Fatigue Life Prediction Method Of Damping Rubber And Its Engineering Applications

Rubber materials are widely used as damping materials because of their excellent elastic and damping properties.Hyperelasticity and viscoelasticity are the basic mechanical properties of rubber materials.The fatigue mechanical behavior characterization and fatigue life assessment of damping rubber are the two crucial topics of common concern to the academic community and engineers.In this paper,the fatigue crack growth characteristics,hysteresis induced thermomechanical coupling effect and fatigue life prediction method of damping rubber materials are studied.The main research work and conclusions are as follows:(1)Reasonable selection of the hyperelastic constitutive model of damping rubber material.Based on the experimental results of uniaxial tension,planar tension and equibiaxial tension,the Ogden model is selected as the optimal constitutive model for the damping rubber material investigated in this work.(2)Fatigue crack kinetics of damping rubber under relaxed cyclic loading.The critical tearing energy and fatigue threshold of damping rubber were respectively determined by planar tensile tear test and prestrained planar tension + cutting test.The relationship between fatigue crack growth rate and peak tearing energy is established for damping rubber under relaxed cyclic loading(R = 0)based on the planar tension fatigue tear test.Moreover,according to the fatigue crack growth kinetics and the fatigue failure tests of hourglass specimens,a method to determine the intrinsic crack size of rubber material is developed,and then the S-N curves under different deformation modes are obtained.(3)Fatigue crack kinetics of damping rubber under nonrelaxed cyclic loading.Based on the planar tensile tear tests including relaxed and nonrelaxed cyclic loading segements with various preset peak strains,a piecewise model is proposed to describe the crack growth.The influence of load ratio R on the fatigue crack kinetics was studied.Combined with the mechanism of strain crystallization strengthening,the fatigue Haigh curve of the rubber material is constructed,which provids an important guide for the long-live design of rubber dampers.(4)Thermomechanical coupling analysis of fatigue behavior of damping rubber.Considering the load frequency-,load amplitude-and temperaturedependence of the dynamic loss modulus of damping rubber material,a model for calculating the hysteresis loss rate is established by considering the thermomechanical coupling effect.A fast fatigue life assessment method is developed based on hyteresis induced self heating temperature rise.A temperature dependent model of critical tearing energy of rubber material is established based on the planar tensile tear tests at various temperatures.The results showed that the critical tearing energy decayed exponentially with the increase in temperature.Furthermore,the temperature dependent fatigue crack kinetics is established,and a fatigue simiulation scheme for thermomechanical coupling behavior of engineering vibration damping rubber components is proposed.