private BiElasticMaterial2D(double youngModulus1, double equivalentYoungModulus1, double poissonRatio1,
                                    double equivalentPoissonRatio1, double thickness1, double youngModulus2, double equivalentYoungModulus2,
                                    double poissonRatio2, double equivalentPoissonRatio2, double thickness2,
                                    MaterialInterface2D bimaterialInterface)
        {
            MaterialUtilities.CheckYoungModulus(youngModulus1);
            MaterialUtilities.CheckPoissonRatio(poissonRatio1);
            MaterialUtilities.CheckThickness(thickness1);
            MaterialUtilities.CheckYoungModulus(youngModulus2);
            MaterialUtilities.CheckPoissonRatio(poissonRatio2);
            MaterialUtilities.CheckThickness(thickness2);

            this.YoungModulus1           = youngModulus1;
            EquivalentYoungModulus1      = equivalentYoungModulus1;
            this.PoissonRatio1           = poissonRatio1;
            this.EquivalentPoissonRatio1 = equivalentPoissonRatio1;
            this.Thickness1 = thickness1;

            this.YoungModulus2           = youngModulus2;
            EquivalentYoungModulus2      = equivalentYoungModulus2;
            this.PoissonRatio2           = poissonRatio2;
            this.EquivalentPoissonRatio2 = equivalentPoissonRatio2;
            this.Thickness2 = thickness2;

            this.bimaterialInterface = bimaterialInterface;
        }
        private HomogeneousElasticMaterial2D(double youngModulus, double equivalentYoungModulus, double poissonRatio,
                                             double equivalentPoissonRatio, double thickness)
        {
            MaterialUtilities.CheckYoungModulus(youngModulus);
            MaterialUtilities.CheckPoissonRatio(poissonRatio);
            MaterialUtilities.CheckThickness(thickness);

            HomogeneousYoungModulus           = youngModulus;
            HomogeneousEquivalentYoungModulus = equivalentYoungModulus;
            HomogeneousPoissonRatio           = poissonRatio;
            HomogeneousEquivalentPoissonRatio = equivalentPoissonRatio;
            HomogeneousThickness = thickness;
        }