Equivalent axle load factor(EALF)is used to characterize the fatigue damage effect of multi-axle loads on asphalt pavement.EALF is calculated as the ratio of the pavement’s fatigue resistance under a single axle load...Equivalent axle load factor(EALF)is used to characterize the fatigue damage effect of multi-axle loads on asphalt pavement.EALF is calculated as the ratio of the pavement’s fatigue resistance under a single axle load to that under a multi-axle load.Existing studies use the same fatigue life function to predict the fatigue life of asphalt mixture under both single-and multi-axle loads,primarily focusing on the differences in pavement strains under these two configurations.However,strain waveforms in asphalt pavement caused by multi-axle loads differ from those under single-axle loads,altering the mixture’s fatigue behavior.To address this issue,this research tests the fatigue responses of asphalt mixtures under actual loading waveforms from single-axle,tandem-axle,and tridem-axle loads.Based on the test results,fatigue life functions are developed for each axle configuration and used to establish an updated EALF model.Since the applied fatigue life functions are based on test results from more realistic strain waveforms,the calculated EALFs provide more reliable predictions of the damaging effect of multi-axle loads on asphalt mixtures.展开更多
Influence of applied potentials and loading waveform on the fatigue crack growth for steel A537 in 3.5% NaCl solution,and corresponding straining electrode behaviour have been studied.Under the applied potentials over...Influence of applied potentials and loading waveform on the fatigue crack growth for steel A537 in 3.5% NaCl solution,and corresponding straining electrode behaviour have been studied.Under the applied potentials over or below -800mV(SCE),the anodic dissolution or the hydrogen embrittlement is predominatant,respectively.For applied anodic potential,the acceleration effect of continuous loading pattern on the CF crack growth mainly appeared at the range of low ΔK values,while for cathodic potential,it appeared at the high ΔK values.The continuous straining causes a decrease of natural potential and an increase of anodic dissolution current.展开更多
In the impact tests of soft materials, we sometimes observe a thorn shape in the rising segment of the impact force waveform. However, the reason for the occurrence of the thorn shape has not been made clear. In this ...In the impact tests of soft materials, we sometimes observe a thorn shape in the rising segment of the impact force waveform. However, the reason for the occurrence of the thorn shape has not been made clear. In this study, thorn-shape waveforms of several soft materials are measured using compact drop test equipment under the condition of a flat frontal impact. A flat frontal impact is the condition where a drop hammer with a flat bottom surface strikes a plate-like soft material in the normal direction. Synchronized impact forces are measured using two sensors installed on both the drop hammer side and the floor side. The examined soft materials are a sponge sheet, sponge rubber sheet, gel sheet, rubber sheet, flat oil clay, low-rebound urethane foam, cork sheet, sliced ham, pork ham steak, and pork. Based on the test results, the features of the thorn-shape waveforms are discussed from a bird’s-eye view. Furthermore, the occurrence mechanism of the thorn-shape waveforms is discussed from the viewpoint of viscosity discontinuity and the double-strike phenomenon.展开更多
基金supported by grants from the National Key R&D Program of China(No.2023YFA1008904)the Guangxi Key Research and Development Project(No.AB22080091)the National Natural Science Foundation of China(No.52108412).
文摘Equivalent axle load factor(EALF)is used to characterize the fatigue damage effect of multi-axle loads on asphalt pavement.EALF is calculated as the ratio of the pavement’s fatigue resistance under a single axle load to that under a multi-axle load.Existing studies use the same fatigue life function to predict the fatigue life of asphalt mixture under both single-and multi-axle loads,primarily focusing on the differences in pavement strains under these two configurations.However,strain waveforms in asphalt pavement caused by multi-axle loads differ from those under single-axle loads,altering the mixture’s fatigue behavior.To address this issue,this research tests the fatigue responses of asphalt mixtures under actual loading waveforms from single-axle,tandem-axle,and tridem-axle loads.Based on the test results,fatigue life functions are developed for each axle configuration and used to establish an updated EALF model.Since the applied fatigue life functions are based on test results from more realistic strain waveforms,the calculated EALFs provide more reliable predictions of the damaging effect of multi-axle loads on asphalt mixtures.
文摘Influence of applied potentials and loading waveform on the fatigue crack growth for steel A537 in 3.5% NaCl solution,and corresponding straining electrode behaviour have been studied.Under the applied potentials over or below -800mV(SCE),the anodic dissolution or the hydrogen embrittlement is predominatant,respectively.For applied anodic potential,the acceleration effect of continuous loading pattern on the CF crack growth mainly appeared at the range of low ΔK values,while for cathodic potential,it appeared at the high ΔK values.The continuous straining causes a decrease of natural potential and an increase of anodic dissolution current.
文摘In the impact tests of soft materials, we sometimes observe a thorn shape in the rising segment of the impact force waveform. However, the reason for the occurrence of the thorn shape has not been made clear. In this study, thorn-shape waveforms of several soft materials are measured using compact drop test equipment under the condition of a flat frontal impact. A flat frontal impact is the condition where a drop hammer with a flat bottom surface strikes a plate-like soft material in the normal direction. Synchronized impact forces are measured using two sensors installed on both the drop hammer side and the floor side. The examined soft materials are a sponge sheet, sponge rubber sheet, gel sheet, rubber sheet, flat oil clay, low-rebound urethane foam, cork sheet, sliced ham, pork ham steak, and pork. Based on the test results, the features of the thorn-shape waveforms are discussed from a bird’s-eye view. Furthermore, the occurrence mechanism of the thorn-shape waveforms is discussed from the viewpoint of viscosity discontinuity and the double-strike phenomenon.
