Type:2-Tensor, or section
Range:[v_1, …, v_9]

Sets the linear thermal expansion coefficient \TField{\alpha}^{(\mathrm{L})} is the fractional change of length of an infinitesimal small body per degree of temperature change, that is

\TField{\alpha}^{(\mathrm{L})}_{\mathrm{L}} & = & \frac{1}{L} \frac{\dd L}{\dd T}.

Units are \units{1/K}. Since the length changes may be anisotropic the thermal expansion coefficient is a rank-2 tensor.

A constant linear thermal expansion coefficient can be defined by assigning a rank-2 tensor:

Material {
  # defines a constant conductivity
  LinearThermalExpansibility =
      [..., ..., ...
       ..., ..., ...
       ..., ..., ...]

Assign a scalar for an isotropic thermal expansibility.

For more general cases, the thermal expansibility may be given as a section in order to deal with space, time, and parameter dependent definitions:

# define the density as a section
LinearThermalExpansibility {
  Python {...}

Field definitions within the section LinearThermalExpansibility are summed up. Consult the subsequent sections to see which types of field definitions are allowed.