Variability of the Fatigue Driving Force within Grains of Polycrystals
Experimental studies in the last few decades have exhibited higher fatigue crack growth rates for cracks with size on the order of grains than would be predicted using growth laws based on LEFM.Small crystallographic fatigue cracks are affected by microstructure features that are not captured by traditional homogenous fracture mechanics theories (i.e.,LEFM,EPFM).Since far-field driving force parameters cannot capture the intrinsic variability of the local fatigue driving force of small cracks induced by microstructure,alternative measures of the fatigue driving force are sought.This work employs finite element simulations that explicitly render the polycrystalline microstructure to compare nonlocal fatigue indicator parameters (FIPs) averaged over multiple volumes.The model employs a crystal plasticity algorithm in ABAQUS calibrated to study the effect of microstructure on early fatigue life of Ni-base RR1000 superalloy at elevated temperature under constant amplitude loading.The results indicate slight differences in the extreme values of distributions of FIPs for each element,slip plane cross-section (bands) and grain volumes.Furthermore,the grain average FIP better reflects the driving force for cracks on the cross section at the center of the grain while the extremes values of the FIPs averaged along bands tend to be located away from the grain centers.
Fatigue Indicator Parameter Microstructurally Small Cracks Fatigue Driving Force
Gustavo M.Castelluccio David L.McDowell
Woodruff School of Mechanical Engineering Georgia Institute of Technology,771 Ferst Drive,N.W,Atlant Woodruff School of Mechanical Engineering Georgia Institute of Technology,771 Ferst Drive,N.W,Atlant
国际会议
北京
英文
1-10
2013-06-16（万方平台首次上网日期，不代表论文的发表时间）