I'm designing an eddy current brake for a rig at work that will use electromagnets to produce the magnetic field. The base architecture will be similar to the wikipedia page for eddy current brakes...axial magnetic flux path through a disc body. I understand how they work in principal, but I'm trying to think of how it would work with AC power versus DC. With DC you get a constant EM field and consistent braking, but if you applied AC current your eddy currents would be formed depending on both disc rotational speed and the frequency of the power (60 Hz).
So, I'm trying to figure out if I can get away with not using a rectifier and use only AC power to make this work. My concern, from what I know about conductive discs and changing magnetic field induced by AC power, is that I'll effectively turn the disc I'm supposed to be slowing down into a really bad induction motor. I.e., after the disc spins down to about 3600 RPM (60 Hz), there will be no relative change in flux between the disc and rotor, and then the AC magnet will act like the stator of an induction motor and act to excite the disc. I want other people's opinion.
Hello. I’m a student studying Materials Engineering Technology in Canada. It’s the time of year when we need to submit an abstract/proposal for our final project and I had a few ideas.
First idea is to build a Electromagnetic Yoke for use in MPI inspection. This is something I have some experience in from a previous job but have no idea how to calculate the electrical side of things. (Input/output, resistance, etc).
Second idea is a wet fluorescent partial Bench with a small electromagnetic coil. (7-8 in ID) I have most of this figured out except the coil.
Third idea was building an induction heater coil for case hardening and use in the program for future years but lack understanding of eddy current.
Any and all feed back is appreciated. Thanks.
Does anyone know what the failure rate is for Piper eddy currents these days? My partner and I have decided to get one done on our 6000 hour Cherokee 6 for peace of mind (not required by AD). I’ve read 4% which seems significant and alternatively my A&P said he’s had 3 fail out of 30 all from the same school, but I’d like to get a gauge here if anyone has experience. Judging from u/andrewbt post a failure seems like a total nightmare.
I have a pretty bad feeling about it for some reason, maybe its the debacle that damaged a landing gear from the previous owner or the $16k+ per wing and indefinite grounding… probably both
https://piperowner.org/talk/discussion/155388/piper-service-bulletin-1345a-published-9-20-2021-main-wing-spar-inspection-improved-procedures
u/BornTuft and u/pilothrowaway111 both asked about the current state of Piper wing spar inspections recently on this sub, so for those affected by it it’s still very much front of mind. Make sure if you’re doing the inspection soon that your inspector follows these updated procedures, which include clarifications on the proper ways to push out the bolts to avoid scratching, and new approved cleaning methods like with Cratex abrasives to polish the holes. These may save you having to trash a perfectly serviceable spar.
Question for discussion: Are you considering doing the inspection / have done it already even if your plane isn’t subject to the service hours requirements of the AD?
Another question - how many part 91 owner/operators actually keep up to date on their Service Bulletins? Their status as “manufacturer mandatory” but not “FAA mandatory” for 91 intrigues me!
Our impeccably cared for and babied 1980 PA28-181 Archer II with 6900 hours total time in service and only 400 factored service hours per AD 2020-26-16 has failed its eddy current test in both bolt holes of the lefthand wing. (The right wing passed lol) The plane has been owned by our flying club since the early 1980s and before that was owned privately by a doctor for just a couple years. The club barely flies it 150 hours a year and we do not allow primary training. If it can happen to our example, it could happen to anyone. The AD has a 5000 factored hours requirement but I am seeing anecdotal reports of airplanes much lower than that failing, like ours.
The inspection failed in such a way that the NDT tech was unsure if it is the left wing spar or the lower cap of the fuselage spar carry through box that failed. This is relevant because if it is the former, only one wing needs to be removed; if the carry through box then both wings need to be removed to access the part for repair. We will have to proceed with removing the left wing and checking it before discovering how much hurt we’re in for.
I am now in the sad position of being flying club President of a single airplane non-equity club with an unairworthy airplane, minimal capital (we bought a new engine 4 years ago and are only a bit more than halfway to rebuilding our reserves), and located at a great community airport near a big city but one that has minimal on-field maintenance facilities.
I am looking for past experiences on how PA28 spar repairs are done, projected costs and time required from those who have already done them, trustworthy maintenance providers to reach out to (ideally local to Philly/NJ), and any leads on good quality used or new lefthand wing spars?
Thanks for the help.
I haven’t spent much time on the game lately and am wondering who the best big men in the game are cuz with all the top tier cards for cheap compared to recent years I want to get a top player in the game.
First, I'm not trying to sink the tail for a stern squirt. That's a different conversation.
I am not in the position to get a different boat at the moment (plus I love my Ripper).
I need to keep a stable platform in the kind of water that is trying to grab the Rippers tail and flip /sink or generally make it hard to stay in control.
I need this stability because I am moving my 9 year old up to harder rivers and I need to be able to be there for him. Also it is disconcerting and distracting to watch Dad getting flipped.
I have been trying to edge so the tail isn't flat and that seems to be working, but I want to make sure I'm not teaching myself bad habits.
Thanks for any help.
Hi all,
I'm pretty new to FEA. Although I have not done a course on FEA, I have read a couple of books and have a fundamental understanding how FEA works.
My PhD work involves studies on impedance changes of a coil due to eddy current.
Brief description of the problem: When alternating current is passed through a coil, alternating magnetic field is generated. When this alternating magnetic field comes near a metal, eddy currents are generated by it. These eddy currents in turn produce magnetic field, which interact with the coil's magnetic field, effectively changing it's impedance.
Now, I would like to model this on FEM, and the choice of my fellow labmates is Comsol 5.5. What I found is that Comsol is like a blackbox (maybe due to my poor understanding). I would like to have control on all steps so that I can validate everything that goes behind and be sure that the model is working as expected.
I started with FEMM and FreeFEM++ and made some progress doing some examples, but I am not sure if I am in the right path. So my question is this.
- Is there a particular FEA software which I should stick to, that specializes in Electromagnetic modeling/Eddy current impedance calculation?
- Can you give some tips for a beginner in FEA?
I made this demo after seeing a few other people do it online. I plan to (eventually) use it when I am a physics teacher. Enjoy.
Notes: Copper block is 3" diameter and 2" thick. Heavy. 1" thick would have been sufficient. Cost about $40. Magnet is a N42 neodymium magnet of 0.75" dia and 1" length. Pull force 55 lbs, and mildly dangerous if you're not careful.
I am looking at the heat generated from wireless charging through a metal enclosure. I have an eddy current loss of 2.68 W in my Ti-6Al-4V metal. I want to compute how much this will rise in temperature. Does anyone know how to convert these losses to temperature rise!
it has a mass of 8.36g
Cheers!
i just commented on their first video (inception time cover) that i'm gonna stream all their videos to support them financially. sharing sc here for context ^(and cause i lowkey want them to read it in case they're lurking) but i wanna talk more about why i'm doing it (and why i think other should too if they want :D)
i know this break is a hard move for them & the team to take cause it's quite a big blow to their income, not to mention corelli-19 & their recent move to singapore. i assume their 5 videos a week strategy is to compensate for their lack of big money sponsored vids, meaning brett & eddy's main source of income are their videos' ad revenue (that isn't fully utilized b/c adblock & skipping ads). i can't buy TSA so i'm gonna stream (aka watch the whole vid w/o skipping ads; common kpop fan activity to support their idol) in hopes that it can somehow support them & make up for their lost YT income during this undetermined timeframe of little to no vids. benefits them & us cause we get to enjoy their efforts of 5 years (can't say enough thank you's for this)
if u guys wanna do the same let me know so i can share some streaming tutorials/tips :> i'm also open to discuss other ways to support the boys!! i saw smth about a ling ling wannabe symphony, that's so cool i'm so proud of this community
sc of said comment for context + appreciation message for them
