What key factor influences the choice of frequency in phased array ultrasonic testing?

The choice of frequency in phased array ultrasonic testing is significantly influenced by the type of material undergoing inspection. Different materials have varying acoustic properties, which affect how sound waves travel through them. For instance, denser materials may require lower frequencies to effectively penetrate and achieve good wave transmission, while thinner or less dense materials can be inspected with higher frequencies, which provide better resolution for detecting small defects.

Furthermore, the frequency also impacts the depth of penetration versus the resolution of the signals. Higher frequencies yield better resolution but have limited penetration depth, making them suitable for detecting surface or near-surface defects in thin materials. Conversely, lower frequencies can penetrate deeper into thicker materials, making them ideal for identifying flaws located deeper within the structure.

In this context, options related to the size of the inspection team and solely environmental conditions are not key influencers for frequency selection. While defects are also a consideration, they are typically secondary to the material type, as the characteristics of the material essentially dictate how effectively sound waves will interact with any defects present.