VOL. 11, NO. 6, MARCH 2016 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences © 2006-2016 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com 3610 DIMENSIONAL MEASUREMENT OF COMPOSITE LAMINATES PLATE THRU SINGLE CRYSTAL IMMERSION TRANSDUCER AND ULTRASONIC RANGEFINDER TRANSDUCER M. F. Mahmod 1,2 and Elmi Abu Bakar 3 1 School of Mechanical Engineering, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang, Malaysia 2 Faculty of Mechanical Engineering and Manufacturing, Universiti Tun Hussein Onn Malaysia, Parit Raja, Batu Pahat, Johor, Malaysia 3 School of Aerospace Engineering, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang, Malaysia E-Mail: mfaisal@uthm.edu.my ABSTRACT Ultrasonic testing has variety of usage. In composite laminates material, it has been use for defect detection such as flaw, un-bonded, void, micro crack, foreign material occurrences and thickness measurement. In this study, glass fiber composite laminates (GFCL) being used and produced in-housed with dimension 120 mm length x 80 mm width x 2.4 mm thickness. It consist an artificial defect which was drilled 6 mm in diameter. Ultrasonic range finder transducer with frequency 42 kHz and single crystal immersion transducer with frequency 2.25 MHz have been applied in order to study the performance between both transducers. During measurement, gap distance between specimen surface and both transducer had been fixed at 10mm. Moreover, linear motion at x-axis with constant speed being controlled during measurement process. Measurement data from ultrasonic rangefinder and single crystal immersion transducer had been compared to determine the accuracy between both transducer. All the data are required in order to develop ultrasonic scanning unit that applicable for those transducer. However, some experimental data need to be analyze before further development to avoid misleading especially on operational and functionality of ultrasonic scanning unit. Keywords: composite laminates, single crystal immersion transducer, ultrasonic rangefinder. INTRODUCTION In composite laminates manufacturing industries, Ultrasonic testing (UT) widely being use especially during inspection and measurement process where some other nondestructive test (NDT) techniques are not appropriate due to complexity during operation, required only metal base existence and poor detectability. In common application, ultrasonic testing has been applied on defect detection such as flaw, dish bond between interlayer, crack and delamination. Besides, it also being use for material characterization and dimensional measurement. Basically, for composite laminates material, the frequency used is between 100 kHz up to 5 MHz and consider as low frequency (M. F. Mahmod, M. Z. Nohamed Pauzi and Elmi Abu Bakar, 2013). However, this determination of frequency selection is dependent on certain condition such as material characterization, dimension and surface roughness of the subject. A typical ultrasonic inspection system normally required several functional unit included transducer, pulse/receiver, graphic user interface (GUI). Modern computerized ultrasonic inspection system come with motion control system where the GUI are able to control the scanning speed, scanning path and gap distance between transducer and specimen. In this system, pulse/receiver produce high voltage electrical pulse where it was important for transducer to generate high frequency ultrasonic energy which is in the form of wave to penetrate through specimen. However, when there are some flaw or crack occur inside the specimen, the wave was reflected back from flaw surface and it transform into an electrical signal by the transducer before displayed on GUI. Beside detect the occurrences of defect, this electrical signal also give some information included defect characteristic. Currently, there are three different format of ultrasonic data can be gathered which are A-scan, B-scan and C- scan. Each different format provide different view as A- scan for cross sectional view, B-scan for top view and C- scan for 3D view. (Annual Book of ASTM Standards, 1999) In current practice, there are no specific guideline on transducer selection during ultrasonic inspection process. Transducer are manufactured base on desire application and sometimes, can be special fabricated when necessary. In general, different type of transducer applicable on certain operation base on specimen geometry, material characteristic and surrounding. According to American Society for Testing of Materials (ASTM) standard, thinner specimen required higher frequency while thicker specimen is suggested to use lower frequency or larger diameter (Annual Book of ASTM Standards, 1999). Therefore, several criteria have to be considered on selecting the proper transducer for some application which is desired frequency, bandwidth and focusing to improve inspection capability. In many cases, transducer have been chosen either to enhance the resolution or sensitivity during inspection (Singh, 2013). Hence, there are potential of inaccurate result when improper transducer is used. Single crystal immersion transducer known as single longitudinal wave transducer where it sealed to allow them for submerged under water. Furthermore, water is used as couplant and wave medium