An Investigation on PVDF Piezoelectric Elements and Linear Array Transducers

Abstract: Ultrasonic waves are widely used in different application e.g. for sonar scanning in water and fetal imaging. Furthermore it is used for doing measurements on different materials to determine the thickness of the material or the velocity of sound inside it. The ultrasonic waves are produced and detected by using piezoelectric elements based on e.g. Polyvinylidene fluoride (PVDF)-film or Lead Zirconate Titanate (PZT)-elements. In this thesis project the aim has been to do measurements on different materials and then develop a linear array transducer based on the use of PVDF-films. Three different methods have been studied to do the measurements on different materials. The first method has been to use a commercial product (ultrasonic (US) key and software from Lecoeur), the second method has been to use the same US-key but in combination with MATLAB. The US-key is an ultrasonic device which is connected to ultrasonic transducer(s) to emit and detect ultrasonic waves. The software was used for displaying plots from the measurements. Finally, the third method involved the use of a generator and an oscilloscope. It has been found that the first and second methods did not work properly to make the linear array transducer because the US-key produced a noise artifact during measurements. The linear array transducer was made by using two industrial ultrasonic transducers of 1MHz which were connected to the generator and three PVDF-films used as receivers and connected to the oscilloscope. The linear array transducer was built up to use it for examining a specific materialaluminum. It was found that aluminum is the best material to be used to do the ultrasonic testing because of its low attenuation of the ultrasonic waves.