Preliminary Detailed Design
Team Vision for Preliminary Detailed Design Phase
For this phase, we had decided to work on an ergonomic analysis to develop a good feel of data and dimensions that would need to be used to design a function toilet. In doing this, we also had to decide on materials that were to be used when building the toilet. Thus, we had to develop a Bill of Materials that would list all of our parts. We found some difficulties with the diverter testing, so that will be spent during a majority of the next phase. This also postponed the development of our tubing methods. Because of this, we were only able to created a base, with the proper elements for a toilet (including the seat, bucket, jug and cookie cutter mold). The development of the mold for the base should take place next phase as well. We were able to gather information on the cement lab on campus at RIT and plan for its use during MSD II. While using Fusion, we were able to compute certain tests on the design which will be covered later on this Preliminary Detailed Design page.
Feasibility: Prototyping, Analysis, Simulation
To get a better understand of the sizing and placement for the components of our design we conducted and ergonomic analysis. Full ergonomic anaylsis can be found here (Ergo Analysis).
To start, we determined the average length by segment of the body by using the chart below. Applying the equations to the average overall height found for both men and women in Haiti.
Average heights in Haiti can be found below.
From there we were able to develop the following body dimensions for both men and women.
Toilet Seat Selection
With the dimensions calculated we took the dimensions of the distance from the hip to the knee for both men and women to determine the size of our toilet seat.
Currently the two toilet size options is rounded and elongated as seen above.Having the dimensions from the hip to the knee will allow us to know the proper dimensions needed for our toilet seat. With males as our larger user we will base our toilet seat on their size. The length of the hip to the knee for men is 16.48 ± 0.79” and a hip width of 12.84± 0.62”. This indicates we need at least a toilet seat that is at least 16.5” long and 13” wide. As a result, the best toilet seat is the elongated seat with dimensions of 16.75” long and a width of 14”.
Toilet Build Measurements
Dimensions for the toilet were determined based on the dimensions of the bucket, jug, and diverter that will be placed inside the toilet.The height of the base was determined by taking the average knee to foot length for both men and women which is roughly 18” high. The width of the toilet base should be roughly 16” wide and 18.5” high and a length of 17”.
Drawings, Schematics, Flow Charts, Simulations
Prototyping, Engineering Analysis, Simulation
Stress analysis done in Fusion 360:
For the first two tests, a 40 pound lifting force was applied at the handles to simulate lifting each separate piece off the ground. The 40 pounds was chosen because that is the target weight per piece. Fusion 360 calculated the max stress in one of the handles to be 53.39 psi which is way under the max tensile strength of concrete (300-700psi).
For the third test, a 152 pound force was applied downward to simulate a human sitting on the toilet seat. 152 pounds was chosen because it was the average weight of women in Haiti, and was higher than the average weight of men, ~146 pounds. The results showed a max compressive stress of 67.73 psi which is well within the safe region when most concretes fail between 2,500 and 10,000 psi of compressive stress.
Bill of Material (BOM)
Below is our current Bill of Material, item list, pricing, and budget for the components for our toilet design.
After going over our engineering requirements we constructed a set of test plan to follow in order to ensure the requirements are being met seen below. Our test plans can also be found here Test Plans Spreadsheet
For this phase we updated of Subsystems Design Risks with further risks we may anticipate to encounter as we worked through our detailed design. Included below is the likelihood and severity of each risks.
Design Review MaterialsInclude links to:
- Presentation Phase 3
- Notes from review
Plans for next phaseHere is an image of some tentative plans for the final phase of MSD I. Because of the difficulties with the diverter testing, we will be focusing a majority of our time on that, along with the tubing method that connects the diverter to the urine jug.
Also in this section is a live document for our preliminary plans before each phase. These plans are decided prior to the phase reviews of the previous phase, so nothing is set in stone.
As a team, below is where we plan to be in the next three weeks for our next review.
- Peter's Phase 4 Plans
- Owen's Phase 4 Plans
- Ricky's Phase 4 Plans
- Tim's Phase 4 Plans
- Aleah's Phase 4 Plans