Wire Rope Isolators Research Articles

Design and shock isolation performances of two-layered ring-spring meta-isolation systems

Two-layered ring-spring-resonator (RSR) based meta-isolation system (RSR-M) has been developed to improve shock isolation effect. In the numerical calculations, shock acceleration ratio (SAR), shock displacement ratio (SDR) and relative displacement ratio (RDR) were introduced to evaluate the shock isolation performances of the conventional isolation system (CON) and the RSR-M, considering the effects of the excitation amplitude, the weight of the middle mass block and the stiffness of the lower isolators. The results demonstrate that the SAR of the RSR-M is always smaller than that of the CON, and the SDR of the RSR-M is first larger than that of CON in the shock amplification region and then smaller in the isolation region. The weight of middle mass blocks has little influence on the isolation performance of the RSR-M because of the softening behavior of the isolators. Finally, shock isolation experiments were also carried out to measure the damping ratios of the selected wire rope isolators and further analyze the isolation performance of the RSR-Ms. In general, meta-isolation system provides a new reference and idea for the design of the isolation system of engineering structures in some sense.

Stiffness Hardening Effect of Wire Rope Isolators under Small Cyclic Loads for Vibration Isolation

Wire rope isolator (WRI) devices are widely used in vibration reduction industrial equipment, and stiffness is the key parameter that determines isolation effectiveness. WRI devices show slight nonlinearity under small loads, and the manufacturers generally only provide the initial parameters. To investigate the mechanical behavior changes in the WRI devices under repeated loads, five types of WRI specimens were tested under various amplitudes, loading speeds, and preloads. The test results of large symmetrical compression and tension loads showed that the WRI devices demonstrated stable hysteresis curves under repeated loads, while the hysteresis curves were independent of the loading speed. The test results of small cyclic loads with large preloads show that the stiffness of the WRI specimen follows the logarithmic law, with the cycle number under various loading conditions. Particularly, the stiffness of the specimen increases by about 10–30% after 50 cycles. The initial stiffness Ka decreases linearly with the preloads, while the decrease is quadratic in relation to the cyclic load. The hardening coefficient Ca shows a positive correlation with the loading capacity of the WRI devices, while it shows a negative correlation with the preload and cyclic load amplitudes. It is recommended to consider the stiffness increase in the WRI devices during the evaluation of isolation effectiveness.

Effects of wire rope isolators on seismic life-cycle cost of UHV bypass switch

The seismic isolation devices reduce the seismic vulnerability of the electrical equipment. Accurately assessing the seismic life-cycle cost (SLCC) of the electrical equipment is beneficial in guiding the design and enhancing the seismic resilience of electrical substations and converter stations. To evaluate the effects of the isolator devices on the seismic life-cycle cost of electrical equipment, a SLCC evaluation model was proposed in this study, and the evaluation was conducted on an ultra-high voltage (UHV) bypass switch (BPS) with wire rope isolators (WRI). The model takes into account equipment purchase, maintenance, transportation and installation costs and indirect losses caused by power outages. Afterward, the SLCC and break-even time of the UHV BPS with and without WRIs in different regions were analyzed. The results indicate that beyond the break-even time, the BPS with WRIs becomes more economically viable. Moreover, its economic viability increases as the service life extends. Therefore, in high seismic cost risk areas, it is recommended to adopt seismic isolation devices to ensure the secure and economically efficient operation of electrical equipment.

A generalized Bouc–Wen model for simulating the quasi-static and dynamic shear responses of helical wire rope isolators

This research investigates the mechanical behavior of a helical wire rope isolator deforming along its shear direction. In particular, we present the results of an extensive experimental campaign including both quasi-static and dynamic tests. The former provide hysteresis loops characterizing the device quasi-static behavior; the latter, performed by using an electro-mechanical shaker, furnish frequency response curves describing the dynamic behavior of a rigid block supported by the tested device. To simulate such a complex behavior, we adopt a generalized Bouc–Wen model and identify its parameters on the basis of the quasi-static test results. Subsequently, such a model is employed to reproduce the frequency response curves of the isolated rigid block. Since the results of the dynamic tests suggest the presence of rate-dependent hysteresis phenomena in the isolated system, the generalized Bouc–Wen model is enhanced by introducing a linear viscous component. Finally, to substantiate the model validation, the experimental results obtained by applying a series of white noise signals are compared with those obtained numerically to demonstrate the model capability of reproducing the device behavior in non-stationary response conditions.

Wire rope isolator identification and dynamic modeling for small amplitude vibrations

Wire rope isolators are used in variety of applications to protect sensitive equipment from vibration. The nonlinear hysteretic behavior of steel wires provides advantages when compared to linear vibration isolators. This study proposes an amplitude dependent stiffness and damping model for low amplitude vibrations under axial loading, where the parameters can be determined with an experimental procedure. Comprehensive experimental results of forced vibration tests with varying loading, frequency and preload were considered in the model identification. Amplitude dependent stiffness and loss energy models were determined from the test data, and the effect of the preload and loading frequency on the model parameters were studied. It is shown, that the effect of preload and frequency is not evidently clear, while the effect of vibration amplitude is more significant. The mathematical model was further verified against measurements from base excitation loading. The proposed model can be used to study the effectiveness of the selected wire rope isolator configurations in chosen application, and to effectively perform dynamic design studies.

Nonlinear wire rope isolator with magnetic negative stiffness

The high-static-low-dynamic-stiffness (HSLDS) isolators have been widely employed to achieve low-frequency vibration isolation. However, traditional HSLDS isolators are prone to nonlinear jump phenomena due to the introduction of nonlinear stiffness characteristics, which will cause the performance deterioration under high excitation levels. To overcome this issue, inspired by the dry friction characteristic of wire ropes, the wire ropes are employed to design HSLDS isolators to suppress nonlinear jump phenomenon by introducing hysteretic damping in this paper. Therefore, a nonlinear wire rope isolator with magnetic negative stiffness is proposed to achieve HSLDS with hysteretic damping. The elastic force of wire rope and the magnetic force are modeled to obtain nonlinear restoring force, and then the dynamic model of the proposed isolator is established to investigate isolation performance. The equivalent beam element method is proposed to model wire ropes for obtaining dynamic characteristics by considering tensile and bending stiffnesses. Then, numerical simulation is performed to investigate the isolation performance of the wire rope isolators with different magnetic negative stiffnesses, and demonstrates that the proposed isolator can work in a higher excitation level than the isolator without dry friction of wire ropes. Moreover, experiments are carried out to show that the onset isolation frequency of the proposed isolator can be reduced by 66.7% compared with the wire rope isolator without magnetic negative stiffness. Therefore, it is demonstrated that the proposed wire rope isolator with magnetic negative stiffness has the preferable performance in low frequency isolation, and can improve the adaptability under a higher excitation level.

Energy dissipation enhancement of wire rope isolators

Wire Rope Isolators (WRIs) are critical in mitigating vibrations in various engineering applications, particularly in seismic isolation. Despite their inherent advantages, the effective damping of WRIs significantly diminishes with increased deformation amplitudes, creating the need to develop improved configurations to enhance their damping capabilities. This paper presents the results of two new experimental approaches to improve energy dissipation in WRIs: applying coatings to wire strands to modify the viscous medium between them and utilizing external confining wires to increase inter-strand frictional forces. Experimental tests were conducted on treated WRIs using sinusoidal displacements across different configurations, including tension-compression, inclined at a 45° angle, shear, and roll. The study evaluated the impact of three coating materials and introduced external confining wires made of steel, copper, aluminum, and solder on the damping properties of WRIs. Among these, steel wires demonstrated a notable increase in damping effectiveness due to their high modulus of elasticity. The results indicate that techniques like confining wires can significantly enhance damping effectiveness at various deformation levels. The findings suggest valuable directions for refining the energy absorption features of WRIs.

Experimental and numerical study on the shock characteristics of an electric switchboard with wire rope isolators in naval ships

Naval vessels face significant challenges owing to vibrations and shocks originating from diverse sources. Maintaining high levels of vibration and shock resistance in ship equipment is crucial to prevent damage and ensure proper functionality in demanding environments. This study experimentally and numerically investigates the shock characteristics of an electric switchboard on a naval ship using wire rope isolators (WRIs). Following the MIL-S-901D standard, impact tests were conducted using a test model. A simplified WRI model was constructed based on a previous study using the finite element method. The tests were performed in the vertical and 30° inclined orientations, and the experimental and simulation results were compared. Although an overall agreement was observed between the two, some inconsistencies were noted. These discrepancies were attributed to the inaccurate representation of the WRI. The dynamic stiffness of the WRI derived from the vibration tests conducted in this study may not be suitable for impact tests. Additionally, the modelled WRI in the simulation, as a 1D spring element with different support points, differed from the experimental setup, possibly causing localized effects that influenced the stress distribution. This study emphasizes the importance of refined WRI modelling for accurate shock simulations and offers insights into enhancing the shock resistance of naval ship equipment.

Design of an ultrathin passive isolator based on multi-layer plain-woven wire mesh

Spacecraft devices have strict restrictions on weight and volume for high fuel efficiency and endurance requirements. In this paper, a method for designing an ultrathin passive vibration isolator based on multi-layer plain-woven wire mesh is proposed. The isolator is structurally inspired by O-type wire rope isolators, and the wire mesh is pre-compressed to buckling for lower stiffness and higher stability. The isolator stiffness in the post-buckling process is analyzed by simplifying the single wire as a strut. The motion equation of the strut is constructed and calculated by the fourth-order Runge–Kutta method and the shooting method. The morphology and stiffness variation of the wire mesh during pre-compression process and repeated compression process are analyzed, and the structural compaction ratio is calculated. This computational method has been experimentally validated and proven to be effective. To prevent collisions between the protected objects and the base during the shock process, the system is simplified and described using a single-degree-of-freedom (SDOF) system with displacement restrictors. The system’s motion equation is formulated and solved using the central difference method. Subsequently, the maximum compression displacement of the isolator is determined through the calculation. A wire mesh isolator with a thickness of less than 10 mm is fabricated for a specific application. Experimental results confirm that the isolation efficiency surpasses 65%, and the isolator is capable of withstanding a peak acceleration of 60 g while maintaining a shock acceleration magnification below 1.2.

Blast wave attenuation of nonlinear meta-isolation system: Theoretical analysis and experimental validation

In the field of protective engineering, wire rope isolators are usually applied in the isolation floor to mitigate the impact and vibration induced by explosive blast. In this paper, two kinds of meta-isolation systems were proposed and designed based on the local resonance, and investigated by means of theoretical analysis, numerical calculation and experimental research. First, the force-displacement hysteresis loops of the selected wire rope isolators are obtained by the cyclic loading tests, and identified by a mathematical model to make preparations for numerical calculation. Then, in order to discuss the influence of mass ratio, stiffness ratio and damping ratio on the shock isolation, the two-degree-of-freedom (TDOF) linear and nonlinear models are studied based on the mode superposition method and fourth-order Rugga-Kutta method respectively. Finally, the blast-induced ground shock experiments were conducted to evaluate the isolation efficiencies of conventional isolation systems and meta-isolation systems. The experiment results reveal that the isolation efficiency of meta-isolation system can increase by 10% points vertically and 16% points horizontally compared to conventional systems, which indicates that the meta-isolation system has great potential to be adopted in the engineering structures and provides a new idea and reference for protective engineering.

Non-linear Wire Rope Isolator Model to Enhance Transportation Simulation of Fragile Equipment

IntroductionWire rope isolators are often used as means of vibration isolation for the transportation of fragile machine equipment. When deployed as suspension systems in a transportation scenario, a simple spring–damper model is often used to predict the dynamic loads that act on the structure being transported. However, this simple model has proved to be too simplistic to be used in the development of an accurate numerical model that can predict the vibration levels experienced by the inner components of fragile equipment during its transportation. This paper describes the experimental tests conducted on a wire rope isolator used for the transportation of the prototype SSR1 cryomodule.Materials and methodsA hysteretic Bouc–Wen model has been used to analytically describe the force–deformation relationship of the wire rope isolators. The developed model of the isolator has been implemented in a larger model to simulate the actual transportation of the prototype SSR1 cryomodule, a section of the new PIP-II linear accelerator under construction at Fermilab. A series of multibody dynamic simulations with rigid and flexible components was used to numerically determine the acceleration of some critical components.Results and conclusionsAn actual experimental transportation was simulated using two numerical models: the developed Bouc–Wen model and a conventional spring–damper model. It is shown how the Bouc–Wen formulation of the isolator characteristics drastically improves the correspondence between experimental and simulated results if compared to a spring–damper model, especially in the range of 0–30 Hz which is the most critical for transportation problems.

Nonlinear analysis of vibration attenuation of ring-spring-resonator based meta-isolation system

Ring-spring-resonator (RSR) based nonlinear meta-isolation system (RSR-M) was proposed and its vibration attenuation characteristic was investigated experimentally and theoretically. The force–displacement hysteresis loops of the selected wire rope isolators (WRIs) exhibit softening under compression and hardening under extension, and are identified by a modified mathematical model combined with the normalized Bouc-Wen model. Frequency response curves of conventional isolation system and RSR-M−2 were calculated based on the single-degree-of-freedom (SDOF) and two-degree-of-freedom (TDOF) models, along with the fourth-order Runge-Kutta method. Shaking table experiments were carried out to evaluate the nonlinear dynamic response and vibration attenuation property of the RSR-M, which proves to be in good agreement with the numerical results of acceptable validity. Dynamic hysteresis loops and phase portraits were plotted to study the dynamic responses and stability of the RSR-M. The experimental results show that, no matter vertical or horizontal direction, the RSR-M possesses better vibration attenuation performance compared to conventional isolation system. In general, the meta-isolation vibration system provides a new reference and idea for the practice designing of the isolation system in some sense.

Experimental and numerical study on the vibration characteristics of an electric switchboard with wire rope isolators in naval ships

In this study, the vibration characteristics of an electric switchboard mounted on a naval ship using wire rope isolators (WRI) were investigated both experimentally and numerically. Naval ships are subjected to various types of vibrations and require high-level vibration resistance to prevent structural damage and ensure the proper functioning of key components. The WRIs used in this study exhibit high damping and are applicable to a wide range of frequencies, effectively isolating vibrations and shocks transmitted from the hull to the equipment. To implement the WRI support structure numerically, a WRI model was created to calculate the stiffness according to the direction, frequency, and initial conditions. The WRI was implemented as a spring element in the entire switchboard model, and a variable-frequency test according to MIL-STD-167-1A was performed on the model. The simulation results were compared with the experimental results, and good agreement was observed in the low- and middle-frequency ranges, with some differences in the high-frequency ranges. The issues encountered during the evaluation of the vibration characteristics of structures equipped with elastic mounts are summarized. Further studies are necessary to address issues, such as deriving the equivalent density for different frequency ranges, calculating the WRI stiffness in various directions, and resolving the local stress issues associated with modeling the WRI as a spring element.

Wire Rope Isolators for the Vibration Protection of Heavy Equipment: Exploratory Research

Wire rope isolators (WRI) are devices that dissipate vibrational energy. They are used in various industrial applications to protect equipment and machinery. Heavy machinery and limited space are still some of the constraints engineers face when designing the WRI system. Heavy equipment requires increased vertical stiffness; however, using larger WRIs decreases their lateral flexibility, which is the target property in the first place. Using several small-sized WRIs is not possible in the case of limited space. Therefore, the present study proposes two improvements to WRIs to overcome the challenges caused by heavy-weight equipment and a lack of the space required to insert the appropriate number and size of WRIs. Two new configurations for WRIs are proposed, Spring-WRI (S-WRI) and Double-WRI (D-WRI), to improve the stiffness and damping properties in order to expand their applications. Monotonic and quasi-static cyclic loading tests were performed on the conventional and proposed WRI variants. Exploratory tests showed that the WRI’s stiffness greatly depends on the wire rope diameter. Adding springs inside a conventional WRI (S-WRI) can improve vertical stiffness while maintaining the required lateral flexibility. The D-WRI was found to preserve the necessary flexibility and to be capable of solving the problem of limited space. The hysteresis behavior of the D-WRI can be expressed as the sum of the hysteresis of each WRI. The proposed configurations effectively improve the stiffness and damping properties of WRIs and expand their applicability for the vibration isolation of heavy equipment and in limited space.

Axial hysteretic behaviour of wire rope isolators: Experiments and modelling

An experimental campaign aiming to study the dynamic response of four different helical Wire Rope Isolators (WRIs) loaded along the axial direction is described in the paper. A total of seventy-one tests have been carried out by applying as input, to each of them, ten cycles of sinusoidal displacement. Specifically, the dynamic response of the WRIs has been analysed by varying input properties, such as amplitudes and frequencies, and simulated by means of a recently developed hysteretic model derived from a new class of uniaxial phenomenological models. For completeness, the influence of the axial preload as well as of the wire rope diameter on the dynamic behaviour of the tested WRIs is also discussed. In particular, a close agreement between predicted hysteresis loops, having asymmetric shape, and experimental ones has been achieved.

An engineering feasible metastructure: Ring-spring-resonator based sandwich metabeam for vibration attenuation

Local resonance mechanisms have attracted a great deal of attention due to their bandgap property. In this paper, an engineering feasible ring-spring-resonator based metabeam (RSR-B), consisting of wire rope isolators and mass blocks, was designed based on the mechanism of two-stage vibration system and local resonance. Three kinds of metabeams were prepared and their vibration attenuation properties were investigated theoretically, numerically and experimentally. These metabeams are easily made and have many advantages in vibration attenuation over ordinary vibration isolation beams. The first and second metabeams are both merely manufactured by one kind of ring-spring-mass resonators, which means the monotonic and narrow bandgap. Considering the arrangement form of resonators, two kinds of resonators are combined to form the third metabeam, which has an obviously widened bandgap, completely covering the bandgaps of the first and the second metabeams.

Quasi-static cyclic behavior of wire rope isolators: comprehensive experimental study and improved mathematical modeling

Wire rope isolators (WRI) effectively isolate shocks and vibrations, making them an ideal choice for many industries, including military and aerospace. A sizeable experimental program was conducted to investigate the cyclic hysteretic behavior of WRIs in all possible loading directions. The test matrix included several isolators subjected to different load-displacement amplitudes at varying rates and other geometries and sizes of the WRIs themselves. This study evaluates the effective stiffness and damping characteristics of WRIs in both the tension/compression (or vertical) and shear/roll (or lateral) directions through laboratory tests and mathematical modeling. It was found that the wire rope diameter significantly influences the stiffness of the WRI more than the other geometric characteristics. Additionally, the damping characteristics of the WRI were found to be correlated to the height-to-width ratio for a given wire rope diameter. The cyclic loading tests showed that, unlike in the lateral directions, in the vertical direction, the load-displacement hysteresis loops are asymmetric. Therefore, the original Bouc-Wen model of hysteresis was used for the lateral direction. A modified version of the same model was developed to simulate the observed asymmetric hysteretic behavior in the vertical direction.

Hybrid isolation system with wire‐rope isolators and magnetorheological dampers for the isolation of blast‐induced vibration

The aim of this research is to improve the isolation performance and energy dissipation characteristics of the widely used passive isolation (PI) system with wire-rope isolators (WRIs) under the excitation of various blast-induced vibration loads through the use of a semi-active control system. A hybrid isolation (HI) system composed of WRIs and an innovative magnetorheological (MR) damper equipped with a motion controller is proposed, which can protect sensitive equipment and nonstructural elements by attenuating their dynamic response. The designs of the MR damper's magnetic circuit and control system were validated by establishing an electromagnetic field finite element model and a motion controller simulation model, respectively. A series of quasi-static and shock table tests were conducted on models using three types of isolation: (1) a PI with WRIs, (2) an HI without a motion controller, and (3) an HI alone. The results show that the proposed MR damper can effectively restrain the tensile vibration of WRIs, significantly increase the isolation rate, and provide greater energy dissipation in HI systems with different weights of static loading subjected to various blast-induced vibration loads.

An experimental investigation into the shock response of a compact wire rope isolator in its axial direction

The use of wire rope isolators (WRIs) for vibration and shock response attenuation is extensive, as these isolators offer a high level of energy storage due to deflection in different directions, combined with high damping due to dry friction. As a result, they are marketed by manufacturers as excellent shock isolators. However, technical information regarding the shock response of these devices is limited, focusing on static properties and vibration isolation, whilst most of the scientific studies aim at the modelling and characterisation of properties. This study presents novel results from experiments involving both static and dynamic testing. Important information concerning the stiffness and damping characteristics are experimentally determined, as well as their behaviour under shock inputs of varying severity and duration for different payloads. It is shown that a WRI under low-level shock loads can be modelled crudely as a low dynamic stiffness system with a 5th order polynomial and nth power velocity damping. Although this approach is limited in predicting high input shocks and the dynamics of the hysteretic system under periodic loads compared to other models, it provides a simpler approach to predict the shock response of a WRI for engineering purposes.

Experimental analysis of nonlinear characteristics of absorbers with wire rope isolators

Abstract Four different configurations of a mass supporting system consisting of a few prototypes of wire rope isolators are considered in the article. These are named “triangle,” “star,” “parallel,” and “serial” configurations. Reasonable models of a fixture assembly that could be utilized as models for cargo transportation are tested statically and dynamically in the laboratory. The main aim of this study is to investigate the impact of the configuration of damper settings on the effectiveness of vibration and shock isolation (in three directions) and to develop a suitable method to determine nonlinear properties and stiffness characteristics of the tested system. The purpose is also to investigate the sensitivity of the tested systems on the eccentricity of vertical loads and its influence on identification results. Experiments are carried out on the specially designed stand for the model parameters identification.