摘要
为了解释超声磨削的高效延性切削现象,进行了纳米复相陶瓷材料在对称循环应力(R=-1)下普通及超声振动条件下的疲劳寿命试验,得到其在两种条件下的循环疲劳特性曲线。基于非局部理论,选取了相应的二维衰减核函数,建立了超声下的非局部本构模型,分析了超声振动作用对纳米复相陶瓷材料的力学行为及断口微观特性的影响规律。试验结果表明:试件在给定频率范围内的超声振动作用下,循环应力幅值明显降低,说明超声振动作用对相同疲劳寿命时所需循环应力幅有衰减作用;对断裂后不同超声频率、相同疲劳寿命的试件断口微观形貌分析表明,超声振动作用改变了材料微观组织结构,使材料的韧性增强,断裂方式发生改变,这些力学性能使超声磨削时的临界磨削深度比普通磨削时大。试验结果与理论分析相吻合。
In order to explain the high efficiency ultrasonic ductile grinding cutting phenomenon,the fatigue properties of nano-composite ceramics are studied in the asymmetric stress cycle（R=-1） under ordinary condition and the condition of ultrasonic vibration,and the cycle fatigue curves under the two conditions are obtained.To explain the effect of ultrasonic vibration on the mechanical behaviors and micro-fractures characteristics,nonlocal theory is introduced to establish the non-local constitutive model under the ultrasonic condition based on the corresponding two-dimensional nuclear attenuation function.The results of experiments show that the cyclic stress amplitude decreases significantly under given frequency range ultrasonic vibration.The microstructure of the same fatigue life under different frequencies are also analyzed,and it shows that the toughness is enhanced,and the microstructure and fracture mode are changed under ultrasonic vibration.Because of these mechanical properties the critical grinding depth of ultrasonic grinding is larger than that of ordinary condition.The experimental results coincide with the theoretical analysis.
出处
《机械科学与技术》
CSCD
北大核心
2010年第5期612-615,共4页
Mechanical Science and Technology for Aerospace Engineering
关键词
超声振动
纳米复相陶瓷
疲劳特性
非局部理论
ultrasonic vibration
nano-composite ceramics
fatigue properties
nonlocal theory
