Elastic Modulus Determination of Thermoplastic Polymers with Pulse-Echo Method Ultrasonic Testing

Abstract

The determination of the elastic modulus of the structural thermoplastic polymers is especially required during in-service monitoring of the components. This elasticity modulus determination can simplify the inspection process and predict the lifetime of the polymer being used. The elastic modulus of the polymer can be determined by pulse-echo method testing ultrasonic which is easier to use than transmission method. This research aims to determine elastic modulus of thermoplastic polymers i.e. polymethylmethaacrylate (acrylic), polyamide (nylon) and low density polyethylene (LDPE) calculated from measurement of velocity and attenuation of ultrasonic pulse-echo. The research begins by looking at the effect of the use of three different probes to ultrasonic velocity readings. Then elastic modulus of material polymers from ultrasonic velocity was calculated using standard equation. The elastic modulus was compared with the elastic modulus from mechanical testing. A linear model elastic modulus from ultrasonic reading which consists of velocity and apparent attenuation was developed. The results were elastic modulus value obtained from ultrasonic velocity and standard equation had a profound error 98% to 158%, especially for polymer with an eminently low density and high ratio of viscous property to elastic property. The attenuation from ultrasonic reading was influenced by the viscoelastic properties and the elastic modulus from ultrasonic velocity reading was influenced by the density. A linear model for thermoplastic elastic modulus determination based on ultrasonic pulse echo testing has been developed and could reduced the error to 3.45%.

Preparation and ultrasonic characterization of modified epoxy resin/coconut shell powder biocomposites

“…The attenuation coefficient (α) of the MER and biocomposites were measured at 20 MHz frequency by the ultrasonic PEOM. The attenuation coefficients of MER and all biocomposites were calculated using the Equation () 62,38 : Where A m and A n , are amplitudes of m th and n th back wall reflections ( n > m ) and d is the thickness of the sample in a unit of the millimeter. The percentage errors in attenuation coefficient (α) measurements were determined at about ±0.34%.…”

“…The ultrasonic testing (UT) method is used as one of the most popular NDT methods for many years. UT method is proven as an economical and sensitive way in materials testing compared with traditional DT methods 36–40 . For determination of elastic constants (Young's modulus, Bulk Modulus, Poisson's ratio, Longitudinal Modulus, and Shear Modulus), acoustic impedance, ultrasonic micro‐hardness and grain size, and so forth the quantities should be measured in UT are only ultrasonic wave velocity values (longitudinal wave velocity and shear wave velocity), and attenuation coefficient 38 .…”

“…UT method is proven as an economical and sensitive way in materials testing compared with traditional DT methods 36–40 . For determination of elastic constants (Young's modulus, Bulk Modulus, Poisson's ratio, Longitudinal Modulus, and Shear Modulus), acoustic impedance, ultrasonic micro‐hardness and grain size, and so forth the quantities should be measured in UT are only ultrasonic wave velocity values (longitudinal wave velocity and shear wave velocity), and attenuation coefficient 38 . UT has been widely carried out in the measurement of isotropic materials' physical properties (elastic constants, microstructural, diffuse discontinuity, and mechanical properties), 41,42,37,43 and the characterization of internal damages, defects, and discontinuities in materials 44–47 .…”

Microstructural Characterization of Additively Manufactured Metal Components Using Linear and Nonlinear Ultrasonic Techniques

“…In this study, pulse-echo (PE) [ 47 ] and through-transmission (TT) [ 48 ] modes were used, where the former measures parameters and and the latter measures parameter . For the PE mode, a single ultrasonic transducer was used, and two consecutive back-wall echoes were measured.…”

Investigation of Soft Matter Nanomechanics by Atomic Force Microscopy and Optical Tweezers: A Comprehensive Review

“…The only weak point that ultrasonic pulse testing technology depicts is the requirement of regular surfaces to enable the accurate measurement of the pulse velocities. Dynamic elastic modulus has been assessed by ultrasonic pulse testing for thermoplastic polymers [ 100 ], photo-clickable poly(ethylene glycol) hydrogels [ 101 ], composite blends [ 102 ], syntactic foams reinforced with hybrid fibers [ 103 ], liquid crystals [ 104 ], biological tissues [ 105 ] such as cortical bone [ 106 ] or pulmonary capillary tissues [ 107 ].…”