We practice a development of new method, systems and equipment for physical material testing of polymeric materials with respect to the simulation of real loading conditions from the first discussions about the problem, over the scientific search, experimental verification of the problem, concept of a solving, development as well as design to the manufacturing of the of measuring equipment. We can work up the complex order from our office or we can support the research team of customers with our research specialists.
Current projects in progress:
|Wear of tyre tread material under simulation of real dynamic load conditions|
Car and truck tyres are among the elastomer moulded parts that have to satisfy the highest safety requirements. They are subjected to highly dynamic and complex loads in daily use. The tread in the tyre system plays special role here. It is the sole connec-tion between the vehicle and the road surface. Its properties define the vehicle’s char-acteristics during acceleration and braking procedures, as well as its driving stability. The tyre tread/substrate interface realises the force transmission between the vehicle and roadway. Adhesion and rolling friction are therefore necessary, but drive the wearing process inevitably. The road surface’s micro- and macro-roughness, and par-ticles that are typically found in the roadway, such as stones, have local dynamic ef-fects on the tyre’s tread. Whether accelerating, braking, driving in bends or straight ahead, or sudden damage from foreign bodies on the road, all these processes condi-tion the tyre tread and cause microscopic cracks and wear through fatigue. A tyre’s abrasion characteristics are, of course, particularly important for the consumer, because a tyre with greater abrasion resistance has a longer service life. At present, determining the tyre’s abrasion characteristics is only reliable by testing the whole wheel either indoors on tyre test drums, or outdoors by means of off-road test drives. These tests are very time- and material-consuming. The measured characteristics refer exactly only to the tested tyre type. These tests have therefore only very slight reference to the material characteristic and can make only a limited contribution to material and product development.
|Characterisation of the crack propagation resistance of several layers of rubber mixtures|
Tyres consist of several layers of different rubber mixtures. Under dynamic operating conditions tyres develop microcracks (crack initiation) in the individual layers, which grow continually. One fracture mechanics characteristic is the crack propagation speed in dependence on the load. Crack growth in the individual layers is itself influenced by the adjacent layers of the material structure. Depending on the interlacing of the layers at their interfaces, cracks grow into each other, the crack stops at the interface, or there is delamination between the layers.
|Characterisation of the penetration resistance of rubber to foreign bodies under real dynamic load conditions|
Because of the dynamically pulsed load on the tyre, every unusually occurring impact event can damage the tyre. In the present research project, close attention is paid to the penetration of foreign bodies (nails, screws, pieces of wire, shards of glass, etc.) into the tyre’s tread or sidewall. Damage of this kind to tyres can cause a change to the ve-hicle’s handling (slow loss of pressure in the tyre) and, in critical cases, to a spontane-ous failure (tyre bursts suddenly), and thus even to an accident with serious conse-quences. The particular complexity of the research work results from the viscoelastic properties of the elastomer materials. Foreign bodies can penetrate into the surface more or less easily, depending on the plasticity of the elastomer materials.
From the aspect of rubber mixture development, active fillers such as carbon black or silicas play an essential role for the rubber’s resistance to penetration by foreign bodies. The penetration resistance depends on the polymer filler and filler-filler interaction.
The aim of the project is to determine the magnitude of the influence of this in-teraction on the penetration resistance to foreign bodies.
|Process for manufacturing rubber powder as a quality-enhancing or quality-maintaining additive in rubber mixtures|
At the end of their service life elastomer components are recycled for further use. The figure below shows the principal paths for material recycling.
Because of the decreasing availability of resources, increasing environmental consciousness and cost aspects, rubber particles (RP) for reuse in rubber mixtures for new products are becoming more and more important. They are manufactured by comminution and pulverisa-tion in different recyclable separation processes from waste rubber, whereby end-of-life tyres form the largest fraction.
The state of the art is downcycling rubber, because the technical and mechanical properties of new products made with a recyclate mixture are of lower quality than the rubber mixture without an admixture. The reason for this is the degeneration of the quality of the rubber mixtures, which are modified by adding rubber powder.
The figure shows a principle representation of the process.
The graph shows the qualitative influence on elasticity module, elongation at break and failure stress applied over the volume share of the rubber powder admixture of one sort on a rubber mixture.
Because, on the one hand, the greatest share of waste rubber comes from end-of-life tyres and, on the other, the greatest demand for rubber comes from tyre manufacturers, it stands to reason to develop processes for manufacturing, processing and admixing rubber particles that guarantee the same mechanical properties of the end product tyre, if not even better ones.