Christopher Sullivan Explanation of States of Loading P12031

Track Platform Ansys WorkYoung’s Modulus Yield Ultimate Density

Structural Steel 200 GPa 250MPa 460MPaAluminum T6 (MatWeb)

70.0 GPa 270 MPa 395MPa 2823 kg / m3

Plywood (The Engineering ToolBox)

1.6GPa N/A 50 MPa 600 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.

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

Figure 10.

Christopher Sullivan Explanation of States of Loading P12031

Figure 11.

Figure 12

Christopher Sullivan Explanation of States of Loading P12031

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.

Figure 13

Christopher Sullivan Explanation of States of Loading P12031

Figure 14 Stern 4.5Gs

Figure 15 Port 5Gs

Christopher Sullivan Explanation of States of Loading P12031

Figure 16 Starboard 5Gs

Figure 17 Bow 5Gs

Christopher Sullivan Explanation of States of Loading P12031

Figure 18 3.5Gs port 3.5Gs Stern

Figure 19 10Gs only one hinge fail

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

As you can see it survives both and therefore should be able to take whatever misfortune might occur during loading and unloading.

Works CitedAnthoni, 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=66a81429bea54053bbdc39cfce0f2407&ckck=1

The Engineering ToolBox. (n.d.). Retrieved 11 3, 2011, from Modulus or Rigidity: http://www.engineeringtoolbox.com/modulus-rigidity-d_946.html

Figure 21 2G stress maximum is in the lower half of the traveler