Christoph Uhlig

High Performance Composites Using Nanotechnology

Lightweight design, using high performance composites, which directly yields a reduced need for fuel is in the focus of new developments for traffic engineering. The increased substitution of traditional, metal based materials by fibre-reinforced composites in the aviation industry exemplifies this trend. In addition to mechanical properties, e.g. an increase in strength, that leads to direct weight savings, or improved dynamical performance, which translates into longer maintenance intervals, i.e. longer service-life. In the field of fibre-reinforced polymer matrix composites possible contributions from nanotechnology are currently reviewed. The modification of the matrix by introducing a “nanophase” has attracted most attention up-to-date. Additional approaches include modification of traditional reinforcements, as well as the development of new reinforcing materials. Desired improvements include mechanical properties, interlaminar shear strength, reinforcement in z-direction, fiber-matrix adhesion, and obtaining new functionalities. Starting from a summary of the most important effects of nano-modifiers in polymeric matrices, the presentation will review published results on the modification of thermoset matrix fiber-reinforced composites by using nanotechnology, as well as some of our own work in that field. Furthermore, applications of such modified composites in component parts are discussed.

Symmetrical napcore and honeycomb sandwich structures under impact load

Sandwich structures are state of the art for construction of lightweight structures with high mechanical load capacity. Beside established core materials like foams, honeycombs or wood, napcore material is an interesting option when economic production costs or the possibility to integrate extra functionality are criteria in addition to specified mechanical values. Napcore material is made from a two-dimensional resin-impregnated knitted fabric that is shaped into a threedimensional nap structure and stabilized by the cured resin matrix. In this paper the mechanical behavior under low velocity impact loads of sandwich structures made with napcores from aramide textile and phenolic resin is investigated and compared with components containing honeycomb cores.