Nanoindentation experiments were conducted under loading rates of 500–6000μN/s and applied peak loads of 4000-12000μN to measure the creep behavior of DD407 Ni-base single crystal superalloy at room temperature.Exp...Nanoindentation experiments were conducted under loading rates of 500–6000μN/s and applied peak loads of 4000-12000μN to measure the creep behavior of DD407 Ni-base single crystal superalloy at room temperature.Experimental results demonstrated that DD407 Ni-base single crystal superalloy had a good creep resistance,but its creep properties were sensitive to the loading rate and peak load.The fitting creep parameters significantly increased with increasing loading rate and peak load based on the Findley’s model,and the corresponding creep mechanism was governed by dislocation based on the calculation of creep stress exponent.During nanoindentation creep tests,it was found that the hardness and reduced modulus decreased with increasing the loading rate and peak load,and through a dimensionless analysis,it was also noted that the effect of the dimensionless loading rate was stronger than that of dimensionless peak load on the creep properties.展开更多
Mathematical model is developed for prediction of physiological changes in man during work in hot environment taking into consideration intensity of work, clothing and environment. To evaluate human functional state t...Mathematical model is developed for prediction of physiological changes in man during work in hot environment taking into consideration intensity of work, clothing and environment. To evaluate human functional state the heat stress index was calculated. Modeling researches made the conclusion that the main risk factor during work in hot environment is water losses that happens through thermoregulatory sweat evaporation. Modeling showed that in humid environment man wearing protective clothing has short time to work as water losses became more than 2% of human weight that means body dehydration. Preliminary model prediction can be used as preventive method to avoid hazard of human health.展开更多
基金financial supports from the National Natural Science Foundation of China(Nos.11772236,11472195)。
文摘Nanoindentation experiments were conducted under loading rates of 500–6000μN/s and applied peak loads of 4000-12000μN to measure the creep behavior of DD407 Ni-base single crystal superalloy at room temperature.Experimental results demonstrated that DD407 Ni-base single crystal superalloy had a good creep resistance,but its creep properties were sensitive to the loading rate and peak load.The fitting creep parameters significantly increased with increasing loading rate and peak load based on the Findley’s model,and the corresponding creep mechanism was governed by dislocation based on the calculation of creep stress exponent.During nanoindentation creep tests,it was found that the hardness and reduced modulus decreased with increasing the loading rate and peak load,and through a dimensionless analysis,it was also noted that the effect of the dimensionless loading rate was stronger than that of dimensionless peak load on the creep properties.
文摘Mathematical model is developed for prediction of physiological changes in man during work in hot environment taking into consideration intensity of work, clothing and environment. To evaluate human functional state the heat stress index was calculated. Modeling researches made the conclusion that the main risk factor during work in hot environment is water losses that happens through thermoregulatory sweat evaporation. Modeling showed that in humid environment man wearing protective clothing has short time to work as water losses became more than 2% of human weight that means body dehydration. Preliminary model prediction can be used as preventive method to avoid hazard of human health.
