Design And Experimental Investigation Of Ultra-low Frequency Vibration Isolation During Neonatal Transport

Newborn babies,especially premature babies and sick children,often need to use incubators and ambulances to transfer to the hospita l for treatment.In the process of transportation,the neonatal will be affected by mechanical vibration due to road surface excitation,and the mechanical vibration frequency is dominated by low-frequency components,and the traditional vibration isolatio n method fails.Therefore,in order to solve the tough issue of ultra-low frequency vibration isolation during neonatal transport,a new incubator with quasi-zero-stiffness(QZS)isolators is proposed,filling the gap in domestic neonatal transfer ultra-low frequency vibration control technology.The main contents of this paper are listed as follows:Firstly,based on the principle realizing quasi zero stiffness in parallel with positive stiffness mechanism and negative stiffness mechanism,a novel magnetic quasi-zero stiffness vibration isolator is proposed.The equivalent magnetic charge method was used to derive the analytical expression of the magnetic force and the magnetic stiffness of the magnetic spring.The finite element software ANSYS Maxwell was used to perform finite element simulation on the negative stiffness magnetic mechanism,which proved the correctness and feasibility of the analytical expression.The influence of differet geometric parameters on the magnetic forec and stiffness of the magnetic spring is analyzed,and the optimal solution of a group of magnetic springs is obtained by consindering the engineering practice.Secondly,considering the inertia of the input end of the vibration isolation system and the load,a single-degree-of-freedom nonlinear dynamics theoretical analysis model is established.The amplitude-frequency response of the QZS isolation system is obtained by solving duffing equation using harmonic balance method,and the numerical solution method was used to verify the accuracy of the analytical results.The harmonic balance method is used to solve the duffing equations,and the QZS vibration isolator is obtained by calculation amplitude-frequency response equation.The numerical solution method was used to verify the a ccuracy of the analytical results.At the same time,the effect of damping ratio,external excitation amplitude and stiffness on the vibration isolation performance of the two system are evaluated using the displacement transmissibility of the nonlinear vibration isolation system and the linear vibration isolation system.Finally,a prototype of a QZS vibration isolator was parpared and an experimental platform for a neonatal transfer vibration isolation system using quasi zero stiffness isolator.Through the liner fitting of the static quasi-zero stiffness isolator,the approximate stiffness value of the isolator is much smaller than that of the linear spring,which greatly reduces the natural frequency of the system.The vibration isolation performance test of magnetic quasi-zero stiffness vibration isolator and ultra-low frequency neonatal vibration isolation system.Experimental results show that the ultralow frequency neonatal transporter has good low-frequency vibration isolation performance.