Research On Protection Technology Against Biological Contamination And Vibration Absorption Optimization Of Stretcher-Support For Emergency Ambulance

With the threat resulting from biological terror and strong infectious disease becoming more serious, it's urgent to develop the emergency ambulance for the sick and wounded with protection function against biological contamination (air filtration and overpressure protection as well as negative pressure protection). This dissertation focuses on the protection technology against biological contamination and the vibration absorption optimization of stretcher-support for the emergency ambulance.Based on the fundamental principles of air filtration and overpressure/negative pressure protection, the devices for air filtration and overpressure/negative pressure protection were developed for the emergency ambulance. Many measures such as the effective airtight compartment, the adjustable and controllable overpressure/negative pressure, the monitor on line and invalidation alarm for work state of the air filter were taken and the function of air filtration and overpressure/negative pressure protection was realized. All of indexes excels the technology demands in GJB1629 and WS233, which can insure not only carrying and rescuing the sick and wounded safely and protect the persons and environment inside compartment from being polluted when the emergency ambulance is passing through the biological contamination zone, but also carrying and rescuing the sick and wounded infected by biological contamination or the patients with strong infectious disease while protecting the outside environment from being polluted at the same time. This emergency ambulance provides a safe and reliable mobile medical treatment platform for tackling biological terror attacks and emergent public health hazards (strong infectious disease).The experimental research on the protection performance against biological contamination for ambulance compartment were carried out using the serratia marcescens, which explored an experimental method to investigate the vehicle equipment protecting against the real bacteria biological contamination under normal conditions (without biosafety laboratory). It was verified that the air filtration and overpressure/negative pressure protection system of the emergency ambulance can resist biological contamination effectively (filtration efficiency runs over the demands of related technology indexes). The realistic state of biological contamination's movement and distribution inside the compartment was mastered and the obvious disadvantage was settled that biological protection performance test had been conducted using ordinary physical particle or tracer gas CO2(SF6) instead of biological particle in the past, which could not reflect the characteristics of biological contamination correctly. The valuable first-hand test data was accumulated for further study of biological contamination protection.The computational fluid dynamics (CFD) method was applied to simulate the distribution of temperature, air flow and contamination inside the compartment. The results show that the distribution of temperature and air flow is quite uniform and the human thermal comfort is good. The stochastic tracking approach of the Lagrangian method can mirror the temporal and spatial distribution of biological particle accurately inside the compartment with overpressure/negative pressure protection. The computed results were in reasonable agreement with the experimental data, which solved the problem that experimental research can only know the contamination concentration at limited location and time inside the compartment instead of mastering the movement and variation of the contamination distribution systematically and provided an effective research method to predict biological contamination concentration inside the compartment at different time and location.The vibration of supine wounded on the ambulance stretcher was simulated by the theory of multi-body system dynamics. The road test results ascertained that the simulation model and method were reasonable and feasible. The vibration absorption properties of stretcher-support in the ambulance were optimized. The optimal matching relation between stiffness and damp for the vibration absorption device of stretcher-support was presented. The vibration transferred to stretcher-support from floor of the compartment was reduced and the secondary vibration absorption was realized effectively. The vibration of supine wounded was controlled and the ride comfort was improved. After optimization design, the vibration energy decayed by 82.6% in human sensitive frequency band from 4Hz to 8Hz and the vibration absorption efficiency of the wire rope isolators as well as damper reached up to 37.8%.