10.1 Stress_Model: Linear Isotropic Elasticity Model

LINEAR_ELASTIC

Material_name = LINEAR_ELASTIC

Material_set_number = mset , etc...

Only two material constants are needed to fully define the linear isotropic elastic model (e.g., Young's modulus and Poisson's ratio.)

Note Variable Name Type Default Description

• Keywords Read Method

Material_set_number integer [1] Material set number Numat

Elastic_case list [*] Elastic case

incremental / total

Plane_stress list [off] Plane stress option

on / off

Mass_density real [0.0] Mass density

Youngs_modulus real [0.0] Young's modulus E

(1) Poissons_ratio real [0.0] Poisson's ratio

Shear_modulus real [0.0] Shear modulus G

Bulk_modulus real [0.0] Bulk modulus B

(2) Mass_damping real [0.0] Rayleigh mass damping coefficient

(2) Stiffness_damping real [0.0] Rayleigh stiffness damping coefficient

(3) Solid_mass_density real [0.0] Mass density (Solid Phase)

(3) Fluid_mass_density real [0.0] Mass density (Fluid Phase)

(3) Fluid_bulk_modulus real [0.0] Fluid bulk modulus

(3) Porosity real [0.0] Porosity

(4) Viscoelastic_data string [none] Viscoelastic data

relaxation_time real [0.0] Relaxation time

relaxation_bulk_modulus real [0.0] Relaxation bulk modulus value

relaxation_shear_modulus real [0.0] Relaxation shear modulus value

(cont’d)

(cont'd)

Note Variable Name Type Default Description

(5) Initial_stress

initial_stress_11 real [0.0] Component 11 ()

initial_stress_22 real [0.0] Component 22 ()

initial_stress_33 real [0.0] Component 33 ()

initial_stress_12 real [0.0] Component 12 ()

initial_stress_23 real [0.0] Component 23 ()

initial_stress_31 real [0.0] Component 31 ()

• List Read Method

Material data must follow in the form:

< m, E(m), Pois(m), (m), (m), (m), (m), Pf(m) >
< Dampm (m), Dampk (m) >

< (Stres(i,m), i = 1, 6) >

< terminate with a blank record >.

Notes/

(1) Poisson's ratio cannot be set equal to 1/2 since it results in division by zero. A value close to 1/2, say .4999, can be employed for incompressible applications.

(2) The element damping matrix is computed as:

c = Rayleigh_mass_damp*m + Rayleigh_stiffness_damp*k

(3) Only applicable to porous media models.

(4) Isotropic viscoelasticity is simulated using an exponential (Prony) series for the bulk and shear functions. The viscoelastic data consists of the relaxation bulk and shear moduli values at specific relaxation times for each term in the series.

(5) Tensile stresses are positive

Notes . .

Notes . .