Application Cases

【Overview】
In this study, the Aigtek ATA-1372A broadband power amplifier was used to build an ultrasonic testing system. High-strength steel welds are widely used in bridge engineering, but welded connections are susceptible to fatigue damage. Traditional nondestructive testing methods are limited by surface noise. Although ultrasonic diffuse field technology is sensitive, its reliability is compromised by the complexity of welds. Existing research lacks systematic evaluations of the degradation of tensile and impact properties and high-cycle/low-cycle fatigue performance of Q690qENH and Q960E high-strength steel welds under welding heat. This paper presents welding process optimization, full-life fatigue testing, digital image correlation (DIC) methods, and ultrasonic theoretical modeling combined with finite element simulations to reveal the laws of ratchet strain and elastic modulus degradation. A damage detection and remaining life prediction method based on ultrasonic energy density and squared amplitude coherence is proposed, providing an innovative solution for the safe operation and maintenance of high-strength steel welds.

Experiment Name: Fatigue Damage Detection and Remaining Life Prediction of High-Strength Steel Welds Based on Ultrasound

Experiment Principle:
This study is based on the formation mechanism of the ultrasonic diffuse field and the theory of signal time shifts caused by fatigue damage. Methods such as the ultrasonic energy density correlation coefficient are used for weld damage detection. The feasibility is verified through finite element analysis and full-life tests. Innovative damage detection models and remaining life prediction methods  are proposed. Experiments demonstrate the capability for early damage warning (high-cycle threshold: 20%–50%, low-cycle threshold: 10%–20%) and improved detection sensitivity, providing a high-precision nondestructive testing solution for the safe operation and maintenance of high-strength steel welds.

Experimental Block Diagram:

Experimental Setup Photos:

Experimental Procedure:
Q690qENH and Q960E high-strength steel butt welds and cruciform  fillet weld specimens were prepared using an optimized gas-shielded welding process (welding heat input: 4–17.5 kJ/cm). Tensile performance tests (electronic universal testing machine, DIC monitoring), Charpy impact tests (MTS pendulum impact tester), high-cycle fatigue tests (MTS hydraulic servo system, stress control), and low-cycle fatigue tests (strain control) were conducted. Ultrasonic technology (PZT sensors, frequency range: 300 kHz–1.83 MHz) was used to acquire diffuse field signals. Damage was evaluated based on the path superposition principle and short-time Fourier transform. The results show that under optimal welding heat input, the tensile and impact properties of the welds approach those of the base metal. The high-cycle fatigue strength exceeds the specifications by a factor of 2–4. Low-cycle fatigue exhibits cyclic softening characteristics. The ultrasonic energy density correlation coefficient and squared amplitude coherence enable early damage warning, validating the effectiveness of this method for fatigue damage detection in high-strength steel welds and supporting engineering safety assessments.

Application Directions:
Fatigue damage detection and remaining life prediction, specifically including health monitoring of welded connections in large-span steel bridges, full-life cycle safety assessment of major engineering infrastructures (e.g., all-welded steel bridges), and early damage warning of high-strength steel components under cyclic loading.

Advantages of Aigtek Amplifiers in This Application:

1. DC–25 MHz wideband coverage – Precisely meets the requirements for wideband excitation signals.

2. Fine control of output intensity – Overcomes the strong attenuation of weld structures, achieving high signal-to-noise ratio signal detection.

3. Four-quadrant output capability – Efficiently drives PZT capacitive loads, ensuring waveform purity.

Recommended Product: ATA-1000 Series

Figure: ATA-1000 Series Broadband Amplifier Specifications and Parameters

The experimental materials in this article are compiled and released by Xi'an Aigtek Electronics. Aigtek has become a large-scale instrument and equipment supplier with a wide range of products in the industry. Demo units are available for free trial. Xi'an Aigtek Electronics is a high-tech enterprise specializing in the research, development, production, and sales of electronic testing instruments such as power amplifiers, high-voltage amplifiers, power signal sources, preamplifiers for small signals, high-precision voltage sources, and high-precision current sources.