【摘要】 在碳纤维增强复合材料(CFRP)板中激励压电晶片产生超声Lamb波,并利用Lamb波对复合材料板在拉伸试验各阶段进行非线性超声研究,分析板中产生的高次谐波以及非线性超声系数与应力的变化关系。实验结果表明:复合材料板在拉伸过程中产生了明显的二次谐波和三次谐波,非线性超声系数在应力较小时随应力缓慢增大;当拉伸应力达到450MPa时,复合材料板中发生了碳纤维断裂现象,非线性超声系数随应力增大产生振荡;当拉伸应力达到850MPa时,非线性超声系数随应力快速增大,直至断裂失效。通过分析可知,非线性超声检测技术可对碳纤维增强复合材料中的微损伤和性能退化进行早期的预警。更多还原

【Abstract】 The nonlinear ultrasonic effects were experimentally investigated in carbon fiber reinforced polymer( CFRP) plate using Lamb waves excited by piezoelectric wafers attached on the plate surfaces. The high order harmonic was generated and the relationship between nonlinear ultrasonic parameter and tensile stress was analyzed. The results showed that the second and third harmonics were generated when the CFRP plate was in tensile state. The nonlinear ultrasonic parameter slowly increases with the stress when the tensile stress is small.When the stress reached 450 MPa,little carbon fibers broke and the parameter fluctuated with the increasing stress. When the stress reached 850 MPa,the parameter quickly increased with the stress until the CFRP plate cracked. According to the analysis results,the application of nonlinear ultrasonic technique can provide early warning for micro-scale damage and performance degradation in CFRP composites.更多还原