Study On Fatigue Propertie Of Basalt Fiber Reinforced Polymer And Temperature Influence On Then

Basalt fiber reinforced polymer(BFRP)is a multip hase material.Its complex mechanical properties are not only determined by its component materials and manufacturing processes,but also easily affected by the loading method and the surrounding environment,especially the temperature.When basalt fiber reinforced polymer composites are used as load bearing structural materials in a project,the fatigue performance under long-term service load is an important safety evaluating indicator.In this paper,through experimental testing and theoretical analysis,the tension-tension fatigue properties of basalt fiber reinforced polymer composites and their temperature influence are studied.The research contents and main conclusions are as follows:1.Through the static tensile failure test,and the tensile strength of basalt fiber dry filament at room temperature,80℃ and 110℃ and basalt fiber reinforced polymer composites at room temperature,50℃,70℃,90℃ and 110℃ were respectively obtained.A series of tension-tension fatigue experiments were performed on these two materials under corresponding environmental temperature.Their S-N curve equation were obtained by the experiment data,to predict their extreme fatigue stresses.The experimental results have indicated that:below 110℃,the tension-tension fatigue performance of basalt fiber dry filament was not affected by environmental temperature.While the fatigue performance of basalt fiber reinforced polymer composites decreased with the increase of environmental temperature,which is attributable to the deteriorated resin bonding performance caused by rised temperature.2.Through the analysis of experimental data,it was found that the tensile fatigue test data of basalt fiber reinforced epoxy resin composites shows great dispersion.The 70 sets of tests were carried out on the tension-tension fatigue life of 70%stress level at room temperature,and the statistical analysis of normal distribution and two-parameter Weibull distribution was conducted.The results have shown that the goodness of fitting of the Weibull distribution can reach 0.99,higher than the normal distribution(0.91).Obviously the former is more suitable for statistical analysis of the fatigue life of basalt fiber reinforced polymer composites than the later.3.Based on the stiffness degradation theory of fatigue damage of composite materials,combined with the stiffness degradation curves of basalt fiber reinforced polymer composites under different loading stress levels at room temperature,50℃,70℃,90℃ and 110℃,a correction model was proposed to describe the stiffness degradation of fatigue damage of composite materials.The model was verified with the experimental data of glass fiber composite laminates in the existed literature,which proved that the model proposed in this paper can describe the stiffness degradation law of composite materials well.4.Two methods were proposed to predict the tension-tension fatigue life of basalt fiber reinforced polymer composites under the influence of temperature:the one is to predict the above-mentioned stiffness degradation correction model of fatigue damage,and the other is based on the semi-empirical formula.The error rate of the tensile fatigue life of basalt fiber reinforced polymer composites at room temperature,50℃,70℃,90℃ and 110℃ predicted by the first method is within 10%;while the second method has a higher error rate,but it is easy to use:to predict the fatigue life of the material under the environment temperature,we only need the fatigue life of the material at room temperature and the static strength of the material under different temperature environments to obtain the predicted value.