Subject: Re: Vibration Specification
From: Mike Chow
Date: 10 Sep 96 12:44:16 -0500
Michael D. Miles, PE wrote:
>
> I'm writing a purchase specification for a blower and the sample
> blowers we've tested all have some speed at which the rotor sets up an
> harmonic, causing some signifigant vibration of the entire blower
> housing and the equipment it is attached to.
>
You might have run into the first critical speed of the blower. What
is the running speed of the blower in relation to the speed which it had
high vibration?
> I'd like to add a spec line referring to the maximum allowable
> vibration (or balance which is more precise in this situation).
>
> Since vibration is defined frequency and amplitude(displacement), I
> can specify an amplitude limit over the entire speed range of the
> blower but I'm wondering if there might be other means of specifying a
> limit of vibration for the source device.
> Is this a machine running at fixed speed? If it is, you can specify a
limit some where between 0.1 and 0.2 ips. However, the limit depends on
other factors such as machine configuration, bearing type, etc.
> If I try to characterize a balance specification, I'm not certain what
> is generally accepted for terms or description. Any suggestions?
>
> Entropy Happens!
>
> Michael D. Miles, PE
> Consulting Design Engineer
> mdmiles@teleport.com
--
Mike P. Chow | The views and comments
Work: mike.chow@srs.gov | expressed herein do not
Home: mike1218@groupz.net | reflect the views of WSRC
| or DOE.
Subject: Re: FEA: Modelling Bolt Holes
From: rizzo@hogpb.ho.att.com (-A.RIZZO)
Date: 10 Sep 1996 20:40:26 GMT
In article ,
Christopher Wright wrote:
>In article <5115cl$gsj@arl-news-svc-6.compuserve.com>,
><71531.3213@compuserve.com> wrote:
>
>>I am currently using MCS/Nastran and have had to analyse a few models
>which included bolted joints.
>
>My approach is to clamp ...
... various and sundry ways of complicating one's life,
as well as a reference to a bodily orifice deleted ...:-)
>
>Christopher Wright P.E.
Might it not be a good idea to first ask the question, "What am
I trying to learn with this analysis?" Or did I miss that one?
Tony Rizzo (slayer of windmills and sacred cows)
"I continue to lunge at the flailing beasts, with loyal Sancho at my side.
On windless days we are victorious. But the wind makes the beasts ever so
fierce. A strange magic they possess, which lets even the lightest breeze
breathe life into their fearsome forms."
Subject: CMM Conference - E-mail address change
From: Kostadin Doytchinov
Date: 10 Sep 1996 14:47:29 GMT
Please, note the change of the E-mail address from the first posting of
this message. Please use acmc@m36sci.lan.nrc.ca
Association for Coordinate Metrology Canada (ACMC) announces its Annual
General Meeting on September 27-28, 1996 at Durham College in Oshawa,
Ontario (near Toronto). The registration fee, which includes two
breakfacts, one lunch, one dinner, and coffee breaks is $110 CAD for
members and $160 CAD for nonmembers. The meeting is open to anyone with
interest in Coordinate Metrology.
For more information:
ACMC
Institute for National Measurement Standards
National Research Council
Montreal Road, Building M36
Ottawa, Ontario K1A 0R6
Tel.: (613) 991-0265
Fax: (613) 952-1394
E-mail: acmc@m36sci.lan.nrc.ca
September 27
8:00 Registration Coffee, refreshments, muffins
8:30 Welcome Opening Address
Mr. Wesley Lowell
ACMC Chairman
General Motors, Oshawa
8:35 Technical Sessions, Papers and Discussions
International vocabulary of basic and general terms in metrology
(VIM)‹ Discussion on principles.
Mr. Michel Portugais
Institute for National Measurement Standards
National Research Council of Canada
8:50 Technical Sessions, Papers and Discussions
Environmental conditions and their effect on CMM accuracy.
Mr. Konrad Busch
PTB Germany
10:15 Coffee break
10:45 Technical Sessions, Papers and Discussions
Errors from touch trigger probes‹modelling and compensation. The
effect of CMM geometric errors on measurements.
Prof. René Mayer
Mechanical Engineering Department
École Polytechnique Montréal
12:00 Lunch
13:30 Technical Sessions, Papers and Discussions
Review of GD&T; ASME Y14.5-1994 standard for proper CMM part
inspection.
Prof. Michel Guillot
The Industrial Metrology Laboratory
Mechanical Engineering Department
Laval University Québec
15:00 Coffee break
15:30 Technical Sessions, Papers and Discussions
Vendor panel discussion
‹What's new with each vendor?
‹Company visions for software development in the future.
17:00 Open discussions. Vendor's time.
18:00 Dinner
September 28
8:15 Coffee, refreshments, muffins
8:30 Technical Sessions, Papers and Discussions
CMM calibration and accreditation: Why, when, and how.
Dr. Steven Phillips
Precision Engineering Division
National Institute of Standards and Technology USA
9:30 Technical Sessions, Papers and Discussions
Gauge R & R study.
Mr. Tony Deviveiros
General Motors of Canada, Ste. Thérèse
and
Mr. Kostadin Doytchinov
Dimensional Metrology Program
Institute for National Measurement Standards
National Research Council of Canada
10:15 Coffee break
10:45 ACMC Business
11:00 Technical Sessions, Papers and Discussions
Open Forum‹Question and Answer Period.
‹Bring your questions and your parts or drawings.
Note: Before the meeting, fax your questions, problems, diagrams, etc.
to Bill Vetzel, General Motors of Canada‹
phone: (905) 644-2555
fax: (905) 644-2225
Subject: Re: ASME boiler and p.v. code question
From: chrisw@skypoint.com (Christopher Wright)
Date: Tue, 10 Sep 1996 22:36:07 -0600
In article <5133k7$pk8@nadine.teleport.com>, pcc60136@teleport.com (Rob) wrote:
>I need to calculate the theoretical bursting pressure of
>a stayed and/or braced surface in a power (locomotive) boiler given the UTS of
>the plate, thickness of the plate, and spacing (pitch) of staybolts and/or
>rivets.
This type of construction is still used in heat exchangers. Suggest you
dig a copy of the Code out of a local University library. What it'll give
you is the allowable working pressure for the construction, not the burst
pressure, provided you follow all the rules for everything, including
material specification. The burst pressure is nominally 3-4 times the
allowable working pressure, but with flat surfaces, the edge conditions
make a big difference, so your value might be higher. If you don't follow
the rules it'll be lower.
Christopher Wright P.E. |"They couldn't hit an elephant from
chrisw@skypoint.com | this distance" (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/subscribers/chrisw
Subject: Job Announcement
From: Brian Grosjean
Date: Tue, 10 Sep 1996 12:25:21 -0700
ERI Services, a fast growing national energy solutions subsidiary of
Equitable Resources, Inc.;, is seeking technical and financial
professionals for its expanding Energy Development group.
Successful candidates will be part of a team responsible for
developing and managing customized energy solution and presentation
data for clients. Position requirements include:
B.S. in Engineering; MBA a plus.
Three to five years' related experience
Knowledge of:
On-Site Power generation
Energy systems and services
Engineering economics and financial analysis
Motivated to implement technical solutions for customer energy needs.
Strong team player
The position is located in the Hartford, CT office of our
Resource Management Divisions. Some travel is required.
Customer service experience, and strong computer and written
communication skills a must.
ERI Services offers and excellent salary, medical benefits, 401(k)
and 100% tuition reimbursement programs. Qualified candidates
should forward resume and salary history to:
EQUITABLE RESOURCES, INC.
HUMAN RESOURCES DEPARTMENT
420 BOULEVARD OF THE ALLIES
PITTSBURGH, PA 15219
We are and equal opportunity employer.
Subject: Publishing Scholarly Work on the Web -- opinion anyone?
From: "N. Gat"
Date: Tue, 10 Sep 1996 23:03:07 -0700
Subject: Publishing Scholarly Work on the Web -- opinion anyone?
I'd appreciate any pro and con arguments on the subject of this letter.
Since this matter touches upon all the sci.*, many comp.* and other
newsgroups, I'll try to cross post this message.
The TechExpo Web site would like to open up a ScienceExpo section
dedicated to the publication of scholarly works in HTML format (TechExpo
already provides an array of services to the science & technology
community; see http://www.techexpo.com).
THE RATIONALE IS AS FOLLOWS:
1) The peer-review process of scientific journals may take from many
months to over a year.
2) The review process is often arbitrary in nature.
3) The access to the work is limited because many libraries do not carry
the journal, or it is too expensive for an individual subscription
4) A journal in any field carries work that is much broader than that of
individual researcher or engineer so important papers are often obscured
because they do not quite belong in any particular journal.
5) Because of the multi-disciplinary nature of technology and science,
some topic have applicability in more than one field, and no journal or
conference may cover such broad fields.
6) Papers posted at ScienceExpo will be searchable not only by key
words, but the author will be able to select any number of applicability
categories from a list of over 400 existing categories (see the TechExpo
classification schedule).
7) papers will be searchable via all the Web search engines.
8) The author can still submit the posted paper to refereed journals.
PUBLICATIONS AT ScienceExpo WILL:
a) Appear within 48 hours of submittal
b) The paper will be immediately available to the entire community
c) The paper will indexed and could be found by all researchers via the
Internet search engines, or internal ScienceExpo search tools (using any
keyword, author name, institution name, etc.)
d) The author can select any number of fields of science and technology
form a list of over 400 (see TechExpo Classification Schedule) to reach
the target audience much broader than any one journal can
e) Authors can hot-link all references directly from their paper
f) On-line discussion of papers can be conducted within the appropriate
UseNet groups
g) Papers may be copies and printed or forwarded to others
electronically or by other means.
SOME PROPOSED GROUND RULES:
(A) Work submitted must be of original nature and of value to science or
technology
(B) The paper must carry the full names of the authors and institution,
including address, phone number, fax, and e-mail.
(C) Ethical conduct: Papers posted at ScienceExpo should be treated as
any other publication. They represent the scientific work of colleagues
and should be treated as such. If information is quoted, the proper
reference should be given credit.
(D) When copying, forwarding, etc., the entire paper, including the
authors information, institution, as well as the ScienceExpo source
should be included.
Obviously ScienceExpo will not referee papers; the authors' names and
the institution they represent are put on the line -- so posting papers
ON-LINE should be given as much or more care and thought as submitting a
paper to prestigious journals
A FEW TECHNICALITIES:
(i) The entire paper must be submitted in HTML, and graphs, figures and
charts in gif or jpg format (this is a deviation from common formats
requiring PostScript or TEX, to allow viewing papers using the
newsreader built into popular browsers, and to allow indexing such
papers by all the Web search engines)
(ii) Maximum size for text files and graphics will have to be observed
(iii) Equation should be edited using the HTML specifications, or
scanned and pasted as graphics files
(iv) It is the author's responsibility to secure authorization of the
institution and/or the research funding authority to submit the
publication.
Finally here is the most sticky point. If the service if totally free
of charge, I'm concerned there will be a deluge of frivolous
publishing. I consider a fee structure to act as a "potential
Barrier." A low, yet significant fee (hopefully) will discourage the
unwarranted publications, but will not be too high to discourage worthy
publications. Perhaps academic institutions will receive a discount,
but corporations will pay somewhat higher fee also to defray the costs
of the service.
So one question is whether a fee imposed on publication will completely
stifle interest? Is for example, a one-time publication fee of $400 for
a corporation, and $100 for academia too high a fee?
One more comment as to why should TechExpo do this. In my opinion
technical societies (and I belong to a few) could do the job but the
problem of cross discipline relevance will not be solved. So being
unaffiliated with any technical society or technical magazine, TechExpo
is a neutral ground most appropriate for this job. What's more,
TechExpo is already providing technology and science information for
almost two years.
Is this idea totally freakish?
Well, the floor is now open for debate.
Private communications are welcomed but posted comments/debate is
preferred.
Nahum Gat, Ph.D.
President
Opto-Knowledge Systems, Inc. (OKSI)
Web: http://www.techexpo.com/WWW/opto-knowledge
E-mail: oksi@cerfnet.com
or
nahum@techexpo.com
Subject: Re: QUES:PLEASE HELP:Model for cracking whip
From: David Kastrup
Date: 11 Sep 1996 11:11:02 +0200
Michael White writes:
> M.E. Moore wrote:
> > Vincent R. Johns wrote:
> > > I believe that baseball
> > > pitchers can throw balls at more than 10% of the speed of sound
> > > (i.e., their hands presumably move that fast at some point), so it
> > > seems not unreasonable that the end of a whip can move far faster
> > > than that.
> >
> > I think that TOP speed for a baseball is about 120 mph.
Which *is* more than 10% of the speed of sound last time I checked.
>
> Actually it is less than 120 mph. I suspect you are recalling the
> April fools story that Sports Illustrated did in back sometime between
> '84-'87 that reported the Mets getting some "natural pitcher" that could
> throw a fastball at ~120 mph (he had mastered the "art of the pitch").
> I think the current record is something like 109-112 mph (and I think it
> is held by Nolan Ryan... I'm sure someone can correct me here). The
> record for a tennis serve (in the US Open) is something like 137 mph (by
> Sampras). This is quite about less than the speed of sound (~774 mph).
Still looks to me like more than 10% of the speed of sound. Anyway,
tennis is *irrelevant*. This post was about whether it is possible for
the tip of a whip to travel faster than the speed of sound, and the
baseball comparison was supposed to show that you can let your hand
travel at more than 10% of that, and so with the leverage the whip
gives this could well support the theory. In tennis you are
a) using the racket as a cheating lever moving faster than your hand
b) transferring impulse to the tennis ball in an elastic way, making
it possible for the tennis ball to depart at a faster rate than the
racket was moving before hitting the ball (don't know whether this
happens, but it certainly is possible).
In baseball, you have no elastic interactions or levers of that kind,
and so we can indeed induce about hand speed pretty correctly.
--
David Kastrup Institut fuer Neuroinformatik, Ruhr-Universitaet Bochum
Email: dak@neuroinformatik.ruhr-uni-bochum.de Telephon: +49-234-700-5570
Subject: Re: FEA: Modelling Bolt Holes
From: Paul Kurowski
Date: Tue, 10 Sep 1996 18:10:17 -0400
71531.3213@compuserve.com wrote:
>
> I am currently using MCS/Nastran and have had to analyse a few models which included bolted joints.
>
> I have tried hexagonal holes at the diameter of the bolt body, with rigis elements jointing
adjacent "bolted" nodes,
> but the localized stresses look to be unrealistic. So I tried an outer hexagonal ring to
match the bolt's head diameter,
> with rigid elements (again high stresses) and then beam elements (better) jointing at the outer
ring, with the inner ring
> left dangling. I have also had problems with adjacent plate structures passing through each
other based on the
> external loading consditions, and laid in some compressive-gap type elements to shore things up.
>
> Am I nuts, or what? Is there a simpler (yet still effective) way to model bolted joints? Is
there a range of
> approaches applicable for the class of problem (shear loading, slip critical, tension only,
bolting flanges, and
> so on....
>
> Anxiously awaiting a reply...
> Steve Sywak
If you model a node to node connection, then you
model a point support which constitutes a
singularity in your model. Your displacements will
then depend on mesh size and/or p-order of your
elements rather than on properties of your
structure. With mesh refinemnt, your displacements
will converge to infinity. If you give me your fax
# I'll fax you a related example from StressCheck
manual.
If you really want to model bolt joints, model them
as features of final shape, not points.
Paul Kurowski
kurowska@julina.uwo.ca
Subject: Publishing Scholarly Work on the Web -- opinions?
From: "N. Gat"
Date: Tue, 10 Sep 1996 22:55:56 -0700
Subject: Publishing Scholarly Work on the Web -- opinions?
I'd appreciate any pro and con arguments on the subject of this letter.
Since this matter touches upon all the sci.*, many comp.* and other
newsgroups, I'll try to cross post this message.
The TechExpo Web site would like to open up a ScienceExpo section
dedicated to the publication of scholarly works in HTML format (TechExpo
already provides an array of services to the science & technology
community; see http://www.techexpo.com).
THE RATIONALE IS AS FOLLOWS:
1) The peer-review process of scientific journals may take from many
months to over a year.
2) The review process is often arbitrary in nature.
3) The access to the work is limited because many libraries do not carry
the journal, or it is too expensive for an individual subscription
4) A journal in any field carries work that is much broader than that of
individual researcher or engineer so important papers are often obscured
because they do not quite belong in any particular journal.
5) Because of the multi-disciplinary nature of technology and science,
some topic have applicability in more than one field, and no journal or
conference may cover such broad fields.
6) Papers posted at ScienceExpo will be searchable not only by key
words, but the author will be able to select any number of applicability
categories from a list of over 400 existing categories (see the TechExpo
classification schedule).
7) papers will be searchable via all the Web search engines.
8) The author can still submit the posted paper to refereed journals.
PUBLICATIONS AT ScienceExpo WILL:
a) Appear within 48 hours of submittal
b) The paper will be immediately available to the entire community
c) The paper will indexed and could be found by all researchers via the
Internet search engines, or internal ScienceExpo search tools (using any
keyword, author name, institution name, etc.)
d) The author can select any number of fields of science and technology
form a list of over 400 (see TechExpo Classification Schedule) to reach
the target audience much broader than any one journal can
e) Authors can hot-link all references directly from their paper
f) On-line discussion of papers can be conducted within the appropriate
UseNet groups
g) Papers may be copies and printed or forwarded to others
electronically or by other means.
SOME PROPOSED GROUND RULES:
(A) Work submitted must be of original nature and of value to science or
technology
(B) The paper must carry the full names of the authors and institution,
including address, phone number, fax, and e-mail.
(C) Ethical conduct: Papers posted at ScienceExpo should be treated as
any other publication. They represent the scientific work of colleagues
and should be treated as such. If information is quoted, the proper
reference should be given credit.
(D) When copying, forwarding, etc., the entire paper, including the
authors information, institution, as well as the ScienceExpo source
should be included.
Obviously ScienceExpo will not referee papers; the authors' names and
the institution they represent are put on the line -- so posting papers
ON-LINE should be given as much or more care and thought as submitting a
paper to prestigious journals
A FEW TECHNICALITIES:
(i) The entire paper must be submitted in HTML, and graphs, figures and
charts in gif or jpg format (this is a deviation from common formats
requiring PostScript or TEX, to allow viewing papers using the
newsreader built into popular browsers, and to allow indexing such
papers by all the Web search engines)
(ii) Maximum size for text files and graphics will have to be observed
(iii) Equation should be edited using the HTML specifications, or
scanned and pasted as graphics files
(iv) It is the author's responsibility to secure authorization of the
institution and/or the research funding authority to submit the
publication.
Finally here is the most sticky point. If the service if totally free
of charge, I'm concerned there will be a deluge of frivolous
publishing. I consider a fee structure to act as a "potential
Barrier." A low, yet significant fee (hopefully) will discourage the
unwarranted publications, but will not be too high to discourage worthy
publications. Perhaps academic institutions will receive a discount,
but corporations will pay somewhat higher fee also to defray the costs
of the service.
So one question is whether a fee imposed on publication will completely
stifle interest? Is for example, a one-time publication fee of $400 for
a corporation, and $100 for academia too high a fee?
One more comment as to why should TechExpo do this. In my opinion
technical societies (and I belong to a few) could do the job but the
problem of cross discipline relevance will not be solved. So being
unaffiliated with any technical society or technical magazine, TechExpo
is a neutral ground most appropriate for this job. What's more,
TechExpo is already providing technology and science information for
almost two years.
Is this idea totally freakish?
Well, the floor is now open for debate.
Private communications are welcomed but posted comments/debate is
preferred.
Nahum Gat, Ph.D.
President
Opto-Knowledge Systems, Inc. (OKSI)
Web: http://www.techexpo.com/WWW/opto-knowledge
E-mail: oksi@cerfnet.com
or
nahum@techexpo.com
Subject: Re: Publishing Scholarly Work on the Web -- opinion anyone?
From: mbrigham@usgs.gov (Mark Brigham)
Date: 11 Sep 1996 14:38:36 GMT
I urge those interested in this topic to get ahold of William Glaze's editorial
in the July issue of Enivronmental Science and Technology (v. 30, p. 273A-274A).
--
Mark E. Brigham, Environmental Engineer -- email: mbrigham@usgs.gov
U. S. Geological Survey, 2280 Woodale Drive, Mounds View, MN 55112-0049
WWW: http://wwwmn.cr.usgs.gov/