Fretting Fatigue Life Prediction And Crack Growth Prediction Of Pin-Loaded CFRP-Strap Hangers

Pin-loaded CFRP strap cable is to wrap a unidirectional fiber CFRP continuous strip on two cylindrical pins in a way similar to the circular runway layer by layer,and the load is transferred to the CFRP loop through two cylindrical pins.Under the action of reciprocating load,there will be friction between the inner ring and pin,which will cause fretting fatigue and reduce the fatigue life of components.In this paper,the fretting fatigue life of the pin type CFRP loop cable is predicted and the crack growth of the component is analyzed by experiments,finite element analysis and theoretical calculation.The main contents of this paper include the following aspects:(1)The fretting fatigue life prediction model of pin type CFRP ring is established.Taking the hinge pin type CFRP ring as the research object,the SWT fatigue damage parameters based on the critical plane method are selected,and the two parameter Weibull distribution is used to establish the functional relationship between fretting fatigue life and damage parameters.According to the fretting fatigue life test results,the ANSYS finite element model is established to verify the accuracy of the life prediction model.The results show that the fretting fatigue life prediction model proposed in this paper can better meet the actual situation,the error is small,and the fatigue life prediction value under 95%reliability can meet the engineering design requirements.(2)A prediction method for the fatigue crack of pin type CFRP ring is proposed.The fracture rule of fretting fatigue is analyzed from two aspects of experiment and theoretical analysis.The fracture crack length of CFRP ring under different stress levels is calculated by boundary collocation method.Finally,the fretting fatigue crack growth rate of CFRP ring is estimated based on Paris formula.The results show that with the increase of tensile stress,the number of fatigue cycles decreases,the crack limit length decreases,but the crack growth rate increases.(3)The influence factors of stress intensity factor calculated by boundary collocation method are analyzed.The validity of the calculation results of the stress intensity factor is verified,and the influence of the internal factors of the boundary collocation method on the stress intensity factor is analyzed.The results show that the anisotropic parameters and the ratio of the long side to the short side have great influence on the stress intensity factor;the number of matching points,truncation terms and the least square method have little influence on the stress intensity factor;the sequence of matching points has no influence on the stress intensity factor.