Structural Health Monitoring of a Military Aircraft using an Analog and Fiber Optic Sensor-based Data Acquisition System for Structural Life Management

Abstract

In the design and development phase, the structural design life of aircrafts is assessed by structural analyses and tests with the baseline design load spectra. The structural life should be reassessed and updated periodically with actual and operational load spectra in the structural life management phase. According to ASIP (Aircraft Structural Integrity Program), an initial FSMP (Force Structural Maintenance Plan) containing inspection, repair and maintenance plans should also be updated with results of reassessed structural life for cost-effective maintenance and operational sustainability. The actual load spectrum is generated by using structural responses like strains, load factors and various flight parameters. In order to collect these kinds of data for military aircrafts, a data collection and analysis system which is named SIDAS(Structural Integrity Data Acquisition System) is currently under development as an SHM(Structural Health Monitoring) system. The architecture of SIDAS is similar to conventional usage monitoring systems, and it is composed of an onboard device and a ground analysis device. The onboard device includes two analog sensor modules, an fiber optic sensor module, a power supply module and a recorder modules. Strain gages, accelerometers and FBG (Fiber Bragg Grating) sensors are attached on major structures and they measure structural responses. Additionally, various flight parameters that are related to structural behavior are recorded through MIL-STD-1553B communication protocol in the onboard device. The ground analysis device consists of a set of hardware and software, and downloads collected data in the onboard device using Ethernet or a memory card to analyze those data and construct database. This paper contains basic design concepts of SIDAS and analysis results of its collected data from fatigue and taxi ing tests of a military aircraft in a design and development phase. The analysis results will ultimately be used for the structural life management.