Objective Quantitative characterization of the extent of incipient damage in polyethylene plate/shell structures is crucial for ensuring the safe operation and preventive maintenance of oil and gas facilities. However, traditional ultrasonic testing techniques are limited by the accuracy of detectable defects due to the wavelength diffraction limit, rendering them insensitive to incipient performance degradation and structural defects at the micro-nano scale. Additionally, the nonlinear guided wave evaluation method is sensitive to temperature variations and structural stress in complex environments, leading to significant impacts on the reliability and accuracy of the results.

Methods By combining thermoacoustic elasticity theory with the hyperelastic constitutive equation, a dispersion analysis model for plate/shell structures under temperature-stress coupling was established. This model quantifies the sensitivity of phase velocities in various guided wave modes to changes in ambient temperature and structural stress, thereby providing guidance for optimizing guided wave excitation modes in damage detection. Instead of traditional interdigital transducers, discrete piezoelectric units were utilized to propose a piezoelectric array structure based on temporal-spatial tuning and a guided wave excitation mode control method. This led to the development of a theoretical analysis model to reveal the array’s excitation characteristics. Additionally, the influence of various excitation parameters on the guided wave excitation sound field was verified through experiments. A nonlinear ultrasonic guided wave detection system was also developed, incorporating phase reversal and low-pass filtering techniques to extract zero-frequency response characteristics in damage signals. The introduction of nonlinear acoustic parameters facilitates the quantitative characterization of the extent of incipient performance degradation in polyethylene samples.

Results Modes S₀, SH₀, and A₀ in the medium and high-frequency range (＞20 kHz) were identified as having weak sensitivity to changes in ambient temperature and structural stress. The independently developed 1-3 type piezoelectric composite array transducer demonstrated its capability for excitation control in a single guided wave mode in polyethylene plates, significantly reducing the difficulty of analyzing detection signals. The time-domain morphology of zero-frequency responses was found to be similar to the pulse envelope of the excitation signals, while the frequency-domain amplitude was observed to accumulate continuously during propagation. Additionally, the nonlinear acoustic parameters in polyethylene samples exhibited an upward trend with the extension of aging time.

Conclusion The zero-frequency response of nonlinear ultrasonic guided waves demonstrates high sensitivity in detecting the microstructural evolution of materials. This approach enables a quantitative evaluation of incipient performance degradation in polyethylene plate/shell structures, providing reliable data to support predictions regarding the remaining lifespan of oil and gas facilities.