membrane.cc

Go to the documentation of this file.

/*
 * MBDyn (C) is a multibody analysis code.
 * http://www.mbdyn.org
 *
 * Copyright (C) 2011-2017
 *
 * Marco Morandini      <morandini@aero.polimi.it>
 * Riccardo Vescovini   <vescovini@aero.polimi.it>
 * Tommaso Solcia       <solcia@aero.polimi.it>
 *
 * Dipartimento di Ingegneria Aerospaziale - Politecnico di Milano
 * via La Masa, 34 - 20156 Milano, Italy
 * http://www.aero.polimi.it
 *
 * Changing this copyright notice is forbidden.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation (version 2 of the License).
 *
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/*
 * Inspired by
 * Wojciech Witkowski
 * "4-Node combined shell element with semi-EAS-ANS strain interpolations
 * in 6-parameter shell theories with drilling degrees of freedom"
 * Comput Mech (2009) 43:307­319 DOI 10.1007/s00466-008-0307-x
 */

#include "mbconfig.h"           /* This goes first in every *.c,*.cc file */

#include "constltp_impl.h"
#include "tpldrive_impl.h"
#include "membrane.h"
#include "mynewmem.h"

#if 0
#define _GNU_SOURCE 1
#include <fenv.h>
static void __attribute__ ((constructor))
trapfpe ()
{
  /* Enable some exceptions.  At startup all exceptions are masked.  */

  feenableexcept (FE_INVALID|FE_DIVBYZERO|FE_OVERFLOW);
}
#endif

Membrane::Membrane(unsigned uLabel, const DofOwner* pDO, flag fOut)
: Elem(uLabel, fOut),
ElemGravityOwner(uLabel, fOut),
ElemWithDofs(uLabel, pDO, fOut),
InitialAssemblyElem(uLabel, fOut)
{
        NO_OP;
}

Membrane::~Membrane(void)
{
        NO_OP;
}

int
ReadMembraneConstLaw(MBDynParser& HP, Membrane::fmh& pD, Membrane::vh& PreStress)
{
        ASSERT(pD.iGetNumRows() == 3);
        ASSERT(pD.iGetNumCols() == 3);

        if (HP.IsKeyWord("diag")) {
                pD.Reset();
                for (unsigned ir = 1; ir <= 3; ir++) {
                        pD(ir, ir) = HP.GetReal();
                }

        } else if (HP.IsKeyWord("sym")) {
                for (unsigned ir = 1; ir <= 3; ir++) {
                        pD(ir, ir) = HP.GetReal();
                        for (unsigned ic = ir + 1; ic <= 3; ic++) {
                                doublereal d = HP.GetReal();
                                pD(ir, ic) = d;
                                pD(ic, ir) = d;
                        }
                }

        } else if (HP.IsKeyWord("isotropic")) {
                doublereal dE;
                doublereal dnu;
                doublereal dG;
                doublereal dh;
                bool bGot_E(false);
                bool bGot_nu(false);
                bool bGot_G(false);
                bool bGot_h(false);

                while (HP.IsArg()) {
                        if (HP.IsKeyWord("E") || HP.IsKeyWord("Young" "modulus")) {
                                if (bGot_E) {
                                        silent_cerr("Membrane isotropic constitutive law: Young's modulus already provided at line " << HP.GetLineData() << std::endl);
                                        return -1;
                                }
                                bGot_E = true;
                                dE = HP.GetReal();
                                if (dE <= 0.) {
                                        silent_cerr("Membrane isotropic constitutive law: invalid Young's modulus " << dE << " at line " << HP.GetLineData() << std::endl);
                                        return -1;
                                }

                        } else if (HP.IsKeyWord("nu") || HP.IsKeyWord("Poisson" "modulus")) {
                                if (bGot_nu) {
                                        silent_cerr("Membrane isotropic constitutive law: Poisson's modulus already provided at line " << HP.GetLineData() << std::endl);
                                        return -1;
                                }
                                bGot_nu = true;
                                dnu = HP.GetReal();
                                if (dnu < 0. || dnu >= .5) {
                                        silent_cerr("Membrane isotropic constitutive law: invalid Poisson's modulus " << dnu << " at line " << HP.GetLineData() << std::endl);
                                        return -1;
                                }

                        } else if (HP.IsKeyWord("G") || HP.IsKeyWord("shear" "modulus")) {
                                if (bGot_G) {
                                        silent_cerr("Membrane isotropic constitutive law: shear modulus already provided at line " << HP.GetLineData() << std::endl);
                                        return -1;
                                }
                                bGot_G = true;
                                dG = HP.GetReal();
                                if (dG <= 0.) {
                                        silent_cerr("Membrane isotropic constitutive law: invalid shear modulus " << dG << " at line " << HP.GetLineData() << std::endl);
                                        return -1;
                                }

                        } else if (HP.IsKeyWord("thickness")) {
                                if (bGot_h) {
                                        silent_cerr("Membrane isotropic constitutive law: thickness already provided at line " << HP.GetLineData() << std::endl);
                                        return -1;
                                }
                                bGot_h = true;
                                dh = HP.GetReal();
                                if (dh <= 0.) {
                                        silent_cerr("Membrane isotropic constitutive law: invalid thickness " << dh << " at line " << HP.GetLineData() << std::endl);
                                        return -1;
                                }

                        } else {
                                break;
                        }
                }

                int got = 0;
                if (bGot_E) got++;
                if (bGot_nu) got++;
                if (bGot_G) got++;

                if (got < 2) {
                        silent_cerr("Membrane isotropic constitutive law: incomplete material data (need at least two among Young's modulus, Poisson's modulus, shear modulus)" << std::endl);
                        return -1;
                }

                if (got > 2) {
                        if (std::abs(dE/(2.*(1 + dnu)) - dG) >
                                std::numeric_limits<doublereal>::epsilon())
                        {
                                silent_cerr("Membrane isotropic constitutive law: inconsistent material data" << std::endl);
                                return -1;
                        }
                } else {
                        if (!bGot_G) {
                                dG = dE/(2.*(1 + dnu));

                        } else if (!bGot_E) {
                                dE = 2.*(1 + dnu)*dG;

                        } else if (!bGot_nu) {
                                dnu = dE/(2.*dG) - 1.;
                                if (dnu <= 0. || dnu >= .5) {
                                        silent_cerr("Membrane isotropic constitutive law: inconsistent material data (computed Poisson's modulus: " << dnu << ")" << std::endl);
                                        return -1;
                                }
                        }
                }

                if (!bGot_h) {
                        silent_cerr("Membrane isotropic constitutive law: shell thickness missing" << std::endl);
                        return -1;
                }

                doublereal C = dE/(1. - dnu*dnu)*dh;
                // doublereal D = C*dh*dh/12;
                doublereal G = dG*dh;
                // doublereal F = G*dh*dh/12;

                pD.Reset();

                pD(1, 1) = C;
                pD(2, 2) = C;
                pD(1, 2) = C*dnu;
                pD(2, 1) = C*dnu;
                pD(3, 3) = 2*G;

/*
                pD(1, 1) = C;
                pD(1, 5) = C*dnu;
                pD(2, 2) = 2*G;
                pD(3, 3) = G*das;
                pD(4, 4) = 2*G;
                pD(5, 1) = C*dnu;
                pD(5, 5) = C;
                pD(6, 6) = G*das;

                pD(7, 7) = 2*F;
                pD(8, 8) = D;
                pD(8, 10) = -D*dnu;
                pD(9, 9) = F*dat;
                pD(10, 10) = D;
                pD(10, 8) = -D*dnu;
                pD(11, 11) = 2*F;
                pD(12, 12) = F*dat;
*/

        } else {
                if (HP.IsKeyWord("matr")) {
                        // tolerate it
                }

                for (unsigned ir = 1; ir <= 3; ir++) {
                        for (unsigned ic = 1; ic <= 3; ic++) {
                                pD(ir, ic) = HP.GetReal();
                        }
                }
        }

        if (HP.IsKeyWord("prestress")) {
                ASSERT(PreStress.iGetSize() == 3);
                for (unsigned ir = 1; ir <= 3; ir++) {
                        PreStress(ir) = HP.GetReal();
                }
        }

        return 0;
}