Vigilancia Tecnológica

The coupling effcets of non?relaxing and high temperature on fatigue lifetime data using strain energy density as predictor.AbstractThis paper presents an extensive experimental investigation on fatigue properties of carbon?black filled isoprene rubber under complex loadings. A basic life prediction model taking strain energy density as fatigue parameter is first proposed based on fatigue crack growth tests and uniaxial tension fatigue tests under relaxing loads at room temperature. A database of fatigue life including relaxing and non?relaxing is established through a great number of fatigue tests under five temperatures. Based on the database, two empirical parameters, that is, temperature factor (NRT/NHT) and life reinforcement factor (Re), are introduced to quantitatively characterize the coupling effects of high temperature and non?relaxing loads on fatigue life. The fatigue mechanisms under different conditions are compared via wide?angle x?ray diffraction tests and postmortem analysis. It reveals that the weakening of life reinforcement at high temperatures is closely related to the strain induced crystallization behavior of rubber.