| The development of marine resources has entered a period of rapid development,and the medium sea area is rich in resources.It is a key area for exploration and development.In this process,solid buoyant material(SBM)is a crucial link.Three phase composite SBM is composed of matrix resin,hollow beads and large-size hollow spheres.The material has low density and high strength.It is suitable to be used as buoyancy material for equipment in medium sea areas.Compared with the deep-sea area,the strength requirements of buoyant materials in the middle sea area are reduced,and more attention is paid to the reliability and stability of material properties.At present,the epoxy resin of two-phase composite SBM is generally used as the matrix resin of three-phase composite SBM.At the same time,the model and type of hollow glass beads(HGM)are not selected and determined according to the working conditions of middle and deep-sea and the characteristics of three-phase composite SBM.Based on this,this paper uses the experimental method to test the mechanical and physical properties of common resins,quantitatively compare the characteristics and differences of resin properties,and use the investigation method or experimental method to compare the type of HGM and the material and particle size of hollow spheres.The comparison results show that HD85＿PU has good strength and modulus,and has high failure compression strain.The material has both rigid and plastic properties.In addition,the exothermic reaction of the material during curing is gentle,and the peak temperature is low,which meets the process requirements.Considering the actual working conditions in medium depth of the sea and the material characteristics,HD85＿PU was used as the matrix phase,S15 HGM was used as the hollow bead phase,and 20 mm PP hollow sphere was used as the third phase to prepare the subsequent three-phase composite SBM.Secondly,The tensile test of HD85＿PU under different strain rates showed that HD85＿PU has obvious strain rate sensitivity.The stiffness and strength of HD85＿PU are positively correlated with strain rate,and the elongation at break is negatively correlated with strain rate;With the change of strain rate,the failure mode of the material changes from the dominance of soft segment macromolecular chain to the synergy of soft and hard segments and the dominance of hard segments.Then,the effect of HGM on the properties of resin matrix was studied.The results showed that the density,compressive modulus,yield strength,compressive strain and ultimate strength of two-phase composite SBM decreased with the increase of S15 HGM content;Based on the two-phase study,the trial production of polyurethane based three-phase composite SBM was completed.Two theoretical formulas were used to predict the material strength.The predicted values of the two formulas were larger than the experimental values.The relative error of the exponential law was 45.42%,and the relative error of Turcsanyi formula was 19.50%.Turcsanyi formula can be used to roughly predict the strength properties of three-phase composite SBM in the subsequent material design.Finally,Python is used to develop ABAQUS and establish an equal proportion model of hollow sphere random distribution.The numerical simulation predicts that the yield stress of the material under uniaxial compression is 15.569 mpa,which is 1.587 mpa different from the experimental yield strength of 13.982 mpa,and the relative error is 11.35%.The model has certain reliability;The model is used to calculate the stress change of the material under the hydrostatic pressure.Under the hydrostatic pressure of 10.50 mpa,the maximum stress of the material reaches 35.73 mpa,which exceeds the yield strength of the matrix.It is predicted that the material can be operated under the water depth of 1050 m. |
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