Research, Verification and Uncertainty Analysis of Aircraft Structural Load/Strain Testing

The load/strain time–history experienced by aircraft structures during service is crucial original input data for structural life reliability design, life extension, and health monitoring management. Accurately and reliably measuring the strain time–history of aircraft structures and their corresponding loading states is key. Aiming to improve upon the shortcomings of traditional airborne strain measurement methods, this paper proposes a key strain airborne measurement method suitable for load-bearing structures based on the characteristics and requirements of a certain type of aircraft load-bearing structure. An airborne multi-channel synchronous sampling test and acquisition system is designed and integrated for airborne measurement and acquisition of key strains and corresponding loading states of load-bearing structures. The main factors affecting the output of aircraft structure strain airborne measurements are summarized. Based on this, an uncertainty evaluation model for the airborne strain testing system is established, and the uncertainty of the output strain is quantitatively given using multivariate fuzzy evaluation. The key strain time–history of the load-bearing structure is obtained through flight measurement data collection and processing, and the collected strain history is analyzed in combination with simultaneously collected flight parameters. The results show that the proposed airborne strain measurement method and the integrated airborne strain measurement and acquisition system can reliably measure and reproduce the real loading history of the structure, providing reliable data support for structural damage estimation and life prediction management. It also provides an effective and practical reference for strain measurement of other aircraft structures.