1 // ============================================================================= 2 // PROJECT CHRONO - http://projectchrono.org 3 // 4 // Copyright (c) 2014 projectchrono.org 5 // All rights reserved. 6 // 7 // Use of this source code is governed by a BSD-style license that can be found 8 // in the LICENSE file at the top level of the distribution and at 9 // http://projectchrono.org/license-chrono.txt. 10 // 11 // ============================================================================= 12 // Authors: Alessandro Tasora, Radu Serban 13 // ============================================================================= 14 15 #ifndef CHVARIABLESSHAFT_H 16 #define CHVARIABLESSHAFT_H 17 18 #include "chrono/solver/ChVariables.h" 19 20 namespace chrono { 21 22 class ChShaft; 23 24 /// Specialized class for representing a 1-DOF item for a system, that is 25 /// a shaft, with inertia and associated variable (rotational speed) 26 27 class ChApi ChVariablesShaft : public ChVariables { 28 private: 29 ChShaft* m_shaft; ///< associated shaft element 30 double m_inertia; ///< shaft inertia 31 double m_inv_inertia; ///< inverse of shaft inertia value 32 33 public: ChVariablesShaft()34 ChVariablesShaft() : ChVariables(1), m_shaft(NULL), m_inertia(1), m_inv_inertia(1) {} ~ChVariablesShaft()35 virtual ~ChVariablesShaft() {} 36 37 /// Assignment operator: copy from other object 38 ChVariablesShaft& operator=(const ChVariablesShaft& other); 39 40 /// The number of scalar variables in the vector qb 41 /// (dof=degrees of freedom) Get_ndof()42 virtual int Get_ndof() const override { return 1; } 43 44 /// Get the inertia associated with rotation of the shaft GetInertia()45 double GetInertia() const { return m_inertia; } 46 47 /// Get the inverse of the inertia associated with rotation of the shaft GetInvInertia()48 double GetInvInertia() const { return m_inv_inertia; } 49 50 /// Set the inertia associated with rotation of the shaft 51 void SetInertia(double inertia); 52 GetShaft()53 ChShaft* GetShaft() { return m_shaft; } SetShaft(ChShaft * shaft)54 void SetShaft(ChShaft* shaft) { m_shaft = shaft; } 55 56 /// Computes the product of the inverse mass matrix by a 57 /// vector, and set in result: result = [invMb]*vect 58 virtual void Compute_invMb_v(ChVectorRef result, ChVectorConstRef vect) const override; 59 60 /// Computes the product of the inverse mass matrix by a 61 /// vector, and increment result: result += [invMb]*vect 62 virtual void Compute_inc_invMb_v(ChVectorRef result, ChVectorConstRef vect) const override; 63 64 /// Computes the product of the mass matrix by a 65 /// vector, and set in result: result = [Mb]*vect 66 virtual void Compute_inc_Mb_v(ChVectorRef result, ChVectorConstRef vect) const override; 67 68 /// Computes the product of the corresponding block in the system matrix (ie. the mass matrix) by 'vect', scale by 69 /// c_a, and add to 'result'. 70 /// NOTE: the 'vect' and 'result' vectors must already have the size of the total variables&constraints in the 71 /// system; the procedure will use the ChVariable offsets (that must be already updated) to know the indexes in 72 /// result and vect. 73 virtual void MultiplyAndAdd(ChVectorRef result, ChVectorConstRef vect, const double c_a) const override; 74 75 /// Add the diagonal of the mass matrix scaled by c_a, to 'result'. 76 /// NOTE: the 'result' vector must already have the size of system unknowns, ie the size of the total variables & 77 /// constraints in the system; the procedure will use the ChVariable offset (that must be already updated) as index. 78 virtual void DiagonalAdd(ChVectorRef result, const double c_a) const override; 79 80 /// Build the mass matrix (for these variables) scaled by c_a, storing 81 /// it in 'storage' sparse matrix, at given column/row offset. 82 /// Note, most iterative solvers don't need to know mass matrix explicitly. 83 /// Optimized: doesn't fill unneeded elements except mass. 84 virtual void Build_M(ChSparseMatrix& storage, int insrow, int inscol, const double c_a) override; 85 86 /// Method to allow serialization of transient data to archives. ArchiveOUT(ChArchiveOut & marchive)87 virtual void ArchiveOUT(ChArchiveOut& marchive) override { 88 // version number 89 marchive.VersionWrite<ChVariablesShaft>(); 90 // serialize parent class 91 ChVariables::ArchiveOUT(marchive); 92 // serialize all member data: 93 marchive << CHNVP(m_inertia); 94 } 95 96 /// Method to allow de-serialization of transient data from archives. ArchiveIN(ChArchiveIn & marchive)97 virtual void ArchiveIN(ChArchiveIn& marchive) override { 98 // version number 99 /*int version =*/ marchive.VersionRead<ChVariablesShaft>(); 100 // deserialize parent class 101 ChVariables::ArchiveIN(marchive); 102 // stream in all member data: 103 marchive >> CHNVP(m_inertia); 104 SetInertia(m_inertia); 105 } 106 }; 107 108 } // end namespace chrono 109 110 #endif 111