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Team Stratus Courtney Herbein Brian Hollingshaus Mark Howe Angela Huenerfauth Brian Hufe Phase III Team 6 – MEEG301 Project: Phase 3 Phase 3 Proposed Final Design: The final design concept that Team Stratus decided upon was a modification of the geared five bar designed by Angela Huenerfauth. This design was selected because it most closely resembles the human running motion. Some minor modifications have been to her original design to help reduce the undesirable force peak found in the original kinetic analysis and also to prevent any risk of the user injuring himself by coming in contact with the gears while exercising. The original design had the gears at too great a height to ensure safe use of the machine and therefore these gears have been replaced by a smaller grooved belt drive. Spacers are being placed at the Link1 – Link 2 interface and at the Link 1 – Link 5 interface in order to prevent the user from running into the belt drive. 3-D Shape / 2 Sided Dynamics: For Phase 3 Team Stratus has started the process of moving our linkage into the third dimension towards the goal of a fully functional machine. Despite the additional cost of the extra parts, Team Stratus has decided to have both sides of the machine independent of each other. By doing this we are able to have the user run in between the two grooved belt drives instead of straddling a single grooved belt drive. The use of the single grooved belt drive for both sides of the machine would cause a safety risk. This is because there would be insufficient clearance between the exerciser and some of the rotating links while the machine was in use. The use of individual resistance elements might also make the machine attractive in the physical therapy market. Safety: Safety is a very important consideration for our human running machine. The first safety consideration that Team Stratus took into account was ensuring that the links in motion would not come in contact with the user. A safety casing is also going to be constructed around the grooved belt drives to prevent small children from getting their fingers pinched there. Materials: Material selection was an important consideration for moving into Phase 3. In our material selection our goal was to optimize strength while minimizing the weight of the material. A high strength material was needed so that our machine would stand up to the forces and fatigue put on it from regular use and a minimal weight was desired in order to make it more user friendly. Our target audience is the in home exerciser and therefore the machine needs to be portable by the average person. The two main materials considered for the frame and main link components were aluminum alloys and graphite composites. Both of these materials are light weight and meet or strength requirements. Aluminum- almost the consensus choice; lightweight (0.0975 lb/in³); relatively inexpensive ($2/inch of 2” diameter 6061-T6); non-toxic; durable; strong (Modulus Elasticity: 10,000 ksi) Graphite- lightweight (0.062 lb/in³); good strength-to-weight (flexural strength: 2400 psi); non-toxic; inexpensive ($1.04/inch of 2”diameter GR060); non-toxic Aluminum was ultimately decided upon due to its availability and the ease in which it can be machined. The main components of the machine are going to be tube links which can easily be obtained for aluminum. Other materials need to be determined for the hand grips and the foot petal/mount. Low costs polymers are being investigated for these applications. Bearings: A key assumption made in creating our linkage- as well as doing the analysis- was the absence (or neglect) of friction. With this assumption, it is imperative that we use low-friction bearings. Initial intuition pointed us towards high-quality ball- or rollerbearings. These will help minimize the force requirements throughout the linkage path. While using high-quality bearings may add an extra cost, we determined that this trade off will prove to be beneficial in the long run. Other fasteners will be necessary throughout the apparatus. These will most likely be typical machine bolts, nuts, and other fasteners. The goal with these is to find low cost vendors that fit our specific needs. Future Plan: The next step for Team Stratus will be to construct a prototype of our proposed human running machine. After we are satisfied with our prototype we will be able to move forward to the production and marketing of our devise. Engineering Drawing Appendix 3-D Assembly Drawing Drawn By: Brian Hollingshaus Link 5 with Spacer Drawn By: Brian Hollingshaus Drive Belt Wheel Drawn By: Courtney Herbein Drawn By: Courtney Herbein Drawn By: Courtney Herbein Coupler Link Drawn By: Angela Huenerfauth Drawn By: Angela Huenerfauth Spacers Drawn By: Brian Hufe Bearing Drawn By: Mark Howe Fixed-Alignment Steel Needle-Roller Bearing Double Sealed For 1/4" Shaft Dia, 7/16" OD, 7/16" WD Price 8.29 Max rpm 35,000 Dynamic load Max: 570 lbs