A Research On Fatigue Life Prediction Of Rubber Vibration Isolator Under High Temperature And Variable Amplitude Loading Conditions

Rubber vibration isolators are usually subjected to time-varying strains, high temperature, oxygen and they are failed with the cracks growth. Therefore fatigue life prediction of a rubber vibration isolator under variable amplitude loading contidtions or high temperature is an important issue. The fatigue mechanism is studied and the methods of fatigue life prediction of rubber isolators under high temperature or variable amplitude loading conditions are developed in this paper.The works this paper studied are mainly following two aspects: one is the experimental research of rubber mount fatigue life at high temperature by using dumbbell simple tension specimens;another is a experimental research on fatigue life of rubbers bushing with variable loads by using dumbbell cylinder specimens.a filled natural rubber specimens of two hardness(shore 45 and shore 50) is used to carry out simple tension fatigue experiment under the temperature of 23℃,60℃ and 90℃. With the results, fatigue life prediction models was established by using peak Engineering strain as the damage parameters. Effects of high temperature softening, hardness and different damage parameters on the fatigue life of rubbers is investigated. A powertrain rubber mount was tested under 90℃ to obtain the fatigue life. A finite element model is established and the fatigue life of the rubber mount is estimated using the damage parameter calculated from the finite element model. Fatigue life estimated through models is compared with the measured, it shows that ratio of the calculated and the measured fatigue life is within a factor of 2. It can be seen, the measurement and prediction methodology for rubber fatigue life in this paper is applicable in predicting fatigue life of rubber mount under high temperature.Another fatigue test is carried out under variable amplitude loading conditions by using dumbbell cylinder specimens. The results show the Miner’s linear damage rule for predicting fatigue lives of variable amplitude tests in rubber is applicable even considering the effects of R-ratio(ratio of minimum to maximum strain rate), strain level, strain arrangement, and dwell times on fatigue life. At last the fatigue life of a rubber bushing loaded under 20 working conditions is predicted by using the Miner’rule.