Shock and vibration are a source of failures in harsh environments such as military, naval and aerospace applications; thus, the use of vibration isolators is extended. Cable isolators are known for their high-energy storage and dissipation properties making them suitable for shock isolation and low frequency vibration. Such isolators present nonlinear stiffness in different directions such as compression, roll and shear, as well as dry friction damping. Although their use is extended, the knowledge regarding their dynamic response under shock loading is very limited. This work presents an overview of the vibration and shock isolation performance of several cable isolators under axial loading. The main contribution of the paper is to investigate and discuss the shock response of the isolators when subjected to pulses of different durations, finding improved isolation performance when compared to an equivalent linear system. Furthermore, a mathematical model based on a Duffing oscillator is proposed as a first approximation, in order to reflect the nonlinear stiffness and predict the shock response, thus facilitating further design and selection of improved shock isolation systems.
Mechanical vibrations normally produce adverse effects in structures, machinery and people. One of the most used methods of vibration control is vibration isolation. Amongst the different configurations of isolators, wire rope springs, also known as cable isolators are used for their high capacities of energy storage and dissipation, which is based on dry friction. As a result, they are used in extreme applications such as aeronautical, military, naval, and others involving high vibration and shock levels. An experimental analysis of the quantification of dry friction damping is presented in this paper, estimating the damping by two methods, namely a low frequency sinusoidal input to obtain the hysteresis loops, then a broadband frequency excitation in order to estimate the modal damping. It is found that there is an optimum value of deflection and load on the springs that produce the highest energy dissipation; a similar trend is observed in the two methods considered. This will give more insight into understanding the mechanism of energy dissipation and use of this information to improve the design of vibration isolators.
Mechanical shock is a common problem that is present in many situations, such as ground motion, blast, explosions, crash, and impact. The development of passive, active, or adaptive control and isolation strategies for shock-induced vibration has experienced recent interest, typically due to the increasing demand in improved isolation requirements for sensitive equipment subjected to harsh environments. This paper presents a review of some of the significant recent works developed in the field, focusing on novel developments that contribute to the shock isolation. The article explores several isolation approaches considering passive, active, and nonlinear systems discussing both theoretical and experimental results. In addition, important outcomes of the work are reviewed. The paper concludes with suggestions for potential developments, applications, and recommendations for future research.
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