Experimental And Theoretical Studies On The Stability Of Pultruded GFRP Axial Compression Members

Glass Fiber Reinforced Polymer(GFRP)is made of glass fiber and its products as reinforcement materials and resin as the matrix.It has light weight,high strength,fatigue resistance,shock resistance,good chemical resistance,and electricity.It has the advantages of excellent insulation and thermal performance,simple construction process and good designability.It is one of the ideal materials for new structural members.Many scholars at home and abroad have done a lot of research on the use of GFRP members as independent stress members,but because of the complex composition of composite materials,so far,the calculation method of the composite member's stable bearing capacity is not yet mature,and there is no recognized unified calculation method.The previous members of my research group have conducted a lot of theoretical and experimental research on pultrusion GFRP axial compression members,which has laid a solid foundation for the numerical simulation,experiment and theoretical analysis of this article.In order to further study the mechanical performance and stability performance of pultruded GFRP axial compression members,verify and revise the research results of the former team members,this paper carried out the following work:1.Introduced the constitutive relationship of pultrusion GFRP and the theoretical basis for achieving its progressive damage and destruction;selected ABAQUS finite element software,based on two-dimensional Hashin's failure criterion and progressive damage failure principle,and adopted a refined modeling method to establish A simulation model of axial compression test of GFRP members with fixed ends at both ends,hinged ends at both ends,and elastic supports at both ends is presented to maximize the true test conditions.2.Based on the"General Principles of Fiber Reinforced Plastic Performance Test Method",the axial compression test of the pultruded GFRP round tube under the hinged,fixed and elastic support boundary conditions was designed,and the GFRP test piece,test equipment and equipment,data measurement plan,test plan and test process were introduced.3.Based on the formulated test plan,12 groups of 36 pultruded GFRP round tubes with 3kinds of boundary conditions were tested for axial compression stability.The test process and test results were described and analyzed in detail.Obtained the test data of the failure mode of the rod,load-axial displacement curve,load-transverse displacement curve,longitudinal stress-strain curve and transverse stress-strain curve at the strain gauges of various parts of the specimen.And the axial compression test results of GFRP round tubes of each boundary condition are summarized.4.The validity and accuracy of the finite element model in different slenderness ratio intervals are verified by the comparison of the test results in this paper,the test results in relevant literature and the calculation results of the finite element.5.Through the analysis of the test results in this paper,the change rule of the equivalent initial bending of the center of the rod of the GFRP axially compressed circular tube is obtained,and the functional relationship between the equivalent initial bending₀ and the relative slenderness ratio?under different boundary conditions is established respectively.The least square method fits the calculation formula of the equivalent initial bending₀,and brings it into the Perry formula to obtain the calculation formula of the ultimate load of the GFRP axial compression member.It is verified that the error between the calculation result and the test result or the finite element analysis result is small And partial security.The formula can be used as a reference for designing axial compression GFRP round tube members.