Ceiling-mounted bicycle lift structural analysis
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This resulted in a holding capacity of over 300 lbs for each screw which corresponds to a safety factor over 50.<br /> | This resulted in a holding capacity of over 300 lbs for each screw which corresponds to a safety factor over 50.<br /> | ||
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- | [[Image:Team1-Rope.jpg|300px]] [[Image:Team1-HookAssembly.jpg | + | [[Image:Team1-Rope.jpg|300px]] [[Image:Team1-HookAssembly.jpg|300px]]<br /> |
Double braided nylon rope with a diameter of 7mm is rated for an approximate tensile capacity of 1900 lbs. For our 50 pound bicycle that results in a tensile load of 12.5 lbs, this is not a cause for concern. However as you will see from our FMEA, there are more issues with the rope than merely it's tensile capacity, with rope durability being a much larger issue. | Double braided nylon rope with a diameter of 7mm is rated for an approximate tensile capacity of 1900 lbs. For our 50 pound bicycle that results in a tensile load of 12.5 lbs, this is not a cause for concern. However as you will see from our FMEA, there are more issues with the rope than merely it's tensile capacity, with rope durability being a much larger issue. |
Revision as of 03:43, 8 March 2007
Contents |
Part # 001: Ceiling Bracket
Stress Concentration Factor
h = 1.22 mm (sheet thickness)
w = 50 mm (section width)
d = 6 mm (hole size)
d/w = .12 d/h = 5
K = 1.7 - From table A-15-12 of (Shigley, Mechanical Engineering Design)
Actual Maximum Stress = 17.1 Mpa
Safety Factor = 12.9 Mpa
Part # 002: U-Pulley Mount
Part # 003: Pulley Wheel
Part # 004: Pulley Rivet
Part # 012: V-Bracket
Part # 013: Hook
Images | Calculations | |
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Material: Carbon steel E = 202,700 N/mm2 | ||
Bending Cross sectional area: 42.9 mm2 (for one hook) | ||
Actual Maximum Stress = 29.8 Mpa Safety Factor = 7.4 |
Overview
There is a total of 8 ceiling screws responsible for holding the 50 pound load. To calculate the holding capacity of a single screw, we used a screw strength formula for attaching to the end grain of a pine wood (one of the weaker woods available). We used the equation P = 108.25 G2*D*L*(.75), where G is the specific gravity of the wood, D is the shank diameter and L is the thread penetration.
G = 350 kg/m3
L = 35 mm (.035m)
D = 4.38 mm (.00438m)
This resulted in a holding capacity of over 300 lbs for each screw which corresponds to a safety factor over 50.
Double braided nylon rope with a diameter of 7mm is rated for an approximate tensile capacity of 1900 lbs. For our 50 pound bicycle that results in a tensile load of 12.5 lbs, this is not a cause for concern. However as you will see from our FMEA, there are more issues with the rope than merely it's tensile capacity, with rope durability being a much larger issue.