Analysis

Further analysis was carried out on two pin sizes for the connection plate point and the truck base plate points. These first two analyses indicate the minimum size allowed at each of these pinpoints with a safety factor of four included due to the uncertainty of blunt forces during sharp cornering with abrupt bumps. Although a size of just 1/8” is allowed for the connection plate pins, ¼” was used since it is easier to acquire and provides more stability. Similarly, the use of ¼” pins at the truck base would meet the design requirements but 5/16” was chosen instead as there is more stress concentration at these points.

See above.

The most important design parameters for a successful project are the material choices of each section. It was originally assumed that an aluminum of 5052 class or better would be suitable for each section, but additional analysis proved otherwise as in the instance of the connection plates (see Appendix A-3). This section was the most complex and handles much more stress in comparison to other sections due to the blunt force each wheel creates at a variety of angles. The analysis showed that aluminum is over three times too weak for the given maximum force and calls for use of steel with a strength exceeding 123psi. Material for the main axles is outlined below.

A maximum dimension was given for the wheel axle extrusion to indicate how far away the wheel could safely sit from the connection plate. Although this is a maximum dimension, this value used was much lower than what was calculated to ensure that the bottom of the connection plate does not interfere with the ground at a maximum turn or leaning of the wheel.

These two analyses give a quantitative value for the amount wheel deflection that will result from application of a maximum force. This ensures that this connection will not deflect to a point that will allow for dragging of the connection plate and aids in construction of a stable design.

See above.

The geometry of the main axles was finalized at this step. Taken from the original design shown in Appendix B-2, it was decided that inclusion of some sort of unusual geometry would increase visual appeal to the NG-Truck. However, the impact this would have on the structural integrity of the main axles had to be considered first. A hexagonal or octagonal axle was sought to provide a unique attachment angle at the pinpoints of each section. Although an octagon was initially desired for the angle present between its vertical and horizontal plane, Appendix A-7 shows that this reduced the integrity significantly. Because of this, a hexagonal axle was chosen as it was calculated to result in a more manageable 28% decrease in strength (see Appendix A-8).

See above. Reference proposal document for appendix.

The minimum axle diameter was given a quantitative value determine the size needed on the main axles.  However, the given diameter will not work for the design, as the design necessitates a hole to be drilled in the center of the axle. This will be addressed below.

As mentioned above, the minimum allowable diameter of the axle could not actually be used for the design. In this analysis, a base value of 0.87” was sought and tested for given that this diameter can be fabricated from a 1” square rod easily. This analysis also approved the material of 5052 aluminum works for the design while hovering above a safety factor of 2.5, showing that a 5052 H-38 aluminum or better must be used for this design.

In this analysis, the deflection of the main axles was calculated in order to ensure that no interference with the ground would be present at maximum loading.