Research On Terahertz Nondestructive Testing Of Rubber Material

Rubber is widely used in aerospace field as high performance sealing material due to its better elasticity than metal,high mechanical strength,good flexing resistance and the specific viscoelasticity which can consume energy.However,rubber material will inevitably be damaged by various factors during the manufacturing processes and in deployment.Based on the above reasons,it is proving necessary to seeking for a technological means which would supply thorough nondestructive testing(NDT)on rubber.Research shows that in term of NDT of rubber materials,terahertz(THz)nondestructive testing technology with the properties of security,effectiveness,noncontact and anti-interference has more advantage than the traditional nondestructive testing technology.In this paper,the optical parameters extraction model of terahertz time domain spectroscopy(THz-TDS)was deduced based on the THz-TDS theory.A propagation simulation model of terahertz wave in material was proposed and validated.Based on the extracted optical parameters and propagation simulation model,the rubber material samples where defects were prefabricated were detected by the reflective THz-TDS system:(1)The rubber samples with 0.06 mm,0.13 mm,0.18 mm,0.26 mm and 0.32 mm thickness prefabricated debonding defects were detected by the reflective THz-TDS system.The results show that the THz-TDS technology can detect the 0.06 mm thickness debonding defect of the rubber material,and the defect thickness has a linear relationship with the flight time difference that characterizes the thickness.(2)The rubber samples with Φ10mm prefabricated inclusion defects of 0.22 mm thickness metal,0.19 mm thickness PTFE plastic and 0.30 mm thickness white cotton glove were detected by the reflective THz-TDS system.Different imaging methods were used to process the detection results.The comparative analysis shows that for the three kinds of samples prepared in this paper,both the minimum value imaging and the power integration imaging of the selected time-domain waveform region can achieve good imaging results,and the power integration imaging of the selected time-domain waveform region effect is better.Besides,the rubber products used in practical engineering were detected by the reflective THz-TDS system.Through the analysis of time-domain waveforms and BScan images,the qualitative and quantitative detection of delamination defects,bonding quality and thickness distribution of rubber products were successfully achieved,and satisfactory results were obtained.Research shows that THz-NDT has the important search value and promising application prospects on quality testing of rubber material.