External damping losses in measuring the vibration damping properties in lightly damped specimens using transient time-domain methods

Abstract

The contaminating effect of external damping sources to the overall measured damping of mechanical structures has always been an issue. Although those sources are qualitatively known, they are often not considered if damping properties are experimentally determined, yielding erroneous results. The aim of this paper is to quantify some of these undesired effects on the overall measured damping value. Free vibrations of steel plate specimens are used to list up several causes of external damping sources. As small modifications to the test setup may lead to totally different results, appropriate actions are offered to design a more accurate test setup. Known observations, such as the damping value's dependence on the specimen size and the excitation level are confirmed. Finally, it is shown that the damping capacity of one type of steel alloy can usually not be generalised to other steel alloys.

A Study of Some Mechanical Properties of Composite Materials with a Dammar-Based Hybrid Matrix and Reinforced by Waste Paper

“…The individual loss factors of the component materials have been used so as to determine the loss factors of hybrid structures. Other studies on the damped vibrations of composite bars can be found in [ 60 , 61 , 62 ].…”

A Study of the Mechanical Properties of Composite Materials with a Dammar-Based Hybrid Matrix and Two Types of Flax Fabric Reinforcement

“…The second mechanism considers that the damping force is proportional to the bending speed, whereas the third mechanism considers that the damping ratios of the specific vibration modes depend proportionally on the square of the frequency. A good number of articles investigate the various aspects and mechanisms of this phenomenon and the influence on vibration behavior of different composite materials (see [65][66][67][68][69][70][71]).…”

A Study Regarding the Mechanical Properties of a Hybrid Matrix with Various Volume Proportions of Dammar

“…The presence of energy dissipation mechanisms is currently accepted in all the models used for simulating mechanical vibrations in mechanical systems. Many articles analyse various aspects and mechanisms of this phenomenon and its influence on the vibration behaviour of different composite materials (see for example [20][21][22][23][24][25][26][27]).…”