Finite element simulation for detecting the foreign body based on ultrasonic sensor

Abstract

This paper presents the design of an ultrasonic sensor for food quality and safety measurement which is modeled using two dimensions (2D) of finite element method (FEM). The measurement process was implemented by evaluating the presence of foreign body in a food container where the Comsol Multiphysics software was used to construct and conduct the design of modeling. This paper discussed briefly about the applied parameters in ultrasonic measurement which are acoustic impedance, attenuation coefficient, frequency and time of flight. Steel and glass are selected for foreign body's materials since these materials are occasionally present in foodstuffs during the manufacturing process. Some parameters such as frequency of ultrasonic sensor, the thickness of container wall and the size of foreign body were investigated and evaluated. The analysis process is based on the outcome of the total acoustic pressure and the time arrival of the receiving signal. The investigation only considered the ultrasonic transmission sensing mode. Two values of frequencies for ultrasonic sensor are being tested, that is, 45 kHz and 300 kHz. The results showed that the total acoustic pressure is reduced when the thickness of container wall and the size of foreign body are increased. For the 45 kHz frequency, the total acoustic pressures recorded were 1.210 Pa and 1.020 Pa for 0.5 mm and 0.9 mm of wall thickness, respectively. The data is obtained using 5 mm diameter of steel material containing as foreign body. The total acoustic pressure showed the same correlation for a frequency of 300 kHz where 0.658 Pa and 0.420 Pa were obtained for 0.5 mm and 0.9 mm of wall thickness respectively. The results revealed the same correlation for a glass material when it was used as a foreign body. The result shows that the finite elements method is very useful in designing an ultrasonic measurement system in food industry field especially in quality and safety food assessment. Practical applications: Food quality is an important aspect for the food manufacturer. It is degraded for example if there is a foreign body in the foods product. It can cause the consumers to lose confidence of the manufacturer. Hence, a suitable sensor should be used to monitor the quality of the products is maintained. Ultrasonic sensors have attracted the attention of the food industry because it is cheap, fast response, and reliable. This paper presents an investigation using the two dimensional finite element method using Comsol Multiphysics software in order to detect the foreign body in a food container using an ultrasonic measurement system. The study demonstrates that the finite element method can assist in the design and development of an ultrasonic measurement system in the food industry field especially in the aspect of food safety and quality assurance.