A6/II Characterization of mineral-bonded materials for damping layers for impact strengthening of flat solid construction elements
Impact loads on flat components can cause various types of damage, depending on the specific nature of the impact. For the overall structure, the influence of the global load-bearing resistance is of particular interest, but for users, local damage, such as chipping or spalling on the front and back of the affected component, or perforation of the impactor can also be essential. Damping layers on the impacted side can have a load distributing and/or energy absorbing effect and thus cause an increase of the load bearing capacity and/or a reduction of the degree of damage.
Left: mineral-bonded composites of various compositions as potential materials for damping layers; right: effect of adding fibres to fine grained matrices in the SHB spallation experiment – above matrix without and below with fibres
This project aims a detailed characterization of materials suitable for damping layers and, based on this, analysis of complex mineral bonded strengthening variants. Small-scale experiments in a split Hopkinson bar serve to determine essential material properties such as strength, deformation behaviour (elastic/plastic or reversible/irreversible), energy absorption and failure modes as well as damage at different speeds and different impactor geometries. In this context, the central question is also to be clarified – which sample form allows conclusions to be drawn about the global behaviour of a flat damping layer. Furthermore, characteristic values result from the tests for further use in numerical investigations and material models, which will be developed in the theoretically oriented PhD projects of GRK 2250/2. Depending on the results, the most promising damping layers or damping systems (e.g. layering of different materials) are selected and applied to large reinforced concrete components. In drop tower tests the global and local component behaviour as well as failure mechanisms and degree of damage are studied. Based on this, a first prognosis model is developed.