Brake Design HW 1
Pair assignment due Thursday 2/22 at beginning of lecture.
This is the first assignment for the brake design challenge, in which each student will setup a working baseline. The next assignment will be optimization.
Complete Working Model 2D Getting Started Tutorial up to Step 8. Turn in print screen of Step 8 that includes trajectory of motion. Handwrite on print out the key parameter values used in your simulation.
Calculate extension and retraction force for pneumatic cylinder given:
Air pressure, P = 300 Kilopascal (this is gauge pressure, which is the typical in industry to specify pneumatic pressures)
Piston Diameter = 20 mm
Rod Diameter = 5 mm
Setup baseline brake WM2D simulation as follows (see figure below as well):
If using Virtual Labs, set pause condition
World => Pause Control => New Condition => Pause When => Set time (typical value is 5 sec).
Set units to metric:
View => Numbers and Units => SI Degrees
Turn grid on
View => Workspace => gridlines
Turn gravity off
World => Gravity => None
Create circle to represent shaft and then set diameter to 20 mm radius
Create circle and then select it.
Window => Geometry => Radius 0.01m
Use pin joint (green dot on left side panel) to constrain circle to background.
Add torque (lower left sidebar) to circle.
Create slider to control torque between 0 and 5 Nm.
Select torque (if hard to select torque by clicking image, then open Windows => Properties. Then select from pull down menu.)
Measure => Torque
Select slider => Windows => Properties => adjust min and max.
NOTE: for most values force, brake pad block to "falls" through the circle. This is because the numerical solver's time step is too large relative to the speeds the objects are moving. The solution is to decrease the time step under "Accuracy" from 20/s to something faster (ie: 1000/s, or something like that.).
Plot circle velocity:
Select Circle => Measure => Velocity => Rotation Graph
Display circle position/velocity/acceleration:
Select Circle => Measure => P-V-A => Rotation
Now is a good time to test simulation by clicking run. Click reset when done.
Create rectangular brake pad above circle
Create rectangle 10 mm above circle
Add vertical keyed slot joint to rectangle so brake pad does not rotate
Apply braking force
Select force of retraction or extension of the cylinder from part 2
Apply vertical force onto brake pad. Select force => Windows => Properties => Type in value in negative Y direction.
Run simulation for a torque level of 1 Nm
Take screen shot of your simulation and printout
Write on printout the final velocity and if the brake pad indeeds stops the break as in its original design.