Study On Mechanical Properties Of GF/PP/Metal Mesh Composite Laminates

With the continuous growth of non-metallic pipelines of the oil and gas pipelines in China,the fiber-metal composite laminate has been used widely in the field of oil and natural gas transportation engineering.Among them,the new fiber-metal composite laminate is a hybrid composite structural material composed of fiber-reinforced polymer composites and metal alloy plates/nets arranged and stacked,which has the advantages of low cost,easy molding,high toughness,corrosion resistance and fatigue resistance.It can reduce the structural damage of composite materials caused by uneven filling,terrain subsidence,external construction and other activities,and can adapt to the complex and changeable oil and gas transportation environment.Therefore,it has important theoretical guidance and application value on the study of the mechanical properties for fiber metal laminate composite structure.The GF / PP / stainless-steel metal mesh composite laminate through was prepared through the hot pressure forming process,adapted the methods of mechanical properties test,microscopic characterization and ABAQUS finite element simulation,studied the influence of different process on metal mesh surface,material combination and bedding microstructure on the mechanical properties of GF / PP / metal mesh composite laminate,analyzed the micro and macro damage mechanism of GF / PP / metal mesh composite laminate under the typical mechanical load.(1)The effect of the bonding strength between stainless-steel and organics after surface treatment by etching and phosphating was studied.The research found that the adhesion of the etched samples was 1.66 times that of the unetched samples,and the adhesion of the phosphating samples was about 2.87 times that of the unetched samples.(2)The static properties of GF/PP/stainless-steel metal mesh composite laminates were studied.The research found that the laminate with the structure of "unetched stainless-steel mesh + maleic anhydride grafted polypropylene + aminosilane glass fiber cloth" had the best tensile strength,and the maximum tensile load reached 5538.4 N,which was improved compared with the original sample.up 21.3%.The main factor affecting the tensile properties of the laminate is the structural integrity of the stainless-steel mesh.The more complete the stainless-steel mesh structure,the greater the tensile load of the laminate.The laminate with the structure of "phosphatized stainless-steel mesh + maleic anhydride grafted polypropylene +aminosilane glass fiber cloth" has the best flexural and compressive strength,and the maximum flexural load reaches 93.2 N,which is 52.6% higher than that of the original sample,the maximum compressive load reaches 1042.4 N,which is 86.3% higher than that of the original sample.The research shows that that the main factor affecting the bending and compressive properties of laminates is the bonding strength of the reinforcing material and the matrix material,The increased surface roughness of the phosphorized stainless-steel mesh increases the mechanical adhesion of the material surface,and thus improves the bending resistance and compression resistance of the laminate.(3)The three-point bending finite element model of GF / PP / stainless-steel metal mesh composite laminate was constructed to analyze the failure mechanism with mechanical test.It is found that in the three-point bending simulation model with different thicknesses,the threepoint bending force-displacement simulation curve is like the reality when the laminate thickness is 1.1 mm.The peak load of the laminate increases with the thickness,and the brittle fracture tendency of the laminate becomes significant with the increase of layer thickness after reaching the maximum bending load.By studying the stress variation law of the laminate,it is found that in the transverse direction,the central element reaches the maximum stress value the fastest and fails the fastest,and the stress value of the element at the edge is relatively low.In the longitudinal direction,the stress value of the elements on both sides of the laminate is the largest,and the stress value of the element near the center is relatively low.(4)Through simulation and experimental comparison,it is found when laminate under the bending strength,the upper surface bears compressive stress and the lower surface bears tensile stress,and the local brittle fracture crack is more likely to produce near the bottom surface of the maximum load direction.The main failure mode of lamina fiber damage is fiber compression failure,and the main failure mode of matrix damage is matrix tensile failure.