The curve material model is available for truss, 2D, brick and tetrahedral elements. This material model is applicable for all MES/nonlinear structural analyses. This model describes the response of geological materials. In the model, the instantaneous bulk and shear moduli are defined by piece-wise linear functions of the current volume strain. An explicit yield condition is not used, and whether the material is loading or unloading is defined by the history of the volume strain only. The material properties will be entered for multiple strain values in a tabular format. You can add a row to the bottom of the table by pressing the Add Row button. You can delete a row from the table by selecting the row and pressing the Delete Row button The strain values must be input in ascending order. The data can be sorted according to increasing strains by pressing the Sort button. The material properties will be linearly interpolated between strain values. The strain values must cover the range of strains that will be encountered in the model. You can also import the material properties from a csv file by pressing the Import button. The data in the csv file must be formatted into 4 columns. The properties should be in the same order as they appear in the table.
Strain
This material property is only applicable to truss elements. Specify the true strain values at which stress data is available. The stress values will be linearly interpolated between strain values. The strain values must enclose the range of strains that will be encountered in the model.
Stress
This material property is only applicable to truss elements. Specify the true stress values at each true strain values. The stress values will be linearly interpolated between strain values.
Volumetric Strain
This material property is only applicable to 2D, brick and tetrahedral elements. Specify the volumetric strain values at which stress data is available. The volumetric strain can be found from the following equation: (strain in local 1 direction + strain in local 2 direction + strain in local 3 direction)/3. The stress values will be linearly interpolated between volumetric strain values. The volumetric strain values must enclose the range of volumetric strains that will be encountered in the model.
Bulk Modulus
This material property is only applicable to 2D, brick and tetrahedral elements. Specify the loading bulk modulus of elasticity for each volumetric strain value. The loading bulk modulus can be found from the following equation: E/3*(1-2ν) where E is the modulus of elasticity of the material and ν is the Poisson's ratio of the material. This term is used when the model is in a loaded state.
Unload Bulk
This material property is only applicable to 2D, brick and tetrahedral elements. Specify the unloading bulk modulus of elasticity for each volumetric strain value. The unloading bulk modulus of elasticity can be found from the following equation: E/3*(1-2ν) where E is the modulus of elasticity of the material and ν is the Poisson's ratio of the material. This term is used when the model is in an unloaded state.
Shear
This material property is only applicable to 2D, brick and tetrahedral elements. Specify the shear modulus of elasticity for each volumetric strain value. The shear modulus of elasticity is the slope of the shear stress versus shear strain of a material before the proportionality limit. This is also referred to as the modulus of rigidity.