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P13675 Bike Helmet Mirror System Detailed Design Review. Team. Rob Fish (Industrial Designer) Zachary Kirsch (Mechanical Engineer, PM) Martin Savage (Mechanical Engineer) Olivia Scheibel (Mechanical Engineer) Henry Woltag (Industrial and Systems Engineer). Guides, Advisor, Sponsor.
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Team • Rob Fish (Industrial Designer) • Zachary Kirsch (Mechanical Engineer, PM) • Martin Savage (Mechanical Engineer) • Olivia Scheibel (Mechanical Engineer) • Henry Woltag (Industrial and Systems Engineer)
Guides, Advisor, Sponsor • Guide • Dr. Richard Lux • Customer Proxy • Dr. B. Brooks • Faculty Support • Dr. M. Gomes • Dr. M. Lam • Sponsor • RIT MSD Project Office
Outline • Project Summary • Design Objectives • Proposed Design • Optical System • Support System • Bill of Materials • Test Plans • Risk Assessment • MSD II Schedule
Mission Statement Current rear view mirrors systems for bicycles are clumsy, unattractive, poor quality, too expensive, or have a small viewing range. Our solution is to create a low cost alternative that requires no power to operate, and attaches to any helmet.
Takeaways from Systems Design Review • Issues regarding geometric optics • Size of mirrors • Range of Adjustability • Model head, neck, eye, helmet positions • Create system in SolidWorks • Team should focus more on shock than vibrations • Testing • Deflection analysis • Drop testing
Takeaways from Systems Design Review • Concerns: • Not enough analysis / data involved in concept selection • Settling on Rob’s prototype vs. alternate designs • Need to determine range of adjustability
Optical System Concepts Based on sensitivity analysis, the 2 mirror system was determined to be advantageous to the 3 mirror system. Three mirror optical system concept. Two mirror optical system concept.
Optical System Feasibility Tests • Conducted Using Prototype • Distance a human was recognizable – 37ft • Distance a van was recognizable – 177ft+ • Distance a car was recognizable – 110ft
Support System Attachment Maximum Area of Dual Lock™ Maximum Allowable Break Away Force, Tensile disengagement of Dual Lock (250 Black), Dual Lock™ is a reclosable fastener made of mushroom-shaped stems that snap together. Similar to Velcro®, Dual Lock ™ will allow users to easily attach and detach the bike helmet mirror system. “3M™ Dual Lock™ ReclosableFastener.” Online image. 2013. 3M. 2 Feb. 2013 <http://www.3m.com/product/information/Dual-Lock-Reclosable-Fastener.html>
Support System Attachment Technical drawings of rear support bracket. Technical drawings of front support bracket.
Front Support System • One Solid Manufactured Piece • ABS Material • 3 mm diameter support legs • Uses cylindrical snap-fits to constrain degrees of freedom • Mylar coating on underside to create mirror surface Bracket with Attachments Standalone Bracket Bracket with Gooseneck/Attachments
Front Support System – Attachment Methods Cylindrical Snapfit – 1 degree of freedom: Cylindrical Insert with adhesive/Epoxy
Rear Support System Materials • Assumptions • Entire weight of top mirror acts as a point force on the end of two, six inch sections of “Gooseneck” Mass of Mirror Volume of Top Mirror: Density of Top Mirror, Mass of Top Mirror: • Material Selection • Each six inch section of Gooseneck needs to support 1.44 oz. • Size (O.D.) 0.142-H can support 3.2 oz at six inches “Flexible Gooseneck Tube.” Online image. 2013. Leflexo. 14 Feb. 2013 <http://www.leflexo.com/new_section.php?sid=204>
Gooseneck Feasibility Analysis • Assumptions • Entire weight of top mirror acts as a point force on the end of two, six inch sections of “Gooseneck” • Energy of impact is unabsorbed by body, helmet, etc. Impact Analysis Potential Energy: Impact Force: Size (O.D.)0.142-H Gooseneck can support 3.2 oz applied on 6 in. Impact Analysis for s=1in • Results • The gooseneck will deform 12 mm after a 1 in drop. • Based on the results of the sensitivity analysis, the optical system will still remain functional
Rear Support System Mirror Attachment Thermal Expansion of Gooseneck Linear Thermal Expansion, Diameter of gooseneck, Thermal Expansion Coefficient of Steel, Initial Temperature (SATP), Final Temperature, • The gooseneck will be secured with a metal to plastic, weatherproof adhesive. Towards Front of Helmet Top Mirror Mirror-Gooseneck Attachment “Gooseneck”- Flexible Tubing
Test Plan: Specification S4 • Specification: The mirror system must be mountable to at least 3 distinctly different helmet styles • Test: Mount the system to three different helmet styles http://bertsbikes.com/product/giro-rift-154856-1.htm
Test Plan: Specification S4 • How to test: • Acquire three distinctly different helmets and mount the mirror system • Go to the bike shop and mock mount the mirror system to three distinctly different helmets • Pass Criteria: Successfully mount to three helmets in either test • Risks and Mitigations: • No foreseen risk
Test Plan: Specification S5 • Specification: Survive drop from height of 3 feet • Test: Release helmet at 3 feet in the following impact orientations • Correct, inverted, nose, back, side http://static6.depositphotos.com/1025312/628/i/950/depositphotos_6280277-Helmet-on-handlebar.jpg
Test Plan: Specification S5 • How to test: Hold the helmet at a 3 foot height above a concrete surface. Release in the required orientations. • Pass Criteria: No part failures. System operable after impact. • Risks and Mitigations: • Part fails during test • All team members wear appropriate PPE while test in progress (eye protection, gloves)
Test Plan: Specification S7 • Specification: Operate in wind speeds of 45 mph (marginal) and 60 mph (ideal) • Test: Place helmet in proper orientation within wind tunnel and subject helmet to various wind speeds 20” 30” * Helmet with mirror measures: 9”W x 8”H x 12.5”L
Test Plan: Specification S7 • How to test: Create a mount to secure helmet within wind tunnel. Subject helmet to speed increments of 5 mph from 0 to 60 mph • Pass Criteria: Mirror position does not deform under wind loading • Risks and Mitigations: • No foreseen risk
Test Plan: Specification S8 • Specification: Mirror mount needs to break away from helmet under a 45 lb applied load to meet NHTSA standards • Test: Measure force required to remove mirror system from helmet http://www.transducertechniques.com/images/hfg-series-force-gauge.gif
Test Plan: Specification S8 • How to test: Attach force gauge to the front of the mirror mount system. Apply force until the mounting system is removed from the helmet • Pass Criteria: Force applied to remove the helmet does not exceed the 45 lb standard • Risks and Mitigations: • The mirror system could violently rip off the helmet • All team members wear appropriate PPE while test in progress (eye protection)
Test Plan: Specification S9 • Specification: The rider must see a horizontal rear image encompassing 10 degrees (marginal) and 25 degrees (ideal) • Test: Measure the rear viewing angle of a team member using the system
Test Plan: Specification S9 • How to test: A team member wearing the helmet stands a measured distance from a white board. Another team member walks behind the one wearing the helmet and marks the extent of vision. This distance is measured and the angle calculated. • Pass Criteria: The calculated angle meets or exceeds the angle specified • Risks and Mitigations: • No foreseen risk
Test Plan: Specification S14 • Specification: Vehicles behind cyclist must be visible at 130 ft (marginal) and 200 ft (ideal) • Test: Team member wearing helmet attempt to identify objects at these distances http://turningplace.files.wordpress.com/2013/01/aaaa.jpg
Test Plan: Specification S14 • How to test: • Team member wearing helmet stands on end zone line of football field and attempts to identify another team member standing 130 and 200 ft away • Team member wearing helmet stands along the edge of the road and attempts to identify a vehicle driven by another team member at 130 and 200 ft away • Pass Criteria: Person visible at given distances or car visible at given distances • Risks and Mitigation: • Safety concern with team members being on the road for testing • Look into traffic control options