Lecture 12Notes courtesy of: Prof. Yoav Peles

ENGR-1100 Introduction toEngineering Analysis

Lecture Outline

• Rigid body equilibrium.

• FBD- Free Body Diagram.

Two-dimensional reaction atsupports and connections

1. Gravitational attraction 2. Flexible cord, rope, chain, orcable

3. Rigid link 4. Ball, roller, or rocker

5. Smooth surface 6. Smooth pin

7. Rough surface 8. Pin in a smooth pinguide

9a. Collar on a smooth shaft

Pin connection

9b. Collar on a smooth shaft:

Fixed connection

ExampleDraw complete free-body diagram of the beam shown, whichhas a mass m.

Solution

Known forces

unknown forcesP

mg

Ay

Ax 450

By

x

Three-dimensional reaction atsupports and connections

1. Ball and socket 2. Hinge

3. Ball bearing 4. Journal bearing

5. Thrust bearing 6. Smooth pin and bracket

7. Fixed support

ExampleDraw complete free-body diagram of the bent bar shown in thefigure. The support at A is a journal bearing and the supports atB and C are ball bearings.

Solution

Az

P1

P2

P3

x

y

z

Ay

Mz My

ByBx

Cz

Cx

Known forces

unknown forces