Experimental Research On Stress Corrosion And Corrosion Fatigue Under Salt Fog Environment And Loading

Cable break accidents and frequently changing cable at home and abroad show that human in the study of cable damage condition evaluation and remaining life prediction field is still far from sufficient.Cable-stayed bridge due to corrosion environments and complex stress joint action during service will shorten it life.And corrosion fatigue easily leads to brittle fracture without warning under corrosion and alternating stress.Thus causing huge casualties and economic losses.How to exclude the above-mentioned risk has become a hot research today.This article simulate cable suffer chloride ions corrosion in coastal areas by indoor accelerated salt spray test.By galvanized steel sheathed sample pack of hot corrosion of different times and different loading conditions,to study the corrosion of steel cable weight loss,mechanical properties,fracture characteristics and analyze its causes.This article also creatively presented that different forms of polyethylene sheath damage,and then analyze the effects of different forms of corrosion damage to the strand.Observation and analysis of the corrosion strand by industrial digital microscope and image processing software GSA-Image Analyser,and measure the size of pits and cracks,then statistics density of pits.Finally,deduction the algorithm of crack propagation rate under stress corrosion and corrosion fatigue through existing research,and simulate the cracks in different length,width,depth by the finite element software ANSYS.The main contents of this article are as follows:① It was found that due to the protective effect of oxidation products,corrosion rate was decreased in the late of corrosion tests,and the rate was independent with the rate in natural environment.② According to the gray level histogram shows that in the same period of corrosion,the degree of corrosion performed:no stress<static stress<alternating stress.③ The reason of tension performance degrade is mainly attributed to the effect of stress concentration pits or weaken effect section;however,the difference in the corrosion rate is not within the scope of the random nature of the effect of pitting corrosion leads to degradation of the degree of tensile modulus of the performance was not significantly correspondence.④ Point and crack damage on PE sheath caused pitting and crevice corrosion and corrosion in alternating expansion worst.⑤ There are two factors affect the fracture shape of the wire.The macro performance of the geometric characteristics of pits,showing the microscopic arrangement of pearlite arrangement.The ultimate tensile strength of the strand is to form pits under the joint action decided digit pits bottom group of pearlite.⑥ The depth of the crack is the main factors that influence the tensile strength and yield strength of the steel wire.Under the same loads,depth is deeper,the stress of the crack tip is greater,on the contrary, the length and width is longer,the stress of the crack tip is less.