L. De Doncker

Influence of Re-adhesion on the Wear and Friction of Glass Fibre–Reinforced Polyester Composites

Based on the well-known pin-on-disc test rig, a new test setup for online measuring of wear and friction behaviour of polymer matrix composites has been developed. In contrast to a traditional friction-and-wear test rig, a steel pin and composite disc are used for studying the influence of wear debris and fibre orientation. During sliding, a thin adhesive film is possibly formed on the wear track of a composite disc, consisting of wear debris that is squeezed under the steel pin and that finally smoothens onto the composite surface. By optical microscopy, it was observed that most of the debris particles originate from the edges of the wear track. The thin film deforms continuously, with large and dark wear particles observed at the edge of the wear track. A lower coefficient of friction is achieved when the particles are re-adhered to the mating surface. The film formation mechanism depends on the normal force, sliding velocity, and bulk composite structure: because pultruded composite profiles are presently used with a layered structure, a change in film properties is observed depending on the wear depth.

Influence of vegetation on the propagation of flood waves

Research on river ecosystems asks for a multidisciplinary approach. All components such as water, macrophytes, sediment, suspended solids, etc. play an important role. The presence of macrophytes in rivers has an influence on water levels and flow patterns since a wealthy vegetation growth causes back water effects and consequently higher upstream water levels. In view of this, flood risk increases in periods of higher flows and greater vegetation growth. So, river management also deals with the control of vegetation. Good management contributes not only to the quality of the water and the ecosystem, but also to flood protection.