Burger’s Contact Model Implementation
See this page for the documentation of this contact model.
contactmodelburger.h
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 | #pragma once
// contactmodelburger.h
#include "contactmodel/src/contactmodelmechanical.h"
#ifdef BURGER_LIB
# define BURGER_EXPORT EXPORT_TAG
#elif defined(NO_MODEL_IMPORT)
# define BURGER_EXPORT
#else
# define BURGER_EXPORT IMPORT_TAG
#endif
namespace cmodelsxd {
using namespace itasca;
class ContactModelBurger : public ContactModelMechanical {
public:
// Constructor: Set default values for contact model properties.
BURGER_EXPORT ContactModelBurger();
// Destructor, called when contact is deleted: free allocated memory, etc.
BURGER_EXPORT virtual ~ContactModelBurger();
// Contact model name (used as keyword for commands and FISH).
virtual QString getName() const { return "burger"; }
// The index provides a quick way to determine the type of contact model.
// Each type of contact model in PFC must have a unique index; this is assigned
// by PFC when the contact model is loaded. This index should be set to -1
virtual void setIndex(int i) { index_=i;}
virtual int getIndex() const {return index_;}
// Contact model version number (e.g., MyModel05_1). The version number can be
// accessed during the save-restore operation (within the archive method,
// testing {stream.getRestoreVersion() == getMinorVersion()} to allow for
// future modifications to the contact model data structure.
virtual uint getMinorVersion() const;
// Copy the state information to a newly created contact model.
// Provide access to state information, for use by copy method.
virtual void copy(const ContactModel *c) override;
// Provide save-restore capability for the state information.
virtual void archive(ArchiveStream &);
// Enumerator for the properties.
enum PropertyKeys {
kwKnK=1
, kwCnK
, kwKnM
, kwCnM
, kwKsK
, kwCsK
, kwKsM
, kwCsM
, kwMode
, kwFric
, kwF
, kwS
};
// Contact model property names in a comma separated list. The order corresponds with
// the order of the PropertyKeys enumerator above. One can visualize any of these
// properties in PFC automatically.
virtual QString getProperties() const {
return "bur_knk"
",bur_cnk"
",bur_knm"
",bur_cnm"
",bur_ksk"
",bur_csk"
",bur_ksm"
",bur_csm"
",bur_mode"
",bur_fric"
",bur_force"
",bur_slip";
}
// Enumerator for contact model related FISH callback events.
enum FishCallEvents {
fActivated=0
,fSlipChange
};
// Contact model FISH callback event names in a comma separated list. The order corresponds with
// the order of the FishCallEvents enumerator above.
virtual QString getFishCallEvents() const {
return
"contact_activated"
",slip_change";
}
// Return the specified contact model property.
virtual QVariant getProperty(uint i,const IContact *) const;
// The return value denotes whether or not the property corresponds to the global
// or local coordinate system (TRUE: global system, FALSE: local system). The
// local system is the contact-plane system (nst) defined as follows.
// If a vector V is expressed in the local system as (Vn, Vs, Vt), then V is
// expressed in the global system as {Vn*nc + Vs*sc + Vt*tc} where where nc, sc
// and tc are unit vectors in directions of the nst axes.
// This is used when rendering contact model properties that are vectors.
virtual bool getPropertyGlobal(uint i) const;
// Set the specified contact model property, ensuring that it is of the correct type
// and within the correct range --- if not, then throw an exception.
// The return value denotes whether or not the update has affected the timestep
// computation (by having modified the translational or rotational tangent stiffnesses).
// If true is returned, then the timestep will be recomputed.
virtual bool setProperty(uint i,const QVariant &v,IContact *);
// The return value denotes whether or not the property is read-only
// (TRUE: read-only, FALSE: read-write).
virtual bool getPropertyReadOnly(uint i) const;
// Prepare for entry into ForceDispLaw. The validate function is called when:
// (1) the contact is created, (2) a property of the contact that returns a true via
// the setProperty method has been modified and (3) when a set of cycles is executed
// via the {cycle N} command.
// Return value indicates contact activity (TRUE: active, FALSE: inactive).
virtual bool validate(ContactModelMechanicalState *state,const double ×tep);
// The forceDisplacementLaw function is called during each cycle. Given the relative
// motion of the two contacting pieces (via
// state->relativeTranslationalIncrement_ (Ddn, Ddss, Ddst)
// state->relativeAngularIncrement_ (Dtt, Dtbs, Dtbt)
// Ddn : relative normal-displacement increment, Ddn > 0 is opening
// Ddss : relative shear-displacement increment (s-axis component)
// Ddst : relative shear-displacement increment (t-axis component)
// Dtt : relative twist-rotation increment
// Dtbs : relative bend-rotation increment (s-axis component)
// Dtbt : relative bend-rotation increment (t-axis component)
// The relative displacement and rotation increments:
// Dd = Ddn*nc + Ddss*sc + Ddst*tc
// Dt = Dtt*nc + Dtbs*sc + Dtbt*tc
// where nc, sc and tc are unit vectors in direc. of the nst axes, respectively.
// [see {Table 1: Contact State Variables} in PFC Model Components:
// Contacts and Contact Models: Contact Resolution]
// ) and the contact properties, this function must update the contact force and
// moment.
// The force_ is acting on piece 2, and is expressed in the local coordinate system
// (defined in getPropertyGlobal) such that the first component positive denotes
// compression. If we define the moment acting on piece 2 by Mc, and Mc is expressed
// in the local coordinate system (defined in getPropertyGlobal), then we must use the getMechanicalContact()->updateResultingTorquesLocal(...) method to
// get the total moment.
// The return value indicates the contact activity status (TRUE: active, FALSE:
// inactive) during the next cycle.
// Additional information:
// * If state->activated() is true, then the contact has just become active (it was
// inactive during the previous time step).
// * Fully elastic behavior is enforced during the SOLVE ELASTIC command by having
// the forceDispLaw handle the case of {state->canFail_ == true}.
virtual bool forceDisplacementLaw(ContactModelMechanicalState *state,const double ×tep);
// The getEffectiveXStiffness functions return the translational and rotational
// tangent stiffnesses used to compute a stable time step. When a contact is sliding,
// the translational tangent shear stiffness is zero (but this stiffness reduction
// is typically ignored when computing a stable time step). If the contact model
// includes a dashpot, then the translational stiffnesses must be increased (see
// Potyondy (2009)).
// [Potyondy, D. 'Stiffness Matrix at a Contact Between Two Clumps,' Itasca
// Consulting Group, Inc., Minneapolis, MN, Technical Memorandum ICG6863-L,
// December 7, 2009.]
virtual DVect2 getEffectiveTranslationalStiffness() const { return DVect2(knk_,ksk_); }
// Return a new instance of the contact model. This is used in the CMAT
// when a new contact is created.
virtual ContactModelBurger *clone() const override { return NEWC(ContactModelBurger()); }
// The getActivityDistance function is called by the contact-resolution logic when
// the CMAT is modified. Return value is the activity distance used by the
// checkActivity function.
virtual double getActivityDistance() const {return 0.0;}
// The isOKToDelete function is called by the contact-resolution logic when...
// Return value indicates whether or not the contact may be deleted.
// If TRUE, then the contact may be deleted when it is inactive.
// If FALSE, then the contact may not be deleted (under any condition).
virtual bool isOKToDelete() const { return !isBonded(); }
// Zero the forces and moments stored in the contact model. This function is called
// when the contact becomes inactive.
virtual void resetForcesAndMoments() { force_.fill(0.0);}
virtual void setForce(const DVect &v,IContact *) { force_ = v; }
virtual void setArea(const double &) { throw Exception("The setArea method cannot be used with this contact model."); }
virtual double getArea() const { return 0.0; }
// The checkActivity function is called by the contact-resolution logic when...
// Return value indicates contact activity (TRUE: active, FALSE: inactive).
virtual bool checkActivity(const double &gap) { return gap <= 0.0; }
// Returns the sliding state (FALSE is returned if not implemented).
virtual bool isSliding() const { return s_; }
// Returns the bonding state (FALSE is returned if not implemented).
virtual bool isBonded() const { return false; }
virtual bool endPropertyUpdated(const QString &,const IContactMechanical *) {return false;}
// Both of these methods are called only for contacts with facets where the wall
// resolution scheme is set the full. In such cases one might wish to propagate
// contact state information (e.g., shear force) from one active contact to another.
// See the Faceted Wall section in the documentation.
virtual void propagateStateInformation(IContactModelMechanical* oldCm,const CAxes &oldSystem=CAxes(),const CAxes &newSystem=CAxes());
virtual void setNonForcePropsFrom(IContactModel *oldCM);
/// Return the total force that the contact model holds.
virtual DVect getForce(const IContactMechanical *) const;
/// Return the total moment on 1 that the contact model holds
virtual DAVect getMomentOn1(const IContactMechanical *) const;
/// Return the total moment on 1 that the contact model holds
virtual DAVect getMomentOn2(const IContactMechanical *) const;
// Methods to get and set properties.
const double & knk() const {return knk_;}
void knk(const double &d) {knk_=d;}
const double & cnk() const {return cnk_;}
void cnk(const double &d) {cnk_=d;}
const double & knm() const {return knm_;}
void knm(const double &d) {knm_=d;}
const double & cnm() const {return cnm_;}
void cnm(const double &d) {cnm_=d;}
const double & ksk() const {return ksk_;}
void ksk(const double &d) {ksk_=d;}
const double & csk() const {return csk_;}
void csk(const double &d) {csk_=d;}
const double & ksm() const {return ksm_;}
void ksm(const double &d) {ksm_=d;}
const double & csm() const {return csm_;}
void csm(const double &d) {csm_=d;}
const double & fric() const { return fric_;}
void fric(const double &d) {fric_=d;}
uint bmode() const {return bmode_;}
void bmode(uint b) {bmode_= b;}
const double & fn0() const { return fn0_;}
void fn0(const double &d) {fn0_=d;}
const double & u_n0() const { return u_n0_;}
void u_n0(const double &d) {u_n0_=d;}
const double & u_nk0() const { return u_nk0_;}
void u_nk0(const double &d) {u_nk0_=d;}
const DVect & u_sk() const { return u_sk_;}
void u_sk(const DVect &v) {u_sk_=v;}
const double & conAn() const { return conAn_;}
void conAn(const double &d) {conAn_=d;}
const double & conB_An() const { return conB_An_;}
void conB_An(const double &d) {conB_An_=d;}
const double & conCn() const { return conCn_;}
void conCn(const double &d) {conCn_=d;}
const double & conDn() const { return conDn_;}
void conDn(const double &d) {conDn_=d;}
const double & conAs() const { return conAs_;}
void conAs(const double &d) {conAs_=d;}
const double & conB_As() const { return conB_As_;}
void conB_As(const double &d) {conB_As_=d;}
const double & conCs() const { return conCs_;}
void conCs(const double &d) {conCs_=d;}
const double & conDs() const { return conDs_;}
void conDs(const double &d) {conDs_=d;}
const double & tdel() const { return tdel_;}
void tdel(const double &d) {tdel_=d;}
const DVect & force() const { return force_;}
void force(const DVect &v) {force_=v;}
bool s() const {return s_;}
void s(bool b) {s_= b;}
private:
// Index - used internally by PFC. Should be set to -1 in the cpp file.
static int index_;
// Burger model properties
double knk_; // normal stiffness for Kelvin section (bur_knk)
double cnk_; // normal viscosity for Kelvin section (bur_cnk)
double knm_; // normal stiffness for Maxwell section (bur_knm)
double cnm_; // normal viscosity for Maxwell section (bur_cnm)
double ksk_; // shear stiffness for Kelvin section (bur_ksk)
double csk_; // shear viscosity for Kelvin section (bur_csk)
double ksm_; // shear stiffness for Maxwell section (bur_ksm)
double csm_; // shear viscosity for Maxwell section (bur_csm)
double fric_; // friction coefficient (bur_fric)
uint bmode_; // FDLaw option, with or without tensile force, default false (with tensile)
double fn0_; // normal contact force 1 step before
double u_n0_; // normal total overlap 1 step before
double u_nk0_; // normal overlap of Kelvin part 1step before
DVect u_sk_; // shear relative displacement of Kelvin part 1step before
double conAn_; // constant A in eq.(), normal
double conB_An_; // constant B/A in eq.(), normal
double conCn_; // constant C in eq.(), normal
double conDn_; // constant D in eq.(), normal
double conAs_; // constant A in eq.(), shear
double conB_As_; // constant B/A in eq.(), shear
double conCs_; // constant C in eq.(), shear
double conDs_; // constant D in eq.(), shear
double tdel_; // current timestep
DVect force_; // current total force
bool s_; // current sliding state
// Constants
inline double A(const double k_k, const double c_k) { return(1.0 + k_k*tdel_/(2.0*c_k)); }
inline double B(const double k_k, const double c_k) { return(1.0 - k_k*tdel_/(2.0*c_k)); }
inline double B_A(const double k_k, const double c_k) { return(B(k_k,c_k)/A(k_k,c_k)); }
inline double C(const double k_k, const double c_k, const double k_m, const double c_m) {
return(tdel_/(2.0*c_k*A(k_k,c_k)) + 1.0/k_m + tdel_/(2.0*c_m)); }
inline double D(const double k_k, const double c_k, const double k_m, const double c_m) {
return(tdel_/(2.0*c_k*A(k_k,c_k)) - 1.0/k_m + tdel_/(2.0*c_m)); }
};
} // namespace cmodelsxd
// EoF
|
contactmodelburger.cpp
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#include "contactmodelburger.h"
#include "module/interface/icontactmechanical.h"
#include "module/interface/icontact.h"
#include "module/interface/ipiecemechanical.h"
#include "module/interface/ipiece.h"
#include "module/interface/ifishcalllist.h"
#include "fish/src/parameter.h"
#include "../version.txt"
#include "utility/src/tptr.h"
#include "shared/src/mathutil.h"
#include "kernel/interface/iprogram.h"
#include "module/interface/icontactthermal.h"
#include "contactmodel/src/contactmodelthermal.h"
#ifdef BURGER_LIB
#ifdef _WIN32
int __stdcall DllMain(void *,unsigned, void *) {
return 1;
}
#endif
extern "C" EXPORT_TAG const char *getName() {
#if DIM==3
return "contactmodelmechanical3dburger";
#else
return "contactmodelmechanical2dburger";
#endif
}
extern "C" EXPORT_TAG unsigned getMajorVersion() {
return MAJOR_VERSION;
}
extern "C" EXPORT_TAG unsigned getMinorVersion() {
return MINOR_VERSION;
}
extern "C" EXPORT_TAG void *createInstance() {
cmodelsxd::ContactModelBurger *m = NEWC(cmodelsxd::ContactModelBurger());
return (void *)m;
}
#endif
namespace cmodelsxd {
using namespace itasca;
int ContactModelBurger::index_ = -1;
UInt ContactModelBurger::getMinorVersion() const { return MINOR_VERSION;}
ContactModelBurger::ContactModelBurger() :knk_(0.0)
,cnk_(0.0)
,knm_(0.0)
,cnm_(0.0)
,ksk_(0.0)
,csk_(0.0)
,ksm_(0.0)
,csm_(0.0)
,fric_(0.0)
,bmode_(0)
,fn0_(0.0)
,u_n0_(0.0)
,u_nk0_(0.0)
,u_sk_(0.0)
,conAn_(0.0)
,conB_An_(0.0)
,conCn_(0.0)
,conDn_(0.0)
,conAs_(0.0)
,conB_As_(0.0)
,conCs_(0.0)
,conDs_(0.0)
,tdel_(0.0)
,force_(0.0)
,s_(false)
{
}
ContactModelBurger::~ContactModelBurger() {
}
void ContactModelBurger::archive(ArchiveStream &stream) {
// The stream allows one to archive the values of the contact model
// so that it can be saved and restored. The minor version can be
// used here to allow for incremental changes to the contact model too.
stream & knk_;
stream & cnk_;
stream & knm_;
stream & cnm_;
stream & ksk_;
stream & csk_;
stream & ksm_;
stream & csm_;
stream & fric_;
stream & bmode_;
stream & fn0_;
stream & u_n0_;
stream & u_nk0_;
stream & u_sk_;
stream & conAn_;
stream & conB_An_;
stream & conCn_;
stream & conDn_;
stream & conAs_;
stream & conB_As_;
stream & conCs_;
stream & conDs_;
stream & tdel_;
stream & force_;
stream & s_;
}
void ContactModelBurger::copy(const ContactModel *cm) {
// Copy all of the contact model properties. Used in the CMAT
// when a new contact is created.
ContactModelMechanical::copy(cm);
const ContactModelBurger *in = dynamic_cast<const ContactModelBurger*>(cm);
if (!in) throw std::runtime_error("Internal error: contact model dynamic cast failed.");
knk(in->knk());
cnk(in->cnk());
knm(in->knm());
cnm(in->cnm());
ksk(in->ksk());
csk(in->csk());
ksm(in->ksm());
csm(in->csm());
fric(in->fric());
bmode(in->bmode());
fn0(in->fn0());
u_n0(in->u_n0());
u_nk0(in->u_nk0());
u_sk(in->u_sk());
conAn(in->conAn());
conB_An(in->conB_An());
conCn(in->conCn());
conDn(in->conDn());
conAs(in->conAs());
conB_As(in->conB_As());
conCs(in->conCs());
conDs(in->conDs());
tdel(in->tdel());
force(in->force());
s(in->s());
}
QVariant ContactModelBurger::getProperty(uint i,const IContact *) const {
// Return the property. The IContact pointer is provided so that
// more complicated properties, depending on contact characteristics,
// can be calculated. Not used with the Burger model.
QVariant var;
switch (i) {
case kwKnK : return knk_;
case kwCnK : return cnk_;
case kwKnM : return knm_;
case kwCnM : return cnm_;
case kwKsK : return ksk_;
case kwCsK : return csk_;
case kwKsM : return ksm_;
case kwCsM : return csm_;
case kwMode : return bmode_;
case kwFric : return fric_;
case kwF : var.setValue(force_); return var;
case kwS : return s_;
}
assert(0);
return QVariant();
}
bool ContactModelBurger::getPropertyGlobal(uint i) const {
// Returns whether or not a property is held in the global axis system (TRUE)
// or the local system (FALSE). Used by the plotting logic.
switch (i) {
case kwF:
return false;
}
return true;
}
bool ContactModelBurger::setProperty(uint i,const QVariant &v,IContact *) {
// Set a contact model property. Return value indicates that the timestep
// should be recalculated.
switch (i) {
case kwKnK: {
if (!v.canConvert<double>())
throw Exception("bur_knk must be a double.");
double val(v.toDouble());
if (val<0.0)
throw Exception("Negative bur_knk not allowed.");
knk_ = val;
return true;
}
case kwCnK: {
if (!v.canConvert<double>())
throw Exception("bur_cnk must be a double.");
double val(v.toDouble());
if (val<0.0)
throw Exception("Negative bur_cnk not allowed.");
cnk_ = val;
return true;
}
case kwKnM: {
if (!v.canConvert<double>())
throw Exception("bur_knm must be a double.");
double val(v.toDouble());
if (val<0.0)
throw Exception("Negative bur_knm not allowed.");
knm_ = val;
return true;
}
case kwCnM: {
if (!v.canConvert<double>())
throw Exception("bur_cnm must be a double.");
double val(v.toDouble());
if (val<0.0)
throw Exception("Negative bur_cnm not allowed.");
cnm_ = val;
return true;
}
case kwKsK: {
if (!v.canConvert<double>())
throw Exception("bur_ksk must be a double.");
double val(v.toDouble());
if (val<0.0)
throw Exception("Negative bur_ksk not allowed.");
ksk_ = val;
return true;
}
case kwCsK: {
if (!v.canConvert<double>())
throw Exception("bur_csk must be a double.");
double val(v.toDouble());
if (val<0.0)
throw Exception("Negative bur_csk not allowed.");
csk_ = val;
return true;
}
case kwKsM: {
if (!v.canConvert<double>())
throw Exception("bur_ksm must be a double.");
double val(v.toDouble());
if (val<0.0)
throw Exception("Negative bur_ksm not allowed.");
ksm_ = val;
return true;
}
case kwCsM: {
if (!v.canConvert<double>())
throw Exception("bur_csm must be a double.");
double val(v.toDouble());
if (val<0.0)
throw Exception("Negative bur_csm not allowed.");
csm_ = val;
return true;
}
case kwMode: {
if (!v.canConvert<uint>())
throw Exception("bur_mode must be 0 (tensile) or 1 (no-tension).");
uint val(v.toUInt());
if (val >1)
throw Exception("bur_mode must be 0 (tensile) or 1 (no-tension).");
bmode_ = val;
return false;
}
case kwFric: {
if (!v.canConvert<double>())
throw Exception("bur_fric must be a double.");
double val(v.toDouble());
if (val<0.0)
throw Exception("Negative bur_fric not allowed.");
fric_ = val;
return false;
}
}
return false;
}
bool ContactModelBurger::getPropertyReadOnly(uint i) const {
// Returns TRUE if a property is read only or FALSE otherwise.
switch (i) {
case kwF:
case kwS:
return true;
default:
break;
}
return false;
}
bool ContactModelBurger::validate(ContactModelMechanicalState *state,const double &) {
// Validate the / Prepare for entry into ForceDispLaw. The validate function is called when:
// (1) the contact is created, (2) a property of the contact that returns a true via
// the setProperty method has been modified and (3) when a set of cycles is executed
// via the {cycle N} command.
// Return value indicates contact activity (TRUE: active, FALSE: inactive).
return checkActivity(state->gap_);
}
bool ContactModelBurger::forceDisplacementLaw(ContactModelMechanicalState *state,const double ×tep) {
assert(state);
// Current overlap
double overlap = - 1.0*state->gap_;
// Relative translational increment
DVect trans = state->relativeTranslationalIncrement_;
// Correction factor to account for when the contact becomes newly active.
// We estimate the time of activity during the timestep when the contact has first
// become active and scale the forces accordingly.
double correction = 1.0;
// The contact was just activated from an inactive state
if (state->activated()) {
// Trigger the FISH callback if one is hooked up to the
// contact_activated event.
if (cmEvents_[fActivated] >= 0) {
// An FArray of QVariant is returned and these will be passed
// to the FISH function as an array of FISH symbols as the second
// argument to the FISH callback function.
auto c = state->getContact();
std::vector<fish::Parameter> arg = { fish::Parameter(c->getIThing()) };
IFishCallList *fi = const_cast<IFishCallList*>(state->getProgram()->findInterface<IFishCallList>());
fi->setCMFishCallArguments(c,arg,cmEvents_[fActivated]);
}
// Calculate the correction factor.
if (trans.x()) {
correction = -1.0*overlap / trans.x();
if (correction < 0)
correction = 1.0;
}
}
trans*=correction;
if (timestep!=tdel_) { // re-calculated constants.
tdel_ = timestep;
// need some protection for divided by zero (k_k c_k k_m c_m = zero)
conAn_ = A(knk_, cnk_);
double conBn = B(knk_, cnk_);
conB_An_ = conBn / conAn_;
conCn_ = C(knk_, cnk_, knm_, cnm_);
conDn_ = D(knk_, cnk_, knm_, cnm_);
conAs_ = A(ksk_, csk_);
double conBs = B(ksk_, csk_);
conB_As_ = conBs / conAs_;
conCs_ = C(ksk_, csk_, ksm_, csm_);
conDs_ = D(ksk_, csk_, ksm_, csm_);
}
// normal force
force_.rx() = 1.0/conCn_*(overlap-u_n0_+(1.0-conB_An_)*u_nk0_-conDn_*fn0_);
if (bmode_ && force_.x()<0.0) force_.rx() = 0.0;
u_nk0_ = conB_An_*u_nk0_+timestep/(2.0*cnk_*conAn_)*(force_.x()+fn0_);
u_n0_ = overlap;
fn0_ = force_.x();
// Calculate the shear force.
DVect sforce(0.0);
DVect sforce_old = force_;
sforce_old.rx()=0.0;
DVect v1 = trans;
DVect v2 = u_sk_ * (1.0-conB_As_);
DVect v3 = sforce_old * conDs_;
sforce = (v1+v2+v3) / conCs_ * (-1.0);
double d1 = timestep / (2.0*csk_*conAs_);
sforce.rx() = 0.0;
v1 = sforce + sforce_old;
u_sk_ = u_sk_*conB_As_-v1*d1;
// The canFail flag corresponds to whether or not the contact can undergo non-linear
// force-displacement response. If the SOLVE ELASTIC command is given then the
// canFail state is set to FALSE. Otherwise it is always TRUE.
if (state->canFail_) {
// Resolve sliding. This is the normal force multiplied by the coefficient of friction.
double crit = force_.x() * fric_;
crit = max(0.0,crit);
// This is the magnitude of the shear force.
double sfmag = sforce.mag();
// Sliding occurs when the magnitude of the shear force is greater than the
// critical value.
if (sfmag > crit) {
// Lower the shear force to the critical value for sliding.
double rat = crit / sfmag;
sforce *= rat;
// Handle the slip_change event if one has been hooked up. Sliding has commenced.
if (!s_ && cmEvents_[fSlipChange] >= 0) {
auto c = state->getContact();
std::vector<fish::Parameter> arg = { fish::Parameter(c->getIThing()),
fish::Parameter() };
IFishCallList *fi = const_cast<IFishCallList*>(state->getProgram()->findInterface<IFishCallList>());
fi->setCMFishCallArguments(c,arg,cmEvents_[fSlipChange]);
}
s_ = true;
} else {
// Handle the slip_change event if one has been hooked up and
// the contact was previously sliding. Sliding has ceased.
if (s_) {
if (cmEvents_[fSlipChange] >= 0) {
auto c = state->getContact();
std::vector<fish::Parameter> arg = { fish::Parameter(c->getIThing()),
fish::Parameter((qint64)1) };
IFishCallList *fi = const_cast<IFishCallList*>(state->getProgram()->findInterface<IFishCallList>());
fi->setCMFishCallArguments(c,arg,cmEvents_[fSlipChange]);
}
s_ = false;
}
}
}
// Set the shear components of the total force.
for (int i=1; i<dim; ++i)
force_.rdof(i) = sforce.dof(i);
// This is just a sanity check to ensure, in debug mode, that the force isn't wonky.
assert(force_ == force_);
return true;
}
void ContactModelBurger::propagateStateInformation(IContactModelMechanical* old,const CAxes &oldSystem,const CAxes &newSystem) {
// Only called for contacts with wall facets when the wall resolution scheme
// is set to full!
// Only do something if the contact model is of the same type
if (old->getContactModel()->getName().compare("burger",Qt::CaseInsensitive) == 0 && !isBonded()) {
ContactModelBurger *oldCm = (ContactModelBurger *)old;
#ifdef THREED
// Need to rotate just the shear component from oldSystem to newSystem
// Step 1 - rotate oldSystem so that the normal is the same as the normal of newSystem
DVect axis = oldSystem.e1() & newSystem.e1();
double c, ang, s;
DVect re2;
if (!checktol(axis.abs().maxComp(),0.0,1.0,1000)) {
axis = axis.unit();
c = oldSystem.e1()|newSystem.e1();
if (c > 0)
c = std::min(c,1.0);
else
c = std::max(c,-1.0);
ang = acos(c);
s = sin(ang);
double t = 1. - c;
DMatrix<3,3> rm;
rm.get(0,0) = t*axis.x()*axis.x() + c;
rm.get(0,1) = t*axis.x()*axis.y() - axis.z()*s;
rm.get(0,2) = t*axis.x()*axis.z() + axis.y()*s;
rm.get(1,0) = t*axis.x()*axis.y() + axis.z()*s;
rm.get(1,1) = t*axis.y()*axis.y() + c;
rm.get(1,2) = t*axis.y()*axis.z() - axis.x()*s;
rm.get(2,0) = t*axis.x()*axis.z() - axis.y()*s;
rm.get(2,1) = t*axis.y()*axis.z() + axis.x()*s;
rm.get(2,2) = t*axis.z()*axis.z() + c;
re2 = rm*oldSystem.e2();
}
else
re2 = oldSystem.e2();
// Step 2 - get the angle between the oldSystem rotated shear and newSystem shear
axis = re2 & newSystem.e2();
DVect2 tpf;
DMatrix<2,2> m;
if (!checktol(axis.abs().maxComp(),0.0,1.0,1000)) {
axis = axis.unit();
c = re2|newSystem.e2();
if (c > 0)
c = std::min(c,1.0);
else
c = std::max(c,-1.0);
ang = acos(c);
if (!checktol(axis.x(),newSystem.e1().x(),1.0,100))
ang *= -1;
s = sin(ang);
m.get(0,0) = c;
m.get(1,0) = s;
m.get(0,1) = -m.get(1,0);
m.get(1,1) = m.get(0,0);
tpf = m*DVect2(oldCm->force_.y(),oldCm->force_.z());
} else {
m.get(0,0) = 1.;
m.get(0,1) = 0.;
m.get(1,0) = 0.;
m.get(1,1) = 1.;
tpf = DVect2(oldCm->force_.y(),oldCm->force_.z());
}
DVect pforce = DVect(0,tpf.x(),tpf.y());
#else
oldSystem;
newSystem;
DVect pforce = DVect(0,oldCm->force_.y());
#endif
for (int i=1; i<dim; ++i)
force_.rdof(i) += pforce.dof(i);
oldCm->force_ = DVect(0.0);
}
assert(force_ == force_);
}
void ContactModelBurger::setNonForcePropsFrom(IContactModel *old) {
// Only called for contacts with wall facets when the wall resolution scheme
// is set to full!
// Only do something if the contact model is of the same type
if (old->getName().compare("burger",Qt::CaseInsensitive)) {
ContactModelBurger *oldCm = (ContactModelBurger *)old;
knk_ = oldCm->knk_;
cnk_ = oldCm->cnk_;
knm_ = oldCm->knm_;
cnm_ = oldCm->cnm_;
ksk_ = oldCm->ksk_;
csk_ = oldCm->csk_;
ksm_ = oldCm->ksm_;
csm_ = oldCm->csm_;
fric_ = oldCm->fric_;
bmode_ = bmode_;
}
}
DVect ContactModelBurger::getForce(const IContactMechanical *) const {
DVect ret(force_);
return ret;
}
DAVect ContactModelBurger::getMomentOn1(const IContactMechanical *c) const {
DVect force = getForce(c);
DAVect ret(0.0);
c->updateResultingTorqueOn1Local(force,&ret);
return ret;
}
DAVect ContactModelBurger::getMomentOn2(const IContactMechanical *c) const {
DVect force = getForce(c);
DAVect ret(0.0);
c->updateResultingTorqueOn2Local(force,&ret);
return ret;
}
} // namespace cmodelsxd
// EoF
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