Study of Elastic Modulus Determination of Polymers with Ultrasonic Method

Abstract

Elastic modulus is one of the mechanical properties of the material that often used in industry or research field as a benchmark to determine materials' performance in term of withstanding load without being deformed. Destructive testing is perpetually used to determine this property. However, destructive testing needs a sample, and in situ testing is implausible. Various types of materials are used in the production process of the industry, e.g., polymers. Polymers have time-dependent properties, which can result in high variety value. By principle, ultrasonic inspection, which depends on sound velocity and density of materials, can be used to determine elastic modulus. Ultrasonic test with through-transmission method has been studied to determine elastic modulus and dynamic elastic modulus for polymers. For the sake of quality control and engineering design, ultrasonic pulse-echo contact is preferable. Ultrasonic testing was conducted with GE USM 35X device, which is a Pulse-Echo method and also contact method type of ultrasonic testing machine. Experiments were conducted on several types of polymers with frequency and thickness as experiment parameters. With an input of specimens' thickness, materials' sound velocity (ν) could be obtained. Thus results of ν were counted to attain the elastic modulus. Comparison between ultrasonic testing results and mechanical testing results of polymers' elastic modulus were performed to analyze the data. In this research, elastic modulus value obtained from the ultrasonic test has a profound error, up to 65% (minimum) and 388% (maximum), especially for a polymer with an eminently low density. Further research should be conducted because of the attenuation effect. Also, lower probe frequency eases the detection of alternating ultrasonic wave. Specimens' thickness adjusted with near-field calculation can eliminate the near-field effect, which is a natural phenomenon of the ultrasonic wave. However, it would not have yielded an accurate value because an excessive thickness will give an attenuation effect.

Mechanical properties of polyamide 12 manufactured by means of SLS: Influence of wall thickness and build direction

“…This difference may be due to the measuring instrument used. The other authors used an extensometer, except Lammes et al [33], which was measured with ultrasound equipment [20,26,37,40].…”

Influence of water environment on paint removal and the selection criteria of laser parameters

“…where a is the proportional coefficient of plasma heat energy to internal energy, taken as 0.1, and z A and z C are the acoustic impedances of paint and water, respectively. Here, the impedance of paint z A is 0.36×10 6 g/cm 2 •s, [24] impedance of substrate z B is 1.5×10 6 g/cm 2 •s, [25] impedance of water z C is 0.15×10 6 g/cm 2 •s, [25] laser fluence is 0.49 J/cm 2 , and peak impact force is 166 MPa. Therefore, when paint is removed in water, the paint is primarily sprayed by the plasma shock wave, as shown in Fig.…”

Top Coating Anti-Erosion Performance Analysis in Wind Turbine Blades Depending on Relative Acoustic Impedance. Part 2: Material Characterization and Rain Erosion Testing Evaluation

“…The speed of sound of viscoelastic materials is directly related with its modulus of elasticity [20]. The viscoelastic characterization of the LEP materials at the appropriate working frequency range is limited for dynamic tests based on the vibration of rods or beams [21,22] and only possible using ultrasonic waves [23][24][25]. Moreover, the use of the ultrasound technique in thin film applications has additional issues as coupled thickness layer determination [26][27][28][29][30].…”

“…The higher limit of 5 MHz proposed in [15] permits one to consider a conservative method for the suitable measurement of the material impedance, providing an upper bound limit on the stiffness variation of the viscoelastic response of the selected material, as demonstrated in [23,24], and for specific impact erosion applications in [16]. Hence, a procedure for the measurement of acoustic impedance with a time-of-flight technique of a thin viscoelastic layer using a planar ultrasonic transducer for the frequency regime of interest is done in this work, in the next section.…”