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#include "SimTKsimbody.h"
#include "SimTKcommon/Testing.h"
#include <cstdio>
#include <iostream>
#include <exception>
using namespace SimTK;
using std::cout;using std::endl;
static const Real smallRad = 5*1.25/100;
static const Real largeRad = 10.5/100;
static const MobodIndex smallBodx = MobodIndex(1);
static const MobodIndex largeBodx = MobodIndex(0);
static const Vec3 smallPos(-.28,0,0);
static const Vec3 largePos(-.28,0,0);
static const Real hSmall = .03; // 6cm=100% strain
static const Real hLarge = .03;
class ForceReporter : public PeriodicEventReporter {
public:
ForceReporter(const MultibodySystem& system,
const CompliantContactSubsystem& complCont,
Real reportInterval)
: PeriodicEventReporter(reportInterval), m_system(system),
m_compliant(complCont)
{}
~ForceReporter() {}
void handleEvent(const State& state) const override {
m_system.realize(state, Stage::Dynamics);
//cout << state.getTime() << ": E = " << m_system.calcEnergy(state)
// << " Ediss=" << m_compliant.getDissipatedEnergy(state)
// << " E+Ediss=" << m_system.calcEnergy(state)
// +m_compliant.getDissipatedEnergy(state)
// << endl;
const int ncont = m_compliant.getNumContactForces(state);
//cout << "Num contacts: " << m_compliant.getNumContactForces(state) << endl;
if (ncont==0)
printf("%g 0.0 0.0 0.0\n", state.getTime());
const SimbodyMatterSubsystem& matter = m_system.getMatterSubsystem();
const MobilizedBody& smallBod=matter.getMobilizedBody(smallBodx);
const MobilizedBody& largeBod=matter.getMobilizedBody(largeBodx);
const Vec3 smallCtr = smallBod.findStationLocationInGround(state, smallPos);
const Vec3 largeCtr = largeBod.findStationLocationInGround(state, largePos);
const Real d = (smallRad+largeRad)-(smallCtr-largeCtr).norm();
for (int i=0; i < ncont; ++i) {
const ContactForce& force = m_compliant.getContactForce(state,i);
const ContactId id = force.getContactId();
cout << state.getTime()
<< " " << force.getForceOnSurface2()[1][1] // Normal
<< " " << force.getForceOnSurface2()[1][0] // Tangential
<< " " << d << "\n"; // penetration distance
//ContactPatch patch;
//const bool found = m_compliant.calcContactPatchDetailsById(state,id,patch);
//cout << "patch for id" << id << " found=" << found << endl;
//cout << "resultant=" << patch.getContactForce() << endl;
//cout << "num details=" << patch.getNumDetails() << endl;
//Real patchArea=0, maxDepth=0, maxf=0;
//Vec3 ftot(0);
//for (int i=0; i < patch.getNumDetails(); ++i) {
// const ContactDetail& detail = patch.getContactDetail(i);
// patchArea += detail.getPatchArea();
// maxDepth = std::max(maxDepth, detail.getDeformation());
// ftot += detail.getForceOnSurface2();
// maxf = std::max(maxf, detail.getForceOnSurface2().norm());
//}
//cout << "patchArea=" << patchArea
// << " ftot=" << ftot << " maxDepth=" << maxDepth << "\n";
//cout << "maxf=" << maxf << "\n";
}
}
private:
const MultibodySystem& m_system;
const CompliantContactSubsystem& m_compliant;
};
// Nylon
static const Real nylon_density = 1100.; // kg/m^3
static const Real nylon_young = .05*2.5e9; // pascals (N/m)
static const Real nylon_poisson = 0.4; // ratio
static const Real nylon_planestrain =
ContactMaterial::calcPlaneStrainStiffness(nylon_young, nylon_poisson);
static const Real nylon_confined =
ContactMaterial::calcConfinedCompressionStiffness(nylon_young, nylon_poisson);
static const Real nylon_dissipation = 10*0.005;
int main() {
try
{ // Create the system.
MultibodySystem system; system.setUseUniformBackground(true);
SimbodyMatterSubsystem matter(system);
GeneralForceSubsystem forces(system);
Force::Gravity gravity(forces, matter, -YAxis, 10);
//Force::GlobalDamper damper(forces, matter, 1.0);
ContactTrackerSubsystem tracker(system);
CompliantContactSubsystem contactForces(system, tracker);
contactForces.setTrackDissipatedEnergy(true);
contactForces.setTransitionVelocity(1e-3);
// g=10, mass==.5 => weight = .5*10=5N.
// body origin at the hinge on the right
Real mass = 0.5;
Vec3 com = Vec3(-.14,0,0);
Vec3 halfDims(.14, .01, .01); // a rectangular solid
Inertia inertia = mass*
UnitInertia::brick(halfDims).shiftFromCentroid(Vec3(.14,0,0));
Body::Rigid lidBody(MassProperties(mass,com,inertia));
lidBody.addDecoration(Vec3(-.14,0,0),
DecorativeBrick(halfDims).setColor(Cyan).setOpacity(.1));
PolygonalMesh smallMesh, largeMesh;
#define USE_VIZ
//#define SHOW_NORMALS
Array_<DecorativeLine> smallNormals;
Array_<DecorativeLine> largeNormals;
const Real NormalLength = .001;
#define USE_MESH_SMALL
#define USE_MESH_BIG
#ifdef USE_MESH_SMALL
smallMesh = PolygonalMesh::createSphereMesh(smallRad, 5);
std::cerr << "small mesh faces: " << smallMesh.getNumFaces() << "\n";
ContactGeometry::TriangleMesh smallContact(smallMesh);
DecorativeMesh smallArtwork(smallContact.createPolygonalMesh());
smallArtwork.setColor(Red);
#ifdef SHOW_NORMALS
for (int fx=0; fx < smallContact.getNumFaces(); ++fx) {
smallNormals.push_back(
DecorativeLine(smallContact.findCentroid(fx),
smallContact.findCentroid(fx)
+ NormalLength*smallContact.getFaceNormal(fx))
.setColor(Black).setLineThickness(2));
}
#endif
#else
DecorativeSphere smallArtwork(smallRad);
smallArtwork.setResolution(2).setRepresentation(DecorativeGeometry::DrawWireframe);
ContactGeometry::Sphere smallContact(smallRad);
#endif
#ifdef USE_MESH_BIG
largeMesh = PolygonalMesh::createSphereMesh(largeRad, 6);
std::cerr << "large mesh faces: " << largeMesh.getNumFaces() << "\n";
ContactGeometry::TriangleMesh largeContact(largeMesh);
DecorativeMesh largeArtwork(largeContact.createPolygonalMesh());
//DecorativeSphere largeArtwork(largeRad);
largeArtwork.setColor(Green);
#ifdef SHOW_NORMALS
for (int fx=0; fx < largeContact.getNumFaces(); ++fx) {
largeNormals.push_back(
DecorativeLine(largeContact.findCentroid(fx),
largeContact.findCentroid(fx)
+ NormalLength*largeContact.getFaceNormal(fx))
.setColor(Black).setLineThickness(2));
}
#endif
#else
DecorativeSphere largeArtwork(largeRad);
largeArtwork.setResolution(4).setRepresentation(DecorativeGeometry::DrawWireframe);
ContactGeometry::Sphere largeContact(largeRad);
#endif
ContactMaterial nylon(
//nylon_planestrain,
nylon_confined,
nylon_dissipation,
.1*.9,.1*.8,.1*.6); // static, dynamic, viscous friction
lidBody.addDecoration(smallPos,
smallArtwork.setOpacity(0.5));
lidBody.addDecoration(smallPos,
smallArtwork.setRepresentation(DecorativeGeometry::DrawWireframe));
for (unsigned i=0; i < smallNormals.size(); ++i)
lidBody.addDecoration(smallPos, smallNormals[i]);
lidBody.addContactSurface(smallPos,
ContactSurface(smallContact, nylon, hSmall));
matter.Ground().updBody().addDecoration(largePos,
largeArtwork.setOpacity(0.5));
matter.Ground().updBody().addDecoration(largePos,
largeArtwork.setRepresentation(DecorativeGeometry::DrawWireframe));
for (unsigned i=0; i < largeNormals.size(); ++i)
matter.Ground().updBody().addDecoration(largePos,
largeNormals[i]);
matter.Ground().updBody().addContactSurface(largePos,
ContactSurface(largeContact, nylon, hLarge));
MobilizedBody::Pin lid(matter.Ground(), Vec3(0.05,smallRad+largeRad,0),
lidBody, Vec3(0,0,0));
#ifdef USE_VIZ
Visualizer viz(system);
viz.setCameraClippingPlanes(.01,100);
#endif
system.addEventReporter(new Visualizer::Reporter(viz, 1./1000));
ForceReporter* frcReporter =
new ForceReporter(system, contactForces, 1./100000);
system.addEventReporter(frcReporter);
RungeKuttaMersonIntegrator integ(system);
//CPodesIntegrator integ(system);
//integ.setMaximumStepSize(.01);
integ.setAccuracy(1e-5);
TimeStepper ts(system, integ);
system.realizeTopology();
State startState = system.getDefaultState();
lid.setOneQ(startState, 0, -Pi/10);
//lid.setOneQ(startState, 0, 0.0610351);
system.realize(startState, Stage::Position);
#ifdef USE_VIZ
viz.report(startState);
#endif
system.realize(startState);
//frcReporter->handleEvent(startState);
//printf("type to go ...\n");
// getchar();
ts.initialize(startState);
ts.stepTo(0.5);
} catch (const std::exception& e) {
std::printf("EXCEPTION THROWN: %s\n", e.what());
exit(1);
} catch (...) {
std::printf("UNKNOWN EXCEPTION THROWN\n");
exit(1);
}
return 0;
}
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