PORES - Investigation of pulse-shaped optoacoustically excited resonance effects using non-contact broadband transmitter/receiver systems

• Applicant: Professor Dr. Marc Daniel Leonhard von Kreutzbruck
• Subject Area: Plastics Engineering ; Lightweight Construction, Textile Technology ; Measurement Systems ; Production Systems, Operations Management, Quality Management and Factory Planning
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 549528608

Non-destructive testing (NDT) describes a wide range of methods that can be used to test and characterize components and parts without damaging them using elastic or electromagnetic waves. NDT methods are used across the board in quality assurance, both in the manufacture and in the operational testing of technical systems. Progress in test reliability through higher sensitivity or increased spatial resolution often goes hand in hand with a reduction in the manufacturing and operating costs. However, most methods are often defect and material selective. The situation is similar when analyzing porous test specimens. The classic NDT methods often reach their limits here. Although the latest research results show that with pulse thermography, the pore density can be approximately determined via the changed thermal conductivity, precise knowledge of the position or size of a pore is still only possible using computed tomography (CT) X-ray analysis. In the field of industrial ultrasonic testing, the first very broadband excitation sources in combination with broadband receiver systems have been available for a few years now. This is achieved by excitation using Laser Excited Acoustics (LEA) and receiving using an optoacoustic laser microphone, which also enables very broadband detection of acoustic waves. In recent studies on broadband LEA, individual pores were detected for the first time by analyzing the frequency spectrum of the response echo, which represents enormous progress for quality assurance. However, there is currently no reliable concept of the interaction mechanism that leads to the successful detection of individual pores. Initial measurements on real components show a significant correlation between the measured resonance frequency and the pore size. However, this phenomenon cannot be described using the usual theoretical models. With the help of simulative methods and experimental testing of the resonance effects of vibrating pores, the information quality of broadband transmitter/receiver systems in relation to pore detection is to be improved and model-based predictability achieved.

• DFG Programme: Research Grants