iMechanica - Blog entry - Comments

How do we find the GLOBAL

nitinchandola — Sun, 12 Feb 2012 09:50:34 -0500

How do we find the GLOBAL ID'S to be coded in to the Multi point constraint user subroutine from the Assembly ID?

contact problem in abaqus

sf_solmaz — Sun, 12 Feb 2012 09:14:57 -0500

hi weidongli

Did you solve your problem?I encountered to this problem as well.

I look forward to hear from you.

thank you.

Re: Know about Phd Admission

Zhigang Suo — Sun, 12 Feb 2012 08:39:11 -0500

Information about application to Harvard School of Engineering and Applied Sciences is available online.

Know about Phd Admission

bhupendra — Sun, 12 Feb 2012 07:30:45 -0500

Hello Zhigang Suo,

I want to know what is the procedure for getting admission for Phd as i am from India its asian country, I Have Master of Technology Degree in Machine Design, and i have interest on Solid Mechanics, Fracture Mechanics, and in Viberation.

Is there any need of TOFEL or GRE score card?

Shoult we trust for example large EU consortia?

Mike Ciavarella — Sun, 12 Feb 2012 05:52:02 -0500

As you know, AIRBUS is a big consortium, and the location of where to build parts, is decided mainly by politicians, with theresult that there are interestingly difficult transportation costs which per se make it interesting, but weird project.

Some people criticize this as a weakness of europe not being really united, but on the other hand, such companies as AIRBUS and BOEING are global these days, so we cannot argue too much.

Similarly, the EU funds huge networks of research, which also have been criticized to be decided politically, with top - down approach, to be elephantiac, and to produce very little.

One such example is FITNET Thematic Network (TN) has worked together with 62 experts from 16

European countries and 41 organisations. Additionally, experts from Japan, USA,
Korea and Norway have provided in-kind contributions to the development of
FITNET FFS Procedure. This network has smoothly operated fro 4,5 years
under the guidance of project coordinator (GKSS, M. Kocak) and FITNET
Management Committee (represented by project contractor partners (GKSSGermany,
JRC-Belgium, VTT-Finland, TWI-UK, University Cantabria-Spain,
CESI-Italy, CORUS-UK, CAT-France, BE-UK, SHELL-The Netherlands).
Acronyms and countries of the FITNET members are:
IWT-Germany, BZF-Hungary, CSM-Italy, HSE-UK, ALSTOM-UK, FhG/IWMGermany,
UMFS-, SCK/CEN-Belgium, ADVANTICA-UK, CRF-Italy, CEIT-Spain,
FORCE-Denmark, RUG-Belgium, INNOSPEXION, KUT-Poland, ROLLSROYCE-
UK, DNV-Sweden, TUD-Germany, IIS-Italy, MPA-Germany, University

of Aveiro-Portugal, University of Maribor, Slovenia, SKODA-Czech Republic,
BUREAU VERITAS-France, CETIM-France, DLR-Germany, NPL-UK, IdSFrance,
EMPA-Switzerland, EPFL-Switzerland, HITACHI-Japan, Osaka
University-Japan, Korea University-Korea, BATELLE-USA, Norwegian University
of Sci.-Norway.

The FITNET FFS Procedure covers four major failure modes, namely fracture,
fatigue, creep and corrosion and their all aspects essential for advanced design
and safety in all industrial sectors. The FITNET FFS Procedure aims to include
most recent advances in structural integrity assessment while providing fully
validated methodologies, assessment routes including well selected case studies
or worked examples for determining the FFS of various structures and welded
components manufactured from metallic materials.

To support this initiative, FITNET TN embraces the results obtained in EC-funded
projects such as SINTAP, ASPOW; HIDA, DISMEW, INTEGRITY, PLAN,
VOCALIST, JOTSUP, WAFS, IDA, WEL-AIR as well as IST Project from Japan.
It also includes the recent advances in international, national standards as well
as industrial codes such as API 579, BS 7910, R5/R6.

FITNET TN aimed also to provide the technical and industrial focal point for the
definition of any future R&D projects which may be required to address specific
structural integrity & damage tolerance analysis aspects of the power generation
and petro-chemical plants, offshore, pipelines, aerospace, transport/railway and
civil engineering structures etc. as well as for demonstration projects to realise
and distribute a prototype software products.

The final report is here . How much should we trust these HUGE excercises? They seem more difficult to run than building the plane itself !!

Have a look anyway, in order to discuss to

and

Revision MK8 of the procedure is now available: click here for an outline of Vol I, click here for an outline of Vol II.
If you would like to comment on any aspect of the MK8 document, click here.
The final report to the European Commission is also available (click here - pdf 5,872kB.

Michele Ciavarella, Politecnico di BARI - Italy, Rector's delegate.
http://poliba.academia.edu/micheleciavarella

An email to David D Dill, an expert in ranking and "market"

Mike Ciavarella — Sun, 12 Feb 2012 05:19:56 -0500

Dear David D Dill,

I have seen you have a number of
interesting papers on comparing university rankings, and also on the
issue whether "market competition" can improve academic question (see
the link below). The question is now how in italy, and I am discussing
this within my groups, which you see in CC. I do not have access to all
PDF of your papers, unfortunately. There is a proposal of the
government which apparently looks like "liberalization" in the spirit of
the Monti government .. but in Italy this will most likely result in
tax increase of students (which are in proportion high as in US) made
also by two economists (Andrea Ichino e Daniele Terlizzese....), whereas
the entire idea of "privatizing" universities comes from other
Economists from Bocconi University (where Monti is also honorary
president), such as Francesco Giavazzi, and Alberto Alesina who is in
Harvard.

However, all this question is badly posed in Italy, as these authors
fail or make it look like "privatization" of Universities would be
good. As you recognize in your paper, I see that this mostly hides
ideas to make more profit, and less students . Also, it fails to
recognize that US universities have large endowments from private donors
(each large university in US has endowment larger than the TOTAL state
spending in Italy of 7 billions). You can find some of this discussion,
at the Harvard blog
http://www.imechanica.org/node/11871

The
people in the CC are a group of about 200 Humboldtians, and a group of
"non virtuous", people in Universities which the governments says are
non virtuous i.e. they are poor! These people are further
discriminated in recruitment. This includes my University Politecnico di
BARI, which according to SCIMAGO is the best public university in
Italy, but according to government funding, is "non virtuous", and will
get more and more cuts.

I wonder if you could help us a little

1) sending PDF of your papers
2) partecipating on this discussion here and in the google groups
3) even much better, discussing on imechanica
4)
help me or point me to a paper about comparing ranking of academias,
since I find that the italian funding in Italy is allocated in a very
strange fashion, and would like to demonstrate this more rigoroulsy. I
have the excel files for Italian Universities funding, so if you have
excel files for their positions in the different rankings, it would be
easy to find a correlation. And maybe even write an interesting paper!

Thanks in advance.
Michele Ciavarella

Quality Assurance In Higher Education

Higher Education Dynamics, 2007, Volume 20, Part I, 47-72, DOI: 10.1007/978-1-4020-6012-0_2

Will Market Competition Assure Academic Quality? An Analysis of the UK and US Experience

David Dill

Abstract

A major change that has accompanied the worldwide
‘massification’ of higher education is the new-found openness of policy
makers to the use of competitive markets to steer the
university sector. In many countries efforts to improve the quality
of publicly provided higher education, both in teaching and in
research, are leading to experiments with market-based policy
instruments (Teixeira et al. 2004). The perceived quality of
universities in the competitive US system – which Trow (2000)
has termed the ‘American advantage’ – has inspired much of this
interest in market forces. While a number of these market
experiments may also be motivated by a desire to restrict
public expenditures in rapidly expanding systems of higher education,
many policy makers and academics believe that there is a
relationship between the degree of market competition and academic
quality (Dill 2005).

Michele Ciavarella, Politecnico di BARI - Italy, Rector's delegate.
http://poliba.academia.edu/micheleciavarella

I am suggesting to treat this problem with FFEMS or ESIS etc

Mike Ciavarella — Sun, 12 Feb 2012 03:48:33 -0500

dear Friends

being in the board of FFEMS, I am suggesting the Editor, Prof. Eann Patterson, to perhaps approach this problem. This was the letter I sent them yesterday.

Mike

Dear FFEMS board members,

I suggest we should take the initiative to look, perhaps in a joint effort as BOARD,
to the A380 worldwide panic about cracks. I have in the mean time
written something of a even too personal perspective on the imechanica
Harvard blog. cracks in A380? Every plane now in the air is an experiment by itself...

You may have heard of Qantas Airways and Korean Air will carry out inspections for wing cracks on their Airbus A380 superjumbo planes earlier than previously scheduled, after European air safety officials ordered global checks, warning of a safety risk if the defects were not fixed.

I would suggest we all give it a look and perhaps join
forces to raise the debate, both as it is instructive to the public, to
the general audience of students in the Harvard blog, and perhaps also
to the journal, as we can introduce ourselves as members of the board. However, I think a common line of action every time we communicate (as we registered also "FFEMS BOARD" in the Imechanica blog is a little too difficult to do. But it is up to Eann to decide even this possibility.

I could try to approach Jaap Scijve yes, as I am doing already with
this email, in case he reads us. I could also contact Schwalbe as
editor of EngFractMechanics, in case the board of FFEMS does not like or
pursue the idea. In fact, so far we are only two to explicitely like
the idea, and we need a lot more to go forward. Perhaps Eann should
take the lead here, suggest how this would work ---

1) a special issue of FFEMS idea? In that case, we need guest editor,
and list of potential authors to invite, including relevant people from
industry (I could try to approach some AIRBUS)

2) a FFEMS "task force" just to write a paper on the subject --- my idea
mainly, as in the http://imechanica.org/node/11898 blog, that every
major innovation brings new problems of fatigue
which in truth we can only expect to very limited extent, as we are
mainly extrapolating. I am particularly worried, for example, of size
effect, when the matter is A380. All the data they use for design,
based on NASA tables of the '60s, are certainly based on materials,
size, and type of vehicles completely different. However, the latest I
heard from them, they wanted to find something LESS conservative for
their A300 who return after 20 years of service with no cracks. I am
sure they will STOP this ideas to find something LESS conservative for
A380 now, and actually maybe they want to know what is going on. Maybe
just manufacturing, or overload with respect to mission loading?

3) I am not familiar with all the procedures. Safe life is not an
approach today. Damage tolerance could be, but I doubt about HCF we
understand enough. Fail safe is a good idea, but if something like a
Japanese disaster
http://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_and_tsunami
occurs, say here we had a turbulence which is outside all possible
spectra? Should we say we induced cracks that we did not predict, but
those are within our analysis, IF ONLY WE USED a better spectrum? And
how to reevaluate all this?

Sorry for long email. Obviously I cannot write more, you should
consider this Email as part of my proposal to the Board, which perhaps I
will even add openly on imechanica.org as it contains possibly
interesting elements of technical discussion.

But we need more people to agree to work on it!

Regards
Mike

1) Prefer C++ and

wallstedt — Sun, 12 Feb 2012 01:26:44 -0500

1) Prefer C++ and Python

2) Prefer a style that defers design decisions and allows me (or others) to change my mind -- some would call it object-oriented

3) Although it has conveniences for matrix operations, Fortran is a real problem as codes get larger; it does not scale well to large instruction sets, IMO. Many smart people will disagree with that though.

tsai wu failure criteria in ANSYS

yashidanadir — Sat, 11 Feb 2012 08:31:59 -0500

dear friends, i want to know how to get the tsai -wu failure criteria for orthotropic material in ANSYS.after modelling and giving the material properties ,should i give anything special to activate this option ,or will i get automatically this criteria for all the elements from the output file itself.

please help me as my research work couldnt able to proceed.

my mail id is

yashidanadir@gmail.com

Biswajit, interesting comments. But why parochial?

Mike Ciavarella — Sat, 11 Feb 2012 05:28:51 -0500

Do you mean parochial in the sense that we involved too much the Church, whereas this is not appropriate?

Or parochial as provincial?

In either cases, there is margin to suggest that the problem does involve the Church in Italy, and is really provincial in the way we discuss normally in Italy, this is why I was trying to share experience with other people here, coming from other parts of the world.

You come from India? How is India university working? How is it ranked? How is funded? How do they ensure not to recruit by nepotism, and to recruit and mantain only the best?

Michele Ciavarella, Politecnico di BARI - Italy, Rector's delegate.
http://poliba.academia.edu/micheleciavarella

Meritocratic criteria

Alan R. S. Ponter — Sat, 11 Feb 2012 05:16:18 -0500

Despite knowing the criteria used you still believe that the opinion of a few individuals have an influence on individual Universities. This implies the system may not be as transparent as it should be as, politically, such considerations should not arise.If the UK Universities have any advantage in the present troubled times, it is that our system of funding allocation is well understood. There is a basis for constructive discussion about principles without having to involve issues of individuals. If anything, one of the problems in the UK system is that Ministers for Higher Education come and go at an alarming rate. But government generally regards UK Higher Education as something of a success story as it has proven to be adaptable and robust. The National Health Service is quite enough for them to worry about.

I rather disparagingly referred to the issues we are currently discussing as the worries of the middle-aged. If you are an academic you just have to accept that life is not necessarily fair. Sometimes things go your way and sometimes they don't. You can rail against the incompetence of government, rectors or heads of department ,but, at the end of the day, you can protest but you then just have to put up with it and go down to the lecture theatre, the laboratory or the research group office and get on with the job - where the real action lies. Whether you University is in the top ten in the world or lies around the 500 mark in 20 years time will depend as much, if not more, on your conversations with your research student tomorrow as anything else. That was what my polemic was about.

No, I was not disparaging Italian Universities. Looking at your list of Universities with the largest reduction in funding I am quite dismayed to see the University of Palermo at the bottom. In my own field they have been energetic, imaginative and highly professional. Of those really good young academics from Italy that I mention, some of them have been from Palermo.Yes, you have inherent difficulties. The allocation of resources for new posts is bazaar. The independence of UK universities allows us to have rolling programs of staff recruitment that allows long term planning. You examination system is unique and I've always rather admired it although it is time consuming. Student/staff discussion at critical points is vital for both student and staff. I once sat in on such exams at Milan Polytechnic and was very impressed. We have a strong tutorial system which perhaps compensates for the rather formal examination system and visiting Erasmus students like our informal open door attitude to students. As I said I have the impression that our subject attracts good students in Italy and they are well taught. The question was: why am I not conscious of Italian names amongst those associated with major developments in my subject, or am I out of date? I want you to tell me I'm mistaken.

I remember you inviting me to one of your national conferences, held in Sardinia. The date is fixed in my mind as it was a day after 9/11. My impression was the following. The standard was high, particularly papers about projects with a strong industrial input or a pan-European element. There was an air of studious professionalism. Contributors knew their stuff and how to present it. There were a larger number of female contributors than you would find in the UK. Much of it was highly professional work carried out within known, often advanced, techniques. You were all pleased to see each other and the atmosphere was very pleasant. I remember a highly entertaining discussion on the quality of pasta during the conference dinner. But if I looked for highly original work it was harder to find. There was a really impressive talk about the design of artificial heart valves with difficult modelling problems but this was carried out in co-operation with a UK university, whose main expertise was ductile fracture mechanics. This is probably how you are seen by your government - as a vital part of the education - industrial complex and you do that well. Government never says to you - "go out and do something startlingly new which will make you all famous in 20 years time". But it is innovation which puts you up the world ranking. There is more than one interpretation of a "virtuous" university. Trying to work out what a transitory government minister means by it may be a waste of time.

As Jose rightly says, the English language is an enormous advantage to the UK. In our subject and mathematics, many, if not most, of our graduates have gone into the service industry during the last 20 years to the higher salaries in the City of London, the insurance and banking industries. That tendancy has dramatically reversed in recent times.

We have kept going in engineering by the ability to recruit overseas students at full cost fees where the actual cost is the marginal cost. The staff at Leicester includes people from Italy, Brazil, Spain and several from China. In mathematics, student numbers have traditionally been fairly constant although the subject has attracted increasing numbers of female students. But the staff have come from all over the world. To some extent this has always been a factor. As an undergraduate understanding the accents of our Maths lecturers was sometimes as difficult as understanding the material itself. But in recent years Maths departments in the UK have recruited particularly well from Russia and Germany. The Maths Department at Bath University, one of the strongest in the country, has a significant proportion of German academics and at Leicester it's Russian. This gives us a flexibility which you lack for reasons of language.

We live in difficult times where much can be lost but some of the best work in our subject has been done in the most disadvantaged conditions. Think of Poland during the the post war period. We don't have real problems.

Xose and Alan, do you know of this Andrew Oswald paper?

Mike Ciavarella — Sat, 11 Feb 2012 04:59:03 -0500

As you yoursef pointed out, different rankings can differ.

But the risk that in UK some patters are vaguely similar to those in Italy, mainly the shift of really top research as measured by Nobel Prize, is real.

Read this please first .

Let us use reliable data to try to discern the truth. In the last 20
years, Oxford has won no Nobel Prizes. (Nor has Warwick.) Cambridge has
done only slightly better. Stanford University in the United States,
purportedly number 19 in the world, garnered three times as many Nobel
Prizes over the past two decades as the universities of Oxford and
Cambridge did combined. Worryingly, this period since the mid 1980s
coincides precisely with the span over which UK universities have had to
go through government Research Assessment Exercises (RAEs).

Very interesting!

And very similar to my conclusion when I interviewed to the former President of Italian Constitutional Court.

See here . I can add a quick translation, sorry if it is not perfect, but mostly google translate, of our public conversation....There is video to witness the words.

MICHELE CIAVARELLA ASKS GUSTAVO ZAGREBELSKY

I wanted to ask a question on "Universities and the Constitution." From
what I understand it is not written on the Constitution that the
University should be public, whereas there is compulsory education. The university I think it is not right guaranteed by the Constitution that should be public.

However,
over many centuries the Italian University has been mostly Public and until at least the 80s (last century), has always been growing, has always been centralized under a Ministry. It
became autonomous (Reform Ruberti, interpreting Article .33
Constitution), and lately, on the basis of this autonomy, the
funding comes from the University is no longer based on "time series",
but there are parts of so-called "meritocratic"
criteria for "merit" of which there was gradually more and more
critical and rebellion by several authoritative sources.
(Also because it defined a posteriori, always changing, and easily subject to manipulation in a context devoid of ethics, ed)

Lately
it has reached a very strong fight, which I think will lead to the
abolition of the legal value of the qualification and, in particular, 3
of 4 State Universities in Puglia are now being underfunded by the Ministry
MIUR with the clear goal of depleting the resources, although they are also great tradition of great universities.

Now,
in everything, including the establishment of discrimination between
people who are taken in these universities and are now presumed innocent
with respect to such collective guilt of those universities.

I
think there are various profiles of Unconstitutionality in this
process, which actually takes the attitudes of pure political propaganda
if, for example. the
last government in the last letter he wrote to Europe (one in 39
points, ed), that the time series of the funding will go (within 5-7
years) to zero! How
does one go to zero when there are open-ended contracts having to be
paid (and even weigh about 90% of funding, other than zero)?

So,
I mean, on a philosophical level, you believe that the Constitution
protects and preserves a degree of Post University also well distributed
within the country? It
's possible that a whole region can be attached and then depleted with
implications on the general "Virtuosity" of the country, the "rating" of
the country, that fact is not "Virtuoso" at the moment? Thank you.

Min.23.22

PRESIDENT OF CONSTITUTIONAL COURT GUSTAVO ZAGREBELSKY RESPONDS. Min.27.00

Distinguished
Professor (Ciavarella is surprised and mocks, and Zagrebelsky asked him
if he does so for calling him a "Distinguished"),

I have since left the C.Costituzionale I never said anything specific about matters that may then get to C.Costituzionale.

The
"ethics of the former Head" should be not to do from outside the "Jiminy
Cricket" (the retired President should not try to put pressure on the present President): I remember that was bothering me that when someone did.

But I can only say one thing. That
the way in which we deal with the problems of Education is
unfortunately a "business-oriented" and this is a betrayal of the deepest
vocation of education especially higher studies.

Because
then when you do the ratings (between University, ed) you go to see
"Productivity," the report members / graduates, the rate of absorption
of graduates into the workforce, the local production.

And
'the continuation of the "logic of three": "Enterprise, Internet,
English," launched this logic by previous governments for the Middle
School, but now is spreading to the University. (Reference to Berlusconi electoral Campaign).

If you think about all this with the "Culture" has almost nothing to do.

These
"three" and what is shaping up (see what happens with the University),
what happened, places, places, problems in the logic of Education
e-cu-if-you-go, the "three "indicate a formation as executive, but the culture is different.

Beyond
the issues of Constitutionality I think we should also have the pride
to say that the University can not be reduced to a thing like that.

Support
which then further urges our responsibility because we cut down the
speeches today, abbatono proposals today, and we are also culled, have
fertile ground in what: to the extent of the inefficiency of which we
all must take responsibility, we are not innocent.

I'm retired now, so I was not blameless either.

NOW IN ITALIAN

Io volevo fare una domanda su “Università e Costituzione”. Da quello che mi risulta non è scritto sulla Costituzione che l’Università debba essere pubblica, mentre invece c’è la scuola dell’obbligo. L’Università che io sappia non è proprio garantito dalla Costituzione che debba essere Pubblica.

Tuttavia, nel corso di molti secoli l’Università italiana di fondo è stata Pubblica e fino ad un certo punto, si è molto espansa. Fino almeno agli anni ’80 (del secolo scorso), è sempre andata crescendo, è stata sempre centralizzata sotto un Ministero. Poi è diventata Autonoma (Riforma Ruberti, interpretando l'art.33 Costituzione, ndr), e ultimamente, sulla base di questa Autonomia, il finanziamento che arriva all’Università non è più basato su “serie storiche”, ma ci sono parti cosiddette “meritocratiche”, per criteri “meritocratici” su cui vi è stata via via sempre più critica e più ribellione da parte di varie autorevoli fonti.
(anche perchè definiti a posteriori, sempre mutevoli, e facilmente aggirabili in un contesto privo di etica, ndr)

Ultimamente si è raggiunto uno scontro davvero forte, che penso porterà alla abolizione del valore legale del titolo di studio e in particolare, 3 Università Statali su 4 in Puglia sono oggi oggetto di obiettivo sottofinanziamento da parte del MIUT con l’obiettivo chiaro di depauperare di risorse, nonostante siano anche grandi Università di grande Tradizione.

Ora, in tutto ciò, creando anche delle discriminazioni tra persone che sono assunte in queste Università e quindi sono oggi incolpevoli rispetto a tali presunte colpe collettive di tali Università.

Io credo che ci siano vari profili di Incostituzionalità in questo processo, che addirittura assume degli atteggiamenti di pura propaganda politica quando per es. l’ultimo Governo ha scritto nell’ultima lettera all’Europa (quella in 39 punti, ndr), che la parte serie storiche del finanziamento andrà (entro 5-7 anni) a zero! Come si fa ad andare a zero quando ci sono dei contratti a tempo indeterminato da dover essere pagati (e che pesano persino per circa il 90% del finanziamento, altro che zero!)?

Quindi, volevo dire, a livello filosofico, Lei ritiene che la Costituzione preservi e protegga un certo grado di Università Pubblica anche ben distribuito nell’ambito del Paese? E’ possibile che una Regione intera possa essere attaccata e depauperata con risvolti poi generali sulla “Virtuosità” del Paese, del “rating” del Paese, che infatti non è “Virtuoso” al momento? Grazie. Min.23.22

GUSTAVO ZAGREBELSKY RISPONDE. Min.27.00

Illustre Professore (Ciavarella si sorprende e schernisce, e Zagrebelsky gli domanda se lo fa per la per averlo chiamato “Illustre”),

io da quando sono uscito dalla C.Costituzionale non ho mai detto nulla di preciso su questioni che possano poi arrivare alla C.Costituzionale.

La “deontologia dell’ex” dovrebbe essere quella di non fare da fuori il “grillo parlante”: ricordo che dava fastidio a me questo quando qualcuno lo faceva.

Però posso solo dire una cosa. Che il modo con cui si affrontano i problemi dell’Istruzione è purtroppo un modo aziendalistico e questo è un tradimento profondo della vocazione degli studi di Istruzione soprattutto quelli superiori.

Perché poi quando si fanno le graduatorie (tra Università, ndr) si va a vedere la “Produttività”, il rapporto iscritti / laureati, il tasso di assorbimento dei laureati nella forza lavoro, nel tessuto produttivo locale.

E’ la prosecuzione della “logica delle tre i”: “Impresa, Internet, Inglese”, lanciata questa logica da governi precedenti per le Scuole medie, ma che adesso si sta estendendo all’Università.

Se ci riflettete tutto ciò con la “Cultura” non ha quasi nulla a che fare.

Queste “tre i” e ciò che si preannuncia (vediamo cosa succederà con l’Università), ciò che è accaduto, inserisce, colloca, i problemi dell’Istruzione nella logica e-se-cu-ti-va, le “tre i” indicano una formazione di tipo esecutivo, ma la cultura è un’altra cosa.

Aldilà dei problemi di Costituzionalità io credo che dovremmo avere anche l’orgoglio di dire che l’Università non può ridursi ad una cosa di questo genere.

Il chè poi ulteriormente sollecita la nostra responsabilità perché i discorsi che oggi si abbattono, le proposte che oggi si abbatono, e si sono anche abbattute, hanno terreno fertile in che cosa: nei limiti della inefficienza di cui tutti noi dobbiamo farci carico, non siamo incolpevoli.

Io oramai sono in pensione, quindi non sono stato incolpevole nemmeno io.

Michele Ciavarella, Politecnico di BARI - Italy, Rector's delegate.
http://poliba.academia.edu/micheleciavarella

wallster, both and none, ubt the point is another!

Mike Ciavarella — Sat, 11 Feb 2012 02:18:26 -0500

Dear Wallstet

you are referring here to elementary concepts, which drive us in the design. Obviously, rounding corners is usually beneficial, as it relieves the "elastic" stress concentration. Whether it does so with plastic limit, is a lot less obvious, and whether it does so under fatigue, also less obvious. Just imagine one of the classical counterexample of notches being detrimental not being true. In Stephen Fuch's paper, he shows how compressive part of the cycle can induce in the stress concentration certain residual stresses wich are later beneficial.

However, the point is.

1) how to transfer this elementary knowledge to components different in scale, in details of the assembly, under spectrum loading which includes also extreme events like turbolence (of the type of the accident we are talking about). This procedure can be used at design stage, but nobody even dreams of letting a new plane in the market only with this!

2) we also rely, at design stages, on tables of data obtained by, say, NASA, in the 1960's, and we constantly refer to those. But maybe they are too old now? Or maybe we are starting to extrapolate when we are changing the size of the plane? My friends at Airbus lately were concerned that design of A300's (the good one, not the one under attack, A380), return after 10 or 20 years of service, and have LESS cracks than expected, so their life can be prolonged. The worry with A380 is that cracks are emerging too soon!

3) We have always, and only learned by mistakes. Limiting attention to aircraft only (but remember the example I made on railways fatigue,on which by the way we undestand very little even after 200 years...), see wikipedia

Structural failure of the aircraft

Examples of failure of aircraft structures caused by metal fatigue include the De Havilland Comet accidents (1950s) and Aloha Airlines Flight 243 (1988). Now that the subject is better understood, rigorous inspection and nondestructive testing procedures are in place.

Composite materials consist of layers of fibers embedded in a resin matrix. In some cases, especially when subjected to cyclic stress, the layers of the material separate from each other (delaminate) and lose strength. As the failure develops inside the material, nothing is shown on the surface; instrument methods (often ultrasound-based) have to be used to detect such a material failure. In the 1940s several Yakovlev Yak-9s experienced delamination of plywood in their construction.

4) You know the story of Comet? They were using static design with factor of safety 2, and they thought it was more than enough. Later, after 7 accidents, they decided appropriate criteria for fatigue should be taken into account, for the pressurization of the cabin was enough of a cycle of stress, in case of stress concentrations at the windows. Notice that we had had the experience of railyways, but people do not always transfer technology, so the progress is not linear and "monotonous" function...

5) Companies such as Airbus and Boing, not not rely only on design. They want to rely on experience on testing full scale. Tests are done and under various harsch conditions. Yet, no test can cover the entire spectrum of what can happen in life.

So I repeat my question. Can we be near the discovery of something equivalent to when we found out why Comet were falling down one after the other for no apparent good reason?

Michele Ciavarella, Politecnico di BARI - Italy, Rector's delegate.
http://poliba.academia.edu/micheleciavarella

Riks method in ABAQUS

Lihua Jin — Fri, 10 Feb 2012 23:50:00 -0500

In ABAQUS, arc length is defined by the combination of the increments of displacement and load. You can get energy for both stable and unstable solutions (fixed points). I got pretty good results of snap-through instability by using Riks method, and I am able to deal with turning points. You may want to take a look at the following ABAQUS documentation on the implementation of Riks method.

http://mse-license1.mse.drexel.edu:2080/v6.8/books/stm/default.htm?startat=ch02s03ath18.html#stm-anl-modifiedriks

Soft machines: increased functionality and extreme performance

Christoph Keplinger — Fri, 10 Feb 2012 20:14:02 -0500

Thanks everybody for this intriguing discussion! So far the comments on this jClub theme have been focused on theoretical aspects to a large degree. Let me throw in some thoughts from an experimental perspective, mainly in the context of dielectric elastomers.

Without question the utilization of mechanical instabilities comprises a great opportunity to increase the functionality of mechanical systems in general and especially of soft systems, which are far less developed in research and practice. Particularly soft machines with a highly nonlinear response or even with a response structure including instabilities have not found many practical applications yet. They are comparably difficult to control and simulation techniques are less developed. To antagonize the hesitancy of industrial engineers to utilize soft machines with complex behavior we have to collectively highlight the advantages of such systems and design prototypes with extreme performance.

So far in this jClub we have discussed the rapid timescale of instabilities, the possibility to maintain a desired state in a bistable system without expending energy and some other aspects. We should also consider the possibility to trigger events that require relatively large amounts of energy with small signals. If we store mechanical energy in a system and operate it near the verge of instability a small amount of "control" energy may be sufficient to trigger an event that would require a lot of external energy without the utilization of an instability. That aspect may be very useful to build sensors, mechanical triggers or amplifiers. Especially for systems that require two distinctly different mechanical deformation states (such as Braille displays or haptic systems in general that require "on" and "off" states), easily switchable bistable systems will be very useful.

Maybe in our effort to increase the functionality of soft machines by harnessing instabilities we should also look into different fields and draw analogies. In electronics an ohmic resistor effects a linear dependence of electrical current on applied voltage. In contrast, a diode exhibits a highly nonlinear response and particularly a tunnel diode (http://en.wikipedia.org/wiki/Tunnel_diode) even shows a N-shaped correlation between electrical current and voltage. Each of these devices can be used for specific purposes and each modification of the current-voltage characteristics results in an altered functionality of the device. Similarly, we can try to utilize modified versions of the stress-strain, pressure volume, ... characteristics of mechanical systems to span their functionality over as diverse application fields as we have for ohmic resistors and diodes.