Rubber accelerated ageing life prediction by Peck model considering initial hardness influence

Accelerated degradation test is an effective means for rapid and convenient prediction of rubber life. In the existing research, the influence of rubber hardness on performance degradation is neglected. Thus, the life prediction results are inaccurate. A rubber ageing model considering hardness influence was established on the basis of modified traditional dynamic degeneration trajectory equation, with which the effect of dispersion of the initial hardness of rubber on service life was described. Three types of natural rubber with different hardness were considered as research objects. On the basis of different high-temperature accelerated ageing tests, the deformation trajectory equation was used to model the compression set of each sample. Identification results show the relatively stable power exponential term coefficient and constant term coefficient, whereas there is large fluctuation in the reaction rate term coefficient. To simplify the research, the power exponent term coefficient and constant term coefficient were set as fixed values. Then, the reaction rate coefficient was estimated again. The rationality of parameter re-identification result was verified by the goodness of fit. The Arrhenius and Peck models were introduced in accordance with the obtained reaction rate coefficient identification results to simulate the reaction rate coefficients. Combined with Peck and dynamic models, a modified rubber ageing life prediction model was established, with which Monte Carlo method was employed to analyse the influence of initial hardness dispersion of rubber on service life under natural environment. The effectiveness of the model was verified by comparison with measured natural ageing data. The proposed ageing life prediction model can simultaneously consider the influences of initial hardness and temperature on rubber ageing with high accuracy. This study can provide a reference for the design and reliability evaluation of rubber parts.