Returned-Part Analysis for Printed Photopolymers: Reconstructing Cure State, Exposure History and Contamination from a Failed Component

This Engineering Review examines the identifiability limits of reconstructing manufacture and service history from a failed vat-photopolymerised component. It separates present observations from historical attribution and explains why continuing cure, ageing and depletion of mobile species can allow different histories to converge on similar measurements. The review defines a bounded framework based on declared candidate histories, discriminating measurements, provenance preservation and known-history validation. It does not support universal reconstruction of cure dose, exposure history, contamination event or manufacturing cause, and it proposes no attribution rule, confidence figure or universal method-capability threshold.