Structural Design And Research Of Ceramic Pressure Hull For Small Full-ocean-depth Underwater Glider

The ocean abyss is the most unknown world on earth,and the abyssal science was born for this and has become one of the current research hotspots in ocean science.Abyssal observation is the basis of abyssal scientific research.The full-ocean-depth underwater glider has low energy consumption,long working time and low cost and is expected to become an ideal platform for scientific observation of the abyss.In abyss environment,underwater gliders must withstand more than 100 MPa ultra-high pressures,which puts forward higher requirements and challenges for underwater glider technical systems,especially pressure hull units.To this end,this paper has conducted a design study on the selection of materials,structural forms,and connection structures of the pressure hull of the full-ocean-depth underwater glider,and provides a pressure hull that meets the technical requirements for the full-ocean-depth underwater glider.Based on the analysis of material specific modulus and specific strength,the silicon carbide ceramic is used as the material of the pressure hull cylindrical shell,and the overall structure of the pressure hull is assembled and sealed by silicon carbide ceramic cylindrical shell and the hemispherical aluminum alloy head;according to the structure stability criteria and strength criteria,as well as pressure hull volume and buoyancy requirements,silicon carbide ceramic cylindrical shells,aluminum alloy heads,aluminum alloy connectors and titanium alloy adapter rings and other pressure hull parts are designed.Establishing finite element model analyzes and checks the strength,stiffness and stability of the pressure hull,and improves the structure of the titanium alloy adapter ring.Based on the Poisson effect,the connection between the gasket and the cylindrical shell was improved;Based on the deformation coordination relationship between the gasket lying in the adapter ring end face and the adhesive layer lying in the cylinder surfaces,a design model for the thickness of the U-shaped adhesive structure gasket and the thickness of the adhesive layer was proposed,and the adhesive structure was designed.The 105 MPa pressure test was carried out on the pressure hull designed and trial-manufactured.The results show that the pressure hull meets the design requirements of pressure resistance and sealing.The above results laid the foundation for the development of deep-sea gliders for full-ocean-depth.The proposed model of the thickness of the end face gasket and the thickness of the side adhesive layer can also be used for other adhesive structure design,which enriches the design theory of adhesive structure.