Abstract

Compression After Impact (CAI) test is normally used for the assessment of damage tolerance of composite laminates. The applicable specification for the execution of these tests is AITM 1-0010. However, for thicknessess under 4mm were buckling occurs, the applicable specification is the AITM 1-0077, which introduces the use of anti-buckling tooling covering the entire surface of the specimens. The tooling, which is used in the aeronautical industry  for the testing of thin specimens presents two problems which are the difficulty of assembly and of obtaining realiable results, and the visibility of the specimen during the test.

This work comprises the design, manufacturing and validation of a novel anti-buckling device for compression after impact thin specimens. For that purpose, a study of the specification toolings along with a review of the already developed anti-buckling tooling literature has been carried. As part of the validation process three series of impacted specimens of 3mm thickness.

This activity is developed as part of the project CERES, which is framed under Clean Sky 2, and has the main objective of validating the manufactured anti-buckling tooling. This tooling has been developed as an innovative solution for its application in compression after impact thin specimens. 

Abstract

The use of hydrogen as an energy source is a promising strategy to replace fossil fuels, in addition to batteries and biofuels. The European aerospace industry is already working on the development of propulsion technologies with low or zero emissions and heavily considers hydrogen technology. It is favoured in aeronautics to store H2 in liquid form, LH2, at temperatures of 20K to have the highest possible energy density of the fuel. This means that all materials in contact with LH2 need to be characterized at this temperature.

INTA began to carry out cryogenic tests on composite materials 27 years ago. Initially in the field of characterization of composite materials for tanks for reusable launchers. Later, the structural monitoring of LH2 tanks, the detection of hydrogen leaks and fuel cells have also been investigated. Currently, INTA is involved in the characterization of composite materials in LH2 tank projects and the composite material structures that these tanks carry for sustainable aviation.

The article gives an overview of the activities carried out in the field of cryogenic tests of composite materials and provides data obtained in these tests, comparing the behaviour of different materials and different types of tests. In addition, the new lines of research that are being carried out at INTA in the characterization of composite materials and their behaviour before and after being in contact with hydrogen will be explained.