Validation and Modeling of Aeronautical Composite Structures Subjected to Combined Loadings: the VERTEX Project. Part 1: Experimental Setup, FE-DIC Instrumentation and Procedures

Abstract

The development and certification of aeronautical composite structures is still largely based on the pyramid of tests. This approach is extremely costly in terms of number of tests and design loops. Moreover, this is made up of uniaxial tests whereas the real structures are mostly subjected to combined forces. The aim of the collaborative research program "VERTEX" is to make progress towards Predictive Virtual Testing and to significantly reduce the development costs of aeronautical and space programs. In this first part, the specific methodology for multiaxial tests of aeronautical structures is presented. The concept of technical specimen and their size are justified. Then, the development of a specific test device is presented. Compression / traction, shear, internal pressure and any combination are possible. Since structural tests were complex to be instrumented, a specific method of field measurement was developed. It is based on multi-camera instrumentation and an original approach named Finite Element Stereo Digital Image Correlation (FE-SDIC). A mechanical regularization with the use of Finite Element (FE) of the optical field measurements allows to calculate the translation or rotation displacement field. Thus this measured field is used for boundary conditions of the VERTEX tests. The experimental procedure, the measurement methodologies and the calculation / test dialogue are validated on isotropic metal plates in this paper.