156B Week 5

Overview of Status of Analysis, Design, Fabrication, Tests, etc.

• • Scale model complete

  • Aluminum plate & foam have been ordered

Accomplishments from Previous Week

• • Scale model made & tested at ATA w/ various profiles

  • Accelerometer data from the test has been processed

    • Checking correlations between mathematical model and gathered results

Goals for Next Week (list names after each item). Use specific and measurable objectives.

• • Get aluminum structure finalized - Sam

    • ATA pointed out stiffness of Al plate vs. stiffness of impact head (has been/can be addressed)

    • New corner frequencies from Roy (impact head stiffness, NOT bolt stiffness)

  • Order ALL other parts to begin with our final design- Leighy

  • Refine corner frequency calculations and impact head stiffness calculations - Roy

  • Impact head frame refinement - Troy

    • Bearing/shaft design is a priority (to allow for bearing order)

  • Arresting mechanism design - all

Sponsor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)

• • Think about the arresting mechanism

    • Return to next meeting with a few arresting mechanism designs

  • Strengthen the hammer frame laterally

    • Gave us suggestions on how to do that

  • Stiffen area that gets hit by the hammer on the excitation plate, if necessary (see Sam's task above)

  • Add 34kg maximum test mass onto plate and check for modes

    • Modeled as point mass (worst case scenario: mass contributes to modes, but article stiffness does NOT; realistically, it would contribute stiffness)

Instructor Comments from Last Meeting and Actions Taken to Address these Comments (indicate date of comments and if via email or in person)

• • Suggestion made to model system as a 3 DOF system (ATA's comments somewhat mitigate this)

  • In material selection, consider acoustic impedance of interacting materials (put on hold while we made scale model etc.)

Comments from Other Students in the Class (indicate date of comments and if via email or in person)

• • General comments were explain modal analysis better

Risks and Areas of Concern

• • Arresting mechanism

    • mechanically triggered (minimally invasive)

    • uni-directional motion when engaged

    • If accidentally left engaged on hammer release, it could break (and will ruin test)

      • Sacrificial weak point to mitigate this

  • Fabrication of excitation plate

    • Convoluted setup requirements

    • ~4hrs. machine time; requires minimum 2 setups; Sam will consider schmoozing one of the SAE alumni for his Hurco...

Resources or Information Required but not Available

• • None-- all resources/info we have needed has been provided by ATA

Schedule

• • First draft of report to be completed by Friday at midnight

  • First draft of webpage to be completed by Friday at midnight

  • Update Gantt chart.

  • Corner frequencies should be done by 4/27; plate optimization done by 4/28 at the latest (preferably same day)

    • New NC program/strategy to be created by 5/1

  • Frame

Budget (list amount spent and amount remaining)

• • Purchased so far:

    • -Delrin impactor ($29.05)

    • -Aluminum 6061-T6 Plate ($832.12)

    • -Acoustic Foam ($72.75)

    • -Aluminum 6061-T6 for scale model ($27.14)

    • -2 x Steel bolts for scale model ($1.19)

    • Remaining: $537.75

Progress on Report and Webpage

• • Webpage has most general information filled out; plenty of formatting to do, cleanup, removal of "add files here"/explanation content

  • Draft of report should be done by Friday; some more small sections filled out

    • All unknowns (final mass, cost, etc.) will be left as blank/NEEDS REFINEMENT (or some other indicator)