2. Data that is given in Handout
1. 5% standard deviation all dimension
2. 99.9% fit in the opener
3. 99.9% operation
4. Length between sensors = 10mm
5. Length of the opener (including push) = 40mm
6. Height of Sensor Box = 10mm
3. Properties of Spring
Music wire
K = 0.3 N/mm
Squared and Ground
d = 0.95mm
G = 81.7 GPa (Table 10-5)
Ls = 20mm
Lfree = 38mm
Nt = 15turns (Table 10-1)
D = 10.12mm (Equation 10-9)
7. #1 Ensure the spring will always fit in the opener,
99.9% of the time.
Conditions :
I. Diameter of Opener should be bigger than the diameter of spring.
II. The diameter of spring should be smaller than 15mm
10. #2 Ensure the button will always be protruding out of
the door opener with enough length to cause a
nominal 3N force to activate the sensor.
The length of the button from the top to the bottom of the
outer part of the sensor was to be 10mm. In order to ensure that
the sensor will be activated, the length of the button was
increased to 13mm for better accuracy.
11. #3 Find out the length of a typical battery (AA or AAA,
depending on what you prefer to use) and size up the sensor
box, so that your sensors from the button and the sensor box
will be aligned 99.9% of the time when the button is depressed
with a maximum force of 3N.
For this condition to be satisfied, the length the button
has to travel is 10mm for the sensor to work. To ensure
that it will be aligned 99.9% of the time, stochastic
analysis was done to find the minimum length that it
need to travel to achieve this success rate.
Calculations are as follows :
14. #4 Think about a minimum force that your device will require
to active the door opener. It cannot be too low, or it is too
sensitive. Make sure your design is not such that the opener is
activated too easily.
For an operation of 99.9%, the length of sensors should be
4.14mm. Hence, the minimum displacement that the spring
needs to travel is 5.86mm ( 10 – 4.14 ).
From equation F =K*x
Fmin = 0.3 * 0.586 = 0.1758N
17. Part 2: Using a standard deviation
of 0.5% instead of 5% for question 1
BASED ON THE
CALCULATIONS DONE, THE
DIAMETER NEEDS TO BE
BIGGER THAN 10.15MM AND
THE CURRENT DESIGN
DIAMETER IS 12.5MM WHICH
IS STILL ACCEPTABLE
18. Using a standard deviation of 0.5%
instead of 5% for question 2
BASED ON THE
CALCULATIONS DONE, THE
LENGTH BETWEEN THE
SENSORS NEEDS TO BE
0.69597MM IN ORDER FOR
THE SENSORS TO WORK 99.9%
OF THE TIME.
19. Summary for change in standard
deviation
For the length between the two sensors, a change in
standard deviation results in a much lower range for
the sensors to work at a rate of 99.9%. For a standard
deviation of 5%, the length was 4.14mm while for a
standard deviation of 0.5%, the length drastically
reduced to 0.69mm which is a reduction in 83.3%.
20. Part 3: garage door opener analysis
using abaqus cae
Material chosen and properties
Aluminum 6061
- Young Modulus : 68.9 GPA
- Poisson's Ratio : 0.33
- Yield Strength : 276 MPA
- UTS : 310 MPA
21. 1st part : Button (original design)
ORIGINAL DESIGN TET MESH WITH
NODES
LOAD OF 10N
APPLIED
22. 1st part : Button (original design)
A MAX
DISPLACEMENT OF
1.675e-08.
Von Miser Stress
23. Design changes made to 1st button
The fillet of the button was reduced from 0.10 inches to 0.05 inches.
This would reduce the stress concentrations on a smaller portion of
the button and distribute the stress more evenly.
24. 1st part : Button (new design)
TET MESH Load and Boundary conditions being applied
25. 1st part : Button (NEW design)
A reduced max displacement
from1.675e-08 to 7.634e-09
Von Miser Stress (Reduced from 5.36e04 to
6.925e03 )
26. 2nd part : holder (original design)
TET MESH WITH
NODES
Load of 45 Newton's applied and
boundary conditions
27. 2nd part : holder(original design)
A MAX
DISPLACEMENT OF
3.3e-06.
Von Miser Stress
28. Design changes made to 2nd
holder
The thickness of the holder was increased from 0.5 in to 0.75 inches
This would reduce the stress concentrations greatly on the
concentrated areas of stress.
29. 2nd part : holder(new design)
A reduced displacement from 3.3e-06 to
2.93e-6 (Load was still maintained at 45
Newton's).
Von Miser Stress (Reduced from 2.882e03 to
2.562e03)
30. Summary for change of parts
design
When either design was changed, a reduction in maximum
displacement that will happen with a lower Von Miser stress.
Other methods to reduce stresses besides design changes would be
to change the material used.
For this analysis, Aluminum 6061 was used. If Aluminum 7075 was
used as an example, the Young’s Modulus will increase from
68.9GPa to 71.7GPa. Other mechanical properties such as UTS will
also increase. This increase in properties will allow for the material to
be stronger hence, it will deform less under constant loading.
31. Part 4 : Heat transfer analysis on
holder (BOX)
Thermal properties of Aluminum 7075
Thermal Conductivity :130 W/m-K
Specific Heat Capacity : 0.96 J/g-°C
Outside BC : 30 Celcius
Inside BC : 45 Celcius
Maximum Temperature : 100 Celcius
Concentrated Heat Flux : 0.5 Watts/m^2
32. Nodes showing where the battery
would transfer heat to the box when in
operation.
Yellow nodes at the edges show the
Boundary Condition and the white nodes
shows the concentrated heat flux that
was applied.
34. The inside has a temperature
boundary of 45 Celsius but
the maximum temperature
that is experienced is 47.47
Celsius. From this high
temperature, a reduction
can be seen until 30 Celsius
as this was the boundary at
the outer box. A temperature
distribution of 47 Celsius to 30
Celsius can be observed for
this box.
