1) The document describes a workflow for improving fatigue analysis quality through virtual iteration of multi-body system (MBS) models using load data from physical testing.
2) Sensors measure response data like accelerations, displacements, and strains during physical testing, which is analyzed to generate load data to drive virtual MBS models through an iterative process.
3) The virtual iteration technique aims to match simulated response data from the MBS model with the physical test response data, allowing internal loads and stresses from the MBS to be used for more accurate fatigue analysis.