Determination of the material properties of polymers using laser-generated broadband ultrasound

Abstract

Abstract. In the non-destructive determination of material properties, the utilization of ultrasound has proven to be a viable tool. In the presented paper, a laser is used to create broadband acoustic waves in plate-shaped specimens by applying the photoacoustic effect. The waves are detected using a purpose-built ultrasonic transducer that is based on piezoceramics instead of the commonly used piezoelectric polymer films. This new transducer concept allows for detection of ultrasonic waves up to 10 MHz with high sensitivity, thereby allowing the characterization of highly damping materials such as polymers. The recorded data are analysed using different methods to obtain information on the propagation modes transmitted along the specimen. In an inverse procedure, the gained results are compared to simulations, yielding approximations for the specimen's material properties.

Towards real-time assessment of anisotropic plate properties using elastic guided waves

“…For a given set of model parameters h, the forward calculation for wave propagation along a principal symmetry axis (i.e., characteristic equation is a second-order polynomial) and an oblique axis (i.e., third-order polynomial) approximately takes $0.01 and $0.04 s, respectively. In contrast, numerical iterative rootfinding algorithms used for the calculation of the dispersion curves last around a few seconds (i.e., a factor of 200) 18 and are prone to numerical errors. 38 All computations were performed using Matlab V R on a standard desktop computer (Intel Xeon CPU E5-2623 v3 @ 3.00 GHz).…”

“…Although scarcely discussed in the literature, their automatic detection can be problematic due to mode superposition and limited spatial resolution. 18 To carefully extract the dispersion curves, a) Electronic mail: claire.prada-julia@espci.fr visual operator selection, 19 peak-finding algorithms and interpolation, 13 image tracing algorithm, 16 matrix pencil method, 20 and more advanced data processing algorithms, as reviewed in Refs. 21 and 22, have been developed, often at the cost of time-consuming procedures.…”

P2.9 - Acoustic Material Characterization of Additively Manufactured Components

“…The instrumental setup applied for the measurement is similar to the one presented in [2] and [4]. As we are to analyze ultrasonic Lamb waves, the specimens need to be in shape of a plate.…”

“…The active element of the transducer is a strip-shaped piezoceramic (PI Ceramic GmbH, type PIC255). A detailed description of the construction of the transducer can be found in [2]. To ensure a good transmission of acoustic waves to the transducer, a thin layer of a coupling agent (GE, type multi-range coupling paste ZGT) is applied.…”

“…In past publications, we present procedures to measure the material properties of metals [1] and polymers [2,3]. In [4] we show that the procedure is applicable to highly anisotropic materials, such as fiber-reinforced plastics.…”