Study On Durability Of Non-metallic Materials For Fishing Vessel Hull

As a traditional fishing country,China is the country with the largest number of fishing vessels in the world.With the constant attention to the exploitation of marine fisheryresources and energy conservation and environmental protection,the comprehensive performance of fishing vessels is required more and more.At present,there are many differences between China and developed fishery countries in use of new materials,new techniques,and new regulations in construction of fishing Vessels.The high energy consumption and low efficiency have seriously affected economic benefits,this phenomenon urgently needs to be updated and reformed.In this paper,two new fishing vessel hull materials,glass fiber reinforced plastic(GFRP)and polyethylene(PE),are used for reference to the failure forms and influencing factors of fishing vessel hull materials under the actual working conditions,and a series of related experiments are carried out to establish the basic data of the performance changes.Provide reference for the design,construction,proper use and maintenance of this kind of fishing vessel.In this paper,the effects of aging experiments on material properties were studied by single-factor aging tests of GFRP and HDPE materials,such as photo-oxidation,thermal oxygen,seawater immersion and seawater freeze-thaw cycles,and multi-factor coupling was established by using SPSS statistical analysis software.The orthogonal aging experiment under the action simulates the aging behavior of the material under the actual working conditions,and analyzes the influence of aging factors on the material properties.The following conclusions are obtained:The combination of ultraviolet light and oxygen has a significant effect on the properties of both materials.The higher the irradiance,the greater the change in performance.By comparing the performance change rate of the two materials after irradiation with irradiance of 1600w/m2,the mechanical properties of HDPE have a large change rate,indicating that GFRP has better photo-aging resistance.After 1920 hours in the thermal aging experiment,the mass loss rate of GFRP was 0.75%,the tensile strength increased by 19.51%,and the bending strength increased by 14.57% under the high temperature conditions of 80℃.However,there was a gradual decline in the later stage;the quality loss of HDPE the rate was 0.24%,the tensile strength retention was 91.62%,and the bending strength retention was 94.35%.Under the normal atmospheric temperature condition of 20℃,there is almost no influence on the performance of the material,indicating that heat is one of the important factors that cause the change of material properties.The higher the temperature,the faster the rate of change of performance.In the water resistance study,the intrusion of seawater into the interior of the material and the destruction of the interfacial layer of GFRP are the main reasons for the decrease of mechanical strength.The decrease of mechanical properties of HDPE is caused by the impact of water molecules and salt ions on the molecular chain of the material.In addition,different seawater salt concentrations have a greater impact on the moisture absorption rate of the material,but have no significant effect on the mechanical properties.It is found through comparison of performance changes that HDPE is more resistant to water.In the environment of freezing and thawing seawater,seawater invades into the interior of GFRP.Due to the volume change of freeze-thawed water,the impact stress is repeatedly applied to the material,causing fatigue damage of the material,resulting in a decrease in mechanical properties.Under the influence of low temperature,the HDPE amorphous zone is produced.The transition from viscoelastic state to glass state has a slight increase in the mechanical strength of the material,and the damage of HDPE is not obvious.HDPE is more resistant to low temperature seawater environments.Multi-factor orthogonal experiment was established by using SPSS statistical analysis software.The results of orthogonal experiment by variance analysis showed that light,heat,salt concentration and time had significant effects on the properties of the two materials,and the results of variance analysis showed that light,heat,salt concentration and time had significant effects on the properties of the two materials.The order of the influence of each factor on the properties of the material was obtained.Reasonable suggestions for avoiding ageing of GFRP and HDPE under actual working conditions are given.