_{1} = P_{2}L_{2}
/A_{2} E_{2}*

*ii) Total load P = load carried by bar (1) +load
carried by bar (2) P = P _{1+} P_{2}*

*Stress
induced in bar (1) = P _{1}/ A_{1} Stress induced in bar (2) = P_{2}/
A_{2}*

*28. State
the relationship between Young's Modulus and Modulus of Rigidity.*

*E= 2C (1+1/m)*

*Where,*

*E-Young's
Modulus C-Modulus of Rigidity 1/m-Poisson's ratio*

*29. **State the
relationship between Bulk Modulus and Young's Modulus *

E= 3K (1-2/m) Where,

E-Young's Modulus K-Bulk Modulus 1/m-Poission's ratio

*30.**Determine
the Poisson's ratio and bulk modulus of a material, for which Young's modulus
is 1.2 x 10*^{5}*
*

*N/mm ^{2}
and modulus of rigidity is 4.8 x 10^{4} N/mm ^{2}. *

*Modulus of rigidity C =
mE/2[m+1]*

*4.8 x 10 ^{4} = 1.2x10^{5} m/2[m+1]*

*Poisson's 1/m =
0.25*

*Bulk modulus K = mE/3[m-2]*

*K = 4x1.2x10 ^{5}/3[4-2]*

*K **= 8 x 10 ^{4}
N/mm^{2} *

*31.
**Define Thermal stress and strain.
*

*If the temperature of a body is lowered or raised
its dimensions will decrease or increase correspondingly. If the changes are
checked, the stress thus developed in the body is called Thermal stress or
temperature stress. And corresponding strain is known as Thermal stress or
temperature stress.*

*32. Define strain energy.*

*The energy absorbed in a body,
when strained within its elastic limit is known as strain energy. It is also
known as resilience.*

*33. Define
proof resilience.*

*The maximum strain energy that
can be stored in a body is known as proof resilience.*

*34.
Define modulus of resilience.*

*The proof resilience per unit volume is known as
modulus of resilience. It is also known as strain energy density.*

*35. Write
down the equation for strain energy stored due to shear stress and explain the
terms.*

*Strain energy due to shear stress
U = [q ^{2}*

*q= Shear
stress* *C=Shear
modulus* *V= Volume
of the body*

*36. Write
down the equation for strain energy stored in a body and explain the terms.*

*Strain energy due to shear stress
U = [q ^{2}*

*q = Shear
stress* *E = **Young's
modulus* *V =
Volume of the body*

*37. Define strain energy theory.*

*According to this theory, the elastic failure
occurs when energy per unit volume in a strained material reaches the value of
the strain energy per unit volume at the elastic limit point in the simple
tension test. According to this theory, the maximum energy which a body can
store without deforming plastically is constant for that material irrespective
of the manner of loading.*

*38. State
the formula for strain energy and deflection due to bending.*

*Strain Energy U = (1/2) W y, Deflection* *y = 2U/W, Where W is the load.*

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