Finite Element Analysis Of Capsular Cavity Structure Underwater Mechanical Properties Of Polypropylene Fiber Reinforced Cement-based Composite Material

With the lack of resources on land,the ocean has become a strategic location for human exploration and development in recent years.Metal materials are the main raw materials for human beings to manufacture submarine detectors,submersibles and submarine structures.However,the high cost of metal materials and the high maintenance costs are the thorny issues that countries need to face.In order to improve and alleviate the above problems,it is necessary to explore a new high-performance material instead of metal materials,which can be used in a complex marine environment,with excellent mechanical properties and durability,and low cost.In this paper,the mechanical properties and durability of polypropylene fiber reinforced cement-based composites were studied,and the optimal material mix ratio was selected and compared to simulate the finite element simulation of the underwater capsule cavity structure.In this paper,three sets of water-cement ratio(0.26,0.30,0.34)and four fiber blends(0%,0.5%,1.0%,1.5%)were designed in the experimental study with water-cement ratio and fiber content as variables.And added a mineral admixture with consistent dosage(10% fly ash and 8% silica fume instead of cement).Under the standard curing conditions,the mechanical properties of polypropylene cement-based composites at 4d,7d,28 d and 56 d and the impermeability at 28 d and 56 d were studied.The results show that the water-cement ratio is the determinant of the strength and impermeability of the cement-based composites,and the test group with low water-cement ratio has better mechanical properties and durability.In the test group with 0.5% fiber content,the compressive and flexural strength of the cement-based composites was significantly higher than that of the reference group,and the compressive and flexural strength of the test materials with the fiber content of 1.0% and 1.5% was higher than the benchmark.The group has seen a decline.With the increase of fiber content,the impermeability of polypropylene fiber reinforced cement-based composites decreased,and the higher the fiber content,the greater the decrease.Based on the test results,the test parameters of the water-cement ratio of 0.26 and the fiber content of 0.5% were selected and the detailed parameters were selected.The ABAQUS nonlinear finite element numerical simulation software was used to establish the numerical value of the thin-walled structure of the capsule cavity.Calculate the model.Based on the numerical simulation results under different water depths,the variation law of the thin-walled structure of the capsule cavity with the hydrostatic pressure is analyzed,and the safe dive depth is obtained.The error is compared with the theoretical analysis in the literature,which verifies the numerical simulation structure.Correctness.At the same time,based on the numerical simulation results of different wall thickness scales,the variation of wall thickness and hydrostatic pressure of the thin-walled structure of the capsule cavity was studied,and the safe dive depth was obtained,and the aspect ratio and safety of the structure were fitted.The relationship between the depth of dive.The results show that the safe submerged depth of the capsule cavity thin wall structure studied in this paper is about 1900 m.When the wall thickness changes,the thickness-to-diameter ratio of the structure is linear with the safe dive depth.