SeismicSource Syntax

The input file syntax for SeismicSource with the the [DiracKernels] block provides syntax for creating the correct SeismicSource dirac kernels for each direction components specified.

Example Usage

[DiracKernels<<<{"href": "../index.html"}>>>]
  [./SeismicSource<<<{"href": "index.html"}>>>]
    [./one_source]
      displacements<<<{"description": "The vector of displacement variables."}>>> = 'disp_x disp_y disp_z'
      point<<<{"description": "The x, y and z coordinate of a single point source."}>>> = '0.25 0.25 0.25'
      slip<<<{"description": "The function describing slip as a function of time."}>>> = y_force
      strike<<<{"description": "The strike angle of the fault in degrees."}>>> = 0.0 # strike angle =0, x aligned with North
      dip<<<{"description": "The dip angle of the fault in degrees."}>>> = 45.0 # dip angle = pi/4, angle fault makes with horizontal
      rake<<<{"description": "The rake angle of the fault in degrees."}>>> = 90.0 # rake angle = pi/2, gives slip direction
      shear_modulus<<<{"description": "The shear modulus of the soil around the seismic source."}>>> = 1.0
      area<<<{"description": "The area over which slip is distributed."}>>> = 1.0
    [../]
  [../]
[]

Input Parameters

areaThe area over which slip is distributed.
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:The area over which slip is distributed.
dipThe dip angle of the fault in degrees.
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:The dip angle of the fault in degrees.
displacementsThe vector of displacement variables.
C++ Type:std::vector<NonlinearVariableName>
Unit:(no unit assumed)
Controllable:No
Description:The vector of displacement variables.
rakeThe rake angle of the fault in degrees.
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:The rake angle of the fault in degrees.
shear_modulusThe shear modulus of the soil around the seismic source.
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:The shear modulus of the soil around the seismic source.
slipThe function describing slip as a function of time.
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:The function describing slip as a function of time.
strikeThe strike angle of the fault in degrees.
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:The strike angle of the fault in degrees.

Required Parameters

active__all__ If specified only the blocks named will be visited and made active
Default:__all__
C++ Type:std::vector<std::string>
Controllable:No
Description:If specified only the blocks named will be visited and made active
alpha0The Hilber Hughes Taylor (HHT) time integration parameter.
Default:0
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:The Hilber Hughes Taylor (HHT) time integration parameter.
epicenterThe x, y and z coordinates of the epicenter.
C++ Type:std::vector<double>
Unit:(no unit assumed)
Controllable:No
Description:The x, y and z coordinates of the epicenter.
inactiveIf specified blocks matching these identifiers will be skipped.
C++ Type:std::vector<std::string>
Controllable:No
Description:If specified blocks matching these identifiers will be skipped.
numberThe number of point sources. This number should be same as number of entries in the function files describing the position of the point source.
C++ Type:unsigned int
Controllable:No
Description:The number of point sources. This number should be same as number of entries in the function files describing the position of the point source.
pointThe x, y and z coordinate of a single point source.
C++ Type:std::vector<double>
Unit:(no unit assumed)
Controllable:No
Description:The x, y and z coordinate of a single point source.
position_functionThe vector of function names that describes the x, y and z coordinates of the source. Only the x positionfunction is required for 1 dimensional problems, x and ypositions are required for 2 dimensional problems and x, y and z positions are required for 3D problems. The firstcolumn in these functions gives source number (startingwith 1) and the second column contains the coordinate.
C++ Type:std::vector<FunctionName>
Unit:(no unit assumed)
Controllable:No
Description:The vector of function names that describes the x, y and z coordinates of the source. Only the x positionfunction is required for 1 dimensional problems, x and ypositions are required for 2 dimensional problems and x, y and z positions are required for 3D problems. The firstcolumn in these functions gives source number (startingwith 1) and the second column contains the coordinate.
rupture_speedThe speed at which the earthquake rupture propogates through the fault (usually around 0.8 * shear wave speed).
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:The speed at which the earthquake rupture propogates through the fault (usually around 0.8 * shear wave speed).

Optional Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.

Advanced Parameters

(test/tests/dirackernels/seismic_source/one_seismic_source.i)

#@requirement F7.1
# Test for seismic source applied at one point.

# This test consists of one brick element of size 1x1x1.

# An earthquake source (double couple) is applied at 0.25,0.25,0.25. The earthquake fault
# has 0 strike angle (i.e., x axis is aligned with geographic north). The dip angle is 45 degrees
# and the rake angle is 90 degrees. The slip (s) is a linearly increasing function of time.

# The forces resulting due to the earthquake source is distributed to the 8 nodes of the element.
# The expression for nodal forces for this particular fault configuration is
# f_x^n = 0.0
# f_y^n = -Mo*dphi_n/dy
# f_z^n = Mo*dphi_n/dz
# where f_x^n, f_y^n and f_z^n are the forces in x, y and z directions, respectively. Mo is the
# seismic moment = area*shear_modulus* slip and dphi_n/dy and dphi_n/dz are the derivatives of
# shape functions corresponding to node n in y and z directions, respectively, evaluated at the
# point (0.25, 0.25, 0.25).
#
# To check if forces are distributed as expected, we apply negative of these nodal forces to the
# nodal points using nodalkernels. The nodeset numbers used for applying nodal forces matches with the node
# numbers in the output exodus file.
# Result: Net force on the element is zero. So element is in equilibrium with zero displacements.

[Mesh]
  file = test_element_3d.e
[]


[Variables]
  [./disp_x]
  [../]
  [./disp_y]
  [../]
  [./disp_z]
  [../]
[]

[Kernels]
  [./DynamicTensorMechanics]
    displacements = 'disp_x disp_y disp_z'
  [../]
[]

[DiracKernels]
  [./SeismicSource]
    [./one_source]
      displacements = 'disp_x disp_y disp_z'
      point = '0.25 0.25 0.25'
      slip = y_force
      strike = 0.0 # strike angle =0, x aligned with North
      dip = 45.0 # dip angle = pi/4, angle fault makes with horizontal
      rake = 90.0 # rake angle = pi/2, gives slip direction
      shear_modulus = 1.0
      area = 1.0
    [../]
  [../]
[]

[NodalKernels]
  [./force_1y]
    type = UserForcingFunctionNodalKernel
    variable = disp_y
    boundary = 1
    function = force_1y
  [../]
  [./force_2y]
    type = UserForcingFunctionNodalKernel
    variable = disp_y
    boundary = 2
    function = force_2y
  [../]
  [./force_3y]
    type = UserForcingFunctionNodalKernel
    variable = disp_y
    boundary = 3
    function = force_3y
  [../]
  [./force_4y]
    type = UserForcingFunctionNodalKernel
    variable = disp_y
    boundary = 4
    function = force_4y
  [../]
  [./force_5y]
    type = UserForcingFunctionNodalKernel
    variable = disp_y
    boundary = 5
    function = force_5y
  [../]
  [./force_6y]
    type = UserForcingFunctionNodalKernel
    variable = disp_y
    boundary = 6
    function = force_6y
  [../]
  [./force_7y]
    type = UserForcingFunctionNodalKernel
    variable = disp_y
    boundary = 7
    function = force_7y
  [../]
  [./force_8y]
    type = UserForcingFunctionNodalKernel
    variable = disp_y
    boundary = 8
    function = force_8y
  [../]
  [./force_1z]
    type = UserForcingFunctionNodalKernel
    variable = disp_z
    boundary = 1
    function = force_1z
  [../]
  [./force_2z]
    type = UserForcingFunctionNodalKernel
    variable = disp_z
    boundary = 2
    function = force_2z
  [../]
  [./force_3z]
    type = UserForcingFunctionNodalKernel
    variable = disp_z
    boundary = 3
    function = force_3z
  [../]
  [./force_4z]
    type = UserForcingFunctionNodalKernel
    variable = disp_z
    boundary = 4
    function = force_4z
  [../]
  [./force_5z]
    type = UserForcingFunctionNodalKernel
    variable = disp_z
    boundary = 5
    function = force_5z
  [../]
  [./force_6z]
    type = UserForcingFunctionNodalKernel
    variable = disp_z
    boundary = 6
    function = force_6z
  [../]
  [./force_7z]
    type = UserForcingFunctionNodalKernel
    variable = disp_z
    boundary = 7
    function = force_7z
  [../]
  [./force_8z]
    type = UserForcingFunctionNodalKernel
    variable = disp_z
    boundary = 8
    function = force_8z
  [../]
[]

[Materials]
  [./Elasticity_tensor_1]
    type = ComputeIsotropicElasticityTensor
    block = 1
    youngs_modulus = 2.e+2
    poissons_ratio = 0.4
  [../]

  [./strain_1]
    type = ComputeSmallStrain
    block = 1
    displacements = 'disp_x disp_y disp_z'
  [../]

  [./stress_1]
    type = ComputeLinearElasticStress
    block = 1
  [../]

  [./density_1]
    type = GenericConstantMaterial
    block = 1
    prop_names = 'density'
    prop_values = '1.'
  [../]

[]

[Executioner]
  type = Transient
  solve_type = 'PJFNK'
  start_time = 0
  end_time = 5.0
  l_tol = 1e-10
  nl_abs_tol = 1e-10
  dt = 1.0
  timestep_tolerance = 1e-12
[]

[Functions]
  [./y_force]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
  [../]
  [./force_1y]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = -0.1875
  [../]
  [./force_2y]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = -0.0625
  [../]
  [./force_3y]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = 0.0625
  [../]
  [./force_4y]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = 0.1875
  [../]
  [./force_5y]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = -0.5625
  [../]
  [./force_6y]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = -0.1875
  [../]
  [./force_7y]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = 0.1875
  [../]
  [./force_8y]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = 0.5625
  [../]
  [./force_1z]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = -0.0625
  [../]
  [./force_2z]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = 0.0625
  [../]
  [./force_3z]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = 0.1875
  [../]
  [./force_4z]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = -0.1875
  [../]
  [./force_5z]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = -0.1875
  [../]
  [./force_6z]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = 0.1875
  [../]
  [./force_7z]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = 0.5625
  [../]
  [./force_8z]
    type = PiecewiseLinear
    x = '0.0 1.0 2.0 3.0 4.0 5.0'
    y = '0.0 1.0 2.0 3.0 4.0 5.0'
    scale_factor = -0.5625
  [../]
[]

[Postprocessors]
  [./_dt]
    type = TimestepSize
  [../]
  [./disp_1]
    type = NodalVariableValue
    nodeid = 0
    variable = disp_x
  [../]
  [./disp_2]
    type = NodalVariableValue
    nodeid = 0
    variable = disp_y
  [../]
[]

[Outputs]
  exodus = true
  csv = true
  print_linear_residuals = true
  perf_graph = true
[]

Example Usage
Input Parameters

Usage

Development

Demonstration

SeismicSource Syntax

Example Usage

Input Parameters

Required Parameters

Optional Parameters

Advanced Parameters