Modal Assurance Criterion (MAC)

Modal Assurance Criterion (MAC) is a measure of the correlation between two vibration shapes.

Supported vibration shapes include:
  • Real modes – vibration data at each node is a scalar value.
  • Complex modes – vibration data at each node is a complex value.
  • Response animation or operational deflection shape - vibration data at each node is a complex value.
The vibration shape results, along with the finite element mesh of the structure, are assumed to come in one of the following result files:
  • H3D – binary result file typically generated using OptiStruct.
  • OP2 – binary result file typically generated using OptiStruct or Nastran.
  • ODB - binary result file typically generated using Abaqus.
  • UNV – ASCII result file typically exported from a testing software.

Typically, the model that has less nodes, such as a test model, is used as the reference model.