Nonlinear Acoustic Shear Wave Detection of Zero Gap Kissing Bonds in Encapsulated Packs
Nonlinear acoustic shear wave harmonic detection resolves zero gap kissing bonds in encapsulated battery packs by measuring contact acoustic nonlinearity.
Shear Wave Transducer
Meaning
Ultrasonic testing relies on specialized sensors to generate and receive specific modes of acoustic wave propagation within a test object. A shear wave transducer is a piezoelectric device designed to transmit acoustic energy where the particle motion is perpendicular to the direction of wave propagation. These transducers are essential for detecting defects that are oriented parallel to the surface, such as delaminations in battery electrodes or composite casings.
Because shear waves do not propagate through liquids, this device is used in solid-state testing where boundary and interface conditions must be precisely evaluated. Sourcing teams select these sensors to ensure accurate inspection of critical structural joints.
Acoustic Mechanism
Piezoelectric crystal elements are cut at specific angles to generate transverse shear deformations when an electrical voltage is applied. The resulting shear waves propagate through the test material with a velocity that is roughly half that of longitudinal waves. This lower velocity increases the sensitivity of the measurement, allowing for the detection of smaller internal defects.
Measurement Application
Inspecting adhesive bonds involves coupling the transducer to the material surface using high-viscosity couplants. The transverse waves are reflected by unbonded areas, enabling the identification of kissing bonds that are invisible to standard compression waves.
Technical Specification
Sourcing criteria for these devices focus on the center frequency and the bandwidth of the transducer. Higher frequencies provide better spatial resolution, while wider bandwidths improve the axial resolution of the measurements.