Bracket Design

Engineering Design I - Bracket

Bracket holds a 25lb weight and satisfies the following constraints:

  • Weight is placed 1.9in from the top of the testing structure

  • Peg locations are outside of black and green areas on pegboard

  • Bracket does not cross “interference zone”, represented by black acrylic box taped to testing structure

Process:

  1. Preliminary hand calculations

  2. SolidWorks design and simulation

  3. Laser cutting

  4. Iteration

Iterations leading to final design:

iterations-page-001.jpg

Challenges:

Variability in manufacturing: The final bracket to be tested during class will be manufactured by the TAs on one of the two available laser cutters. Each laser cutter cuts differently, in such a way that affects the reliability of the part. The pictures below show differences between the two (most noticeably the jagged edges on one set of brackets). To account for this difference, I made the slots on each side of the bracket slightly smaller to increase the factor of safety. Also, sometimes the laser cutter does not cut cleanly, leaving shards of acrylic left behind. Although it seems worrying, the bracket still functioned normally.

Fabrication:

  • Size of laser and turning radius: The part will be smaller than what was modeled in SolidWorks, due to the size of the laser itself. At this scale, this really matters when cutting very small curves. I had inconsistent success when I had the slots extended closer to the center of the “V” because the small curve at the ends was difficult for the laser cutter to cut consistently. To remedy this, I making the slots slightly shorter so that any imperfections in the slots would not have such a drastic effect on the strength of the bracket.

  • Thermal warping: The acrylic sometimes warped in particularly delicate sections of the design. This was also remedied by moving the slots very slightly further up.

Simulations in Solidworks:

Click to see full size picture and scale/numbers for stress distribution.

Reliability Testing:

I cut my final bracket design multiple times on all the laser cutters and tested them to make sure that the design was reliable.

IMG_20180923_174341.jpg