Simulation of nonlinear vibration responses of cab system subject to suspension damper complete failure for trucks

The strong vibration responses of the cab system can be restrained by the damper force and the friction of the suspensions for trucks.After the failures of dampers,especially in the case of the complete failure,the anti vibration effect of the friction is prominent.However,the nonlinear vibration response characteristics of the cab subject to the damper complete failure have not been revealed.In order to reveal the nonlinear vibration response characteristics,a dynamic model of the cab system was established and its vibration equations were given.The friction forces existing in the suspensions were determined by the bench test.The influences of the friction forces on the cab vibration under different amplitude harmonic inputs were investigated when the dampers completely fail.The cab vertical displacement changes with the excitation amplitude and the vibration represents various motion states,including the periodic motion,the quasi-periodic motion,and the chaotic motion.The simulation results show that when the dampers fail,the proper friction forces help to suppress the quasi-periodic motion and the chaotic motion of the cab and to reduce the amplitude of the periodic motion.The proper friction forces can make the cab movement far away from the chaos area.They also help to avoid the fatigue damage of the cab floor and suspension parts to improve the service life of the suspension parts and to reduce the maintenance cost of the cab suspensions.

Related Factors of in vitro Fertilization and Embryo Transfer Patients with Complete Fertilization Failure

Objective To find the possible factors predicting fertilization failure of in vitro fertilization-embryo transfer （1VF-ET）. Methods The IVF-ET patients with complete fertilization failure （experimental group, n =32） were analyzed retrospectively. The patients whose oocytes retrieved at the same day and cultured on the same incubators with ≥ 50% fertilization rates were matched as the control （n=56）. Results The infertility duration, superovulation days, the rates of primary case, progesterone （P） level 〉3.12 nmol/L rate and rate of severe abnormal sperm （abnormal sperm rate 〉95%） in experimental group were significantly higher than those in the control （6.4 ±3.1 years, 12.6 ±2.2 d, 56%, 43%, 43% vs 4.6±2.9years, 11.6 ±% 1.3 d, 33%, 23%, 23%, respectively, P〈0.05）. Conclusion We should pay attention to these patients with primary infertility, longer infertility duration and superovulation days （〉6.4 years and 〉12.6 d） and having increased level of P on hCG injection day （〉3.12 nmol/L）, abnormal sperm rate 〉95% at the same time. They should be included in such patients at high risk of fertilization failure.