Fracture mechanics testing under aerospace environmental conditions

6 Fracture mechanics testing under aerospace environmental conditions 

Fire resistance of FRP composites is also of concern in aerospace applications a review [120] found severe degradation in postfire flexural properties for FRP epoxy composites which were induced by delamination formation due to resin combustion. 

In some specimens, irradiation was followed by annealing. DMTA indicated some changes in transition temperature for a certain irradiation dose range, but less for others which correlated with changes in delamination resistance. The experiments discussed in the literature noted in this section all indicate a complex interaction between irradiation and temperature which would have to be taken into account in irradiation test development. Effects on composites from the space environment (irradiation with particles and electromagnetic waves, temperature variation etc.) wUl be considered in the new Composite Materials Handbook (version G, 2012 ff. [12]). For space applications, the impacts of micrometeorites and of space debris, for example from other spacecraft [124], will also contribute to damage of FRP composites and hence to ageing. 

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This chapter will first discuss fracture mechanics applications to polymer composites in aerospace, and then compile the different test methods by type of load. The industiy-specific fracture mechanics test procedures for FRP composites, such as the Airbus Industries Test Method (AITM) or Boeing Support Specification (BSS), are essentially based on test procedures developed by national or international standardization agencies. This will be followed by a section with literature data to highlight selected effects of processing and material layup and type. Further sections will discuss non-unidirectional reinforcement and testing under environmental conditions that are relevant to aerospace applications, and the chapter concludes with an outlook on materials and test development trends. 

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