Preliminary Detailed Design
Team Vision for Preliminary Detailed Design PhaseLast phase’s goals that were proposed during the last phase review were all completed as following :
- perform further analysis, simulation, prototyping.
- Requirements flow-down to subsystems (subsystems specs)
- complete Bill of Materials according to budget.
- Risk assessment, mitigation plans & triggers
Top Level Design Concept
Feasibility: Prototyping, Analysis, Simulation
A stiffness analysis was performed to compare the stiffness of the new baseplate design compared to the previous baseplate. The team’s target when designing the new baseplate was to maintain equal or better stiffness in the new design. An arbitrary 50 lbf. load was applied in the z direction (perpendicular to the plane of the baseplate) on one side of the baseplate, while a fixed support was applied on the opposite side. It was found that the new baseplate design can be expected to be at least an order of magnitude more stiff (1000% increase) compared to the old baseplate in both the x and y directions. This means that the new design meets the target of having equal or better stiffness.
A modal analysis was performed to ensure that the resonance modes of the new baseplate design were not near the operating frequencies of the vibrating system. The model determined that the first resonance frequency is about 315 Hz for the new design. This is sufficiently far from the expected 12 Hz operating frequency of the vibrating system. For future testing, the resonance modes of the entire vibrating system should be found, since the assembly could have different resonance from the individual parts.
A mass analysis was performed to ensure that the new baseplate would weigh less than the original baseplate, to fit with the team’s projected weight reduction target. Using the density of 6061 aluminum alloy, the model determined that two baseplates of the new design would weigh 2.7 lbm less than the old baseplate design.
link to the full file here
Abstract:Provide a clear enclosure to prevent injury to customer or LORD personnel while allowing clear view of device function.
Objective:Ensures meeting of custom requirements: A02, A03, D03, ER07
Setup:Slow-motion video testing shows a maximum deflection of 3mm. Cover plate will be made by an acrylic contractor used by P18310 and have a minimum of a 8mm gap between the vibrating mounting plate and the baseplate.
Results:Cover is expected to function identically to P18310’s, as the only change is the sizing to fit the new design
- Pending completion of baseplate and cover to conclude*
Shipping Pin design
link to the full file here
New Electric Box
Abstract:Determine if mass of new electronics system is below prior system to ensure weight saving goals are met
Objective:Ensures meeting of custom requirements: R01, R02, R03, R04, O02, O03, A03
Setup:Weigh both systems in prior and new configuration. New system is estimated to save 7 to 10 lbs over old system.
Results:New system should meet minimum expected savings
- Pending completion arrival of parts to conclude*
Draft Packaging Plan
Abstract:Packaging layout for all components necessary for ensuring system will fit in allocated space in Pelican cases
Objective:Ensures meeting of custom requirements: R01, R04, O03
Setup:Model all parts in CAD and layout potential packaging plans. Check weights to ensure 45 lbs per case is not exceeded
- Pending finalization of components*
- Pending finalization of components*
Abstract:Optimize flywheel design to ensure connecting rods are mounted identical distances from the center of rotation.
Objective:Assist in meeting ER06, accurate vibration measurement relies in part on systems being set-up identically between models and finished design.
Design and machine new flywheel. New flywheel will have a single hole to mount the connecting rod to. This was a slot before hand, this made it extremely difficult to ensure connecting rods were in same locations. Additionally this allows reduction in size from the current flywheel.
Hole placed at bottom of original slot, any higher causes isolators to max out
- Pending completion of flywheel to conclude*
In the GUI the variables created need to be assigned to their respected places in the GUI
- Freq must be initially set to 12 - this gets assigned into the TVA Frequency and Non-TVA frequency adjustable buttons
- The increase and decrease frequency buttons for each system need to be assigned to adjust the setFreq value for their respective systems
- The calculated frequency number array must be assigned to the graph of the frequency
- The acceleration arrays need to be assigned to the graph of acceleration
- The calculated reduction percentage needs to be assigned to the value in the Reduction Percentage number
- The drop down menu needs to be set to change the graph that is shown
link to the current Psuedo Code here
link to the code outline here
Abstract:A heat test was performed to ensure quality of performance with a smaller electric box design.
Objective:The goal of this test is to determine the temperature of the electronics in a box without fans.
- Gather all necessary materials.
- Run system at normal
- Record Temperature
- Plot Data
Conclusion:The data was taken over a period of 20 minutes. From the data it is clear that the temperature did not reach equilibrium. Further testing will be required once smaller a electronics box is obtained until the data stabilizes.
link to the test data here
Bill of Materials
link to full BOM here
Review of Overall Design
Future Test Plans
Frequency Change/TVA Mass:
During prior testing (Phase 2), the team determined that the best vibration reduction percentage occured when the system was running at a target of 13 Hz. This is likely due to the fact that the TVA is best tuned for approximately 13 Hz. However, with the current system set-up, the 13 Hz vibration is too violent and causes the hardware to jump around on the table.
To handle this, the team is looking at re-tuning the TVA so that the optimal vibration reduction occurs at a lower frequency, or adjusting the mass of the vibrating system so that the higher frequency vibration does not cause the system to move around. As a parallel effort, the team is investigating ways to clamp down the system or otherwise prevent motion on the tabletop. Since the TVA will likely need to be re-tuned anyways, due to the shipping pin design, the team will be focusing on improving the vibration reduction at the lower frequency and reducing the vibrating mass concurrently. A model will be developed that will determine a target TVA mass given the new vibrating mass and isolator stiffness.
Vibrating System Mass:
Related to the optimization of the vibration reduction percentage at the target operating frequency, the team will investigate the potential for mass reduction in the vibrating system. Similar to the new baseplate design, excess material can be removed some several parts, including the mounting plate (plate which motor, piston, accelerometer, etc. are mounted to), the piston supports, and the TVA mounting plate. Analysis will be conducted to ensure that the structural properties of the parts are not compromised by removing too much material.
link to live Risk Assesment here
- Refer to the guide as much as possible
- It is better to keep the EE’ and ME’s working separately for better productivity
- Always have a at least 2 plans in case something goes wrong
- Planning is better discussed with the ME and the EE leads. Keeping them involved in planning is crucial.
- How to shift focus on what is more important
Team Vision For Next Phase
- Finalize a complete design output
- Update and complete all design documentations
- First Draft of MSD II plan
- complete ER
- complete Risk Assessment
- Order any long lead-time parts