Elastic Properties

In Examine2D there are two options for defining the elastic properties of your material:

• Isotropic - elastic properties are the same in all directions

• Transversely Isotropic - elastic properties vary with direction

To define the Elastic Properties:

1. Select the Elastic Properties type (Isotropic or Transversely Isotropic) from the Project Settings dialog, or by clicking on the Elastic Properties button in the Sidebar.

2. Enter the Elastic Properties (e.g. Young's Modulus, Poisson's Ratio) in the Sidebar. See below for more information.

NOTE: if your material is rock, then you must enter the elastic properties of the rock mass (i.e. the large scale deformation modulus and Poisson's ratio of the rock mass, NOT the intact rock properties). The program RocData can be used to estimate rock mass modulus, click here for details.

Isotropic

An Isotropic material implies that the material properties do not vary with direction. The elastic properties of an Isotropic material are fully defined by:

• a single value of Young’s Modulus (Em)

• a single value of Poisson’s Ratio.

Transversely Isotropic

A Transversely Isotropic material has properties which vary with direction. The elastic properties are specified in two orthogonal directions (1 and 2) as follows:

• Em1 and Em2 are the IN PLANE values of Young's Modulus (i.e. deformation modulus) in the 1 and 2 directions. NOTE: the letter "m" denotes the rock mass properties, as opposed to the intact rock properties.

• Emz (the OUT OF PLANE elastic modulus) is assumed to be equal to Em1, for a Transversely Isotropic material.

• Shear Modulus (1-2) is the IN PLANE shear modulus

• The Angle is measured between the X-direction and the direction of E1, as shown in the figure below.

• Two values of Poisson’s Ratio are required:  n12 and n1Z (=nZ1 = n). Note that nij implies strain in the j-direction due to strain in the i-direction. Also note that Ei / Ej = nij / nji. Therefore, the plane 1-Z is an isotropic plane.

Definition of Angle for Transversely Isotropic materials

NOTE:

• If you use Transversely Isotropic elastic properties, then you must use Analysis Type = Plane Strain, and Element Type = Constant.

• You CANNOT use Transversely Isotropic elastic properties in conjunction with Analysis Type = Complete Plane Strain, or Element Type = Linear or Quadratic.