Modern Solutions for Ground Vibration Testing of Small, Medium and Large Aircraft

Ground Vibration Testing (GVT) of aircraft is typically performed very late in the development process. Main purpose of the test is to obtain experimental vibration data of the whole aircraft structure for validating and improving its structural dynamic models. Among other things, these models are used to predict the flutter behaviour and carefully plan the safety-critical in-flight tests. Due to the limited availability of the aircraft for a GVT and the fact that multiple configurations need to be tested, an extreme time pressure exists to get the test results. The aim of the paper is to discuss recent hardware and software technology advancements for performing a GVT that are able to realize an important testing and analysis time reduction without compromising the accuracy of the results. The paper will also look at the connection between the GVT and the other components of the development process by indicating how the GVT can be planned using the virtual prototype of the aircraft and how the GVT data analysis results can be used to obtain a highly reliable model for flutter prediction. Although, the presented modern GVT solutions apply to all types of aircraft, the paper will discuss the application to very large aircraft, recently tested at EADS CASA on the A310 and the A330 MRTT. The paper will discuss the following: Section 1 discusses the history, challenges and trends in Ground Vibration Testing. Section 2 highlights a modern hardware and software architecture allowing a 1000+ channel GVT. Different aircraft excitation techniques and modal parameter estimation techniques will be critically assessed. The technology is extensively illustrated by means of several recent GVT cases. Section 3 discusses the integrated use Finite Element (FE) models during the GVT. The FE model available before the GVT can be used to make predictions on the aircraft dynamic behaviour and to optimize the test arrangement and duration. Afterwards, the FE model is updated to better match the test results.