# The Effect of Ultrasonic Probes on the Ability to Inspect Adhesive Joints

## TL;DR

This paper explores how different ultrasonic probes affect the inspection of adhesive joints, finding that frequency significantly impacts signal accuracy.

## Contribution

The study introduces a novel analysis of ultrasonic probe performance across a wide frequency range for adhesive joint inspection.

## Key findings

- Frequency significantly affects ultrasonic wave attenuation and wavelength in adhesive joints.
- Certain adhesives can alter the maximum frequency of ultrasonic pulses by up to 25%.
- Reference samples are necessary to avoid erroneous signals from specific frequencies.

## Abstract

Ultrasonic tests are widely used, both in laboratory and industrial settings, to assess the quality of joints, mainly welded joints. Studies are being carried out on the possibility of ultrasonic evaluation of adhesive joints. This study was conducted using signal analysis in the time and frequency domains. The ultrasonic probes used in the tests were selected on the basis of the properties of the test elements. For example, when testing welded joints, ultrasonic probes with a water delay line bounded by a thin diaphragm were used. Since adhesives have different acoustic properties, it is necessary to evaluate the capabilities of different ultrasonic probes to test adhesive joints. Tests were conducted for two different adhesives (cyanoacrylate and structural) and eight ultrasonic probes with a frequency range of 1.660 to 13.70 MHz. In the literature, no studies have analyzed the use of ultrasonic probes at such different frequencies. Frequency has the greatest effect on the attenuation of ultrasonic waves and the ultrasonic wavelength, and it was noted that the adhesive could cause a 25 percent change in the maximum frequency of the ultrasonic pulse. It was also found that it is necessary to make reference samples before ultrasonic testing of adhesive joints, since specific frequencies can produce erroneous signals for the selected adhesives.