10 th ANKARA INTERNATIONAL AEROSPACE CONFERENCE AIAC-2019-056 18-20 September 2019 - METU, Ankara TURKEY VIBRATION ANALYSIS OF PASSIVELY ISOLATED JET AIRCRAFT AVIONICS Zafer Eker 1,2 Middle East Technical University Ankara, Turkey Yavuz Yaman 3 Middle East Technical University Ankara, Turkey ABSTRACT This paper presents techniques for the vibration analysis of passively isolated airborne electronics to investigate them under adverse effects of vibration exposure. Establishment of an accurate mathematical model precedes the normal modes and random response analysis. In the mathematical model, elastic properties of isolators, their installation locations and orientations are allowed for arbitrary definition. Viscous damper is considered in the formulation as the damping mechanism to represent realistic conditions in the case of random excitation. Though the employed techniques herein are general, they are demonstrated through the application on jet aircraft avionics. Mathematical model and vibration analysis are verified through FE model results with very well agreement. Entire process is implemented in the open software Python environment and brought into use via a GUI. INTRODUCTION Avionics are defined as the electronic systems used in the air and space vehicles. In the modern aerospace industry, it is inevitable to utilize electronic systems which ensure the control of the air vehicles. Airborne electronics are subjected to adverse effects of vibration exposure. It is important to ensure the sustainability of such equipment through vibration isolation. Otherwise, it might result in a disaster in the vehicle. According to the failure history of electronic equipment hardware, which is observed and investigated by United States Air Force for about two decades, failures due to the operating environments are graded by percentage weight. Thus, high temperature and cycling through extreme temperatures get a percentage of 55, humidity gets a percentage of 20, and vibration and shock get a percentage of 20 [Steinberg, 2000]. Vibration isolation in order to reduce vibratory loads transmitted from the base structure, which acts as the vibration source, to the equipment through resilient mountings has been a much-discussed issue over years because of the fact that vibratory loads may eventually lead to fatigue failure on relevant parts of aircraft. Isolation relies on the separation of the equipment and excitation forces in phase by decoupling them through resilient supports. In 1 MSc. Student in the Department of Aerospace Engineering, Email: zafer.eker@metu.edu.tr 2 Stress Engineer in Turkish Aerospace, Email:zafer.eker@tai.com.tr 3 Professor in the Department of Aerospace Engineering, Email: yyaman@metu.edu.tr