the great team1 week 8 : engineering analysis bunk bed converter adam brown blaine gardner sarah...
TRANSCRIPT
The Great Team 1
Week 8 : Engineering Analysis
Bunk Bed Converter
Adam Brown
Blaine Gardner
Sarah Gleaton
Jimmy Jiang
Addisu Lemlem
Lee Tschaepe
7/12/2006
The Great Team 2
Locking Mechanism
The Great Team 3
Locking Mechanism
The Great Team 4
Pin Analysis
The Great Team 5
Bed PositionsUp Position- 0 degrees
rotation
Down Position- 90 degrees rotation
The Great Team 6
Free Body Diagram
Force from mattress and mattress frame
Force due to weight of arm
Torque to be generated by spring
*Maximum Torque is required in the vertical position
The Great Team 7
Pivot Arm
• Arm is 2” x 2” mild steel square tubing
• Each arm is 41” long
• Each arm weighs 10.905 lbs
• Torque generated @ 90 by each arm=
T= F(lbs) x L/2(in) => 10.905 x 41/2=
223.45 lb-in
The Great Team 8
Frame and Mattress
• Frame weighs 25 lbs
• Mattress weighs 50 lbs
• This force is distributed over 4 arms; each arm must support ¼ of this force.
The Great Team 9
Calculations
-Torque due to mattress and frame: (50/4)*41+(25/4)*41=768.755
-Torque due to weight of Pivot Arm:10.905*(41/2)=223.45 lb-in
Total Torque generated for one arm:992.25lb-in
The Great Team 10
Results
• If a torque of 850 lb-in is applied using a torsion spring, the user must lift 3.47 lbs per arm
• Total user required force to upper bunk assembly is 13.88 lbs
The Great Team 11
Bed Frame Analysis
Bed Frame Analysis
33
3
1acbabcbbacI
433 1845.0125.085.025.1125.025.185.025.125.185.025.03
1inxI
Secondary Moment of Inertia
c = center of mass = 0.85 in
Frame Analysis – Long Side Bending Stress
Long Side of Bed Frame
I
cMbending
max
Maximum Bending Stress
inlbinlbxFlM 8.64185.395.162max
kpsiin
ininlbxbending 6.29
1845.0
85.08.64184
Material: Carbon Steel 1040 CR, Yield Strength = 71kpsi
4.26.29
71
kpsi
kpsiSN y
Frame Analysis – Short Side Bending Stress
Short Side of Bed Frame
I
cMbending
max
Maximum Bending Stress
inlbinlbxFlM 3170205.158max
kpsiin
ininlbxbending 3.14
1845.0
85.031704
Material: Carbon Steel 1040 CR, Yield Strength = 71kpsi
0.53.14
71
kpsi
kpsiSN y
Frame Analysis – Bearing Stress
LONG SIDE SHORT SIDE
kpsiininx
lb
Dl
R
A
F ybearing
0.525.025.0
5.3124
max
kpsiininx
lb
Dl
R
A
F ybearing
5.225.025.0
1554
max
Bolt: D = 1/4”, Carbon Steel 1010 CR, Yield Strength = 44 kpsi
8.80.5
44
kpsi
kpsiSN y
6.17
5.2
44
kpsi
kpsiSN y
Frame Analysis – Shear Stress
LONG SIDE SHORT SIDE
kpsiininx
lb
Dl
R
A
F y
4.625.025.0
414.3
5.3124
max
kpsiininx
lb
Dl
R
A
F y
2.325.025.0
414.3
1554
max
Bolt: D = 1/4”, Carbon Steel 1010 CR, Yield Strength = 44 kpsi
9.64.6
44
kpsi
kpsiSN y
8.13
2.3
44
kpsi
kpsiSN y