Transcript Pliable Writing Desk Shaft

Wilfredo Ruiz
Jose Rosa Molina
Keven Alvarado
Pliable Writing Desk
Shaft
Final Report
Machine Component Design
Prof: Dr. Pablo G. Caceres
Description:
►
Our mechanism design consists of the
component that carries out the work to giving
movement to the uper part of the student writing
desks that are in the classroom. This system is
necessary since there is limitation of space
between writing desk, this disables to maintain
this part fixed, like in the regular writing desks. We
looked for the security and convenience for the
users of our product. Between the requirements of
the mechanism one is due to take into account
that the design has supported part of the weight
of the student and its materials
Pliable Writing Desk Mechanism
Above View
What is the unique part of your project?
Area Zoom
Why do you design this device, what is its
application ?
1) The main application of this device is to use it if you have a room that
you use to make conferences and you use as a classroom.
2) We design this device because is a common daily use mechanism for
students.
3) Also it is an interesting foldable device.
What are the most important engineering
considerations in your design?
1) COSTS
2) SAFETY
3) DEFLECTION
4) POSIBLE FAILS
5) CRITICAL POINTS
6) DESIGN FOR FATIGUE
What is the most challenging part in
your project?
1) BEGIN WITHOUT ANY INFORMATION
2) ASSUME FORCES ( DECIDE HOW MANY FORCES
ACTS IN OUR COMPONENT)
3) APPLY K FACTORS
4) THE MATERIAL SELECTION ( FOR WHAT WE
WHERE DISIGNING FOR)
What is the weakness of your project?
1) The device could be over design because we do
not know exactly the forces that the component
receive.
2) Most of our data have to be assumed studying
the student behavior at the classroom.
3) If the forces that the component receive are
smaller, we could find a more economical
material.
4) If the forces that the component receive are
bigger, the material could fail.
What you learn from this project?
1) Applying the class material to a real device
2) Conditions of design
3) Material selection applications.
4) Design a device for fatigue possible failure.
Forces in Component
► Bending
hacia arriba
► Torsion en el eje x
Provocando en C
► Stress
► Shear
Provocando en D
► Pure shear
Beam
► Beam
► Shear
diagram
► Moment
diagram
Deflection
► Beam
► Angle
of deflection
► Deflection
Punto crítico C (excel): AISI 1040
Fuerza (N)
Diametro (m)
Area (m^2)
I (m^4)
J (m^4)
Infor. General
Pieza
l (m)
d (m)
kf,bending
kf,τ
Sut
S΄e
Mz
x
177.5
0.012
0.000113097
0.017
0.098
1.63
1.35
6.20E+08
3.95E+08
17787038.55
T (N.m)
τT
17.395
51268522.87
σA (MPa)
27747780.13
69212505.88
τA (MPa)
σVMS,A (Mpa)
σVMS,M (Mpa)
1.96E+00
Se
ktemp
Krea
3.10E+08
1
0.753
1.01788E-09
2.03575E-09
3.0175
(Mpa)
Goodman Safety
Factor n
123048983
123048983
Ksurf
ksize
kload
K
0.8838
1.9139
1
1.273703129
Punto crítico D (excel): AISI 1040
Fuerza (N)
Diametro (m)
Area (m^2)
Q (m)^3
I (m^4)
J (m^4)
Infor. General
Pieza
l (m)
d (m)
kf,bending
kf,τ
Sut
S΄e
τv
Mz
x
(Mpa)
T (N.m)
τT
σA (MPa)
τA (MPa)
σVMS,A (Mpa)
σVMS,M (Mpa)
177.5
0.012
0.00011309
7
0.00000014
4
1.01788E-09
2.03575E-09
0.017
0.098
1.63
1.35
6.20E+08
3.95E+08
2.09E+06
3.0175
0
17.395
53361522.8
7
0
72038055.8
8
124773572.
9
124773572.
9
Goodman Safety
Factor n
1.93E+00
Se
ktemp
Krea
3.10E+08
1
0.753
Ksurf
ksize
kload
K
0.8838
1.9139
1
1.27370312
9
MATERIAL SELECTION
E Al  73.1 _ GPa
E AISI 1040  200 _ Gpa
I  1.02 E 9 _ m 4
M  17.4 _ N .m
P  177 .5 _ N
vmax( Al )
Longitudinal Wave Velocity:
1
 17.4(0.017 ) 2 177 .5(0.017 ) 3 




(73.1E 9  1.02 E 9 ) 
2
3

1
 17.4(0.017 ) 177 .5(0.017 ) 



9
(200 E  1.02 E ) 
2
3

2
9
vmax( AISI )  1.37 E 5 _ N .m
E

v Al 
vmax( Al )  3.76 E 5 _ N .m
vmax( AISI ) 
v
3
v AISI 
73.1
 1.62 E 4 _ m s
2780
200
 1.59 E 4 _ m s
7845
MATERIAL SELECTION
• The selected material was Steel 1040 due to its mechanical
properties; ej. UTS=620 MPa, E=200 GPa, Sy=550 MPa, etc.
• fulfilled the requirements established for this element.
• advantage due to his availability and cost.
•Although Aluminum 2024 presents/displays similars properties
and a high availability was discarded because AISI 1040 has
smaller deflection and I surpass to the A the 2024 in the factor
of safety (nAISI=1.96; nAl=1.77)
QUESTIONS
?