| Carbon Fiber Reinforced Plastic(CFRP)has been widely used in ship field because of its excellent mechanical properties and designability,and its corrosion in the marine environment has attracted more and more attention.Hygrothermal aging is a more serious problem of the marine environmental corrosion,hygrothermal environment would lead matrix,fiber or fiber-matrix to change or destroy,thereby to affect the structure and properties of CFRP.Box girder and drive shaft are commonly used CFRP parts in ship field.During service,CFRP parts are inevitably subject to corrosion in hygrothermal environment,resulting in degradation of their performance,shortening the service life of CFRP parts,and affecting the normal work of the ship.Therefore,it is necessary to study the hygrothermal aging behavior of CFRP parts,so as to provide a theoretical basis for improving the environmental adaptability of CFRP parts.In this dissertation,CFRP box girder and drive shaft,which are widely used in ship field,were taken as research objects.The immersion method was used to study the moisture absorption characteristics of CFRP box girder in different media,and the mechanical properties of CFRP box girder before and after hygrothermal aging were tested by three-point bending test,in order to further understand the influence of moisture absorption on bending strength of CFRP box girder.At the same time,the accelerated hygrothermal aging test with constant temperature and humidity was adopted to study the aging law of CFRP drive shaft by comparing the change of torsional strength and failure mode.In addition,the working life of CFRP drive shaft in hygrothermal environment was predicted,and to evaluate the durability of CFRP drive shaft in the marine environment.The hygrothermal aging test of CFRP box girder show that:(1)In distilled water and 5%NaCl solution,the moisture absorption characteristics of CFRP box girder was obeyed the Fick's second law;(2)The higher the temperature of the solution,the faster the moisture absorption rate and the higher the equilibrium moisture absorption content of CFRP box girder;(3)The equilibrium moisture absorption contents of CFRP box girder were as follows: 90°C distilled water,90°C 5%NaCl solution,60°C distilled water,60°C 5%NaCl solution,and the corresponding moisture contents were 2.40%,1.86%,1.63%,1.23%,corresponding bending strength retention rates were 77.9%,82.9%,84.9%,91.7%;(4)The bending strength of CFRP box girder decreased with the increase of moisture absorption content during hygrothermal aging,and its durability in the hygrothermal environment was poor.For CFRP box girder working in marine environment,its environmental adaptability can be improved from two aspects of design and maintenance.The hygrothermal aging test of CFRP drive shaft show that:(1)After 48 h,96h,144 h and 192 h hygrothermal aging test in 5%NaCl solution at 60°C,the retention rates of torsional strength of CFRP drive shaft were 90.1%,81.6%,77.6%,74.1%,respectively,in the 90°C 5%NaCl solution,the torsional strength retention rates were 84.1%,77.7%,73.8%,and 70.8%;(2)The torsional strength of CFRP drive shaft decreased with the prolongation of the hygrothermal aging time,and it decreased most rapidly at the initial stage of the hygrothermal aging;(3)The torsional failure modes of the drive shaft before and after hygrothermal aging were all CFRP shaft tube failure.After the hygrothermal aging,the carbon fiber stratification of the failure part was obvious,and the failure area was larger;(4)The accelerating effect of the laboratory hygrothermal aging test was obvious,and the life prediction result showed that the durability of CFRP drive shaft in the hygrothermal environment was poor.Therefore,certain protective measures should be taken for CFRP drive shafts that are used in marine environment. |
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