Il Bar dell'Ingegneria

Votes taken by texitaliano64

  1. .
    CITAZIONE (afazio @ 11/12/2022, 14:25) 
    Questo è un topic assai interessante.
    Per conto mio ho iniziato a studiare le verifiche di resistenza al fuoco di profilati metallici. La determinazione della curva di riscaldamento risulta piu semplice rispetto a quella di una sezione in c.a.
    Mi propongo di aprire un topic apposito con lapubblicazione di codice in VBA-Excel specifico.

    grazie afazio per l'apprezzamento.
    Caronte potrebbe essere utilmente impiegato per fare l'analisi termica di qualsiasi materiale di cui si conoscano le proprietà termiche, ed anche di conglomerati di materiali, come ad esempio il cemento armato.

    (ps. ho appena caricato un aggiornamento di contour2D, ora renderizza i grafici più velocemente, i link di scarico sono quelli precedentemente segnalati)
  2. .
    Intervista di alcuni anni orsono a Tariel Kapanadze dopo una convincente dimostrazione pubblica del suo dispositivo.
    l'intervista è stata tradotta dal Georgiano in inglese ed è visibile in un vecchio video su YT.
    La trascrizione dei sottotitoli in inglese è la seguente.


    CITAZIONE
    ....

    -Intervistatrice:
    Tell, please to the usual person.
    Here that today you ave shown.
    Why it important and in general what in it new?

    -Tariel Kapanadze:
    The usual person one may say today
    that they have seen the device,
    which can be named the receiver
    of energy from space surrounding us.
    We have seen work of this device.
    This device should only primary energy,
    and then he works on their energy,
    without any help.
    Well, now i do not know how
    one may determine or how to say...
    most important here, that the
    energy problem is solved.
    This device, wich now provides 5 kilowatts
    Takes 40 watt, gives 5000 watt.
    But in principle, it then takes nothing,
    working on its energy.
    It is difficult to name area,
    branch where is impossible to use this device.
    It can be used in electric locomotives.
    Also wires will be not necessary, and on both
    sides post, in the ships, in cars, in planes.
    Also it is possible to dare slightly
    and further to go, but it later on, in the future,
    because this inexhaustible
    energy comes from space.
    Our environement is impregnated by energy.
    The god knows how many it is possible
    to take there from.
    We took the maximum 200 kilowatts.
    But now we can safetly tell, after last experiment,
    when we have received 200 kwt.
    Now we can any quantity energy to take from space.
    All of us saw it, basically.
    Basically we saw all.

    -intervistatrice:
    You speak, that it is possible
    to solve many problems.
    Whether it is possible,
    local the Georgian energy crisis to solve?

    -Tariel Kapanadze:
    Consider that crisis is already solved.
    I have calculated for example if to give...
    basically, if the government...
    I think that they should accept it.
    If will begin this work, a maximum in 2 years
    Georgia will not need any power plant.
    The power station is not necessary
    and the energy will be a lot, moreover also will sell.
    My God how many it will be possible
    to sell i do not know.
    How to tell in Russian...
    It is possible to receive profit in the budget
    not only from this branch, in a 1000 times more.
    And in the country there will be
    no deficiency of the electric power.
    It is possible to use it in difensive area,
    Because have us highland and to mountains
    to submit the electric power difficultly.
    Install this device and all.
    It is not necessary to pull wires, and anything.
    No such branch where this device cannot be used.
    We then...
    Zviad, lift up the accumulator on the table.
    Here it is possible to tell one.
    Here there is at us an accumulator.
    The first power we take from the accumulator.
    Later on already... we were switched
    to a battery charger of the accumulator.
    Have included a battery charger
    on a current received by us.
    And have started charge the accumulator.
    But in order not to spoil it... primary
    energy is necessary
    and then already the accumulator is not necessary.
    The rectifier, the converter and...
    But it can be made so, that all
    to establish in one device.
    Is required primary, or from
    the accumulator or from a network
    Small energy, and then already receive free energy
    If to put houses, 5 kwt suffices usual family.
    It is possible to make and 10, yes we do not know
    here a ceiling how much more it will give the current
    Whe have received 5 kwt and we do not depart
    from it because this device is very gentle.
    As the saying goes, in the throes gave birth to him,
    so we are afraid, but we have to destroy it.
    Tell me please, what are impact stray currents
    and how important their role in your device.
    stray currents for my invention not matter...
    I have already confirmed during experiment.
    And it, on mine will best tell Mister Tengiz.
    Why is not present.
    Main power engineer polytechnic
    university of Georgia.
    Here he will tell because he has offered me.
    Make a separate grounding, se that people
    do not think that stray currents are used.
    This is a small circuit is sufficient for the device.
    And we have checked up that
    i do not take stray currents.
    I have told that this energy
    goes from an environment.

    -intervistatrice:
    Tell please how you will name
    your invention and the device.
    And to whom devote the invention.

    -Tariel Kapanadze:
    I would not become impudent so that to tell,
    this my invention, but i have
    found something. Properly.
    It is the invention of Nikola Tesla.
    And devoted to him, for he had lived such a life,
    so much for mankind has made.
    And today he is forgotten.
    Ask many scientists, they seldom
    heard about it something and nothing more.
    Here it is devoted to it. It is its devices, its work.
    But it was afraid of that people will be destroyed.
    If he gave would have given
    this device 100-120 years ago... for people.
    It spoke in last letter that "My invention
    will leave together with me".

    -intervistatrice:
    Why you so are assured, that this
    invention belongs Tesla?

    -Tariel Kapanadze:
    I used schemes.
    I have simply found a resonance and a method,
    wich automatically adjusts a resonance
    between primary and secondary coils.
    If there will be no resonance,
    here how recently i read.
    From a computer has pulled out
    the information about such person...
    Its surname Melnichenko.
    The unique person, unique material with wich
    i have had time to familiarize for last years,
    who decided exactly this question.
    It speaks: hold a resonance and all will turn out.
    As he said, it has not reached transformer Tesla,
    and has already begun work,
    to make this installation.
    But...
    he will make this device, to my mind,
    still it is not fast, but...
    he is very close.
    And probably our government should
    take it into consideration.
    It is necessary to think of that...
    i do not wish someone to offend, but
    pseudo-scientists oppose.
    I wish to refuse citizenship
    of the country and to emigrate.
    In this country such chaos, you will not understand.
    I have lost one invention.
    My engine of the car worked on water.
    I filled the water and it worked.
    4 years, i broke on the door
    of our former government.
    Nothing happened, and then suddenly, please hello.
    The filipino has done the same thing,
    and a patent got. I stayed on zero.
    Now my second invention under impact but,
    i do not intend to back down.

    -intervistatrice:
    You said you keep the resonance,
    where is your resonance?

    -Tariel Kapanadze:
    Here, the resonance between primary
    and secondary windings.
    The resonator is inside.
    This is exactly what is, so to speak...
    secret but, as soon as i shall receive the patent
    Certainly, when will open, will be all right,
    But i could not reach it.
    I have no means to take the patent.
    To sell it is not desirable, but i do not know,
    or i shall go abroad, i shall work there
    and there i shall take the patent,
    i do not know, i have no time.

    -intervistatrice:
    One more question: how many it is necessary to you
    of means, to take the patent for your invention?

    -Tariel Kapanadze:
    To speak the truth i do not know.
    I was not engaged in this question.
    Precisely i do not know, how many it is necessary
    money to receive the patent for this installation,
    because... yes, where and in what country...
    in Georgia it costs cheaply.
    But here it is necessary to think very long,
    and then to dare to receive here the patent,
    it, consider, that it is lost.
    To this institution there is no trust.
    Abroad it can and expensive costs, but
    it is guaranteed your invention is protected.

    -intervistatrice:
    Protected by law?

    -Tariel Kapanadze:
    Yes.
    That at us here: installation, the converter,
    the accumulator and the rectifier
    for chargin the accumulator, and then
    the accumulator is removed.
    i once again shall repeat, all this
    is maybe placed in one box
    there will be one plug outside and 2 terminals for
    connections of the accumulator.

    -intervistatrice:
    How many it is necessary money
    to create such qualitative device?

    -Tariel Kapanadze:
    Let me thell you this, if the first copies...
    not to take into account,
    if to construct a line for manufacture devices...
    i to you shall tell the maximal sum,
    it should not cost more than 300-400 dollars.
    It where that 700-800 lari on our money.
    And dollars already nearby 300-400.
    Whe here will say: 5-6 kwt,
    but when the line will already work.
    It will not be necessary run
    from someone and to hide the secrets,
    and one part to do one end
    of city, another in other.
    And do so that the masters
    each other did not know.
    It is the Georgian variant, so to say...
    Here, my God, slightly you will be mistaken and all,
    hold out hand, he bite off a hand.
    I'll tell about one case. we wrote
    a proposal to the president of Georgia.
    When he appeared, Michael Saakashvili
    the hope has appeared, that... just a minute
    Hope appeared that he will take up this matter.
    Because for the country as air is required the device.
    It has come. has looked device and ...
    has given the task to minister of power.
    He gave him 10 days and whereupon
    1 month has passed.
    I don't know what they told him.
    What kind of information they
    reported to the president.
    But i see that they are busy by
    something in chancellery...
    Of course, I'll tell you if it will be cut out.
    Peter Mamradze. There is such person.
    Excuse me! I do not know, call him a scientist?
    He is a physicist?
    They say a physicist. On what direction
    i think astrophysics.
    I explained to him very popularly ...
    I have higher education, but
    27 years ago i have thrown a pencil.
    One time i was the architect, but today
    i have no right to tell, that i the architect
    because i fell behind.
    And never i can catch up with anybody.
    I have repeated is in an office of the prime minister.
    i can not say that i am an architect because
    i do not have anything to do with architecture.
    So i not educated person, but...
    you don't have a right, when you say,
    that 15 years past, you graduated ...
    you don't have anything common with physics
    i don't argue with him about management
    of administrative machine of Shevardnaze.
    Or clerical work because there i incompetent.
    And i do not give myself the right
    to interfere in their affairs.
    It has arranged such corps de ballet here,
    when prime-minister minister has come,
    what i steal electricity from the faucet.
    The insult was awful.
    When prime-minister minister has passed
    through a cable and has reached the faucet.
    He him has told, that there the current is not present,
    i took the faucet with a wet hand,
    and the other touched the earth.
    If would there was current,
    then me would not be here.
    Whose a task is performs this person ...
    It categorically demanded experiment
    in chancellery of the government.
    Specially... not that that, that specially,
    it not a toy, for presentation
    in offices if to whom that will want...
    To it submit on the saucer.
    On this issue we have our differences
    i do not know, that they have told to the president.
    I know one thing, if this setting Georgia loses,
    then the lion's share of blame falls
    on the, so to say, astrophysics Peter Mamradze.
    Its lion's share because owing, to it Georgia
    will lose this device, and all future blessings.

    -intervistatrice:
    Tell please! How many money
    you have spent for this installation?

    -Tariel Kapanadze:
    And to One person it was difficult...
    it was necessary to make quickly
    have divided the circuit into 20 parts
    and it was done in different workshops.
    Approximately 8000 dollars spent.
    When has started to do the device
    by power of 200 kwt...
    As the begger i ask money if will give, well.
    When they give money, such conditions of the offer,
    in the georgian business:
    "In a share i sit". what share while nothing is made?

    -intervistatrice:
    Tell please, it is your house?

    -Tariel Kapanadze:
    No. i and my family, we rent here an apartment
    because have sold everything, that was.
    Have spent for this device... I became beggars.
    Our government and many scientists opposed:
    "We are not interested. because it does not exist".
    Device which we see, for them does not exist!

    -intervistatrice:
    And how your family looks at it?

    -Tariel Kapanadze:
    About, family it, excuse me...
    such conditions offered me abroad...
    Probably it is time to me to leave there.
    The wife every day threatens me a stick!
    What i have refused!
    It's a joke, of course.
    Because i have refused good offering,
    and the reason was not that i want this device
    here to introduce yes...
    many scientists speak, if it is the truth, that it
    good device why it does not leave abroad?
    In the same place it with hands and legs will take.
    They can speak something, but before to tell,
    it is necessary to think, about what speak
    Not therefore i here have remained, that in Georgia
    i want.. yes certainly also i wish to leave in Georgia
    this device. But what behind it stand?
    Behind this device there is a chain,
    so to say... defensive importance.
    Therefore i wished to leave it at country.
    i ought not to speak this word.
    But who will hear about transformer Tesla, and
    then everyone will guess, that
    stands up for this device.
    I have told it to the president, and primer-minister.
    But i do not know that do with the president,
    i trust, that it does not know the truth.
    He does not know.
    Interview is finished.

    ....
  3. .
    Non tutti sanno che in windows 10 ci sono due menù start. Per visualizzare il menù start nascosto basta cliccare col tasto destro del mouse sul menù start in basso a sinistra. Questo menù consente di accedere velocemente ad alcune utili funzioni come il vecchio "Pannello di controllo", il comando "Esegui" o anche avviare con un clic il "Prompt dei comandi" come amministratore.
  4. .
    Nel foglio attuale consiglio di mantenere quanto già fatto con la semplice sostituzione della riga
    yn = (yn1 * Ntot2 - yn2 * Ntot1) / denom
    con questa
    yn = ((yn2 - yn1) * (nd - Ntot1)) / denom + yn1
    perchè come aveva rilevato LagunaLoire in presenza di sforzi assiali (di solito assenti nelle travi ca/cap) la procedura attuale non và a convergenza, e pertanto ripiega sulla procedura originaria di zax

    CODICE
    Do While cont < 50 'max 50 tentativi
           cont = cont + 1
           Dim denom As Double
           denom = (Ntot2 - Ntot1)
           If denom = 0# Then
               yn = (yn1 + yn2) / 2
           Else
               'yn = (yn1 * Ntot2 - yn2 * Ntot1) / denom
               yn = ((yn2 - yn1) * (nd - Ntot1)) / denom + yn1
           End If
           ' Calcola le deformazioni ultime della sezione
           deform = deform_ultime(polic, ymax, npm, yamin, yn)
           ' Calcola lo sforzo normale nella parte compressa della sezione
           nc = risult_compr(polic, armco, armcp, deform, ymax, yamin, yn)
           ' Calcola lo sforzo normale della parte tesa della sezione
           nt = risult_traz(polic, armco, armcp, deform, ymax, yamin, yn)
           ' Totale sforzo normale sulla sezione da confrontare con Nd
           Ntot = nc.n + nt.n
           If Abs(Ntot - nd) < 0.01 Then Exit Do
           If Sgn(Ntot) <> Sgn(Ntot1) Then
              yn2 = yn
              Ntot2 = Ntot
           Else
              yn1 = yn
              Ntot1 = Ntot
           End If
       Loop
  5. .
    In questo thread andrò a parlare del programma di calcolo per precompresso Cap2015, di cui posto uno screen shot.
  6. .
    in riferimento alla tecnica di costruzione di pilastri prefabbricati multipiano suggerita da Ruy, segnalo questo documento trovato in rete, che tratta della instabilizzazione delle barre di armatura compresse, che potrebbe chiarire meglio il comportamento del nodo in funzione del fattore di snellezza adottato.

    CITAZIONE
    COMPORTAMENTO
    SPERIMENTALE E
    MODELLAZIONE NUMERICA DI
    BARRE DI ARMATURA LISCE
    COMPRESSE
    EDOARDO COSENZA, Università di Napoli Federico II
    ANDREA PROTA, Università di Napoli Federico II

    https://www.google.it/url?sa=t&rct=j&q=&es....93990622,d.bGQ
  7. .
    In questo thread mi occuperò di tradurre il programma FIRES-T3 sviluppato da: R. Iding, B. Bresler, e Z. Nizamuddin, Department of Civil Engineering, University of California, Berkeley, California, 1997.
    Il programma in questione è stato scritto in un dialetto di FortranIV che era in dotazione all'epoca nei mainframe della serie CDC6000.
    http://en.wikipedia.org/wiki/CDC_6600

    Una prima difficoltà nella traslazione è che non si tratta di un linguaggio che segue le specifiche standard del Fortran77 pur essendo per gran parte simile, ed in rete non ho trovato un manuale che descriva questo dialetto.
    Per le caratteristiche del linguaggio differenti dal Fortran77 standard vedremo di dedurle previo reverse-engineering, durante la prima fase di studio.

    Il programma FIRES-T3 valuta la storia della distribuzione della temperatura nelle strutture in ambienti esposti al fuoco. Si considerano tre tipi di elementi solidi tridimensionali, sezioni bidimensionali, e aste monodimensionali che possono essere usati contemporaneamente. Nella formulazione del problema si può utilizzare sia un materiale omogeneo isotropo come l'acciaio o anche materiali compositi quali il cemento armato.

    Il metodo adottato dal programma per la risoluzione del problema termico non-lineare è un metodo agli elementi finiti. La non linearità del problema richiede una soluzione iterativa. I tipi di elementi con cui si debbono suddividere gli elementi da analizzare possono essere tridimensionali come esaedri a 8 nodi e tetraedri a 4 nodi, ma anche elementi bidimensionali come quadrilateri a 4 nodi e triangoli a 3 nodi, o elementi monodimensionali come aste a due nodi. Inoltre vengono considerati sia meccanismi convettivi che radiativi.

    Il link al documento con la descrizione dettagliata ed il sorgente di FIRES-T3 è il seguente:
    http://fire.nist.gov/bfrlpubs/fire78/PDF/f78001.pdf
  8. .
    Il calcolo viene fatto sia col metodo rigoroso che semplificato con l'isoterma 500°C.
    Sul mio laptop con I5 M460 dual core a 2.5Ghz l'elaborazione impiega 58 secondi.
    Un collega col software commerciale di Zax ottiene Mu = 33621140 kgcm pari a 3297kNm
    Questi sono i risultati da validare:

    Edited by texitaliano64 - 27/8/2014, 22:13
  9. .
    La mesh stavolta la diradiamo e la portiamo a 3cm di lato per velocizzare i calcoli.
    Ecco l'immagine:
  10. .
    Proseguiamo con i test.
    Il test precedente è andato in stallo e non raggiungeva la convergenza, tanto che pareva un calcolo alle calende greche.
    La trave da verificare è la stessa di inizio post ma portata a verifica a 120'.
  11. .
    PROCEDURA DI CALCOLO DELLA RESISTENZA DI MANUFATTI IN CA e CAP ESPOSTI AL FUOCO SECONDO LA CURVA DI INCENDIO ISO834.

    Per il seguente post mi rifaccio alla norma:

    CITAZIONE
    EN 1992-1-2 (2004) (English): Eurocode 2: Design of concrete
    structures - Part 1-2: General rules - Structural fire
    design [Authority: The European Union Per Regulation
    305/2011, Directive 98/34/EC, Directive 2004/18/EC]

    Propongo una procedura di calcolo alternativo al metodo semplificato dell'isoterma 500°C, per la verifica allo SLU di manufatti in CA/CAP sottoposti alla curva di incendio ISO834.
    Buona parte del codice che vado a modificare/adattare è già stato in parte pubblicato in questo forum in varie sezioni da afazio, zax, giaria, se dimentico qualcuno me ne scuso.
    Tralascio la parte fisico/teorica del problema per la quale rimando alla letteratura di riferimento, e come i gamberi partirò dalla parte pratica conclusiva.
    Per l'analisi termica a monte utilizzerò software FEM open source, del quale parlerò più avanti al termine dell'articolo.
    Premetto che la procedura numerica che vado ad implementare, è una procedura poco efficiente, che richiede tempi di elaborazione lunghi, in minima parte legata al linguaggio di programmazione VBA che andrò ad utilizzare.
  12. .
    Senza utilizzare software commerciali, con XMaxima otteniamo gli stessi risultati:
    CITAZIONE
    Maxima 5.31.2 http://maxima.sourceforge.net
    using Lisp GNU Common Lisp (GCL) GCL 2.6.8 (a.k.a. GCL)
    Distributed under the GNU Public License. See the file COPYING.
    Dedicated to the memory of William Schelter.
    The function bug_report() provides bug reporting information.
    (%­i1) 7^99;
    (%­o1) 462068072803536855906378252728602401551029028414946485847699333055955922805275437143
    (%­i2) mod(7^99,12);
    (%­o2) 7
    (%­i3)
  13. .
    A dimostrazione che il metodo PLV implementato è numericamente corretto allego un foglio di excel che calcola la freccia di tavi a sezione rettangolare variabile lungo l'asse e caricate con un carico distribuito su tutta la trave.
    In questo esempio ho volutamente semplificato l'oggetto del calcolo, ma è estendibile a qualsiasi geometria di trave comunque caricata e comunque vincolata, basta usare calcoli di proprietà geometriche generici e calcoli di momenti generici per carichi distribuiti o concentrati disposti nelle maniere più disparate.
    questo è il link di scarico:
    https://app.box.com/s/2iu9x2rz2hmmvvw3375k
  14. .
    Adesso penso di aver risolto i problemi ultimamente riscontrati.
    Ho inserito il link per il download più avanti

    Edited by texitaliano64 - 5/4/2014, 13:35
  15. .
    La nuova versione del foglio è stata migliorata con la possibilità di inserire fino a 4 poligoni oppure anche dei fori.
    Le modifiche principali le ho fatte sulla carrozzeria, ovvero sul frontend, l'unica modifica di rilievo nel motore di calcolo è stata la definizione per convenienza dei fori con -1 al posto di 0, nella variabile omog relativa a ciascun poligono.
    CODICE
    ' -------------------------------------------------------------------------- '
    ' Struttura dati in cui sono definiti i dati dei singoli poligoni che com-   '
    ' pongono la sezione                                                         '
    ' -------------------------------------------------------------------------- '
    Public Type poligono_sezione
      X() As Double                        ' coordinata x del vertice (1 To NMaxVrt)
      Y() As Double                        ' coordinata y del vertice (1 To NMaxVrt)
      numv As Integer                      ' numero di vertici del poligono
      fck As Double                        ' fck
      fd As Double                         ' Resistenza massima di calcolo (per verifiche SLU)
      omog As Double                       ' 1=pieno -1=foro in genere 0 < omog < 1 se cls getto
      traz As Integer                      ' 0=non reagente a trazione; 1=reagente a trazione
      epsc0 As Double                      ' Deformazione in corrispondenza della fine della parte parabola/lineare del dominio
      epscu As Double                      ' Deformazione ultima del dominio
      sigma() As Double                    ' (1 To NMaxVrt)
    End Type
    ' -------------------------------------------------------------------------- '

    Come accennato precedentemente ho eseguito un test di prova.
    Geometria:
    6f69
    Uploaded with ImageShack.us
    Armature:
    6mid
    Uploaded with ImageShack.us
    Cassero:
    i45j
    Uploaded with ImageShack.us
    Dominio di rottura:
    8ens
    Uploaded with ImageShack.us
    PS. col VCASLU non è stato possibile fare la verifica in quanto non gestisce i getti di 2a fase integrativi
    Ecco il link:
    Ho inserito il link per il download più avanti

    Edited by texitaliano64 - 4/4/2014, 20:07
20 replies since 4/1/2013
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