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This paper describes the derivation and validation of a numerical material model that predicts the highly dynamic behaviour of CFRP (carbon fibre reinforced plastic) under hypervelocity impact. CFRP is widely used in satellites as face sheet material in CFRP-Al/HC sandwich structures (HC = honeycomb), that can be exposed to space debris. A review of CFRP-Al/HC structures typically used in space was performed. Based on this review, a representative structure in terms of materials and geometry was selected for study in the work described here. An experimental procedure for the characterisation of composite materials is documented in [1]. The test results from the CFRP of the current study allow for the derivation of an experimentally based orthotropic continuum material model data set that is capable of predicting the mechanical behaviour of CFRP under hypervelocity impact. Such a data set was not previously available. In [2] an orthotropic material data set was used for modelling HVI on AFRP (aramid fibre reinforced plastic), which shows relatively high deformability before failure. The enhancements of the modelling approaches in [1] and [3] necessary to model brittle CFRP are specified. An experimental hypervelocity impact campaign was performed at two different two stage light gas guns which encompassed both normal and oblique impacts for a range of impact velocities and projectile diameters. Validation of the numerical model is provided through comparison with the experimental results. For that purpose measurements of the visible damage of the face sheets and of the HC core are conducted. In addition, the numerically predicted damage within the CFRP is compared to the delamination areas found in ultrasonic scans.

Recent advances in the description of fibre-reinforced polymer composite material behaviour under extreme loading rates provide a significant extension in capabilities for numerical simulation of hypervelocity impact on composite satellite structures. Given the complexity of the material model, extensive material characterisation is required, however, as the properties of composite materials are commonly tailored for a specific application, experimental characterisation is not efficient, particularly in preliminary design phases. As such, a procedure is outlined in this paper that applies a number of commonly accepted composite mechanics and shock physics theories in conjunction with generalised material properties which allows for the theoretical derivation of a complete material data set for utilisation of the new modelling capabilities. The derivation procedure has been applied to a carbon fibre/epoxy laminate, and is validated through a comparison of derived material properties with experimentally characterised values and numerical simulation or damage induced by hypervelocity impact on a representative space debris shielding configuration employing the CFRP laminate. For the specific structures and impact conditions considered, application of the material property derivation procedure in place of experimental characterisation provided comparable accuracy in the prediction of damage induced by particles impacting at hypervelocity

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