Review and summary

REVIEW AND SUMMARY

• In this chapter, the basics of static and dynamic force analysis are addressed.

• When the inertia effect due to the mass of the machine members is neglected while analysing the mechanism, then the analysis is called static force analysis.

• When the inertia effect due to the mass of the components is also considered in addition to the externally applied load, then the analysis is called dynamic force analysis.

• The external forces acting on a system of body from outside the system are called applied forces.

• When two or more bodies are connected together to form a group or system, the pair of action and reaction forces between any two of the connected body is called constraint forces.

• A free body diagram is a sketch or drawing of the body, isolated from the rest of the machine and its surroundings upon which the forces and moments are shown in action.

• Conditions for static equilibrium are:

(i) The vector sum of all forces acting upon it is zero, and

(ii) The vector sum of the moments of all forces acting about any arbitrary axis is zero.

ie., ΣFx = 0; ΣFy = 0; and ΣΜ = 0

• The three methods used for static force analysis of mechanisms are:

1. Principle of superposition,

2. Principle of virtual work, and

3. Method of normal and radial components.