INTERVIEW QUESTIONS

BENDING EQUATION

M/I = f/y = E/R

M Bending Moment Kg-mmI Moment of Inertial about

Centroidal Axismm4

F Internal Resistance Stress Kg/mm2

Y Distance of the fiber from neutral axis

mm

E Young’s Modulus/Elastic Modulus

Kg/mm2

R Radius of Curvature mm

Where

TORSION EQUATION

T/J = Gθ/L = τ/R

T Torsional Moment Kg-mm

J Polar Moment of Inertia Mm4

G Modulus of Rigidity Kg/mm2

θ Angle of Twist Radians

L Length of the Shaft Mm

τ Shear Stress in the element Kg/mm2

R Distance of the element from the centre of the shaft

mm

DIFFERENCE BETWEEN BOLT AND RIVET

Bolt Rivet

It is temporary fastener It is permanent fastener

It is basically meant for taking tension loads

It is basically meant for taking shear loads

WHERE BOLT IS USED

•Bolted Joints are used where applied loading is high.•where the joint must be capable of being disassembled.

WHERE RIVET IS USED

It is used in structure where the structure thickness is up to 2D

WhereD = Rivet Diameter

PARTS OF BOLT

WHAT IS LOAD PATH

It is a path followed from the load application to the supports.

TYPES OF LANDING GEAR

Fixed Landing Gear

Retractable Landing gear

Landing gear is an under carriage of an aircraft.

Tri-Cycle Landing Gear

Tandem Landing Gear

Conventional Landing Gear

LIGHTENING HOLES

As the name it-self says that these are the holes introduced for reducing the weight of the structure in-order not to compromise in the structural integrity.

WHAT IS STIFFNESS

K = F/δ

The Stiffness of a member is defined as the resistance offered against deformation.

WHY BOLTS ARE NOT USED IN AIRCRAFT SKIN

Bolts are not used in aircraft skin because it causes drag when it is flying.

When drag is caused the aircraft consumes more fuel and more thrust required to move forward.

By using the bolt the weight of the structure will increase because if we want to use nut for tightening the bolt.There will be chances of loosening the nut due to the

vibration of the structure.

WHY RIVETS ARE USED IN AIRCRAFT SKIN

Rivets are used in aircraft skin because of the smooth flow of wind when it is flying.

HOW WILL YOU VALIDATE THE RESULT

BY TESTING

FACTOR OF SAFETY

Factor of Safety = Design Ultimate Load / Design Limit Load

Factor of Safety has no limits it’s depend on the designer’s view.Higher the Factor of Safety more safer the structure.

But it is not acceptable in the buyer’s point of view due to weight of the structure.

If the factor of safety is higher then the structure will be heavy.

It measures how safe a Design of a Structure is.

Buildings = 2.0Pressure Vessels = 3.0 – 4.0Automobiles = 3.0Space Vehicles = 1.2 – 2.0

MARGIN OF SAFETY

Margin of Safety = Factor of Safety - 1

Margin of Safety should be in a positive value. If the Margin of Safety is zero then the structure will not take any

additional load. If the Margin of Safety is one then the structure will take one

Additional Load equal to the Maximum Load the structure is designed for.

If the Margin of Safety is in a negative value then the stressed part Of the structure is more like to fail.

Margin of safety is a measure of the excess capacity of the structure regarding Load.