Added nodal_target_force load, which can be used to ramp down reactio…

…n forces produced by prescribed displacements.

FEBioMech/FEBioMechModule.cpp

@@ -272,6 +272,7 @@ SOFTWARE.*/
 
 #include "FEInitialVelocity.h"
 #include "FENodalForce.h"
+#include "FENodalTargetForce.h"
 
 #include "FEPreStrainElastic.h"
 #include "FEPreStrainUncoupledElastic.h"
@@ -632,6 +633,7 @@ void FEBioMech::InitModule()
 	//-----------------------------------------------------------------------------
 	// classes derived from FENodalLoad
 	REGISTER_FECORE_CLASS(FENodalForce, "nodal_force");
+	REGISTER_FECORE_CLASS(FENodalTargetForce, "nodal_target_force");
 
 	//-----------------------------------------------------------------------------
 	// classes derived from FESurfaceLoad

FEBioMech/FENodalTargetForce.cpp

@@ -0,0 +1,78 @@
+/*This file is part of the FEBio source code and is licensed under the MIT license
+listed below.
+
+See Copyright-FEBio.txt for details.
+
+Copyright (c) 2021 University of Utah, The Trustees of Columbia University in
+the City of New York, and others.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.*/
+#include "stdafx.h"
+#include "FENodalTargetForce.h"
+#include "FEBioMech.h"
+#include <FECore/FENodeSet.h>
+#include <FECore/FEMaterialPoint.h>
+#include <FECore/FENode.h>
+
+// NOTE: We pass FEModelLoad as the base since I don't want the relative flag
+BEGIN_FECORE_CLASS(FENodalTargetForce, FEModelLoad)
+	ADD_PARAMETER(m_w, "scale")->setUnits(UNIT_NONE)->SetFlags(FE_PARAM_ADDLC | FE_PARAM_VOLATILE);
+	ADD_PARAMETER(m_f, "force")->setUnits(UNIT_FORCE);
+	ADD_PARAMETER(m_shellBottom, "shell_bottom");
+END_FECORE_CLASS();
+
+FENodalTargetForce::FENodalTargetForce(FEModel* fem) : FENodalLoad(fem)
+{
+	m_w = 1;
+	m_f = vec3d(0, 0, 0);
+	m_shellBottom = false;
+}
+
+void FENodalTargetForce::Activate()
+{
+	// use a little hack to get the initial reaction forces
+	m_brelative = true;
+	FENodalLoad::Activate();
+	m_brelative = false;
+}
+
+bool FENodalTargetForce::SetDofList(FEDofList& dofList)
+{
+	if (m_shellBottom)
+		return dofList.AddVariable(FEBioMech::GetVariableName(FEBioMech::SHELL_DISPLACEMENT));
+	else
+		return dofList.AddVariable(FEBioMech::GetVariableName(FEBioMech::DISPLACEMENT));
+}
+
+void FENodalTargetForce::GetNodalValues(int inode, std::vector<double>& val)
+{
+	assert(val.size() == 3);
+	const FENodeSet& nset = *GetNodeSet();
+	const FENode& node = *nset.Node(inode);
+
+	FEMaterialPoint mp;
+	mp.m_r0 = node.m_r0;
+	mp.m_index = inode;
+
+	vec3d f = m_f(mp);
+
+	val[0] = m_rval[inode][0] * (1.0 - m_w) + m_w * f.x;
+	val[1] = m_rval[inode][1] * (1.0 - m_w) + m_w * f.y;
+	val[2] = m_rval[inode][2] * (1.0 - m_w) + m_w * f.z;
+}

FEBioMech/FENodalTargetForce.h

@@ -0,0 +1,52 @@
+/*This file is part of the FEBio source code and is licensed under the MIT license
+listed below.
+
+See Copyright-FEBio.txt for details.
+
+Copyright (c) 2021 University of Utah, The Trustees of Columbia University in
+the City of New York, and others.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.*/
+#pragma once
+#include <FECore/FENodalLoad.h>
+#include "febiomech_api.h"
+
+class FEBIOMECH_API FENodalTargetForce : public FENodalLoad
+{
+public:
+	FENodalTargetForce(FEModel* fem);
+
+	void Activate() override;
+
+protected: // required functions of FENodalLoad
+
+	// Set the dof list
+	bool SetDofList(FEDofList& dofList) override;
+
+	// get the nodal values
+	void GetNodalValues(int inode, std::vector<double>& val) override;
+
+private:
+	double			m_w;
+	FEParamVec3		m_f;
+	bool			m_shellBottom;
+
+	DECLARE_FECORE_CLASS();
+};
+

FECore/FENodalLoad.h

@@ -80,7 +80,7 @@ class FECORE_API FENodalLoad : public FEModelLoad
 	//! evaluate the contribution to the global stiffness matrix
 	virtual void StiffnessMatrix(FELinearSystem& LS) override;
 
-private:
+protected:
 	FEDofList	m_dofs;
 	FENodeSet*	m_nodeSet;
 	bool		m_brelative;