2. This questionnaire is prepared for mechanical engineers .
A quick brush up on SOM for mechanical engineers.
The topics covered under this will be questions based on Strength Of
Materials.
Only important topics are covered.
No formulas are provided except very important ones.
Let’s start.
3. What is stress and strain?
Whenever external forces acts on a body, it undergoes deformation. The
resistance per unit area to deformation is stress. That is force acting per
unit area is stress. Unit is N/m2
As said above, when force acts on a body it causes deformation. And the
deformation per unit length is strain.
What is Hooke’s Law?
When a material is loaded, within its elastic limit, the stress is
proportional to strain.
What is moment of a force?
It is the turning effect produced by a force, on which it acts. The
moment of a force is the product of the force and perpendicular distance
of the point.
4. What is couple?
The two equal and opposite forces, whose lines of action are different,
form a couple.
What is Centre of Gravity?
The point through which the whole mass of the body acts.
What is moment of inertia?
It is the moment of moment of mass or area of a body.
What is shear stress and shear strain?
When a body is subjected to two equal and opposite forces, acting
tangentially across the resisting section, as a result of which the body
tends to shear off the section, then the stress induced is shear stress and
corresponding strain is shear strain.
5. What is Poisson’s ratio?
The ratio of lateral strain to linear strain.
What is bulk modulus?
When a body has 3 mutually perpendicular stress of equal intensity acting on it,
the ratio of direct stress to corresponding volumetric strain.
What is a principal plane and stress ?
A plane on which have no shear stress acting on it is a principal plane. The
magnitude of direct stress across a principal plane is principal stress.
What is the purpose of Mohr’s circle?
A graphical method of finding the normal, tangential and resultant stresses on
an inclined plane. This method is used when 2 mutually perpendicular principal
stresses are unequal and alike.
6. What is resilience?
The ability to store strain energy in a body due to external loading within the
elastic limit.
What is the difference between malleability and ductility?
The ability of the material to deform under compressive stress is malleability
whereas the ability of the material to deform under tensile stress is ductility.
What are the types of beams?
Cantilever beam : Fixed at one end and free at the other end.
Simply supported beam : Supported at two ends.
Overhanging beam : End portion extend beyond the support.
Fixed beam : Both ends are fixed.
Continuous beam : Beam with more than 2 supports.
7. What are the types of loading?
Point load : A load acting at a point of a beam.
Uniformly distributed load : A load which is spread over a beam in such a
manner that each unit length is loaded to the same extent.
Uniformly varying load : In this, load varies uniformly t each unit length
What is shear force and bending moment?
Shear force at the cross section of a beam is the algebraic sum of all the
forces on either side of the section.
Bending moment at the cross section of a beam is the algebraic sum of all
the moments of the forces on either side of the beam.
BENDING MOMENT EQUATION:
M/I=S/Y=E/R : M=Bending moment : I=moment of inertia of the cross
section : S=Stress : Y=Distance of external fibre from the neutral axis :
E=Young’s modulus : R=Radius of curvature.
8. How to calculate the maximum shear stress?
Maximum shear stress : 1.5 average shear stress.
SHEAR STRESS EQUTION FOR SHAFTS
t/R=T/J=Gx/L : t=shear stress : R=shaft radius : T=torque : J=polar moment
of inertia, that is second moment of area of the section about its polar axis :
G=rigidity modulus : x=angle of twist in radians : L=shaft length.
What are the types of riveted joints?
Lap and butt joints.
Lap joint : One plate overlaps the other.
Butt joint : Main plates are kept in alignment touching each other and a cover
plate is placed on one side or on both sides of the main plates.
Types of riveted joint : Single strap butt joint, double strap butt joint, single
riveted and double riveted joints.
9. Pitch in a riveted joint : It is the distance from the centre of one rivet to the
centre of the next rivet measured parallel to the seam.
Diagonal pitch : Distance between the centres of he rivets in adjacent rows of
zig zag riveted joint.
Margin : Distance between the centre of rivet hole to the nearest edge of the
plate.
10. Here ends this topic.
I hope this will be useful for you.
Soon, other questionnaires on other subjects based on mechanical engineering
Will be published soon.
THANK YOU!
