预埋光纤光栅传感器的碳纤维复合材料螺旋桨水下动应变在线测试

Underwater online dynamic strain test of CFRP propeller with embedded FBG sensors

[目的]碳纤维复合材料(CFRP)螺旋桨具有轻质高强、低振动、低噪音、耐腐蚀、抗疲劳等优势。为了准确获知CFRP螺旋桨桨叶在水动力载荷下的变形和应变,提出一种水下运转状态下CFRP螺旋桨动应变在线测试方法。[方法]将光纤光栅(FBG)传感器预埋于CFRP螺旋桨,搭建CFRP螺旋桨水下动应变测试系统,设置2类测试工况:进速为0 m/s,转速从50~400 r/min依次增加;转速保持427 r/min不变,进速从0~1.6 m/s依次增加。通过FBG传感器采集上述2类工况下CFRP螺旋桨的动应变数据,对动应变数据进行时域和频谱分析。[结果]结果表明,CFRP螺旋桨上各测点的动应变特征频率一致,且与转速相关;各测点的动应变峰值取决于测点位置,即螺旋桨的结构力学特征。[结论]实现了CFRP螺旋桨在水下运转状态下的动应变在线测试,测试结果合理可靠,可为CFRP螺旋桨的理论设计和分析提供重要的实证依据,对研究螺旋桨振动噪声和水动力性能具有重要意义。

[Objective]The carbon fiber reinforced plastic(CFRP)propeller has such advantages as light weight,high strength,low vibration,low noise,corrosion resistance and fatigue resistance.In order to accurately ascertain the deformation and strain of CFRP propeller blades under hydrodynamic load,this paper proposes an online measurement method for CFRP propeller dynamic strain under submerged operation conditions.[Method]Fiber bragg grating(FBG)sensors are embedded in a CFRP propeller,and an underwater dynamic strain test system is built.Two types of test conditions are set:(1)the velocity is 0 m/s,and the rotation speed increases from 50 to 400 r/min;and(2)the rotation speed is 427 r/min,and the velocity increases from 0.0 to 1.6 m/s.The dynamic strain data of the CFRP propeller under the above conditions is obtained by the FBG sensors and analyzed in the time and spectrum domains.[Results]The results show that,the dynamic strain frequencies of each FBG sensor on the CFRP propeller are the same and related to the rotation speed,while the dynamic strain amplitude of each FBG sensor has no obvious relationship with the rotation speed or velocity,but depends on the position of the sensor,which reflects the structural mechanics features of the propeller.[Conclusion]The underwater online dynamic strain test of the CFRP propeller is realized,and test results are reasonable and reliable.This provides an important empirical basis for the theoretical design and analysis of the CFRP propeller,which is of great significance for the study of its vibration noise and hydrodynamic performance.