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Acquiring numerical means in the laminated glass fracture domain is a challenge. Such a composite layout, made of two float glass plates sandwiching a transparent polymeric interlayer, shows indeed quite complex behaviors, differing drastically with respect to the time domain experienced. The first part of the present report details a complete analysis of those phenomena with literature findings and identifies existing material model and brittle fracture methods especially. Beside the explanations, key material parameters for suitable numerical simulations are particularly pointed out.
Among the approaches followed by main brittle fracture methods, 2 families are distinguished:
a continuum one with element erosion and a discrete one with cohesive zone model. As introduction case to fix glass fracture modeling capabilities, comparison between Abaqus/Explicit - Brittle Cracking (continuum) and Gmsh - DG/ECL (discrete) is carried out in the second part of the report. The chosen framework was the monolithic glass plate fracture under 4-point bending.
Unfortunately, difficulties entailed by this choice restricted the analysis because of the software
intrinsic limitations (especially observed for Abaqus). In that sense, comparison with experimental testing was quite unbalanced. However, in combination with traction test simulations on dog-bone shaped glass sample, a clear conclusion can be drawn. In terms of fracture energy and ability to generate relevant glass cracks pattern, Gmsh- DG/ECL stands out particularly, suggesting that a complete match with actual testing could be achieved through a large CPU expense. At the opposite, beside quite poor cracks patterns, Abaqus/Explicit- Brittle Cracking exhibit a large disproportion between captured fracture energy and viscous dissipation (and sometimes hourglass control) to stabilized the numerical scheme.

DG/ECL , Brittle Cracking, 4-point bending, laminated glass --- Ingénierie, informatique & technologie > Ingénierie aérospatiale --- Ingénierie, informatique & technologie > Ingénierie mécanique

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The present final work project has been performed at Sonaca, a Belgian company which is producing aeronautical components. The objective was to study composite leading edge slat designs and more precisely the feasibility of using aluminium honeycomb cores as
energy absorption elements to handle the issues of composites parts submitted to bird impact. After a validation of the numerical simulation on a well known aluminium slat design, two composite designs have been studied. A hybrid design which combines an aluminium slat top skin and a composite rear structure has been found compliant with birdstrike requirements while cutting down the weight of the whole structure by 17.2% and the weight of the slat itself by 27.1% with respect to a reference aluminium slat design. Thereafter, the constitutive model used to represent the crushing behavior of aluminium honeycomb core has been identified using quasi-static crushing experiments before it has been validated under dynamic conditions using an birdstrike experiment carried out on a fixed leading edge. A full composite slat design associated to a fixed leading edge reinforced with aluminium honeycomb core has been proven compliant with birdstrike requirements while cutting down the weight of the whole structure by 17.5% and the weight of the slat itself by 41.7% with respect to a reference aluminium slat design. Key prerequisites for slat design integrating aluminium honeycomb cores such as the absence of localised stiff points and a sufficient stiffness of the part which support the core have been identified. The influence of the some design parameters has finally been assessed to give a first insight of the elements which should be taken into account during sizing of fixed leading edge reinforced with aluminium honeycomb cores.

Impact d'oiseau --- Nid d'abeille aluminium --- Simulations numériques --- Plastique à renfort fibre de carbone --- Birdstrike --- Aluminium honeycomb --- Carbon fibre reinforced polymer --- Numerical simulations --- Ingénierie, informatique & technologie > Ingénierie mécanique