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This paper deals with the investigation of crack stop elements for carbon-fibre-reinforced polymer (CFRP)/foam core sandwich structures manufactured by using liquid composite moulding technology under fatigue loading. The novel crack stoppers consist of CFRP and they connect the face sheets. In this way, they are suited to be used as crack stoppers to decrease the face sheet debonding and as load introduction elements. Two types are investigated, a box section and a double-T beam. Quasi-static and cyclic Single Cantilever Beam (SCB) and Cracked Sandwich Beam (CSB) tests are run to evaluate their crack stop capability under global mode I and global mode II loading. The double-T beam shows the better crack stop effect. In the SCB test the box section increases the specimen durability by less than 2%, whereas the double-T beam increases the load cycles to failure by a factor of 2.7 to 447. In the CSB test, both crack stoppers have a significant impact on the crack propagation behaviour. The box section increases the durability by a factor of 11 to 95, and most of the double-T beam sandwich specimens sustained 3 million load cycles without global failure

Hybrid foams consist of two different interpenetrating or particulate‐embedded foam‐material classes and, therefore, an enhanced multifunctionality of the material and of the final product can be expected. This paper illustrates the concept of hybrid foams with two selected examples. The cells of an open‐cell steel host‐foam are filled either with a polymer foam or a newly developed direct ceramic foam.The results of compression tests and non‐destructive resonance‐frequency‐damping analyses are presented. An improvement in the deformation is observed for the metal‐polymer hybrid foam, while the deformation behavior changes from brittle to ductile for the metal‐ceramic hybrid foams. Additionally, the damping and Young's modulus of the metal foam are enhanced by the interpenetrating direct foamed ceramic.