Chaste Commit::baa90ac2819b962188b7562f2326be23c47859a7
CompressibleExponentialLaw.cpp
1/*
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34*/
35
36#include "CompressibleExponentialLaw.hpp"
37
38template<unsigned DIM>
40{
41 mA = 0.88; // kPa
42
43 double bff = 18.5; // dimensionless
44 double bss = 3.58; // dimensionless
45 double bnn = 3.58; // dimensionless
46 double bfn = 2.8; // etc
47 double bfs = 2.8;
48 double bsn = 2.8;
49
50 mCompressibilityParam = 100.0;
51
52 mB.resize(DIM);
53 for (unsigned i=0; i<DIM; i++)
54 {
55 mB[i].resize(DIM);
56 }
57
58 mB[0][0] = bff;
59 mB[0][1] = mB[1][0] = bfs;
60 mB[1][1] = bss;
61
62 if (DIM > 2)
63 {
64 mB[2][2] = bnn;
65 mB[0][2] = mB[2][0] = bfn;
66 mB[2][1] = mB[1][2] = bsn;
67 }
68
69 for (unsigned M=0; M<DIM; M++)
70 {
71 for (unsigned N=0; N<DIM; N++)
72 {
73 mIdentity(M,N) = M==N ? 1.0 : 0.0;
74 }
75 }
76}
77
78template<unsigned DIM>
80 c_matrix<double,DIM,DIM>& rInvC,
81 double pressure /* not used */,
82 c_matrix<double,DIM,DIM>& rT,
84 bool computeDTdE)
85{
86 static c_matrix<double,DIM,DIM> C_transformed;
87 static c_matrix<double,DIM,DIM> invC_transformed;
88
89 // The material law parameters are set up assuming the fibre direction is (1,0,0)
90 // and sheet direction is (0,1,0), so we have to transform C,inv(C),and T.
91 // Let P be the change-of-basis matrix P = (\mathbf{m}_f, \mathbf{m}_s, \mathbf{m}_n).
92 // The transformed C for the fibre/sheet basis is C* = P^T C P.
93 // We then compute T* = T*(C*), and then compute T = P T* P^T.
94
95 this->ComputeTransformedDeformationTensor(rC, rInvC, C_transformed, invC_transformed);
96
97 // Compute T*
98
99 c_matrix<double,DIM,DIM> E = 0.5*(C_transformed - mIdentity);
100
101 double QQ = 0;
102 for (unsigned M=0; M<DIM; M++)
103 {
104 for (unsigned N=0; N<DIM; N++)
105 {
106 QQ += mB[M][N]*E(M,N)*E(M,N);
107 }
108 }
109 assert(QQ < 10.0);
110 double multiplier = mA*exp(QQ);
111 rDTdE.Zero();
112
113 double J = sqrt(Determinant(rC));
114
115 for (unsigned M=0; M<DIM; M++)
116 {
117 for (unsigned N=0; N<DIM; N++)
118 {
119 rT(M,N) = multiplier*mB[M][N]*E(M,N) + mCompressibilityParam * J*log(J)*invC_transformed(M,N);
120
121 if (computeDTdE)
122 {
123 for (unsigned P=0; P<DIM; P++)
124 {
125 for (unsigned Q=0; Q<DIM; Q++)
126 {
127 rDTdE(M,N,P,Q) = multiplier * mB[M][N] * (M==P)*(N==Q)
128 + 2*multiplier*mB[M][N]*mB[P][Q]*E(M,N)*E(P,Q)
129 + mCompressibilityParam * (J*log(J) + J) * invC_transformed(M,N) * invC_transformed(P,Q)
130 - mCompressibilityParam * 2*J*log(J) * invC_transformed(M,P) * invC_transformed(Q,N);
131 }
132 }
133 }
134 }
135 }
136
137 // Now do: T = P T* P^T and dTdE_{MNPQ} = P_{Mm}P_{Nn}P_{Pp}P_{Qq} dT*dE*_{mnpq}
138 this->TransformStressAndStressDerivative(rT, rDTdE, computeDTdE);
139}
140
141// Explicit instantiation
142template class CompressibleExponentialLaw<2>;
143template class CompressibleExponentialLaw<3>;
T Determinant(const boost::numeric::ublas::c_matrix< T, 1, 1 > &rM)
void ComputeStressAndStressDerivative(c_matrix< double, DIM, DIM > &rC, c_matrix< double, DIM, DIM > &rInvC, double pressure, c_matrix< double, DIM, DIM > &rT, FourthOrderTensor< DIM, DIM, DIM, DIM > &rDTdE, bool computeDTdE)