This is just about the mechanical properties of materials. I have uploaded this file only to clear the basic concept of people related with Civil Engineering.

1. Strength of Materials

2. What do you mean by strength?
• The ability of a material to withstand external load safely
without failure is called strength of that material.
• A material has 2 kind of properties- Mechanical and
chemical. Mechanical properties are those which show
response against the applied load. Chemical properties are
those which are not affected by the application of loads.
• Strength of a material itself is a mechanical property which
is dependent on various other mechanical properties of
that material like modulus of elasticity, brittleness, ductility,
toughness etc. [Although strength is also dependent on
chemical properties, but this subject only deals with the
mechanical properties of materials]

3. Behavior of a material towards
external loads
A material’s behavior towards an external load is
of 2 types:
• Failure which can be resisted by strength of
that material.
• Deformation which can be resisted by stiffness
of that material.
[Note: Strength is affected when stiffness of a
material fails].

4. Properties of materials
• Ductility: It is the ability of a material to get elongated or
deformed in shape. For example, an iron rod can be bent
into any shape. Hence, iron is a ductile. [Note: Every metal
is ductile].
• Brittleness: It is just the opposite of ductility. A brittle
material cannot be elongated nor be deformed in any
shape.
• Malleability: It is the ability of a material to be beaten into
thin sheets. For example: Tin sheets used in roofing.
• Elasticity: It is the ability of a material to return in it’s
original shape and size after the removal of external load.

5. • Toughness: It is the ability of a material to absorb shocks
and withstand any impact without damage. [Plastic
deformation may occur but no fracture].
• Hardness: It is the resistance of a material to any kind of
wear, machining, cutting, scratching, indentation, etc.
• Stiffness: It is the resistance against deformation like
twisting, bending, rotation, elongation, elongation. [Force
applied but no deformation is considered to be stiff].
Note: The above three properties are independent of each
other. A material may be tough but not hard, for example
plastic. Likewise a material may be hard but not tough, for
example glass. The same goes for stiffness.

6. • Strain energy: It is the total energy stored in an elastic
material which helps it to regain its original shape and size
after the removal of load.
• Resilience: It is the ability of a material to regain its shape
and size by using its strain energy. For example: A spring
regains its original size after the compressive load is
removed.
• Creep: When a load is applied on a body for a long time,
the body relaxes with time due to which plastic
deformation occurs. Even when the load is removed, the
body does not regain it original shape and size which is
called creep. For example- A Cable wire attached in
between two poles sag downwards for being subjected
under gravitational force for a long time.

7. • Fatigue- It is the phenomenon where a material
fails when subjected under cyclic loading. For
example- A metal wire say copper is repeatedly
curved and straightened. A time will come when
the amount of strain energy exceeds its
toughness value causing the wire to break.
[Note: Toughness is also defined as the amount of
energy that can be stored in a body before
fracture.]