156B Week 7

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

• • Major components are starting to be machined

  • Frame design is complete

  • Wood frame construction started; various foam layouts tested

  • Aluminum fixture plate received

  • Continuing analysis of energy/stiffness requirements for target profiles

Accomplishments from Previous Week

• • Frame almost entirely done

    • FInish up bolt holes

    • Check dimensions

    • Check for "ergo" (make sure things can be bolted together)

      • Currently some bolts need to be put in one way not the other (threads/nuts would interfere with each other if put on backwards): this is annoying to assemble!

      • Can be addressed: some dimensions bigger, some bolt patterns bigger.

    • ~89 kg (185lb) If all steel, 1/8" tabs

      • Considering aluminum tabs: lighter, quicker/easier to waterjet. Also less painting required...

    • Entirely bolted together; no welding required

      • Can be "flattened" against a wall for storage

    • Check for indexing to wood slider: consider extra long bolts in specific spots; goes into holes in wood (think like dowel pins)

      • Would be nice to have a place to rest sliding wood against frame: so impactor always hits the same spot/same distance from frame

  • Almost every part has been ordered (besides the tubes/winch)

  • I think we stopped saying "soft" when we meant "compliant"

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

• • Machine aluminum fixture plate

  • Small bolt on strike zone plate FIRST

  • REQUIRED threaded holes (top and sides)

    • Time permitting: optimized shape on back

      • Needs to be re-optimized (higher stiffness than initial optimization)

  • Waterjet frame tabs; order (manufacture as well?) frame tubes

    • Req. completed frame design

  • Finish up impactor design

    • Arms

    • Impact mass: method of changing mass (bolt on mass to a fixed, minimum mass? Entire head/mass swapped out?)

      • Basically, bolt-together heads, or entirely changeable heads

    • Impact tips: geometry, all the good stuff

  • Since we will probably not be able to fully test the product at ATA by beginning of week 8 presentation, set up a day with them to test the final product

  • Order any parts as necessary

    • Frame feet, winch (McMaster)

    • Delrin/teflon sheet for slider base

    • Some "local" parts: i.e. nuts, bolts, wood, wood wax, etc.

  • Tweaking of the final product

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

• • All in person

  • More budget should not be an issue and they will email professor letting him know it is okay

  • Advice on alterations of frame

    • Change orientation of some triangulating members

    • Discussion on "comfortable height to work with": ~8ft. tall is acceptable.

  • Figure out requirements for short pulse: what heights, masses, and stiffnesses give the correct duration/amplitude: are they possible/practical?

    • Yes, they are achievable; frame extended in height, impactor stiffness allowed to rise a little (previously wanted plate to be >=10x stiffer than impactor; will now accept ~7x stiffer)

  • Chamfer everything!

    • Will probably do with air tool by hand for aluminum fixture plate; strike zone will be done with mill while it is being manufactured

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

• • All in person

  • Report (All to be addressed by Friday of Week 7)

    • More detail

  • Annotated figures, esp. for equations

    • Word 2003 conversion apparently messes up some formatting (some diagrams moved, some annotations got lost)

    • Don't repeat: some sections are fine as bullets; use only bullets

  • Tom is pretty much on board with the strategy for the fixture plate (drill first, pocket/optimize later)

    • Reduce size of edge fillets to machine quicker (less material removed

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

• • No additional comments since the last presentation

Risks and Areas of Concern

• • Timing-- We will probably not be able to test at ATA for the presentation during week 8, but this will definitely be accomplished week 9

  • Foam base assembly

    • Certain foam arrangements provide low frequencies but are too unstable/inconsistent for the fixture plate (uneven/foam spills over in some direction)

    • More foam ordered: to be constructed with more stable structure that still has low enough frequencies.

Resources or Information Required but not Available

• • Only resource that is scarce is money, but ATA said they could help with this

Schedule

• • Machine/assemble the shock impulse machine by this week

  • Set up a testing day at ATA by next week

  • Presentation Monday of Week 8

Budget (list amount spent and amount remaining)

• • Spent: $1110.34

  • Remaining: $398.66

  • ATA is aware of budget concerns; plans underway to extend by <= $500

Progress on Report and Webpage

• • First draft complete

  • Will submit suggested changes by Friday midnight

  • More annotations!!!

  • Presentation beginning of Week 8