Research On Laser Ultrasonic Monitoring Method And State Characterization Technology Of Lining Curing State

As a highly elastic bonding material,butylated hydroxy lining is widely used to bond the shell and propellant of the solid rocket motor combustion chamber.Loading the propellant when the liner is in a semi-cured state is an effective means to ensure the quality of the charge.Premature or too late loading of the propellant is likely to cause the phenomenon of weak bonding interface,thereby affecting the stability and safety of the solid rocket motor.Therefore,In-line detection of the curing state of the liner is critical.Laser ultrasonic detection technology has the characteristics of non-contact,high resolution,and online detection,which can meet the technical requirements and realize the detection of polymer curing reaction.In this paper,the hybrid bonding structure of the metal plate lining layer is taken as the research object,and the monitoring method and state characterization technology of the curing state of the butylated hydroxy lining layer based on laser ultrasound are studied.Aiming at the mixed state and discontinuous impedance characteristics of the metal plate lining bonding structure,the paper studies the propagation path of ultrasonic longitudinal waves in the bonding structure from the aspects of laser ultrasonic experiment and ultrasonic simulation.The characteristic echo carrying solidification state information;on the basis of analyzing the time domain and frequency domain characteristic information of the characteristic echo,an accurate solution method of the longitudinal wave transit time based on the calibration time difference is proposed,and the ultrasonic wave in the metal plate and the lining is established.The relative acoustic attenuation model in the layer reveals the propagation law of longitudinal waves in the discontinuous impedance medium,and studies the quantitative characterization method of the solidification state of the lining based on the time-domain characteristics.The modulated wave was affected and the curing state was qualitatively characterized.The third-order spectral peaks of nonlinear harmonics were accurately obtained by diagonal slice spectrum,and the curing state of the liner was quantitatively characterized.The research results show that the laser ultrasonic testing technology is feasible and effective to detect the curing state of the butylated hydroxy lining layer online,and this achievement provides a new solution for the detection of the gel state of polymers in related fields.