[
  {
    "id": 1,
    "name": "matrix",
    "description": "Matrix material with lower stiffness",
    "isotropy": 0,
    "density": 1000.0,
    "e": 1.0e9,
    "nu": 0.3
  },
  {
    "id": 2,
    "name": "inclusion",
    "description": "Spherical inclusion material with higher stiffness",
    "isotropy": 0,
    "density": 2500.0,
    "e": 1.0e11,
    "nu": 0.25
  }
]