Experimental Characterization of Mechanical Properties of Rubber
|Bearbeitung:||ext. M. Dämgen, R. Schuster (German Institute of Polymer Systems (DIK))|
The mechanical behaviour of a total of 8 well specified rubber systems build up from four basic polymers, three different carbon black fillers and one silica filler is investigated. In one setup the uni-axial cyclic tension / compression behaviour is analyzed by use of cylindrical probes as well as flat probes. An example of the measured response curves is given in fig. 1. The typical characteristics are described by the strain dependent filler network damage, hysteric behaviour, remaining strain after unloading etc. In contrast to highly non-linear response observed in the tensile / compression tests, a quite linear behaviour results from shear tests, an example is shown in fig. 2. The result from a typical relaxation test is depicted in fig. 3. After initial conditioning of the probes in five quasistatic cycles the strain is kept fixed for defined times while the relaxation behaviour is recorded. Additional experiments are performed regarding anisotropic stress-softening, temperature dependency and damage annealing. Average tangent modules depending on the maximal strain are compared for all systems to characterize the different stress softening behaviour. Hysteretic work as well as relaxation times is tabulated as measure for damping potential of different rubber systems. From this a quite broad database is provided for the constitutive modelling of rubber materials at large strains.