Orthotropic Linear Elastic Material

Linear orthotropic, linear elastic material model. The model parameters are summarized in table 2. Local coordinate system, which determines axes of material orthotrophy can by specified using lcs array. This array contains six numbers, where first three numbers represent directional vector of local x-axis, and next three numbers represent directional vector of local y-axis. The local z-axis is determined using vector product. The right-hand coordinate system is assumed. Local coordinate system can also be specified using scs parameter. Then local coordinate system is specified in so called ``shell'' coordinate system, which is defined locally on each particular element and its definition is as follows: principal z-axis is perpendicular to shell mid-section, x-axis is perpendicular to z-axis and normal to user specified vector (so x-axis is parallel to plane, with being normal to this plane) and y-axis is perpendicular both to x and z axes. This definition of coordinate system can be used only with plates and shells elements. When vector is parallel to z-axis an error occurs. The scs array contain three numbers defining direction vector . If no local coordinate system is specified, by default a global coordinate system is used.

For 3D case the material compliance matrix has the following form

$$\mbox{\boldmath$C$}=\left[\begin{array}{cccccc} 1/E_X & -\n... ...G_{xz} & 0\\ 0 & 0 & 0 & 0 & 0 & 1/G_{xy} \end{array}\right]$$ (1)

By inversion, the material stiffness matrix has the form

$$\mbox{\boldmath$D$}=\left[\begin{array}{cccccc} d_{xx} & d_... ...& G_{xz} & 0\\ 0 & 0 & 0 & 0 & 0 & G_{xy} \end{array}\right]$$ (2)

where $\xi=1-(\nu_{xy}*\nu_{yx}+\nu_{yz}*\nu_{zy}+\nu_{zx}*\nu_{xz})-(\nu_{xy}*\nu_{yz}*\nu_{zx}+\nu_{yx}*\nu_{zy}*\nu_{xz})$ and

$$d_{xx} = E_X(1-\nu_{yz}*\nu_{zy})/\xi,$$ (3)

$$d_{xy} = E_y*(\nu_{xy}+\nu_{xz}*\nu_{zy})/\xi,$$ (4)

$$d_{xz} = E_z*(\nu_{xz}+\nu_{yz}*\nu_{xy})/\xi,$$ (5)

$$d_{yy} = E_y*(1-\nu_{xz}*\nu_{zx})/\xi,$$ (6)

$$d_{yz} = E_z*(\nu_{yz}+\nu_{yx}*\nu_{xz})/\xi,$$ (7)

$$d_{zz} = E_z*(1-\nu_{yx}*\nu_{xy})/\xi.$$ (8)

$E_i$ is the Young's modulus in the $i$-th direction, $G_{ij}$ is the shear modulus in $ij$ plane, $\nu_{ij}$ major Poisson's ratio, and $\nu_{ji}$ minor Poisson's ratio. Assuming that $E_x>E_y>E_z$, $\nu_{xy} > \nu_{yx}$ etc., then the $\nu_{xy}$ is refered to as major Poisson's ratio, while $\nu_{yx}$ refered as minor Poisson's ratio. Note, that there is only nine independent material parameters, because of symmetry conditions. The symmetry condition yields

$$\nu_{xy}E_y=\nu_{yx}E_x,\ \ \nu_{yz}E_z=\nu_{zy}E_y,\ \ \nu_{zx}E_x=\nu_{xz}E_z$$

The model description and parameters are summarized in table 2.

Table 2: Orthotropic, linear elastic material - summary.

Description	Orthotropic, linear elastic material
Record Format	OrthoLE num(in) # d(rn) # Ex(rn) # Ey(rn) # Ez(rn) # NYyz(rn) # NYxz(rn) # NYxy(rn) # Gyz(rn) # Gxz(rn) # Gxy(rn) # tAlphax(rn) # tAlphay(rn) # tAlphaz(rn) # [ lcs(ra) #] [ scs(ra) #]
Parameters	- num material model number
	- d material density
	- Ex, Ey, Ez Young moduluses for x,y, and z directions
	- NYyz, NYxz, NYxy major Poisson's ratio coefficients
	- Gyz, Gxz, Gxy Shear moduluses
	- tAlphax, tAlphay, tAlphaz thermal dilatation coefficients in x,y,z directions
	- lcs Array defining local material x and y axes of orthotrophy
	- scs Array defining a normal vector n. The local x axis is parallel to plane with n being plane normal. The material local z-axis is perpendicular to shell mid-section.
Supported modes	3dMat, PlaneStress, PlaneStrain, 1dMat, 2dPlateLayer, 2dBeamLayer, 3dShellLayer, 2dPlate, 2dBeam, 3dShell, 3dBeam, PlaneStressRot