Aspects of Damage Tolerance and Fatigue of CFRP Structural Components 2015-01-2596
Lightweight structures are one key issue for all future mobility concepts. Carbon fibre reinforced plastics (CFRP) play an important role in these disciplines due to their outstanding mechanical performance regarding to their weight. Therefore, CRFP structures have been widely used since decades in aerospace industry resulting in improvements in payload, fuel consumption and range. The Airbus A350, Boeing B787 in civil airplane industry as well as military products like the NH90 transport helicopter are examples of this development towards “all composite”-aircrafts.
A main difference of CFRP-structures towards metallic ones is the behaviour regarding damage tolerance and fatigue. For helicopter composite structures this issue is newly defined in §573 of the relevant certification specifications (CS and FAR). This paper summarizes the necessary efforts and possible methods to show compliance for this specific topic in the aerospace industry to design robust and lightweight CFRP structural components.
Methods to predict accurately damage propagation in composites via increasingly powerful numerical tools are presently widely investigated. Numerical derivation or at least relevant approximation of design allowables of laminates made of any sequence of laminas would be a great achievement making doubtlessly the overall design process cheaper and shorter. In this paper, a new methodology is proposed to simulate progressive damage occurring after low velocity impact (LVI) and to assess the residual strength of pre-damaged plates submitted to compressive loading (Compression After Impact). These numerical analyses are carried out with the FE commercial code Abaqus/Explicit. The relevance of the FE results is assessed through correlation with experiments.