1 8 th International Congress of Serbian Society of Mechanics Kragujevac, Serbia, June 28-30, 2021 NUMERICAL MODELING THE MOTION OF OTOCONIA PARTICLES IN THE SEMICIRCULAR CANAL UNDER WHOLE BODY VIBRATION Igor Saveljic 1,3 , Slavica Macuzic Saveljic 2 , Dalibor Nikolic 1,3 , Tijana Djukic 1,3 , Smiljana Djorovic 2,3 , Jovanka Lukic 2 and Nenad Filipovic 2 1 University of Kragujevac, Institute for Information Technology, 34000 Kragujevac, Serbia e-mail: isaveljic@kg.ac.rs 2 University of Kragujevac, Faculty of Engineering, 34000 Kragujevac, Serbia 3 Bioengineering Research and Development Center, 34000 Kragujevac, Serbia Abstract: Vibrations of the human body are a multisciplined field that includes knowledge and other disciplines, such as: ergonomics, engineering, mathematics, medicine and others. Exposure to whole body vibrations reduces the comfort of passengers in the vehicles, causing stress, fatigue and discomfort. Vibrations can affect the lumbar spine, the gastrointestinal system, the peripheral veins and the vestibular system. The semicircular canals, as a part of vestibular system, are responsible for sensing angular head motion in three-dimensional space and for providing neural inputs to the central nervous system. In this study, one male subject was exposed to root-mean- square WBV acceleration levels of 0.7 m/s 2 and 1.1 m/s 2 at the frequencies of 0.5–20 Hz while seated on an electro hydraulic vibration simulator with multi-axial excitation. The movements recorded on the head of the examinee were transferred to a 3D model as input data. In this research, a numerical model is presented that enables the analysis of motion of multiple otoconia particles within the labyrinth and the change of cupular displacement due to this motion. Key words: numerical analysis, random vibration, semicircular canals, whole body vibration 1. Introduction The vestibular system is the sensory apparatus of the inner ear that helps the body maintain its postural equilibrium. The information furnished by the vestibular system is also essential for coordinating the position of the head and the movement of the eyes. There are two sets of end organs in the inner ear, or labyrinth: the semicircular canals, which respond to rotational movements (angular acceleration); and the utricle and saccule within the vestibule, which respond to changes in the position of the head with respect to gravity (Figure 1). The information these organs deliver is proprioceptive in character, dealing with events within the body itself, rather than exteroceptive, dealing with events outside the body, as in the case of the responses of the cochlea to sound. Functionally these organs are closely related to the cerebellum and to the reflex centers of the spinal cord and brainstem that govern the movements of the eyes, neck, and limbs. Because the three semicircular canals - superior, posterior, and horizontal - are positioned at right angles to one another, they are able to detect movements in three-dimensional space. When the