文档介绍：Statics
静力学
物体系统的平衡
Equilibrium analysis posite bodies
Bilingual Edition
Equilibrium analysis posite bodies
1. Equilibrium analysis posite bodies
PART SIX
Drawing the FBD of posite bodies and parts of bodies
Usually we begin by drawing the FBD of the entire body and, if possible, calculate the external reaction forces.
Analyze the on or more parts of the bodies.
Hint: From the FBDs of the entire body and any parts, we begin to write the equations of the part which has at most three unknowns.
Equilibrium analysis posite bodies
2. Sample problem 1
PART SIX
A ladder placed on the smooth horizontal surface is in equilibrium, F=60kN, l=3m, α=pute the reaction forces on pin C and surface
[solution]
Firstly, draw the FBDs of the whole and each part, find out the number of unknowns.
Equilibrium analysis posite bodies
2. Sample problem 1
PART SIX
[FBD of the whole]
Coplanar parallel force system, 2 unknowns, 2 equations.
[FBD of AC]
mon force system, 4 unknowns, 3 equations
[FBD of BC]
mon force system, 4 unknowns, 3 equations
Equilibrium analysis posite bodies
2. Sample problem 1
PART SIX
From the FBDs above, we can make the procedure of solving the problem, that is:
FA, FBFcx,Fcyverify
Equilibrium analysis posite bodies
2. Sample problem 1
PART SIX
Equilibrium analysis posite bodies
2. Sample problem 1
PART SIX
Verify:
If the following equations are satisfied, then your results are correct.
Equilibrium analysis posite bodies
3. Sample problem 2
PART SIX
The structure shown in the figure left, AB=BC=1 m, EK=KD, P=1732 kN, Q=1000 kN, neglect all the gravity forces, compute the reaction forces and force in lever DC
Equilibrium analysis posite bodies
3. Sample problem 2
PART SIX
[solution] Draw the FBDs, find out the path of solution:
[FBD of the whole]
mon force system 3 equations 5 unknowns can not determine all the unknowns