Implementation of polyCMUT-based Ultrasound Arrays in the Manufacturing Process of Lightweight Composite Structures
Implementation of polyCMUT-based Ultrasound Arrays in the Manufacturing Process of Lightweight Composite Structures
Thursday, May 8, 2025: 9:00 AM
Room 15 (Vancouver Convention Centre)
To meet the increasing demand for fuel-efficient and cost-effective aircraft designs, manufacturers are adopting improved materials, such as thermoplastic composites (TCs). A key advantage of TCs is their ability to be remelted, facilitating novel production processes like continuous ultrasonic welding (CUW). This fast and efficient technique eliminates the need for adhesives or complex joining methods. During CUW, a 20 kHz ultrasonic signal is applied to the welding zone, where friction causes the material to melt. A compaction unit applies pressure, forming a reliable joint between welded parts.
Ensuring process reliability and efficiency is crucial for establishing CUW in the industry. This requires real-time, non-destructive testing (NDT) to assess joint quality during welding. To achieve this, polymer-based capacitive micromachined ultrasonic transducers (polyCMUTs) were implemented. These sensors can transmit and receive ultrasonic signals in the low megahertz band, avoiding acoustic interference from the kilohertz frequency CUW process.
This selective frequency response is what enables the measurement and sets the polyCMUTs apart from piezoelectric transducers. The 20 kHz welding signal and its multiple higher harmonics were shown to oversaturate traditional NDT-transducers.
For the system electronics a novel, open source system named WULPUS (Wearable Ultra-Low Power Ultrasound Probe) was chosen, integrating an 8-channel pulser, an analog-to-digital converter, and wireless data transfer in a compact, power-efficient package. The polyCMUT transducer and the WULPUS system are mounted on a polyetheretherketone (PEEK) block to prevent damage and glycerin is used as the coupling medium. This setup minimizes space requirements and the system’s impact on fabrication equipment.
This presentation details the ongoing development and implementation of polyCMUT-based NDT, the performance of WULPUS, and the challenges faced in integrating this system for inline quality assurance in continuous ultrasonic welding.
Ensuring process reliability and efficiency is crucial for establishing CUW in the industry. This requires real-time, non-destructive testing (NDT) to assess joint quality during welding. To achieve this, polymer-based capacitive micromachined ultrasonic transducers (polyCMUTs) were implemented. These sensors can transmit and receive ultrasonic signals in the low megahertz band, avoiding acoustic interference from the kilohertz frequency CUW process.
This selective frequency response is what enables the measurement and sets the polyCMUTs apart from piezoelectric transducers. The 20 kHz welding signal and its multiple higher harmonics were shown to oversaturate traditional NDT-transducers.
For the system electronics a novel, open source system named WULPUS (Wearable Ultra-Low Power Ultrasound Probe) was chosen, integrating an 8-channel pulser, an analog-to-digital converter, and wireless data transfer in a compact, power-efficient package. The polyCMUT transducer and the WULPUS system are mounted on a polyetheretherketone (PEEK) block to prevent damage and glycerin is used as the coupling medium. This setup minimizes space requirements and the system’s impact on fabrication equipment.
This presentation details the ongoing development and implementation of polyCMUT-based NDT, the performance of WULPUS, and the challenges faced in integrating this system for inline quality assurance in continuous ultrasonic welding.