Study on vibration analysis for cab-system with high-damping mount for construction machinery

Abstract

For vehicle-type construction machinery, it has been obligated to reduce vibration of cab, in which operator is being exposed continuously to severe vibration, for manufacturer on the view point of occupational safety and health. Usually operator controls any kinds of earthwork at construction site in cab, which is isolated from sources of sound and vibration by vibration absorber. As this absorber, i.e. cab mount, rubber mount of natural rubber (NR) had been replaced to viscous mount, in which silicon oil is enclosed inside, from the later of 1990s, then viscous mount has contributed to reduce vibration and extend endurance life of cab much more than rubber mount up to now. This system involves several major eigenvalues below 10Hz, so viscous mount has been developed to add much damping to them, but it has very complicated frequency characteristics for dynamic stiffness though rubber mount could be expressed simply by constant dynamic spring and loss factor. But in spite of this kind of difficulties to represent dynamic stiffness of viscous mount, it has been proposed to analyze cab vibration with suitable mechanical model of viscous mount. Furthermore though the establishment of vibration analysis for cab has been required to shorten development time and reduce its expenses for ensuring design confidence at product design, it could be considered that the vibration analysis of cab system with viscous mount could not be applied enough to concept design. In this study, so as to establish analysis methodology of cab vibration with viscous mount, a mechanical model of four elements, i.e. two springs and dampers, is proposed and the results of verification to compare analysis with measurement for cab vibration are shown.

Keywords

• construction machinery
• cab vibration system
• high damping mount
• viscous mount
• identification of mechanical model
• complex eigenvalue
• transient response analysis