Innovative approach to real-time diagnostic of bolted joints and elastic couplings to prevent their fractures
Riga Technical University, Faculty of Mechanical Engineering, Department of Railway Engineering, Transport and Aeronautics, LV-1048 Riga, Latvia
*Correspondence: dmitrijs.gorbacovs@edu.rtu.lv
Abstract:
Failure of fasteners can lead to undesirable consequences. Fatigue failure of machine parts is difficult to predict and prevent. Vehicles and agricultural machinery include various systems such as engine, transmission, and many other systems that are fixed and connected using fasteners. Without a doubt, the performance of an individual system depends on the design of its kernel. But for the system to work, it must be properly fixed. Premature failure of bolts is subject of interest of engineers.
The purpose of this study is to identify the causes of the failure of the fixing bolts and develop device and algorithm for early detection of conditions that might lead to bolt failure. The experimental data is collected analysing bolts and elastic couplings of electric passenger trains.
Laboratory studies included the measurement of tensile strength, hardness, microanalysis of the metal structure and chemical analysis of failed old and new bolts. The authors present various visual and numerical results from this study. It also provides detailed conclusions about the causes of failure and recommendations for the selection of bolts for critical mechanical connections under dynamic loads and variable temperatures.
The authors have developed a device that can be used in mechanical engineering, shipbuilding and other industries to control the deformation, vibration and shocks acting on a bolted joint. This device for monitoring the load and vibrations of bolted connections allows to constantly collect and analyse data during the operation of the vehicle in order to reduce the number of unscheduled repairs of vehicles due to its damage, as well as to reduce the number of accidents or other incidents. The authors also have developed a method and algorithm for calculating and evaluating the influence of external factors on the shell of a rubber-cord coupling. The study is based on statistical, material, and mathematical analysis of unexpected failures of rubber couplings. A numerical analysis of the operating conditions of the couplings before failure was performed.
The results obtained are encouraging and prove that the use of an impact force measuring device and real-time data analysis can be cost-effective and can eliminate the problem of bolt and elastic coupling failure in one go, as well as reduce the cost of operating and repairing vehicles.
Key words:
chemical composition, fastening bolt, hardness, metal structure, rubber cord coupling, static stress