# Wind-Load Response and Evacuation Efficiency Analysis of Marine Evacuation Inflatable Slide
## 3 Wind-Load Response Analysis of Inflatable Slide under Fluid-Solid Coupling
### Wind-Load Response of Emergency Inflatable Slide under Different Inflation Pressure  
From the content of the previous section, it can be seen that the wind direction angle of 30\({}^{\circ}\) is the most disadvantageous condition considering the changes of wind direction and speed. This section will not analyze the other working conditions. It will study the response of the internal pressure of the structure to the wind load by changing the inflatable internal pressure for the representative wind direction angle of 30\({}^{\circ}\).  
The inflatable internal pressure range is 3000 Pa, 3500 Pa, 4000 Pa, 4500 Pa, and 5000 Pa. As shown in Figure 14, the simulation results show that with the increase of the internal pressure of the inflatable slide, the displacement deformation decreases, which indicates that the increase of the air pressure obviously improves the anti-wind stiffness of the slide.  
It can be seen from Figure 15 that when the inflatable internal pressure is lower than 4000 Pa, the displacement deformation of the inflatable slide decreases obviously with the increase of the internal pressure. When the inflatable internal pressure is higher than 4000 Pa, the displacement deformation of the inflatable slide no longer changes significantly, and the range of change is within 1 cm, which can meet the requirements of use. Under the action of wind load, there exists ideal internal pressure in the slide of the emergency evacuation system. When the internal pressure is lower than the ideal internal pressure, the displacement deformation changes greatly and does not reach enough rigidity. When the ideal internal pressure range is reached, the displacement deformation changes are no longer obvious. Redundant inflatable internal pressure means that the evacuation system needs to carry more gas cylinders, which will occupy more storage space and prolong the time of inflatability and deployment of the facilities, thus reducing the speed of the evacuation system.  
Figure 13: Displacement deformation curves of the inflatable slide at different wind directions and different wind speeds.  
Figure 14: Displacement response of the inflatable slide under different inflatable internal pressures. **(a)** Deformation at inflatable internal pressure of 3000 Pa; **(b)** Deformation at inflatable internal pressure of 3500 Pa; **(c)** Deformation at inflatable internal pressure of 4000 Pa; **(d)** Deformation at inflatable internal pressure of 4500 Pa pressures; **(e)** Deformation at inflatable internal pressure of 5000 Pa.  
Within the range of inflatable internal pressure studied in this section, 4000 Pa is an ideal inflatable internal pressure.  
Simulation and Analysis of Inflation and Evacuation Efficiency of Emergency Evacuation Inflatable Slide  
According to the International Safety Rules for High-Speed Vessels, the design of evacuation facilities should enable ships to evacuate passengers completely within the evacuation time under controlled circumstances [21]. The evacuation time (T\({}_{\text{e}}\)) is one third of the structural fire protection time (_SFP_) of the main fire hazard area minus the 7 min required for the initial detection of danger and removal of the hazard [22].  
\[\text{T}_{\text{e}}=\frac{\text{{{SFP}}-7}}{3} \tag{6}\]  
In the Equation, _SFP_ is the time of structural fire protection (min). The time of structural fire prevention of high-speed ships studied in this paper is 30 min, and the evacuation time is calculated as 7 min.