Christopher Sullivan
Explanation of States of Loading
P12031
Track Platform Ansys Work
Structural Steel
Aluminum T6
(MatWeb)
Plywood (The
Engineering
ToolBox)
Young’s Modulus
200 GPa
70.0 GPa
Yield
250MPa
270 MPa
Ultimate
460MPa
395MPa
Density
1.6GPa
N/A
50 MPa
600 kg / m3
2823 kg / m3
So starting with the boundary conditions the bolts on the arms that lock into the existing
traveler are considered fixed location. Each hand hold is held so that it wouldn’t be able to fall though
the boat, and it is fixed at sides only at the top where the part would be inside the hand hold. The feet
and the base of each chuck of plywood is not allowed to move though the boat, but is able to shift to
either the bow or stern. The plywood is also constrained so that each panel that comes into contact with
the sides of the boat, is not allowed to bow out through the boat. This model neglects the contact
friction between the track and the surface of the boat presumably this would absorb a large amount of
the force that is otherwise distributed in this model.
To start off figure 9 depicts the factor of safety of the system based on our analysis of Richard
swinging across the boat, 6000N have been applied directly to the end face of the track.
Figure 9.
Christopher Sullivan
Explanation of States of Loading
P12031
As you can see the load is shifted to the handholds evenly, and with a large factor of safety. The lowest
factor of safety can be found on the hinge shown in figure 10. And is nothing to worry about.
Figure 10.
The next assessment will be of Richard in bad weather conditions. This will be done by applying a point
force of 1425N (320 lb) down into the boat, and 25N towards the bow of the boat. The force will be
applied in 3 different locations, over a plywood support figure 11, in-between the cross brace and the
plywood support and figure 12, and in the middle of the boat figure 13
Christopher Sullivan
Figure 11.
Figure 12
Explanation of States of Loading
P12031
Christopher Sullivan
Explanation of States of Loading
P12031
Figure 13
As you can see from the individual sections there is never a time when Richard should be in danger of
the rig breaking during the worse kinds of seas, but rough seas are not the only thing that can cause
extreme forces to be applied to a boat. There is always the chance of collision.
In this section we look at seeing just how many factors of gravity our system can handle before
it breaks, this can be related to severity of collision via table 1. In each case Richards assumed mass will
also be present in the system to apply additional stress to the structure. In each case his mass is
centered on the starboard plywood support. Figure 14 shows an acceleration of 4.5Gs towards the stern
and a minimum factor of safety of 1.09. Figure 15 shows an acceleration of 5Gs towards Port with a
minimum factor of safety of 1.20. Figure 16 shows an acceleration of 5Gs towards Starboard with a
minimum factor of safety of 1.25. Figure 17 shows an acceleration of 5Gs towards Bow with a minimum
factor of safety of 1.18. A combined state of acceleration was attempted the results of which are in
figure 18, an acceleration of 3.5G stern and 3.5s port where reached with a factor of safety of 1.00 this is
consistent with the other values because the magnitude of this collision would be on the order of 4.5Gs.
Lastly a collision of 10Gs to the stern is shown in figure 19. This was to show what would break, and only
a hinge did.
Christopher Sullivan
Figure 14 Stern 4.5Gs
Figure 15 Port 5Gs
Explanation of States of Loading
P12031
Christopher Sullivan
Figure 16 Starboard 5Gs
Figure 17 Bow 5Gs
Explanation of States of Loading
P12031
Christopher Sullivan
Figure 18 3.5Gs port 3.5Gs Stern
Figure 19 10Gs only one hinge fail
Explanation of States of Loading
P12031
Christopher Sullivan
Explanation of States of Loading
P12031
During the detailed design review it was brought up that our design might not hold together
during the rigors of loading and unloading into the boat. This can be easily addressed like the collision
problem. One of the plywood pieces is assumed to be picked up the rest of the system is left dangling.
This was achieved by constraining individual faces of the plywood rather than calling a single point a
fixed position. Now that the system is fixed we can apply acceleration in the opposite direction
mimicking gravity. There will be two scenarios, the first is under its own weight figure 20, and the
second is under 2Gs worth of acceleration and is shown in figure 21. 2Gs is much faster than anyone
should be able to lift this device up and down.
Picking rig up
Figure 20 1G stress maximum is in the lower half of the travler
Christopher Sullivan
Explanation of States of Loading
P12031
Figure 21 2G stress maximum is in the lower half of the traveler
As you can see it survives both and therefore should be able to take whatever misfortune might occur
during loading and unloading.
Works Cited
Anthoni, D. J. (2000). Oceanography: waves theory and principles of waves, how they work and what
causes them. Retrieved 10 27, 2011, from seafriends:
http://www.seafriends.org.nz/oceano/waves.htm
MatWeb. (n.d.). Retrieved 11 3, 2011, from Aluminum 2011-T6:
http://www.matweb.com/search/DataSheet.aspx?MatGUID=66a81429bea54053bbdc39cfce0f2
407&ckck=1
The Engineering ToolBox. (n.d.). Retrieved 11 3, 2011, from Modulus or Rigidity:
http://www.engineeringtoolbox.com/modulus-rigidity-d_946.html