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  • Users: dmalicky
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  1. dmalicky

    Quieting impact harshness/boom

    I have a 2005 Honda Accord sedan, 51k, and am attempting to quiet the car both for my ears and as a learning exercise. Mostly I want to soften the impact harshness/boom over bumps. (Tires are 65-series H Michelin MXV4 which are quiet for cruising). I gather that impact boom is more difficult...
  2. dmalicky

    VFD noise and motor frame material?

    For a VFD-driven motor, does the material of the motor frame make much difference in the noise emitted from the VFD's carrier frequency? I know cast iron has higher damping than steel or aluminum, but I'm not sure how much this damping actually affects the acoustic noise in practice. If the...
  3. dmalicky

    Local buckling of thin-wall tubes in bending

    For thin-walled square and rectangular tubes, I'm trying to find a formula for the loss in bending strength due to local buckling in the compression 'flange' and side walls. I've heard of heuristics like keeping (width/t) < 50 to avoid dimpling of the walls; I'm looking for something more...
  4. dmalicky

    WF5 Mechanica: new features?

    I'm trying to find out what new features WF5 has for Mechanica and Advanced Mechanica. Most importantly, can it do contact and large deformation in the same analysis (not possible in WF4)? Also, can it do multi-pass adaptive in a contact and/or large deformation analysis?
  5. dmalicky

    Radial vs. Backward Inclined Centrifugal Blowers: noise and dust

    Some questions on centrifugal blowers-- 1. For the same installation, CFM, and DP (ours will be ~5000cfm and ~10iwg), roughly how much noise difference (dB) is there between a Radial Blower and a Backward-Inclined Blower? I'm mostly concerned about the airstream noise (not housing). 2...
  6. dmalicky

    Pro/E WF v. SWx for college setting: anyone for Pro/E?

    I got many responses to a similar post in the SWx forum. But since that forum might be biased, it would be great to hear from some Pro/E WF users, too. We're evaluating which package to teach and use with undergraduate mechanical engineering students. I know WF2/3 is easier to use and...
  7. dmalicky

    College setting: how much faster to learn &amp; use is SW v. ProE?

    We are re-evaluating which package to teach and use with undergraduate mechanical engineering students. We currenly have ProE/M though we are not heavily vested in it. I know historically SW has been faster to learn and use, compared to ProE. But ProE has improved in recent years and I don't...
  8. dmalicky

    Most important topics for undergraduate Manufacturing Systems course?

    We are in the process of revising our Manufacturing Systems course, for undergraduate mechanical and industrial engineers. The students will have already taken Manufacturing Processes (machining, forming, molding, etc). We are trying to prioritize topics for this course and particularly the...
  9. dmalicky

    Strain gage errors: bending cancellation in thin metal?

    We are trying to measure tensile/compressive strains in 0.020" thick steel, using strain gages. With material this thin, the surface strains are dominated by local bending effects (e.g., oil canning). As usual, I average the top and bottom strains to get the neutral axis strain. I setup some...
  10. dmalicky

    Low CTE castings: NiResist, Invar, or ?

    We need to cast some ~16" diameter pump housings with good dimensionally stability over a temp range 0 to 400 deg F. To maintain required rotor tip clearances over that temp range, we need a material with a CTE of ~4.5*10^-6/deg F or lower (~8... /deg C). The only alloys I can find that meet...
  11. dmalicky

    Endtruck design for underrunning bridge crane

    I'm thinking of a design for an underrunning endtruck, and wondering why I haven't seen it in commerical cranes. Basically, take a standard rigid dual-C-channel endtruck and replace the fixed U-channel endcap with a tie-rod (with bushing on each end): 0-------------0 (end view) The tie...
  12. dmalicky

    Re-heat-treating 4140

    We are making torsion bar springs (like an anti-roll bar) out of 5/16" diameter 4140, 36" long, and are on a tight time frame. At a safety factor of 1.3, we need a yield stress of 180,000 psi. They won't see more than a thousand loading cycles. They may see a little (20%) reverse torsion. I...
  13. dmalicky

    Crane Runway Straightness and Specs

    I am designing an overhead under-running bridge crane for a manufacturing company: 1 ton capacity, 46 foot span, 75 foot runway length (supported at 25 foot intervals), Class C service. I have ordered the CMAA 74 spec and plan to follow it as much as possible. From preliminary data and calcs...
  14. dmalicky

    Regrease a bearing or leave it alone?

    We make industrial machines used in a fairly dirty environment. We are debating whether or not to recommend regreasing for some pillow block bearings on our machines (SKF SYR series, 1 15/16&quot; bore, with labyrinth seals). The bearings run 24/7/365 at ~3400rpm (thus the labyrinth seals) and...
  15. dmalicky

    Stainless steel casting alloys: machinability

    Does anyone have experience with the relative machinabilities of these stainless steel casing alloys, compared to CF-8? CC-50 CD-4MCu CB7Cu1 Sea-Cure 29-4..., 2204 2205 20Cb-3 I have some source books but they are incomplete and contradictory. If anyone has first-hand experience with any of...
  16. dmalicky

    Stainless steel casting alloys with low CTE

    We are seeking a stainless steel casting alloy for a pump housing. The pump moves ~dry granular solids (it is a rotary airlock valve for pneumatic conveyance). Here are our requirements, and my understandings. I would appreciate any suggestions/corrections on this! 1) Low thermal expansion...

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