Abstract
This study refers to the relationship between dynamic characteristics and rubber shapes of some torsional rubber dampers by torsional rigidities and loss constants, which indicate their dynamic characteristics, against shape factors of rubber. The torsional rigidity in this study, which is called a complex torsional rigidity, consists of a typical torsional rigidity and a damping coefficient. The shape factor is determined as the ratio of free loaded area to loaded area of rubber. Four kinds of test dampers that only rubber shapes are different are used in this study. The test is engine experiment with the damper and exciting vibration experiment. The experiment with damper is an engine test in the rated engine speed range with each test damper attached to the crankshaft front edge. The frequency set in exciting vibration test was made to be able to generator the frequencies occurred at the crankshaft of the engine. Changing the shape of a pulley for exciting vibration can change the exciting vibration amplitude. The dynamic characteristics obtained from the experiment results are estimated in consideration of rubber shapes. The relation between amplitude dependence and the shape factor is particularly notified. As a result, the following knowledge can be provided. [1] The dynamic characteristics of the damper depend on shape factor. [2] The dependent tendency presents conspicuously with increase of the shape factor. [3] Damper with smaller shape factor contributes to easily predict dynamic characteristics on the design stage. However, the damper of the small shape factor is hard to satisfy a torsional rigidity to tune to the vibration mode of the crank shafting of the engine.
Keywords: Dynamic Characteristics, Rubber Damper, Rubber Shape, Torsional Vibration, Shape Factor, Spring Constant, Damping Coefficient, Area Ratio, Diesel Engine, Crankshaft System, Experiment, Forced Frequency Ratio, Amplitude Ration