XFEM Failure Analysis Report

Introduction

The FAR for the XFEM module describes the system functional and non-functional requirements that describe the expected interactions that the software shall provide.

Dependencies

The XFEM module is developed using MOOSE and can itself be based on various MOOSE modules, as such the FAR for the XFEM module is dependent upon the following documents.

Framework Failure Analysis Report
sqa/tensor_mechanics_far.md

Failure Analysis Requirements

The following is a complete list for all the requirements related to failure analysis for the XFEM module.

xfem: Mesh Cut 2D Fracture
23.9.1
The XFEM module shall represent a propagating crack in a 2D mechanics model with XFEM, where the crack is defined using a topologically defined surface cutting mesh by MeshCut2DFunctionUserObject
1. and crack growth and direction is computed by a fracture integral with constant fracture toughness.
2. and crack growth and direction is computed by a fracture integral with fracture toughness sampled from a material at the crack tip.
3. and crack growth is a maximum stress criterion and the growth direction is in the original crack direction.
4. and crack growth and direction is computed by a fracture integral with constant fracture toughness or maximum stress criterion.
5. and produce an error when fracture toughness is specified by more than one input source.
6. and crack growth is defined by a function. The average crack tip stress changes with crack orientation and properly accounts volume averaging near surfaces.
Specification(s): 2D/k_growth, 2D/kvpp_growth, 2D/stress_growth, 2D/k_stress_growth, 2D/k_error, 2D/stress_check
Design: MeshCut2DFunctionUserObject
Issue(s): #23572 #27659
Collection(s): FUNCTIONALFAILURE_ANALYSIS
Type(s): RunExceptionCSVDiffExodiff
24 24 24 24 24 24

xfem: Nucleation Uo
23.12.4The system shall error if the nucleation length is smaller than the element being cut.
Specification(s): errorSmallCut
Design: MeshCut2DRankTwoTensorNucleation
Issue(s): #27054
Collection(s): FUNCTIONALFAILURE_ANALYSIS
Type(s): RunException
24


[k_growth]
  type = Exodiff
  input = 'edge_crack_2d_propagation.i kcrit_based_meshCut_uo.i'
  exodiff = 'kcrit_based_meshCut_uo_xfemcutter_XFEMCutMeshOutput.e-s0004'
  abs_zero = 1e-8
  map = false
  # XFEM requires --enable-unique-ids in libmesh
  capabilities = 'unique_id'
  detail = ' and crack growth and direction is computed by a fracture integral with constant fracture toughness.'
[]


[kvpp_growth]
  type = Exodiff
  input = 'edge_crack_2d_propagation.i kvpp_based_meshCut_uo.i'
  exodiff = 'kvpp_based_meshCut_uo_xfemcutter_XFEMCutMeshOutput.e-s0004'
  abs_zero = 1e-8
  map = false
  # XFEM requires --enable-unique-ids in libmesh
  capabilities = 'unique_id'
  detail = ' and crack growth and direction is computed by a fracture integral with fracture toughness sampled from a material at the crack tip.'
[]


[stress_growth]
  type = Exodiff
  input = 'edge_crack_2d_propagation.i stress_based_meshCut_uo.i'
  exodiff = 'stress_based_meshCut_uo_xfemcutter_XFEMCutMeshOutput.e-s0004'
  abs_zero = 1e-8
  map = false
  # XFEM requires --enable-unique-ids in libmesh
  capabilities = 'unique_id'
  detail = ' and crack growth is a maximum stress criterion and the growth direction is in the original crack direction.'
[]


[k_stress_growth]
  type = Exodiff
  input = 'edge_crack_2d_propagation.i kcrit_stress_based_meshCut_uo.i'
  exodiff = 'kcrit_stress_based_meshCut_uo_xfemcutter_XFEMCutMeshOutput.e-s0004'
  abs_zero = 1e-8
  map = false
  # XFEM requires --enable-unique-ids in libmesh
  capabilities = 'unique_id'
  detail = ' and crack growth and direction is computed by a fracture integral with constant fracture toughness or maximum stress criterion.'
[]


[k_error]
  type = 'RunException'
  input = 'edge_crack_2d_propagation.i kvpp_based_meshCut_uo.i'
  cli_args = "UserObjects/cut_mesh2/k_critical=100"
  expect_err = 'Fracture toughness cannot be specified by both k_critical and k_critical_vectorpostprocessor.'
  detail = ' and produce an error when fracture toughness is specified by more than one input source.'
[]


[stress_check]
  type = CSVDiff
  input = crack_front_stress_function_growth.i
  csvdiff = 'stress_check_CrackFrontNonlocalStress_0001.csv stress_check_CrackFrontNonlocalStress_0002.csv stress_check_CrackFrontNonlocalStress_0003.csv stress_check_CrackFrontNonlocalStress_0004.csv'
  # XFEM requires --enable-unique-ids in libmesh
  capabilities = 'unique_id'
  detail = ' and crack growth is defined by a function.  The average crack tip stress changes with crack orientation and properly accounts volume averaging near surfaces.'
[]


[errorSmallCut]
  issues = '#27054'
  type = RunException
  input = nucleate_bulkCrack.i
  cli_args = 'UserObjects/nucleate/nucleation_length=.001'
  expect_err = 'Trying to nucleate crack smaller than element length'
  # XFEM requires --enable-unique-ids in libmesh
  capabilities = 'unique_id'
  requirement = 'The system shall error if the nucleation length is smaller than the element being cut.'
[]

Introduction
Dependencies
Failure Analysis Requirements