Week 15 Engineering Analysis
Table of Contents
Updated Frame Tube Sizing
The impact analysis of the base of the system frame was rerun with more conservative numbers. Steel impacts have conservative coefficient of restitution of 0.4. This means that the frame will absorb approximately 60% of the impact energy. In the scenario of being brought to a complete stop from human walking speed, with a 0.4 coefficient of restitution the minimum required square tube size is 2x2x1/4". In this case the system only absorbs 147.15ftlb of energy instead of 408ftlb
Jaw Size Selection
The jaw size was determined by FEA analysis inside of the Autodesk CAD model. The jaws will be made of 1/4" steel.
Vertical Column Sizing
The vertical column system was modeled as an eccentrically loaded buckling column. Inputs were determined based on table weight and structural steel material properties. This analysis gives us a minimum moment of inertia about the symmetry axis of a C channel beam. This allowed us to select a component size for the C channels.
Fatigue Analysis for the loading and unloading of tables from the jaws was not performed as this action will be completed so infrequently. However, analysis of fatigue caused by moving over bumpy surfaces such as cobblestone needed to be performed. Using the dynamic bumping model average and amplitude stresses were found. The average stress was not at 0Psi, so the stress was normalized per the Goodman model. The resulting Stresses were found to be lower than the endurance limit of the metal. The system will not fail do to fatigue caused by hitting bumps.