Subject: Understanding Electro-Mechanical Engineering
From: ljkamm@aol.com (LJKamm)
Date: 9 Oct 1996 12:48:19 -0400
"Understanding Electro-Mechanical Engineering, An Introduction To
Mechatronics"
http://members.aol.com/ljkamm/elmech.htm
Your computer's electro-mechanical devices are its keyboard, hard drive,
floppy drive, CD-ROM drive, switches, connectors, cables, and overall
packaging. The electrons inside your monitor are moving parts which are
electro-mechanically accellerated and their trajectories
electro-mechanically steered.
Your car has electro-mechanical motors, a generator, transducers, and
solenoids and your home has electro-mechanical appliances which range from
toasters to furnaces. Factories, airplanes, weapon systems, and
laboratories have long lists of electro-mechanical devices and systems.
This book classifies and explains all electro-mechanical (mechatronic)
devices and systems. It also gives the basic electrical and mechanical
science and their principles of design. The URL gives the full Table of
Contents and data on the author and publisher.
LJKamm@aol.com
http://members.aol.com/lkamm18392/consult.htm
Subject: Re: Fun questions
From: sripada@red.seas.upenn.edu (Srinivas Sripada)
Date: 9 Oct 1996 17:25:37 GMT
Darren D. Schmidt (dschmidt@rti.org) wrote:
: Question #2
: Trains have wheel assemblies with solid axles where the axle rotates at
: the same rate as both wheels. Cars are designed with a differential to
: compensate for different wheel rotation rates when making a turn. How is
: it possible then for a train to make a turn without one of the wheels
: skidding on the track?
Because trains do not turn the way cars do? Cars turn by rotating the
left (or right) rear wheel about the right (or left) rear wheel in a plane
parallel to the ground. So the distance travelled by the wheels is
different. For trains, the track turns are so designed that at any part of
the curve, the wagons form a chord on the curve such that the wheels
are still on the track, and the turning motion is provided by the
track wedge that nudges (and so slides the wheels sideways). Thus the
total turn is composed of a series of these `nudges'. To borrow from
calculus, you integrate these nudges to get a smooth turn. I think
this would be the right explanation, but someone else may be able to
explain it better.
Srinivas
Subject: Problems with Application of Belleville Springs
From: dhortvet@natoil.com (Douglas R. Hortvet, Jr.)
Date: Tue, 08 Oct 1996 19:21:35 GMT
Can someone please advise a means to calculate the friction in a
series stack of Belleville springs? In our application we have 8
springs, approx. dims. are: 7.875" o.d., 4.5" i.d., .690" free height,
.562" material thickness, stacked in series and installed in a
cylinder.
Our problem is the hydraulic pressure required to achieve desired
deflection is approximately 1.6 x the calculated pressure. We have
tried different lubricants with no change in the force vs. pressure
relationship. Also, we have determined there is no evidence of
interference on either the spring's i.d. or o.d. and seal friction is
negligible. We believe there are significant losses in the spring
stack but do not know the source or mechansim of how the losses are
generated and subsequently how they may be reduced.
Thanks in advance for any comments.
Regards,
Douglas R. Hortvet, Jr.
Subject: Re: hardness=strength?
From: dave lawson
Date: Wed, 09 Oct 1996 16:24:48 -0700
TangoLima wrote:
>
> hello pple,
>
> Was just wondering about the legitimacy of the two terms above.
>
> Also, can a material with a high modulus be soft at the same time?
>
> Is modulus = strength ?
>
> Pls advise.
>
> :)
According to the ASTM standard for toys, anything with a value of Youngs
Modulus less than 100,000 is soft.
Now, in steel, there is a direct relationship between hardness and
tensile strength. If you take the Brinell hardness value. divide by two
you get an approximation of the tensile strength in ksi. (ie. 300 BHN
"equalls" 150 ksi.) This calculation is slightly non-conservative.
Source: 'Machine Design' by Deutschman, Michels and Wilson.
Dave
Subject: Re: McMaster-Carr (was Re: Your Most Often Used References)
From: felice@pioneer.net (Felice Luftschein & Nicholas Carter)
Date: Wed, 9 Oct 1996 21:12:33 GMT
In article <325BB097.7481@icd.teradyne.com> "Adam E. Ek" writes:
>>I agree; this is a great catalog - but how did you get one? I've tried
>>to replace our office's now 10 year old copy for the last 5 years -
>>they're always friendly on the phone and promise to send it, but nothing
>>ever shows up (and we're a small enough office that I'm sure it's not
>I got nothing via phone, but I did get one after sending a fax,
>email, and a regular letter. In each I mentioned that the
>person I was sharing a cubicle with had left to work for a
>different company and had taken his McMaster-Carr catalog with
>him.
There was a long thread on this in the rec.crafts.metalworking newsgroup,
it seems that McMaster Carr has some sort of bureaucratic psychosis
about sending a catalog even to the most qualified of buyers. The new MSC
catalog seems to have almost as much stuff, and they love to send catalogs.
Subject: Re: hardness=strength?
From: jeffe@red.seas.upenn.edu (george)
Date: 9 Oct 1996 21:23:42 GMT
:Was just wondering about the legitimacy of the two terms above.
being rather elemental, these things are pretty well defined
(and often incorrectly interchanged)
modulus/stiffness is the resistance to small elastic deflection
strength is the force to break or yield.
generally there is little relation between them, which is to
say a material can be extremely stiff but break easily or vice
versa. In fact for some classes of materials they are a bit mutually
exclusive.
Now hardness is a tough thing to put a finger on..it is defined
in terms of a test (scratch, indentation, etc). You can easily
rank one material as harder than another, but it is difficult to
quantify what hardness means in terms of strength/stiffness, because
both quantities enter into it. Additionally hardness is really a
surface property where strength/stiffness are bulk properties.
:Also, can a material with a high modulus be soft at the same time?
high and soft relative to what..? I'd say if A is harder than B
then you can not straight away conclude that A is also stiffer
than B. You might draw that conclusion if you are comparing
very similar materials though.
--
george
george@mech.seas.upenn.edu
Subject: Help,Corrosion,electro-mechanical products
From: lionsgate.com@lionsgate.com
Date: Wed, 09 Oct 96 15:17:50
I'm looking for a product that we can use to provide corrosion protection to our power supply
product lines. We do not apply conformal coating to our PCB's and our looking for faster and
easier method of protecting them. We plate and anodize fasteners, metal work, ect, but are
still seeing corrosion problems on some parts within our products that are used in tropical
regions (high heat & humidity).
Can you advise me on products that will provide corrosion protection to ;
a) PCB's (high operating temps, heatsinks, components)
b) inductors (encapsulation, and corrosion protection)
c) various types of metal work (various types of plating)
Ideally one product could "do all", but I'm interested in all products that may only be applicable
for each catagory. Can you offer any insight to similar experiences with your electro-mechanical
products. I have some info on a product called "corrosion block", but I need to get more info
and options.
thanks in advance
Mike Shaw
Canadian Fax : (604)436-2713
Email : mike_shaw@argus.iceonline.com
Subject: Re: Need help on ANSYS
From: gardnerw@gnn.com (William Gardner)
Date: Wed, 09 Oct 1996 07:54:58
In article <325BE777.412F@ime.gov.sg> EHWong wrote:
>I would like to seek your advice on the following:
>
>1. It is possible to assign specific kekpoint number when creating it. Can
> the same thing be done for line and
>area?
The second field in the Keypoint command (K,#,X,Y,Z) is for explicit
numbering of keypoints. The same can not be done for lines and areas. I
would recommend assigning components.
>
>2. It is possible to extract the keypoint number using APDL function
> kp(x,y,z). Is there similar functions for
>line, area and volume?
Yes, for all of the above and more. Use the *GET command
>
>3. The death and live function allows one to put selected elements to
> death to simulate their absence. Can we
>achieve the same purpose by unselecting the element before runing the
> solution? What are the diffenences?
>
Killing elements is done by assigning them a very small stiffness. When
elements are dead, most checking usually associated with a solution is not
done. You can not change your selection of elements in the middle of an
analysis (the stiffness matrices are assembled based on the starting
selection).
For more info, refer to the ANSYS on line documentation.
-----------------------------
Will Gardner
gardnerw@gnn.com
-----------------------------
Subject: Antique Scientific Instrument Forum
From: "R.C. Blankenhorn"
Date: Wed, 09 Oct 1996 16:56:44 +0000
The Antique Scientific Instrument Forum was set up by The Gemmary to
satisfy the needs of collectors and historians of scientific instruments
to keep in touch and exchange information.
It can be accessed from our web site:
http://www.gemmary.com/rcb/
or directly:
http://www.gemmary.com/rcb/insts/forum/forum.shtml
Users can post announcements, comments, questions and answers, as well
as For Sale/Swap and Wanted-to Buy ads. The Forum is free and open to
all. Help us make The Forum a success by using it.If you have comments
or questions about The Forum, post them or e-mail us directly.
--
***********************************************************
***********************************************************
** R.C. Blankenhorn/Vince Austin **
**The Gemmary Rare Books & Antique Scientific Instruments**
** P.O. Box 2560, Fallbrook, CA 92088 **
** Phone: (619) 728-3321, Ans/Fax: (619) 728-3322 **
** e-mail: rcb@gemmary.com **
** internet home page: http://www.gemmary.com/rcb/ **
***********************************************************
***********************************************************
Subject: Re: Fun questions
From: Reg Hardman
Date: Thu, 10 Oct 1996 09:51:39 +1100
Darren,
Hope you don't mind me butting in on your Fun Question series, but I've been
wondering about this one for a while:
A train is travelling in a straight line.
A bee is travelling along the same straight line towards the train.
They collide, the bee is splattered on the train's windshield, the train
continues.
Before the collision:
the train was going 100Km/h,
the bee was going, say -4Km/h (opposite direction).
After collision, the bee was going ~100Km/h on the windshield.
The bee has changed from a -ve velocity to a +ve velocity.
It therefore, at some stage, had a velocity of zero Km/h.
If it is reasonable to assume that the bee's zero velocity occured on impact,
then on impact:
the bee had zero velocity
the bee was in contact with the train's windshield
Therefore, the train had zero velocity, and the bee stopped the train
instantaneously???
If the *reasonable assumption* is incorrect, when did the bee have zero
velocity? If this took place in a vacuum where there were no wind effects, what
then?
I'm looking forward to an interesting answer/s.
-----------------------------------------------------------------------
Advanced Power Products Pty Limited:
Engine driven Welders, Diesel & Gas driven Generators, Control Systems.
Liverpool, Australia
Phone: +61 02 9600 6555
Fax: +61 02 9821 1936
Subject: Re: Fun questions
From: andy@engr.mun.ca (Andy Harbin)
Date: Wed, 9 Oct 1996 22:51:32
In article <325C2C7B.4102@ans.com.au> Reg Hardman writes:
>Path:
>coranto.ucs.mun.ca!news.unb.ca!news.uoregon.edu!arclight.uoregon.edu!feed1.news.
>erols.com!howland.erols.net!swrinde!ihnp4.ucsd.edu!munnari.OZ.AU!news.mel.connec
>t.com.au!news.syd.connect.com.au!news.ci.com.au!usenet
>From: Reg Hardman
>Newsgroups: sci.engr.mech
>Subject: Re: Fun questions
>Date: Thu, 10 Oct 1996 09:51:39 +1100
>Organization: Advanced Power Products Pty Limited
>Lines: 38
>Message-ID: <325C2C7B.4102@ans.com.au>
>References:
>NNTP-Posting-Host: ip137.ans.com.au
>Mime-Version: 1.0
>Content-Type: text/plain; charset=iso-8859-2
>Content-Transfer-Encoding: 7bit
>X-Mailer: Mozilla 2.01 (Win95; I)
>Darren,
>Hope you don't mind me butting in on your Fun Question series, but I've been
>wondering about this one for a while:
>A train is travelling in a straight line.
>A bee is travelling along the same straight line towards the train.
>They collide, the bee is splattered on the train's windshield, the train
>continues.
>Before the collision:
> the train was going 100Km/h,
> the bee was going, say -4Km/h (opposite direction).
>After collision, the bee was going ~100Km/h on the windshield.
>The bee has changed from a -ve velocity to a +ve velocity.
>It therefore, at some stage, had a velocity of zero Km/h.
>If it is reasonable to assume that the bee's zero velocity occured on impact,
>then on impact:
> the bee had zero velocity
> the bee was in contact with the train's windshield
>Therefore, the train had zero velocity, and the bee stopped the train
>instantaneously???
Not instantaneously - there would be a short (order of mircro seconds?) period
in which the molecules comprising the bee would be accelerated in the opposit
direction. This acceleration is not constant throughout the bee, thus causing
a deformation in shape and deterioration of the structure of the bee. There
would also be some give to the front of the train proportional to the kenitic
energy that the bee had originally. The real trick to it is to realize that
neither the bee nor the train are perfectly rigid bodies and both deform on
impact, and that the impact takes a duration of time.
Andy Harbin
Senior Mechanical Engineering Student
Memorial University of Newfoundland
CANADA
Subject: Re: Help : Siemens motor vibrations
From: Erik Torbergsen
Date: Wed, 09 Oct 1996 17:37:28 +0200
Stephen Mitchley wrote:
>
> I'm urgently looking for specs on vibration limits in mm/s
> for a siemens 525V 445A 50hz 355kw 3600rpm motor
>
> serial no :1N133 ICI F
> or 465512/1993 MB3 ICI F
>
> Please email me : chapel@icon.co.za if you have details on
> acceptable axial and radial vibration limits.
I was working in a company some years ago with vibrations on rotating
machinery and we had a case with a large electrc motor, I think it was a
ABB motor. I think we used a standard for vibrations in electric motors
but I dont remember what the name of the standard was. Anyway, I think
the bearing house limit was 1.8 mm/s and we had a problem with the axial
vibration, typical 3 - 4 mm/s. What I remember was that we concluded
that in such motors the axial vibration often was quite high and that
was structur related, often induced by the stator, typically 120 Hz if
you have a 60 Hz motor. Many electric motors of that size dont have
thrust bearings so the vibration is usually not connected with shaft
vibration. I will try to e-mail you if I can remember the name of the
standard.
Regards,
Erik Torbergsen
Subject: Re: Mech. Eng. Handbook on CD-ROM
From: IMSGRP@massey.ac.nz
Date: Thu, 10 Oct 1996 14:14:11 +1300
> Does anybody know of the existance of a Mechanical Engineering Handbook
> published on a CD-ROM. I would appreciate it if you could indicate me where
> can I find such a CD.
"The Electronic Marks' Handbook for MECHANICAL ENGINEERS"
Technical Standards Services Ltd
Blakes House, 98 Ickelford Road
Hitchin, Herts, SG5 1TL, England
Tel. (01462) 453211, fax (01462) 457714
"CD-ROM version of the best-selling classic handbook for mechanical
engineers..."
Steve
s.j.schaare@massey.ac.nz
Subject: Re: hardness=strength?
From: folsomman@aol.com (FolsomMan)
Date: 9 Oct 1996 22:24:59 -0400
eng40073@leonis.nus.sg (TangoLima) wrote:
>hello pple,
>Was just wondering about the legitimacy of the two terms above.
>Also, can a material with a high modulus be soft at the same time?
>Is modulus = strength ?
Modulus does not equal strength, but modulus and strength are positively
correlated. You need to specify what measure of strength you are talking
about before anyone can give you a specific answer. Hardness is a measure
of compressive or bearing yield strength, but you can't correlate it very
well with tensile strength unless you exclude brittle materials. You
might get the same hardness in both white cast iron and low alloy steel,
but the tensile strengths can be very different.
Mark Folsom, P.E.
Consulting Mechanical Engineer
Subject: Re: Hydrocode simulations - Where?
From: zagz@ix.netcom.com(Ken Zagzebski )
Date: 10 Oct 1996 05:59:25 GMT
In <53h1uc$1uq@portal.gmu.edu> tvalesky@osf1.gmu.edu (Thomas B Valesky)
writes:
>
>
>Hello! I'm a computer science grad student working on a project to
>do (near) real-time simulation of explosions. I've run across a
>couple of references to hydrocode packages that do this sort of thing,
>but I've been unable to locate any such software. Where can I find it?
>(I'm on a tight budget, so free stuff would be best :-) ).
>
>Thanks,
>
>Tom Valesky
>
>--
Try contacting Los Alamos, Sandia or Livermore. Also someone in this
newsgroup or sci.engr -- with in the last day or two -- described how
to get US Gov. tech. reports from the Defense Technical Information
Center (DTIC). A search of there database should be promising. I
think there is still a Defense Nuclear Agency (DNA) in DC where you
could inquire. Also the Air Force Weapns Laboratory at Kirtland AFB in
Albuquerque might still be doing some work in that area. That should
be a useful place to look. For what it is worth, two code names I
remember are SLAM and PUFF.
Ken Z.
Subject: Re: Finding an M.E. job in the Bay Area
From: Patrick Campbell
Date: Wed, 09 Oct 1996 23:08:36 -0700
Dave Winn wrote:
>
> Can someone help me to locate some good sources for a friend who's in
> search of M.E. design jobs in the Bay Area? What web sites are best to
> check? I've already looked at OCC with limited results. What companies
> are hiring in the area?
>
> Thanks,
> Dave
> --
> Dave Winn
> Cisco Systems
> Mechanical Engineer
> ACCESS - NPI
> 408-527-1446
You may want to specify which bay area you are talking about. Based
on your phone # area code, I assume its the San Francisco Bay area.
There are other "bay areas", Green Bay, Tampa Bay, etc.
If it is the SF Bay Area, I always found it tough to find ME jobs
that were 2nd fiddle to EEs. For example, I interviewed with Silicon
Graphics and they wanted an ME to design sheet metal boxes for their
computers. Not very exciting.
--
Patrick Campbell OOO
Team Minus Zero O O
Robot Warriors ==== O
patrick@tmz.com O O
http://www.tmz.com OOO
Subject: Re: Fun questions
From: Reg Hardman
Date: Thu, 10 Oct 1996 16:15:43 +1100
From:
andy@engr.mun.ca (Andy Harbin)
>The real trick to it is to realize that
>neither the bee nor the train are perfectly rigid bodies and both deform on
>impact, and that the impact takes a duration of time.
So if we look at it on a molecular level, bee molecules whizz past windshield
molecules, some slowing down and decelerating to the train's velocity in the
molecular interstices due to inter molecular forces, others colliding with windshield
molecules and being deflected at angles (which eventually add up to 180 degrees)?
Sounds like a plausible explanation, I guess.
Reg
-----------------------------------------------------------------------
Advanced Power Products Pty Limited:
Engine driven Welders, Diesel & Gas driven Generators, Control Systems.
Liverpool, Australia
Phone: +61 02 9600 6555
Fax: +61 02 9821 1936
Subject: Re: Fun questions
From: pcc60136@teleport.com (Rob)
Date: Thu, 10 Oct 96 03:28:32 GMT
>The wheels on a train are tapered with the outside of the wheelsets having
>a smaller diameter than the inside.
It's true the tapered tread of most railroad wheels contributes a differential
effect when negotiating curves, although on more than moderate curves a good
deal of slippage still occurs, and is characterized by the squealing sound
often heard. On some equipment, often passenger cars, a cylindrical, rather
than tapered, tread is used due to problems encountered with the tapered wheel
tending to "hunt" at high speed.
I understand that a major reason for staying with a solid axle, rather than
independently rotating wheels, is the increased tendency for the wheels to
slide during braking when able to rotate independently. With a solid axle both
wheels have to break loose simultaneously. Does anyone know if this is true?
-Rob S.
Subject: Re: Fun questions
From: Dean Taylor
Date: Thu, 10 Oct 1996 08:26:35 +0200
Wayne Borrowman has it correct as far as I know. Normally contact
between the
flange and the rail is the limiting factor.
The geometry of the wheel/flange profile is important. It is not a
simple cone, and
it wears as the wheel is used. The geometry of the rail cross-section
is important.
This all makes for a very interesting nonlinear dynamics problem, with
critical speed,
flutter instabilities, limit cycles, etc. Probably even chaos in
certain circumstances.
Subject: Re: Help,Corrosion,electro-mechanical products
From: "David Allenberg"
Date: 10 Oct 96 05:42:25 GMT
We have used a clear reasonable fast drying polyurethane furniture varnish
for this, and have done so now for about 9 years without any problems at
all.
It supplies an excellent barrier, and it is not difficult to repair the
board either if you have too. We just apply the soldering iron straight to
the board, and have no problems with it.
We could not find anything else suitable at the time, had a problem that
needed solving instantly, and still use it.
lionsgate.com@lionsgate.com wrote in article
<53h1mt$83l@saltspring.teleserve.ca>...
> I'm looking for a product that we can use to provide corrosion protection
to our power supply
> product lines. We do not apply conformal coating to our PCB's and our
looking for faster and
> easier method of protecting them. We plate and anodize fasteners, metal
work, ect, but are
> still seeing corrosion problems on some parts within our products that are
used in tropical
> regions (high heat & humidity).
>
> Can you advise me on products that will provide corrosion protection to ;
> a) PCB's (high operating temps, heatsinks, components)
> b) inductors (encapsulation, and corrosion protection)
> c) various types of metal work (various types of plating)
>
> Ideally one product could "do all", but I'm interested in all products
that may only be applicable
> for each catagory. Can you offer any insight to similar experiences with
your electro-mechanical
> products. I have some info on a product called "corrosion block", but I
need to get more info
> and options.
>
> thanks in advance
>
> Mike Shaw
>
> Canadian Fax : (604)436-2713
> Email : mike_shaw@argus.iceonline.com
>
Subject: Re: Help: Manufacture of aircraft propellers before NC
From: pcc60136@teleport.com (Rob)
Date: Thu, 10 Oct 96 03:45:48 GMT
David M. wrote:
>Can anyone tell me where to find information about how aircraft
>propellers (airscrews) were manufactured before NC machines were
>available?
NASA Ames Research Center used to have a machine made by Danley (sp?) which
was used to make aluminum propeller (actually turbine) blades for wind tunnels
there. It was a very large machine which held the blade vertically and had, I
believe, two vertical spindles which held rotating milling cutters. I believe
the blade was rotated about its axis while the cutters fed in and out to
develop the required contour. I'm not sure how this was done, possibly by
tracing a template or following cams. After milling, the blade was finished by
hand to remove machining marks, much like is what is done after most CNC
contouring.I'm not sure if this was a typical method used for aircraft
propellers or not. I suspect that many aluminum props were forged to a shape
very near to finish and finished by hand.
-Rob S.