This document discusses static force analysis in machines. It explains that static force analysis is used to evaluate the forces acting on machine members in a particular configuration when the machine is in static equilibrium. The goals are to find the load carried by each part and analyze the external and internal forces like applied forces, constraint reactions, friction, and inertia. It provides examples of static force analysis in mechanisms like slider-crank and 4-bar linkages. Key equations for static equilibrium involving the sum of forces and sum of moments are also presented.

1. DYNAMICS OF MACHINES
• To know the purpose for which the m/c is
needed.
• To develop concept design.
• To analyze the motion involved
- Kinematics
• To calculate & analyze the forces and torques
required for producing the motion
- Kinetics
• To give physical shape to the components.
- Machine Design

2. STATIC FORCE ANALYSIS IN
MACHINES
• To evaluate the forces acting on the machine
members at a particular configuration.
• Each configuration is considered as system of
rigid bodies in static equilibrium
under the action of external forces.
• Helps in finding load carried by each part of the
machine during cycle of its operation

3. TYPES OF FORCES
• Applied forces :
Gas, hydraulic & pneumatic forces etc..
Electrical, magnetic & gravity forces
• Constraint forces :
Reaction forces.
• Friction forces.
• Inertia forces.
Due to mass of accelerating parts

4. Condition for static equilibrium
• ∑ F i = 0
• ∑ Mi = 0
F1
F4
F2
F3
F5
CG
M/c part

5. Fi = 0
M i = 0
EQUATIONS FOR STATIC
EQUILIBRIUM

6. EQUILIBRIUM OF TWO FORCE
AND THREE FORCE MEMBERS
Two force member in equilibrium
F1
F2

7. THREE FORCE MEMBER IN
EQUILIBRIUM
F1
F2
F3
O
F1
F2
F3
O

8. P O2
A
B
P
3 2
4
1
F14
F34
A
B
3
F32
F12
2
4
STATIC FORCE ANALYSIS IN SLIDER-CRANK MACHANISM
C12
F43
F23
P
F14
F34
FBDof
Link 4
FBDof
Link 3
FBDof
Link 2

9. A
B
P
2
4
O4
O2
3
P
F34
F14
O
P F14
F34
F23
F43
F32
F12
C12
STATIC FORCE ANALYSIS IN 4-BAR MECHANISM
3
4
h
C12 = F32 X h
O2
C

10. O2
B
4
2
O2
O4
5
C
6
A
3
P
C
6
P
5
F16
F56
P
F16
F56
1

11. C
5
F45
F65
4
F54
O
F54
F34
F14
F43
F23
3
2
O2
A
F32
F12
3
C12

12. Inertia force - m a
-Inertia torque - I α

13. D’ Alemberts principle
In order to find the effect of inertia of
the actual link on the forces
transmitted to the adjacent links of a
mechanism, the actual link may be
replaced by a rigid mass-less link to
which inertia force F i = -ma is applied.
The mass-less link is then under
equilibrium under systems of forces
along with inertia force.