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  1. dmalicky

    Quieting impact harshness/boom

    Thanks, Greg. I've been wondering if any would help, too. My tires are already on the cushy side -- actually I'd like +1" for better handling. If CLD & MLV won't help, I wonder how Honda made the TL quieter using the same platform and +2" wheels. Honda notes many things compared to the prior...
  2. 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...
  3. dmalicky

    VFD noise and motor frame material?

    Thanks, all, for the helpful replies! Many variables at play, I see, so it's hard to generalize. That is interesting that a small part can be the worst offender. Thanks also for the link. Yes, I'm watching the derating curves for higher carrier freqs... fortunately the VFD I'm looking at...
  4. 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...
  5. dmalicky

    Local buckling of thin-wall tubes in bending

    Thanks, all, for the very helpful replies! I checked the formulas against a range of square and rectangular tubes (up to 4" square... I'm an mech engr) and almost none fell into the Slender or Class 4 category. The only exceptions were a few thin walled 4130 tubes, both because the walls are...
  6. 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...
  7. dmalicky

    WF5 Mechanica: new features?

    Thanks again, brep, for the helpful reply. And I think I understand how the nonlinear problem would have very different demands on the tuned algorithms. So for single-pass adaptive, is there a way I can estimate errors in the solution? Thanks, David
  8. dmalicky

    WF5 Mechanica: new features?

    Thanks, brep, for the quick and informative reply! Yes, those are some very nice enhancements. I'm curious... what makes multi-pass adaptive difficult to do in a LDA? And/or, is there a way to estimate error/accuracy with single-pass adaptive in WF4 or WF5? Thanks again, David ps. Sounds...
  9. 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?
  10. 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...
  11. 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...
  12. dmalicky

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

    Thanks everyone for the great replies—very helpful! I tried posting in the Pro/E forum but no response... I’ll try again. For ease of use there doesn’t seem to be much controversy. For completeness, the academic Pro/E package is actually pretty good—includes ISDX, sheetmetal, machining...
  13. 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...
  14. dmalicky

    Most important topics for undergraduate Manufacturing Systems course?

    Thanks, everyone, for your great feedback! This will be very helpful as we prioritize topics and make a cohesive course. We especially like the real-world and/or semi-real-world problems as vehicles for teaching the methods. The apprenticeship consultant model makes a lot of sense, too...
  15. 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...
  16. dmalicky

    Strain gage errors: bending cancellation in thin metal?

    Thanks for the helpful replies. Jstephen, I had forgotten about thin beam theory--yes, we are certainly in that territory. You are correct--that boosts the effective modulus by 1/(1-nu^2). That would imply that our gages are reading a little high when in compression, and a little low (but...
  17. dmalicky

    How do interference fits change as temperature increases?

    Some assumptions usually made in differential thermal expansion problems: 1. The temp of each part is ~uniform throughout 2. The temps of each part vary together with time; i.e., one does not heat up or cool down dramatically before the other. They need not reach the same steady state temp...
  18. 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...
  19. dmalicky

    Low CTE castings: NiResist, Invar, or ?

    Looks like EdStainless's $/lb estimate was pretty good, based on the first quote we've gotten so far. Harris Industries in TX and Midwest Metals in MN are the closest ones I could find that would do these types of NiResist. Anyone have experience with either of those? Big4 is gone, Tonkawa...
  20. dmalicky

    Low CTE castings: NiResist, Invar, or ?

    Thanks, everyone, for your tips. EdStainless, I'm reading in the NIDI Pub (R. Covert et al., 11018) on Ni-Resists and it indicates the low chromium alloys machine easiest--e.g., 5 or D-5. But, I don't know if the difference is really significant or how the other factors play in. Any...

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