Research On Bearing Capacity And Influencing Factors Of Fiberglass Reinforced Plastic Thread Connections At The Low Temperature

Fiberglass reinforced plastic is a fiber reinforced composite material,it is applies to low temperature engineering due to its low thermal conductivity and low density and other advantage,the threaded connection of fiberglass reinforced plastic has become an important component of compressive support in low temperature engineering.As the connection part is the key part for supporting,it has guiding significance to low temperature engineering structure design for researching the carrying capability and reliability of fiberglass reinforced plastic threaded connections in low temperature.This papers takes the supporting components of a large-scale low temperature performance lab as application target,adopts the method of theoretical analysis,simulation analysis and experimental analysis,studies the carrying capacity and influencing factors of the threaded connection structure of FRP fiber reinforced composite materials in the environment of-196℃.The main research contents show as below:1.Based on the analysis of the existing strength theory of fiber reinforced composites,this paper selects the maximum stress theory as the basis for strength calculation and failure judgment of FRP threaded connections;through the theoretical stress analysis of the threaded connection parts,this paper analyzes the deformation forms of fiberglass reinforced plastic threads,and deduces the deformation formulas;combines with the theory of heat transfer analysis and thermo-elastic structure,this paper analyzes the thermo-mechanical coupling process of fiberglass reinforced plastic threaded connections in low temperature environment.2.This paper respectively tests the low temperature mechanical properties and thermal performance parameters of epoxy laminated fiber reinforced plastic body materials,and obtains the performance parameters of fiber reinforced plastic composite materials at low temperature of-196℃,including tensile strength,elastic modulus,Poisson’s ratio,shear strength,thermal expansion coefficient,etc.,which provides accurate material basic parameters for the establishment of simulation analysis model.3.Based on the Abaqu,establishes a thermal-mechanical coupling simulation model of fiberglass reinforced plastic thread connection load at low temperature,and obtains the variation laws of tensile stress,compressive stress and shear stress in FRP fiber direction and layup direction after FRP thread load,and combines with the maximum stress criterion of composite materials,this paper analyzes the the reliability of threaded connection of the research object under the actual working condition.4.The simulation analysis of fiberglass reinforced plastic threaded connection support columns under different axial ballasts is conducted,and this paper analyzes the failure modes and failure positions of the threads after carrying and obtains the ultimate carrying load of the research object in this paper is 70 kN when it fails;at the same time,this paper conducts the compressive bearing test of FRP threaded connection support column at low temperature,and the axial compressive load is 66.7kN;through the comparison between the experimental and simulation results,verifies the correctness of the simulation results,and obtains a set of strength analysis methods and failure judgment criteria for fiber reinforced composite threaded connection.5.The simulation analysis is conducted on FRP threads with different structural parameters,such as fillet radius of tooth root,tooth of screw thread bearing,depth of screw teeth,etc,and obtains the influence law of various structural factors on the bearing performance of FRP threads,which provides a basis for structural design of fiber reinforced plastic thread connection in low temperature environment.