Hi Niekie!
I agree that the original choices made for the design of this (low speed) maglev system did'nt make sense as far as matching the selected metals...
I recognized that as soon as the structural engineer gave us (AWS Pittsburgh Section) a presentation regarding this system...
Remember the last time we discussed galvanic corrosion???
When I heard the choices this gentleman made, I immediately thought of you and the others in the thread regarding the weld overlays...
During the presentation, this person took questions, and my hand was up in there immediately!!! I asked him why his group decided to choose the base metal types with respect to the critical factors that had to be considered... Both the Galvanic compatibility, and Magnetic permeability were an issue in their choices that stuck out like a sore thumb!!! He gave us a powerpoint presentation complete with their assesments, and calculations. Oh yeah, the low speed guideways were assembled in about 50ft. sections, and the high speed MAGLEV Inc. guideways are to be assembled in 204ft, sections.. In case anyone is confused, these are two totally different designs!!!
The structural Engineer's response was'nt satisfactory as far as I'm concerned!!! If anything, some of the alternatives were better choices and yet, none were satisfactory either!!! Basically, his rationale for these choices were, and I quote: "Well - this is only going to be a temporary - experimental demonstration guideway so, after all of the analysis is completed, the track will no longer be necessary" he also added that "by "cold working the material prior to fabrication, and assembly then performing PWHT (Annealing), they could minimize the gap between the two dissimilar steels as far as the magnetic permeability was concerned". Although he explained that well, I challenged that explanation because he avoided the galvanic compatibility issue - by later asking him: "Well did'nt you just finish stating before that the university where this is being installed, will inherit this system. They would put it to use by incorporating this system into their expansion plans as a shuttle from the parking lots to the variety of new buildings scheduled to be added to their campus?"
His response was: "Well - that's why I'm asking for any suggestions to tackle some of the issues the design has problems with."
I found that hard to believe coming from a structural engineer that had previously done work for the Office of Naval Research!!!
This is mainly the reason why I posted the question on this thread...
For anyone that does'nt understand what Niekie, GRoberts, Chet, and I are talking about when we mention the Galvanic compatibility, and later Magnetic Permeability - Please refer to this website which is one that's written so that most people can understand...
http://www.corrosion-doctors.org/Aircraft/galvseri-compat.htm
In this chart Iron, wrought, gray or malleable, plain carbon, and low alloy steels (A-36 is included in this group) have an anodic index(V) of roughly 0.85 .
The 18% chromuim steels have an anodic index(V) of 0.50, and the 12% chromium type steels are 0.60 respectively
The top part of this page explains that for "Harsh Environments" such as outdoors, high humidity, and salt environments fall into this category.
Typically, there should NOT be more than a 0.15V difference in the anodic index when matching these metals...
Since these guideways are outdoors, this design falls into the "Harsh Environments" category... The differences are self explanatory!!! Way TOO MUCH!!! Now, if certain corrosion mitigation methods are used such as cathodic protection, and choosing the appropriate coatings then, the potential for galvanic corrosion could be minimized while at the same time if properly done, minimize of even eliminate the risk of
distortion by the choice of coating... Now I do like what MAGLEV Inc. is incorporating when they assemble their Guideway sections. They use a "passive" method of vibratory stress relief as the
welding takes place in order to reduce the residual stresses, and eliminating the need for PWHT...
Magnetic permeabilty is another important factor as is the requirement for handling cyclical loads in emergency situations whereby if the "Train cars" or transport vehicles temporarily lose levitation because of a loss of electrical power fed by the guideways or the computerized high speed switching systems that pulse the magnetic fields in "waves" fail, the train will have wheels that will make contact (run by back up battery/fuel-cells for power and on board computers for redundancy), and then mechanical/magnetic emergency braking systems will be used to stop the train or transport vehicle until the restoration of power. This poses another potential issue which was also incorporated into the design by also having the ability to deploy a specialized maintenance vehicle to repair/replace any damaged coating surface area of the guideway and the brake pads also... So Niekie, those "M" alloys you suggested may or may not be appropriate for this design but, I appreciate the suggestion nonetheless, and I will look into them!!! When I find out more, I'll post my findings
As GRoberts and Niekie mentioned the metals chosen did not have the same magnetic permeability as the A-36 CS does...
However there are a multitude of alloys that have higher magnetic permeability rates than A-36 but, costs/availability must be taken into account when considering the amount of steel that's necessary to construct miles of guideways...
This site explains magnetic permeability in simple terms, and this company's offerings are: CO-NETIC AA alloy or NETIC S3-6 etc.
http://www.magnetic-shield.com/faq/pma.html
There are others but, I really like this one on certain stainless steels:
http://accelconf.web.cern.ch/AccelConf/p91/PDF/PAC1991_2322.PDF
I like the Japanese design better myself but it also has some issues!!! What I really do not understand is why the MAGLEV 2000 of Florida project's design, and technology was not the final choice of the "powers that be" when they gave the go ahead for the implementation phase of this relatively new transportation system!!!
Unlike the German, and Japanese design, the MAGLEV 2000 of Florida project is TOTALLY AMERICAN TECHNOLOGY!!! Man! this system makes a hell of alot more sense because of the flexability of this system!!!
Now that I've looked into the alternatives to the German "Transrapid" system, I cannot help but wonder why the American designed system was'nt chosen for implementation!!! I think the rationale for choosing the Transrapid system was that the MAGLEV "attraction" levitation propulsion technology, being further along in demonstration testing than the original "repulsive" superconducting propulsion technology which Physicists Dr. David Powell, and Dr. Robert Danby not only invented back in 1966 but, also has been implemented already in Japan!!! Go Figure!!! Thus, this was the Justification from the FRA to choose the German system over our own for implementation!!!
TOO much politics were involved in the decision making process if you ask me!!! Boy did we (The U.S.) ever drop the ball on this way back in 1975 when we abandoned the initial research!!! All of that money wasted on the superconducting super collider in texas that was abandoned!!! Just think of how our economy would've benefitted if we were already working on a second generation system by now!!!
Lawrence Livamore National Labs have come up with some pretty interesting work on the possible next generation of MAGLEV technology called: "Inductrack"... A good explanation below on their webpage..
Here are some interesting websites regarding MAGLEV 2000, and other MAGLEV projects:
Lawrence Livamore Labs "Inductrack"
http://www.llnl.gov/str/Post.html
http://www.maglev2000.com
http://www.faculty.washington.edu/jbs/itrans/powelldanby.htm
http://www.faculty.washington.edu/jbs/itrans/ammaglev.htm
http://www.faculty.washington.edu/jbs/itrans3.htm
http://www.faculty.washington.edu/jbs/itrans37.htm
http://www.monorails.org/tMspages/TPM2000.html
http://www.wsdot.wa.gov/ppsc/research/TRB_Special/TRB2003-001083.pdf
http://www.pref.aichi.jp/kotsu/rinia/index_e.html
http://www.rtri.or.jp/index.html
http://www.transrapid.de/en/index.html
http://www.swissmetro.com/en/00_Home/index_E.htm
http://www.magnemotion.com/index.shtml
http://www.kyrene.K12.az.us/itech/amsitech/activities/maglev/links.htm
http://rip.trb.org/broese/dproject.asp?n=6896
http://www.21stcenturysciencetech.com/articles/summer03/maglev2.htm
http://future.newsday.com/10/fmon1025.htm
http://www.amlevtrans.com/
http://dmoz.org/Science/Physics/Electromagnetism/Magnetic_Levitation/Transportation/
Here is where we stand right now in the deployment program...
http://www.fra.dot.gov/Content3.asp?P=209
http://www.fra.dot.gov/Content3.asp?P=210
http://www.fra.dot.gov/Content3.asp?P=515
http://www.fra.dot.gov/Content3.asp?P=567
http://www.fra.dot.gov/Content3.asp?P=1209
http://www.fra.dot.gov/downloads/RRDev/maglev_rod.pdf
http://ntl.bts.gov/DOCS/TNM.html
http://www.nctransportation.com/
I hope these are sufficient for reading... Actually, I have more but, then again - I think I already commited overkill with all of these web pages & websites!!! Look foward to your comments...
Respectfully,
SSBN727 Run Silent... Run Deep!!!