Experimental Studies On Mechanical Property Of CFRP Ply Splice Structures

Due to high strength and low density,FRP is widely applied in aerospace,high-rise structure and long-span bridges.The length and width of the existing reinforced materials can’t meet the needs of large FRP structures,therefore splice structures play an important role in FRP structures.Splice structures inevitably cause the complex stress distribution within the material,leading to serious safety hazards.In order to improve the mechanical property of polymer splice structures,this paper studies the splice structures in CFRP through the experiments and simulation,reveals the relationship between the tensile property of splice structures and the influence factors,including thickness and width of the slice.The main research is as follows:(1)In terms of the preparation craft,Vacuum-assisted infusion molding process and mold process craft are used to prepare CFRP,the shortcomings and merits of the two crafts are compared before making the choice,then the specimen needed in the experiment are prepared.(2)In terms of testing technology,for the purpose of displacement and strain test in small areas through DIC technique,new speckle producing method is proposed,displacement and strain experiments are conducted to testify the reliability of the DIC results.In Acoustic emission technique,the judging standards of acoustic signals reflecting different failure mode are obtained,and the reliability of the standards is testified through the experiments.(3)In splice property respect,tensile test is conducted,while DIC and AE technology are also applied during the loading process,numerical simulation is conducted on the basis of experiments.The comparative analysis of tensile property show that the width of slice has little effect on the tensile strength of CFRP but the strength is proportional to the numbers of layers without slice;the modulus of elastic has nothing to do with the width of the slice,but with the increase of the thickness of slice,the modulus decreases.Through DIC technology,real time monitoring is conducted on the surface of specimen,the strain distribution characteristics of different structures is thus obtained.Through AE technology,AE signals are obtained,which are divided into fiber fracture,fiber/matrix debonding and matrix cracking,assisting in the analysis of failure process.