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B. Design Process

B. Design Process

May 09, 2021

  1. Linkage Variables:

The goal is to define the length of the linkages so that that built mechanism works in full range of operation of the mechanism. (the 2nd linkage must rotate one full circle). Considering the mechanism as Figure 2, to achieve the goal, there are some conditions that must satisfied:

a. OA < O1O2: If OA > O1OB, the length of link AB b < 0. (Figure 3)

b.  AB > AO1 + O1O2: if AB < AO1 + O1O2, O2 cannot move along line AB (Figure4)

c. max(O2Bcos(theta3)) - l6 < c: Proof at (Figure 5)

d. b + c - sqrt(a^2 - dy^2) > dx + l6 (Figure 6)

Variable Input:

Variable

Value (cm)

a

5.25

b

15

c

8.25

dx

6.55

dy

2.01

l6

9

Construct the mechanism step by step:

  • Construct fix point O1, the defined O2 with dx and dy

  • Draw the circle (O1, a = 5.25). A is defined anywhere on the circle.

  • Construct line AO2, B on the line AO2 satisfied AB = b = 15 cm

  • Construct the track of the slider distanced from O2 = l6 = 9 cm

  • C is the intersection of the track and the circle (B, c=8.5)

2. Design Choices:

Quantitive Score Assignment

 

 

 

 

 

 

 

great

10

 

 

 

 

 

 

good

8

 

 

 

 

 

 

okay

6

 

 

 

 

 

 

fair

4

 

 

 

 

 

 

poor

2

 

 

 

 

 

 

 

 

Material

 

 

Thickness(cm)

 

Factor

 

Steel

PLA

Cardboard

0.25

0.5

1

 

Material Cost

4

8

10

10

8

6

0.3

Time

4

8

8

10

8

6

0.1

Reliability

8

8

2

4

6

8

0.3

Repairability

6

8

6

6

6

6

0.2

Manufacturing Cost

2

8

10

10

8

6

0.1

Score

5.4

8

6.6

7.4

7

6.6

 

Final Choices: Linkages use PLA as material and have thickness of 0.25 cm