Study On Mechanical Properties Of Solid Buoyancy Materials

Solid buoyancy material(SBM)is a structural material widely used in marine engineering equipment.Due to its low density,excellent mechanical properties and low water absorption,it plays an indispensable role in engineering practice such as marine resource exploration.SBM has a special operating environment and complex operating conditions,so it is of great significance to study its mechanical properties in both theoretical analysis and engineering application.In this paper,glass microspheres/epoxy resin was used as the research object.The effects of hollow glass microspheres(HGM)content on the mechanical properties of SBM were analyzed by experimental test and theoretical calculation methods.Based on the micromechanical method,the SBM representative volume element model was constructed to predict the Young's modulus,Poisson's ratio and Yield stress of the material through simulation calculation,and the failure process of SBM damage was numerically simulated by the cohesive model.The main conclusions are as follows:(1)The density of SBM decreases with the increase of microspheres content.When the content of microsphere is less than 60vol%,the water absorption of SBM decreases with the increase of HGM content,but when the content of microsphere exceeds 60vol%,the water absorption rate of the material increases significantly,and the water absorption rate decreases with the extension of time.(2)With the increase of HGM content,the tensile strength and compressive strength of SBM first increase and then decrease.When the content of microspheres is 30vol%,the tensile strength of the material reaches a maximum of 36.48 MPa.When the content of microspheres is 50vol%,the compressive strength of the material reaches a maximum of 156.25 MPa.(3)The influence of microsphere content,wall thickness and particle size distribution on the mechanical properties of SBM is numerically simulated.The simulation results show that,the Young's modulus and Yield stress of the solid buoyancy material increased with the increase of HGM content,but the Poisson's ratio is decreases gradually.The Young's modulus predicted by logarithmic normal distribution of microspheres particle size is closer to the experimental data than that predicted by three-dimensional random represent volume model.(4)The damage failure process based on the bilinear cohesive model can be divided into three stages: the linear elastic loading stage of the interface,initial stage of interface damage and accumulation stage of the interface damage.During the linear elastic loading stage of the interface,the microspheres and the matrix are effectively connected,and the stress can be fully transmitted;At the initial stage of interfacial damage,the debonding begins to occur between the microspheres and the matrix,and the material appeared damage;In the stage of interfacial damage accumulation,the interface gradually softened with the increase of displacement,and the stress could not be transferred effectively.