Centroids Example
1) Design a centroid based on the shapes available in MDSolids (in general this means you should have symmetry in your design)
2) Take measurements of your shape to do your own centroid calculations (calculators are allowed)
3) Create a physical model of your shape, then using a plumb bob (string with a heavy weight to pull it towards) draw three lines from random points. Find the intersection point of these three lines of gravity and measure the intersection
4) Model your shape in MDSolids, then calculate its centroid locations
5) Compare the techniques and your answers. What measurements match, which ones do not. Which method was easiest?
2) Take measurements of your shape to do your own centroid calculations (calculators are allowed)
3) Create a physical model of your shape, then using a plumb bob (string with a heavy weight to pull it towards) draw three lines from random points. Find the intersection point of these three lines of gravity and measure the intersection
4) Model your shape in MDSolids, then calculate its centroid locations
5) Compare the techniques and your answers. What measurements match, which ones do not. Which method was easiest?
Hand Calculations
After designing my Z- shaped cross section, I set up a table to calculate the centroid location. As I started doing the calculations, I noticed that the shape was supposed to have symmetry, but my numbers could not be right, so I double checked my measurements. Not entering X locations correctly, I had to redo some of my calculations. In all of my calculations, I avoided rounding numbers until the very end. Ultimately I found an X location of 2.375" from the left or right, and a Y location of 1.25 inches from the top or bottom.
Irregular Shape / Physical Centroid Measurements
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Step 1: Cut out the desired shape
Step 2: Use a plumb bob line and poke a hole in the shape Step 3: Let your piece dangle freely Step 4: Draw the line laid out by rope Step 5: The line drawn shows balance in your object Step 6: Repeat steps 2 to 5 2 more times Step 7: Note the three lines and where they intersect. Measure the distance from the reference lines used earlier Step 8: Compare the measurements of the physical model to the calculations you did by hand |
MDSolids Measurements
Conclusion:
I found that my hand calculations and MDSolids calculations matched up, however I was able to make more mistakes with my own calculations. In my physical measurements, treating the Z-shape like an irregular shape, I came close to having the same results, but my measurements were off by about 1/10th of an inch. For a small physical shape, with a relatively large string to guide my measurements, I think that all my measurements are close enough to be accepted.