Mechanical Engineering - Engineering Mechanics - Discussion

An Imperfect frame not satisfies the relation between the number of members and a number of joints given by the equation n = 2j – 3.

This means that number of members in an imperfect frame will be either more or less than (2j-3) It is known as a redundant frame.

Perfect Frame.

The frame, which is composed of such members, which are just sufficient to keep the frame in equilibrium, when the frame is supporting an external load, is known as the perfect frame. Hence for a perfect frame, the number of joints and number of members are given as n = 2j -3 Imperfect Fram An Imperfect frame is one that does not satisfy the relation between the numbers of members and number of joints given by the equation n = 2j -3. This means that the number of members in an imperfect frame will be either more or less than (2j-3) It may be a deficient frame or a redundant frame. Deficient Frame If the numbers of members in a frame are less than (2j-3), then the frame is known as a deficient frame. Redundant Frame If the numbers of members in a frame are more than (2j-3), then the frame is known as a redundant frame.

Imperfect when n>2j-3 redundant and when n<2j-3 deficient.
n=2j-3 Perfect frame.

Deficient is the correct answer.

Two types..perfect frame and imperfect.

Perfect frame when n=2j-3

Imperfect when N>2j-3 redundant and when N<2j-3 deficient.

N=2j-3.

If N more than above then redundant, if less then deficient.

So we said in frame case only perfect or no of joint is equal to no of member is perfect otherwise all are imperfect.

Frame n = 2j-3.

So perfect frame n = 2j-3.

Imperfect frame:

n<2j-3 (deficient frame).
n>2j-3 (redundant frame).

Redundant frame is an extra frame in the system which has a same function as another part such that the entire system will not fail if the main part fails.

Redundant frame is one which require no force to move it moves by itself.