Behavior Of Ropes Research Articles

Real-time explicit co-simulation of wire-rope systems for industrial mobile harbor cranes

This paper presents an investigation into the real-time explicit co-simulation of mobile harbor cranes under hoisting operation. The system is divided into two subsystems, with Subsystem 1 representing the payload and Subsystem 2 encompassing the wire-rope system. To capture the real-time behavior of the wire ropes accurately, the ALEM (Arbitrary Lagrangian–Eulerian Modal) method is employed in this study. Using this formulation, the intricate behavior of the wire ropes, encompassing elasticity, bending effects, and dynamic influences, is rigorously considered. The dynamic equations governing the payload are solved using the Runge–Kutta4 method, while the Generalized Alpha method is utilized to solve the wire-rope system. Both the Gauss–Seidel and Jacobi methods are investigated as two coupling techniques to connect the subsystems. Additionally, the study delves into the impact of the extrapolation method and macro time step on results accuracy and efficiency. The findings demonstrate that co-simulation employing the Gauss–Seidel method and FOH (First-Order Hold) extrapolation yields optimum and accurate simulations. Moreover, the study successfully achieves real-time simulation by optimizing the wire-rope system simulation, accounting for all degrees of freedom inherent in a 3D system. Remarkably, the maximum error observed in the axial force amounts to a mere 0.6% when employing real-time simulation. These findings can hold practical value for employing the current wire-rope subsystem in the interface modeling of real-world industrial cranes.

Experimental-Numerical Assessment of Mechanical Behavior of Laboratory-Made Steel and NiTi Shape Memory Alloy Wire Ropes

The mechanical behaviors of laboratory-fabricated steel and superelastic shape memory alloy (SMA) wire ropes are assessed in this study through a comprehensive approach encompassing both experimental investigations and finite element (FE) numerical simulations. The assessment of steel wire ropes involves experimental scrutiny under sinusoidal cyclic loading and natural earthquake loading conditions. In parallel, SMA wire ropes’ behaviors are analyzed utilizing FE simulations employing the widely acknowledged ABAQUS software version 2020. The validation of all numerical simulations is undertaken against the experimentally observed behaviors. Moreover, full-scale steel wire ropes are subjected to shaking table tests to validate the simulations, facilitating a comparative analysis between the mechanical responses of SMA and steel wire ropes. The findings demonstrate that SMA wire ropes exhibit superelastic behavior akin to SMA wires, with marginal variations in overall response observed across distinct configurations, akin to steel wire ropes. Furthermore, augmenting the helix angle of SMA wire ropes results in reduced stress and increased strain when exposed to the El Centro earthquake scenario. Nevertheless, the mechanical response of SMA wire ropes closely mirrors that of a single wire.

A novel fiber-reinforced polymer rope: Concept design and experimental evaluation

The present study proposes using a twisted rope with flexible fiber-reinforced polymers (FRPs) instead of wire rope and synthetic rope in environments requiring high load-bearing capacity and corrosion resistance. Resin toughening modification was conducted to manufacture flexible FRPs, and experimental evaluations were performed to assess the tensile and flexural properties of the impregnated fiber bundles (IFBs), as well as the tensile behaviors of the seven-IFB strands and the seven-strand ropes. The results demonstrated that the modified epoxy resin exhibited a decrease in both strength and elastic modulus, while its ductility was enhanced. Tensile and bending experiments confirmed that incorporating an additional 10% of Qishi toughener (QS-VA-3) was the optimal choice for producing low-modulus and high-toughness resins. Although the tensile properties of resin modified IFBs may show a slight reduction, their repeated bending behavior can be significantly improved. The tensile load-displacement curves of the FRP strand and rope displayed a linear increasing trend and experienced intermediate fracture failure, resembling that observed in IFBs. Furthermore, it was found that the tensile strength and elastic modulus of the strand decreased with an increase in lay length. The secondary twisting can enhance the tensile behavior of ropes compared to strands with equivalent lay lengths.

Energy distribution and chaotic pressure pulsation analysis of vortex ropes in Francis-99

Francis turbines, essential for stability in diverse operating conditions and variable-speed scenarios, encounter efficiency-compromising vortex rope formations in the draft tube, leading to substantial pressure fluctuations. This research delves into the analysis of energy loss and pressure fluctuations associated with these vortex ropes. Employing the local entropy generation rate (LEGR) method and chaos theory, we scrutinize the behaviour of vortex ropes and their resultant pressure fluctuations. Notably, vortex ropes exhibit maximum LEGR near the runner cone, with secondary vortices escalating instability downstream. In the elbow section, the collision of vortex ropes with the outer elbow amplifies LEGR, primarily driven by fluctuating velocities (approximately 90%). Leveraging the GWO-VMD algorithm, non-stationary signals are decomposed, unveiling a significant 1.6 Hz vortex rope frequency under partial load (PL) conditions and isolating external noise frequencies, such as the prominent 300 Hz. Following decomposition, chaos theory tools, including phase space reconstruction and phase trajectory graphs, unveil the chaotic nature of PL conditions attributed to spiral vortex ropes, resulting in profound pressure fluctuations. This study enhances our understanding of such systems and provides methodologies for improved noise reduction and optimization of turbine performance.

Eruptivity Criteria for Solar Coronal Flux Ropes in Magnetohydrodynamic and Magnetofrictional Models

We investigate which scalar quantity or quantities can best predict the loss of equilibrium and subsequent eruption of magnetic flux ropes in the solar corona. Our models are initialized with a potential magnetic arcade, which is then evolved by means of two effects on the lower boundary: first, a gradual shearing of the arcade, modeling differential rotation on the solar surface; and second, supergranular diffusion. These result in flux cancellation at the polarity inversion line and the formation of a twisted flux rope. We use three model setups: full magnetohydrodynamics (MHD) in cartesian coordinates, and the magnetofrictional (MF) model in both cartesian and polar coordinates. The flux ropes are translationally invariant, allowing for very fast computational times and thus a comprehensive parameter study, comprising hundreds of simulations and thousands of eruptions. Similar flux rope behavior is observed using either magnetofriction or MHD, and there are several scalar criteria that could be used as proxies for eruptivity. The most consistent predictor of eruptions in either model is the squared current in the axial direction of the rope, normalized by the relative helicity, although a variation on the previously proposed eruptivity index is also found to perform well in both the MF and MHD simulations.

Research on Underwater Straightness Measurement Method Using Ropes

In this paper, we study the behavior of a rope impacted by currents in underwater crossflow and propose a method for measuring the straightness of long distance underwater objects using the rope as a reference line. The theoretical model includes the behavior of ropes under different loads and the composition of loads, which can simulate the displacement state of ropes in actual sea areas and be used for straightness measurement. This method provides an idea for conducting long-distance straightness measurement underwater to meet practical needs.

Experimental investigation on service safety and reliability of full-scale HMPE fiber slings for offshore lifting operations

In recent years, high modulus polyethylene (HMPE) fiber slings have been increasingly used in marine transportation and installation projects due to their numerous advantages including lighter than steel ropes, easily handling operation, and no fish hooks et al. Due to the complex behavior of fiber ropes, an effective bedding-in method is necessary to proposed to stabilize the sling length and ensure the safety and reliability of offshore lifting operations. This study proposes a detailed procedures and techniques for evaluating the creep behaviors and load elongation properties of full-scale slings with a normal breaking strength of 10,000 kN. The experimental results reveal that the HMPE exhibits the viscoelastic-viscoplastic behavior and load history effect. Based on the experimental results, the crucial mechanical parameters such as Young's modulus and static stiffness of the HMPE sling are established. A bedding-in procedure of HMPE slings is proposed to remove the structural elongation and to ensure the stability of the length of the sling. The present results have been applied and verified on the evaluation of the slings in Sewol Salvage Engineering. The results can serve as a reference for the application of HMPE slings in offshore lifting operations.

Study on mechanical behavior and fatigue life of defective ropes in HTHP gas well with high-sulfur content

As demand for energy increases, the number of “three-high” (high-pressure, high-yield, high-sulfur) gas Wells has doubled, the severe stress fluctuation of pipe string caused by downhole high-pressure environment leads to the failure of rope fracture is particularly prominent. It is easy to cause pipeline blockage and large amount of high-pressure toxic gas leakage caused by tool string accidental falling. Therefore, based on the theory of Love and elastoplastic contact theory, and considering the influence of Poisson’s ratio effect, this article establishes a calculation model for tensile fatigue of interaction between rope strands to study the influence of key structural parameters and breaking wire position on stress distribution and fatigue life of rope. The results show that: the core strand of the rope is the main force position, the overall stress shows the trend of decreasing with the increase of winding radius; when the rope is stretched, the axial deformation near the core of the rope is smaller than the deformation far from the core; under the same number of broken wires, the fatigue life of different ropes is related to the location of broken wires, the farther the location of broken wires from the core of the rope, the higher the fatigue life. The research work in this article provides theoretical guidance for the safe operation of ropes in “three-high” gas wells.

Three-dimensional finite element simulations of fretting wear in steel wires used in coal mine hoisting system

Fretting wear is a surface damage phenomenon that occurs at contacting surfaces due to the micro relative movements of contacting surfaces. It is not easy to consider the parametric study of this phenomenon by experimental methods. For example, it is not straightforward to measure the contact stresses and wear scars under different loading conditions during the experimental process. Furthermore, the experimental process is economically expensive and time-consuming. In this paper, the fretting wear behavior of steel wire ropes used in coal mine technology is numerically investigated and the results are compared with experimental data. The numerical results of the effect of contact parameters on the fretting wear process during the fretting cycles are also analyzed. For this purpose, a three-dimensional Finite Element (FE) model is created and validated with an analytical solution. The simulations of the FE model are performed using the commercially available FE tool ABAQUS combined with subroutine UMESHMOTION. The available experimental data of fretted wires in the form of coefficient of friction is used to define the interaction between the contacting surfaces of FE model and the maximum wear depth is used to validate the wear depth obtained through the numerical model. A convergence study is also carried out to select the most suitable parameters for the simulation of contacting surfaces. After the validation of the FE model, the effect of fretting amplitude, contact load and different contacting angles of fretted wires on wear characteristics is considered. The results show that higher fretting amplitude and contact load have a significant effect on wear profile, wear depth, and wear scar. The maximum wear depth, wear depth increasing rate and contact stress decreasing rate is high for higher contact angles compared to smaller contact angles.

Wire ropes with diamond beads for multi-wire machines optimization by means of DoE: Numerical models and choice of design parameters

This paper reports FEM model’s development to optimize the stress–strain state of wire ropes used in multi-wire machines for cutting hard blocks of stone: numerical models and experimental observations were carried out with the company Pedrini SpA ad Unico Socio, located in Carobbio degli Angeli, Bergamo (Italy). The aim of the paper is to develop a numerical FEM model useful to understand the mechanical driving forces and highlight the damage mechanisms of wire ropes with diamond beads, in order to increase service life of these important cutting tools. DoE (Design of Experiments) and DACE (Design and Analysis of Computer Experiments) were applied to the numerical models to optimize the design of the wire ropes with diamond beads. Microscope observations and penetrating liquids method were used to analyze the damaged wire ropes. Fatigue, corrosion, and contact fatigue problems were observed and the effect of the centering of the beads on the wire rope was studied. Full scale and in service tests were carried out too, to better understand the behavior of the wire ropes mounted on real cutting multi-wire machines.

Short and long term creep behaviour of polyamide ropes for mooring applications

Polyamide 6 fibres are of interest for mooring lines of floating wind turbines and these are continuously loaded throughout their service life. Such applications require the long term response of polyamide 6 ropes in water to be characterized. This paper presents results describing the long term creep behaviour of polyamide 6 sub-ropes with tests that lasted 2 years. A specially designed experimental set-up for long term creep test in water is presented first. Then, a kinetic study comparing creep and recovery is performed using a logarithmic identification of the strain rate. The need for performing long term creep tests is evaluated by comparing the long term creep results to those from short term creep tests lasting 3 h. The results show that a 3 h long creep test provides a reasonable prediction of long term creep strain using a single logarithmic linear law. Finally, a latch-based Weibull model is compared to a single linear logarithmic law to describe and predict creep and recovery response. It is shown that the Weibull model allows a better description of the recovery behaviour of polyamide 6 but is less well adapted for the description of creep.

Study on vibration characteristics of elevator ropes by elemental test

Elevators are essential for means of a vertical transportation. Recently, high-rise buildings are increasing. Those elevator ropes become longer. As a result, the natural period of the elevator rope becomes closer to the natural period of the high-rise building. The risk of resonance increases. When the high-rise buildings receive an external force such as the strong wind and the earthquake, the elevator rope may sway intensely. The rope may be hooked to the equipment in the hoistway. The accurate analysis of a rope is important to grasp the actual rope behavior during an earthquake. In this study, the free vibration test on elevator ropes is carried out with an element testing equipment. Furthermore the vibration characteristic of elevator ropes is investigated. In this paper, the free vibration test was carried out with the 5 mm-diameter elevator rope, further the vibration characteristic was investigated. As a result, it was confirmed that the damping ratio of the elevator rope depends on the displacement of the horizontal direction.

Vibration analysis of elevator rope

When an elevator rope for a high-rise building is forcibly excited by long-period ground motion, rope displacement becomes large even if the ground acceleration and the buildings acceleration is small. Therefore, in order to prevent damage to the elevator, an accurate estimation of rope behavior is required. This paper introduces the following topics;(1) relation between damping factor and magnification factor/response curve of rope (string model), (2) vibration characteristics of rope (string model) with vibration suppressors, (3) estimation method of 3 parameters (equivalent flexural rigidity, viscous damping ratio, structural damping ratio) of rope (beam model).

Internal flow phenomena of a Pump–Turbine model in turbine mode with different Thoma numbers

In the low-flow rates of off-design conditions in the pump–turbines, complicated flows can develop with vortices in the flow passages, which significantly increase the vibrations and noise, resulting in destabilizing the pump–turbine system. Under low-flow-rate conditions, an appropriate Thoma number is the most essential requirement for stable operation in turbine mode of the pump–turbine. Thus, this study elucidated to examine the internal flow and unsteady pressure phenomena in a laboratory-scale pump–turbine model operated in turbine mode with different Thoma numbers. The experimental investigations were conducted under 70% of the flow rate at the best efficiency point with different Thoma number to observe the unsteady pressures and vortex rope behavior. Then, the numerical validations were conducted by three-dimensional unsteady-state RANS analyses in a SAS–SST model. The Thoma number did not significantly affect the performance of the pump–turbine model or the unsteady flow phenomena in the vaneless and runner regions. However, the Thoma number affected the draft tube region at low flow rate condition. At low Thoma numbers, the irregular flow phenomena along the flow direction enhanced the unsteady pressure characteristics.

Optimal structural patterns of multi-strand wire ropes

A quantitative approach for guiding the optimal structural design of multi-strand ropes with hierarchical helical structures has been developed. The structural pattern is optimized to maximize the capacity to bear axial loads and minimize the global toque of the rope simultaneously. In the light of the hierarchical calculation method for calculating the internal forces of wire ropes, a procedure of structural optimization is proposed for the multi-strand ropes. Two typical multi-strand wire ropes, namely 7 × 7 and 19 × 7 ropes, are treated in detail. The favorable structural patterns are identified, providing a database that covers most practical applications. It is demonstrated that the crisscross arrangement of strands or wires within the multi-strand ropes is beneficial for achieving a torque-balanced state. The influence of structural parameters on the global mechanical behavior of ropes increases gradually from inner strands to outer strands. The initial helix angle of the outer strands has a significant effect on the axial stiffness of the wire ropes.

Bond behavior of stainless steel wire ropes embedded in engineered cementitious composites

Engineered cementitious composites (ECC) feature high post-cracking resistance and ductility. The stainless steel wire rope meshes have been successfully used to restore or increase capacity of existing structures. By combining the advantages of these two materials, an innovate jacketing of ECC reinforced with high-strength stainless steel (HSSS) wire rope meshes are expected to significantly improve structural performance while used for repair or strengthening of existing structures. To understand the bond behavior of HSSS wire ropes embedded in ECC, experimental studies were conducted by using direct pull-out specimens. Test variables consisted of nominal diameter of HSSS wire rope, embedded length and strength of ECC. The failure mechanism and bond-slip characteristics of HSSS wire ropes in ECC were investigated. Based on analyses of test results, the effects of the test variables on the bond properties of HSSS wire ropes embedded in ECC were revealed. A bond-slip model and the expressions of the model parameters were developed for charactering the bond-slip relationship between HSSS wire ropes and ECC.

Experimental Assessments on the Evaluation of Wire Rope Characteristics as Helical Symmetrical Multi-body Ensembles

The existing literature provides various computational models related to the dynamic behavior of strand wire ropes. It starts from the simple longitudinally oscillating beam, to the complex nonlinear multi-body configuration based on helical structural symmetry. The challenge is the prior availability of characteristic parameters for material behavior, structural configuration, and functional capability. Experimental investigation is the main source for evaluation of these characteristics. However, tests have specifically been performed according to each case, minimizing the generalization aspect. This is the main frame of this study. Hereby, the authors propose an ensemble of spectral investigations, applied to a reduced set of experimental tests regarding wire rope dynamics. The research goal consists of wire rope characterization in terms of the flexible and adaptive groups of parameters, related to the conservative and dissipative behaviors. An experimental setup is considered here according to the rope exploitation conditions in order to enable an extension of the method application from the experimental mode to the operational mode. Experiments are conducted based on classical vibration measurement procedures. The analysis is performed using a spectral method ensemble, including discrete Fourier transform, time-frequency joint analysis, and the Prony method. The result show that the proposed assessments can provide suitable information related to a large group of wire rope models.

Bending behavior of CFRP cables in the nonlinear displacement range

The tensile behavior of cables and wire ropes has been widely explored in the literature, with many analytical, numerical and experimental results available. However, their bending behavior is still not yet fully comprehended, especially when dealing with cables made of non-isotropic materials. When these materials are bended over small diameter sheaves or drums, they may experience large strains, causing nonlinearities that are not captured by any known analytical model. The aim of the present work is to numerically verify through finite-element method the tensile and bending behavior of composite CFRP cables. The numerical results were compared with experimental data. Good correlation between them was found in a four-point bending test configuration, even at large displacements and with a nonlinear response. Hybrid cable constructions (using aramid and glass rods) were also numerically analyzed relative to their tensile and bending behavior, achieving satisfactory results.

Investigation of the correlation mechanism between cavitation rope behavior and pressure fluctuations in a hydraulic turbine

Vortex ropes occurred in the draft tube when hydraulic turbines operating at off-design conditions, which can generate pressure fluctuations. Cavitation vortex rope is one of the most harmful factors to the safety of hydroturbines which may induce further pressure fluctuations. A study of the multiphase flow in a model turbine is presented in this paper using the software ANSYS CFX. The main emphasis is spending on understanding the mechanism of cavitation evolution and underlying its correlation mechanism with flow instabilities. The results indicate that two types of pressure variations can be captured with a cavitation rope: 1) The type due to the vortex rope rotating whose frequency is 1/5–1/4 times runner rotating frequency; 2) The type due to cavitation volume surge, whose frequency is less than that of vortex rope rotating. The frequency of pressure fluctuation due to cavitation keep contanst as the cavitation number decreases, while the amplitude much increases. While the frequency and amplitude of the pressure variation caused by votex rope rotating increase a little. Based on vorticity transport equation, the vortex and cavitation have a close relation. Cavitation increases the vortex production as well as the pressure fluctuation frequency caused by the rotation of vortex rope.

Effect of lay direction on the mechanical behavior of multi-strand wire ropes

The effect of lay direction of individual wires on the mechanical behavior of multi-strand wire ropes under axial loading is investigated based upon Love's thin rod theory. A typical 7 × 7 wire rope with an independent rope core is treated. Eight different lay directions of the wire rope are considered, in which the lay direction of the double helix wires is emphasized. Two theoretical models, namely the hierarchical calculation method and the direct calculation method, are used to calculate the internal forces of the rope. The numerical results based on the two models are assessed within the context of the finite element analysis of the multi-strand rope. It is highlighted that the result given by the hierarchical calculation method is closer to the FEM result. The mechanical responses on simple strand and multi-strand rope predicted by the two theoretical models are in good agreement with experimental data. The lay effect of wire rope and the effect of initial helix angle of individual wires on the internal forces of rope are analyzed in detail. It is demonstrated that the lay direction mainly affects the torque of the rope, but not the tensile force; while both the torque and the tensile force strongly depend on the initial helix angle of individual wires. It is implied that the global mechanical properties of wire rope can be adjusted with the lay direction and the helix angle of wires within the rope.