public static PlateBendingStressTensor Multiply(PlateBendingStressTensor t1, double coef)
        {
            var buf = new PlateBendingStressTensor();

            buf.Mx  = t1.Mx * coef;
            buf.My  = t1.My * coef;
            buf.Mxy = t1.Mxy * coef;

            return(buf);
        }
        public double Mx, My, Mxy; //fig 3, AN EXPLICIT FORMULATION FOR AN EFFICIENT TRIANGULAR PLATE-BENDING ELEMENT

        public static PlateBendingStressTensor operator +(PlateBendingStressTensor left, PlateBendingStressTensor right)
        {
            var buf = new PlateBendingStressTensor();

            buf.Mx  = left.Mx + right.Mx;
            buf.My  = left.My + right.My;
            buf.Mxy = left.Mxy + right.Mxy;

            return(buf);
        }