Download Team 6

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height to ensure safe use of the machine and therefore these gears have been replaced by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