•Identification of microscopic damage mechanisms from acoustic emission signals.•Fiber-reinforced polymer-matrix specimens with single dominant damage mechanism.•Single dominant damage mechanisms active in limited volume or at selected time/load.•Extrapolating from microscopic damage mechanisms to structural integrity. Acoustic emission (AE) analysis for identifying microscopic damage mechanisms in fiber-reinforced polymer (FRP) composites has a long history. Recently, combining unsupervised pattern recognition with Finite Element Modelling (FEM) of signal generation, propagation, and sensor transfer function yielded source mechanism identifications of located sources for laboratory-scale FRP composite specimens. Designing FRP specimens yielding one specific damage mechanism that dominates the damage behavior, at least for selected stages of the damage development, allows for validating the pattern recognition-simulation approach for identifying the damage mechanisms. The challenge of using identified source mechanisms of located AE signals for structural integrity assessment is also discussed.