Testing F-35’s airframe in BAE Systems integrated structural testing program

Static and Fatigue Tests

Both fatigue tests and static tests are undertaken by S&DT. Fatigue tests take much longer to complete than static tests and are based on data trending which looks for changes in the structural response over time. These can easily signify the possibility of cracks or other in-service related conditions. The tests are undertaken by applying various loads to different structural components in an accelerated timeframe to reproduce potential operational damage. Complex PC-based test control and data acquisition systems are used to control how the forces are applied to the different test structures and the responses carefully monitored. Test specimens are usually instrumented with strain gauges enabling real-time recording of strains generated. S&DT’s structural tests utilise HBM’s equipment to capture and analyse data. The equipment includes a data acquisition system from HBM comprising catman^® Enterprise software connected to 32 MGCplus devices distributed in eight cabinets across the test rig. The HBM equipment is fully synchronised giving BAE Systems one of the world’s largest structural DAQ systems. The MGCplus supports a wide spectrum of sensors, transducers, fieldbus connections and standard PC interfaces making it a suitable choice for this application. The modular design ensures that it can be easily expanded or modified should BAE Systems’ requirements change. The catman® Enterprise software suite is specifically developed for high channel-count measurements using the MGCplus DAQ system while its dedicated Measurement Data Server (MDS) performs the actual measurement enabling monitoring and evaluation in real-time. This set-up gives test engineers access to some 3,800 channels populated with HBM’s ML801 cards and AP815 connection boards terminating in RJ45 connectors for data acquisition.

Sharing data

Another challenge was to successfully share test data in a timely manner with multiple sites. These included the BAE Systems’ sites at Brough and Samlesbury along with three Lockheed Martin plants and Northrop Grumman’s El Segundo factory in the USA. This was important because it meant the test teams could take immediate decisions in a collaborative manner regardless of their actual location. HBM supplied its MD Client software which is used to share test data in real-time and compare these against predictions and upper/lower alarm limits with the various structural integrity teams. BAE Systems has a Local Area Network (LAN) to facilitate communications between each test system computer. HBM’s Measurement Data Server (MDS) is configured to communicate with BAE Systems’ control network over Ethernet using industry standard TCP-IP protocol. BAE Systems also uses HBM’s nCode Automation™ for data storage and to produce statistical data automatically during the upload process while HBM’s nCode GlyphWorks^® is used to generate graphical plots. HBM’s nCode Automation provides automated data storage, analysis and reporting as well as a web-based collaborative interface for sharing test data and associated information. Using this, BAE Systems was able to release data to the different teams within two hours of completing a test. HBM’s nCode product range is designed to complement HBM’s DAQ and analysis tools. The fully traceable system is kept constantly calibrated and fully operational by HBM UK staff working in conjunction with BAE Systems. This gives engineers additional confidence and security in any results acquired while testing the airframes. HBM UK has ISO 9001 accreditation ensuring optimal support for critical engineering challenges.