Study On Interfacial Properties Of SMA Reinforced GFRP Composites

Fiber reinforced composites?Fiber Reinforced Polymer,FRP?have outstanding properties such as high specific strength,good corrosion resistance and easy preparation and processing because of their own structural characteristics.They have played an active role in many engineering fields.For example,in the fields of civil engineering,automobile structure and aerospace,fiber reinforced composites have replaced many traditional materials.It has greatly promoted the development of human society.However,fiber reinforced composites also exhibit many deficiencies.For example,in the external load under the effect of fiber reinforced composite material is prone to matrix cracking,fiber matrix interface debonding and fiber fracture and other forms of damage.This damage may not be observed with the naked eye,but on the safety of the structure poses a great threat.Shape memory alloy?Shape Memory Alloy,SMA?with shape memory effect?Shape Memory Effect,SME?and super elastic elasticity?Superelasticity,SE?and other excellent performance has been widely used in construction engineering,aerospace,industrial automation,energy,instrumentation,medical,machinery manufacturing and other industrial fields,the huge economic benefits.In recent years,people began to study the use of SMA as a reinforcement to enhance the composite material,thereby enhancing its ability to resist external load.However,as a metallic material,SMA has a smooth outer surface,which leads to the problem of poor compatibility between SMA fiber and resin matrix in SMA reinforced composites.Therefore,based on the above problems,the following work:?1?Theoretical analysis of interface damage behavior based on bilinear softening cohesive zone model.In this paper,the mechanical behavior of the interface initial damage and the complete failure is studied,and the initial damage displacement value and the complete separation failure displacement value are given.?2?The SMA/epoxy resin single fiber pull-out specimens were fabricated by casting,and the interfacial properties of SMA fiber reinforced composites were analyzed by single fiber pull-out test.The finite element software ABAQUS was used to simulate the fiber pull-out process of the shape memory alloy?SMA?composites based on the damage model.The results show that the ultimate pullout load of single fiber reinforced composites increases gradually with the increase of SMA fiber embedment depth from 1 cm to 2 cm.Weak interface effect is the key factor of interface performance?3?Experimental study on interface properties of shape memory alloy reinforced composites.The surface of SMA fiber was treated by SiO₂ nanoparticles coated with acid etching.The surface morphology of SMA fibers with different surface treatments were analyzed by electron microscopy?Scanning Electron Microscope,SEM?.The pull-out load displacement curves of SMA fiber reinforced composites were obtained by single fiber pull-out test.The results show that the morphology of nano SiO₂ particles modified by acid etching is rough and the distribution is relatively uniform.Compared with the untreated SMA fiber reinforced composite material,through the method of SMA acid etching after coated SiO₂ nanoparticles can effectively improve the single fiber pull-out load and critical shear strength,so as to improve the interfacial properties of composite materials.?4?The SMA fiber reinforced composite laminates were fabricated by vacuum assisted forming?Vacuum Assisted Resin Infusion,VARI?,and then the three point bending test was performed on the composite laminates,and the data were analyzed from the experimental data and the failure morphology in two aspects.Research shows that compared with the untreated SMA fiber reinforced composite laminates,effectively improve the bending strength of composite laminates by SMA etching method after coating nano SiO₂ nanoparticles;from damage morphology,the modified laminate appeared tensile fracture,effectively avoid the stratification of unmodified laminates failure phenomenon.The epoxy resin was attached to the surface after failure,and the interface between SMA fiber and its composites was good.The modification of SiO₂ nano particles after acid etching can effectively improve the interfacial properties of composite laminates.