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rAKA/src/model/contact_mechanics/contact_detector_inline_impl.hh
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contact_detector_inline_impl.hh
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/**
* Copyright (©) 2019-2023 EPFL (Ecole Polytechnique Fédérale de Lausanne)
* Laboratory (LSMS - Laboratoire de Simulation en Mécanique des Solides)
*
* This file is part of Akantu
*
* Akantu is free software: you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option) any
* later version.
*
* Akantu 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 Lesser General Public License for more
* details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Akantu. If not, see <http://www.gnu.org/licenses/>.
*/
/* -------------------------------------------------------------------------- */
#include "contact_detector.hh"
/* -------------------------------------------------------------------------- */
#ifndef __AKANTU_CONTACT_DETECTOR_INLINE_IMPL_CC__
#define __AKANTU_CONTACT_DETECTOR_INLINE_IMPL_CC__
namespace akantu {
/* -------------------------------------------------------------------------- */
template <class Derived, std::enable_if_t<aka::is_vector_v<Derived>> *>
inline bool ContactDetector::checkValidityOfProjection(
Eigen::MatrixBase<Derived> & projection) const {
Real tolerance = 1e-3;
return std::all_of(projection.begin(), projection.end(),
[&tolerance](auto && xi) {
return (xi > -1.0 - tolerance) or (xi < 1.0 + tolerance);
});
}
/* -------------------------------------------------------------------------- */
template <class Derived>
inline void ContactDetector::coordinatesOfElement(
const Element & el, Eigen::MatrixBase<Derived> & coords) const {
coords = mesh.extractNodalValuesFromElement(positions, el);
}
/* -------------------------------------------------------------------------- */
template <class Derived, std::enable_if_t<aka::is_vector_v<Derived>> *>
inline void ContactDetector::computeCellSpacing(
Eigen::MatrixBase<Derived> & spacing) const {
spacing.fill(std::sqrt(2.0) * max_dd);
}
/* -------------------------------------------------------------------------- */
inline void
ContactDetector::constructGrid(SpatialGrid<Idx> & grid, BBox & bbox,
const Array<Idx> & nodes_list) const {
auto position_it = make_view(this->positions, spatial_dimension).begin();
auto to_grid = [&](auto node) {
auto && pos = position_it[node];
if (bbox.contains(pos)) {
grid.insert(node, pos);
}
};
std::for_each(nodes_list.begin(), nodes_list.end(), to_grid);
}
/* -------------------------------------------------------------------------- */
inline void
ContactDetector::constructBoundingBox(BBox & bbox,
const Array<Idx> & nodes_list) const {
auto to_bbox = [&](auto node) {
auto && pos = make_view(this->positions, spatial_dimension).begin()[node];
bbox += pos;
};
std::for_each(nodes_list.begin(), nodes_list.end(), to_bbox);
Vector<Real> lower_bound = bbox.getLowerBounds().array() - max_bb;
Vector<Real> upper_bound = bbox.getUpperBounds().array() + max_bb;
bbox.setLowerBounds(lower_bound);
bbox.setUpperBounds(upper_bound);
AKANTU_DEBUG_INFO("BBox" << bbox);
}
/* -------------------------------------------------------------------------- */
inline void ContactDetector::computeMaximalDetectionDistance() {
Real elem_size;
Real max_elem_size = std::numeric_limits<Real>::min();
Real min_elem_size = std::numeric_limits<Real>::max();
auto & master_nodes = this->surface_selector->getMasterList();
for (auto & master : master_nodes) {
Array<Element> elements;
this->mesh.getAssociatedElements(master, elements);
for (auto element : elements) {
Int nb_nodes_per_element = mesh.getNbNodesPerElement(element.type);
Matrix<Real> elem_coords(spatial_dimension, nb_nodes_per_element);
this->coordinatesOfElement(element, elem_coords);
elem_size = FEEngine::getElementInradius(elem_coords, element.type);
max_elem_size = std::max(max_elem_size, elem_size);
min_elem_size = std::min(min_elem_size, elem_size);
}
}
AKANTU_DEBUG_INFO("The maximum element size : " << max_elem_size);
this->min_dd = min_elem_size;
this->max_dd = max_elem_size;
this->max_bb = max_elem_size;
}
/* -------------------------------------------------------------------------- */
inline Vector<Idx>
ContactDetector::constructConnectivity(Idx & slave,
const Element & master) const {
auto && master_conn = this->mesh.getConnectivity(master);
Vector<Idx> elem_conn(master_conn.size() + 1);
elem_conn[0] = slave;
elem_conn.block(1, 0, master_conn.size(), 1) = master_conn;
return elem_conn;
}
/* -------------------------------------------------------------------------- */
template <class Derived, std::enable_if_t<aka::is_vector_v<Derived>> *>
inline void ContactDetector::computeNormalOnElement(
const Element & element, Eigen::MatrixBase<Derived> & normal) const {
Matrix<Real> vectors(spatial_dimension, spatial_dimension - 1);
this->vectorsAlongElement(element, vectors);
switch (this->spatial_dimension) {
case 2: {
normal = Math::normal(vectors);
break;
}
case 3: {
normal = Math::normal(vectors.col(0), vectors.col(1));
break;
}
default: {
AKANTU_ERROR("Unknown dimension : " << spatial_dimension);
}
}
// to ensure that normal is always outwards from master surface
const auto & element_to_subelement =
mesh.getElementToSubelement(element.type)(element.element);
Vector<Real> outside = mesh.getBarycenter(element);
// check if mesh facets exists for cohesive elements contact
Vector<Real> inside;
if (mesh.isMeshFacets()) {
inside = mesh.getMeshParent().getBarycenter(element_to_subelement[0]);
} else {
inside = mesh.getBarycenter(element_to_subelement[0]);
}
auto projection = (outside - inside).dot(normal);
if (projection < 0) {
normal *= -1.0;
}
}
/* -------------------------------------------------------------------------- */
template <class Derived>
inline void ContactDetector::vectorsAlongElement(
const Element & el, Eigen::MatrixBase<Derived> & vectors) const {
auto nb_nodes_per_element = Mesh::getNbNodesPerElement(el.type);
Matrix<Real> coords(spatial_dimension, nb_nodes_per_element);
this->coordinatesOfElement(el, coords);
for (auto i : arange(spatial_dimension - 1)) {
vectors(i) = coords(i + 1) - coords(0);
}
}
/* -------------------------------------------------------------------------- */
template <class Derived1, class Derived2,
std::enable_if_t<aka::are_vectors<Derived1, Derived2>::value> *>
inline Real
ContactDetector::computeGap(const Eigen::MatrixBase<Derived1> & slave,
const Eigen::MatrixBase<Derived2> & master) const {
auto gap = (master - slave).norm();
return gap;
}
/* -------------------------------------------------------------------------- */
inline void ContactDetector::filterBoundaryElements(
const Array<Element> & elements, Array<Element> & boundary_elements) const {
for (auto elem : elements) {
const auto & element_to_subelement =
mesh.getElementToSubelement(elem.type)(elem.element);
// for regular boundary elements
if (element_to_subelement.size() == 1 and
element_to_subelement[0].kind() == _ek_regular) {
boundary_elements.push_back(elem);
continue;
}
// for cohesive boundary elements
UInt nb_subelements_regular = 0;
for (auto subelem : element_to_subelement) {
if (subelem == ElementNull) {
continue;
}
if (subelem.kind() == _ek_regular) {
++nb_subelements_regular;
}
}
auto nb_subelements = element_to_subelement.size();
if (nb_subelements_regular < nb_subelements) {
boundary_elements.push_back(elem);
}
}
}
/* -------------------------------------------------------------------------- */
template <class Derived, std::enable_if_t<aka::is_vector_v<Derived>> *>
inline bool ContactDetector::isValidSelfContact(
const Idx & slave_node, const Real & gap,
const Eigen::MatrixBase<Derived> & normal) const {
Idx master_node{-1};
// finding the master node corresponding to slave node
auto it = std::find_if(
contact_pairs.begin(), contact_pairs.end(),
[slave_node](auto && pair) { return pair.first == slave_node; });
master_node = it->second;
auto && slave_elements = this->mesh.getAssociatedElements(slave_node);
// Check 1 : master node is not connected to elements connected to
// slave node
Vector<Real> slave_normal(spatial_dimension);
auto predicate = [](auto && element) {
return element.kind() == _ek_regular;
};
for (auto && element : filter_if(slave_elements, predicate)) {
auto && connectivity = this->mesh.getConnectivity(element);
auto coords = mesh.extractNodalValuesFromElement(positions, element);
// finding the normal at slave node by averaging of normals
auto normal = GeometryUtils::normal(mesh, coords, element);
slave_normal = slave_normal + normal;
auto node_iter =
std::find(connectivity.begin(), connectivity.end(), master_node);
if (node_iter != connectivity.end()) {
return false;
}
}
// Check 2 : if gap is twice the size of smallest element
if (std::abs(gap) > 2.0 * min_dd) {
return false;
}
// Check 3 : check the directions of normal at slave node and at
// master element, should be in opposite directions
auto norm = slave_normal.norm();
if (norm != 0) {
slave_normal /= norm;
}
auto product = slave_normal.dot(normal);
return not(product >= 0);
}
} // namespace akantu
#endif /* __AKANTU_CONTACT_DETECTOR_INLINE_IMPL_CC__ */
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