Search results

Three test platforms for long-term continuous loading are adopted to test the actuator prototypes of the 500-meter aperture spherical radio telescope (FAST). However, the wire ropes that are the key components of these platforms often break during testing. The purpose of this paper is to present an effective dimension design method for these wire ropes. This method is based on fatigue reliability theory.

Three types of stresses are introduced into the total stress model of the wire rope according to the complicated stress conditions. The fatigue strength of the ropes is also discussed in this paper. Then, the total stress model and the results of fatigue strength analysis are applied to set the optimization function for these wire ropes. Subsequently, this optimization function is used to calculate the reliability of previously developed wire ropes in relation to the actuator test platform.

The wire rope is unreliable, which is a finding that corresponds to those of previous tests. Upon drawing the optimal curve from the optimization function (whose optimal objective is the wire diameter), a wire rope is optimized for the FAST actuator test platforms. Finally, this optimized rope is used on the new actuator test platform. No fracture phenomenon has been detected in tests conducted over the past six months.

The fatigue reliability theory-based optimization function for wire ropes can be adopted for the universal dimension design of other wire ropes.

Discusses the distress of mine rope‐wires, under the diverse states of stresses and strains of physical, chemical and mechanical origin. Mine rope‐wires undergo complicated cycles of stresses and strains inside the depth of coal and metal mines. This assumes special significance during summer inside the deeper mines. Summarizes recent studies in this field and compares their results.

This is the first of three articles dealing with this very important subject. In this part, the intention is to convince the reader, if he should need any convincing, of the vital necessity for correct wire rope lubrication. Part Two will deal with the duties and properties of wire rope lubricants. Part Three will cover the methods of application of wire rope lubricant and should be of interest to every large user of wire ropes.

The objective of this paper is to determine fretting parameters of hoisting rope according to the hoisting parameters in coalmine and to explore the effect of contact load on fretting-fatigue behavior of steel wires.

Based on the mechanical model of hoisting rope in coalmine, the dynamic tension simulation of hoisting rope was performed. Static equations of hoisting rope under tension and torsion and theories of contact mechanics were applied to obtain fretting parameters. Fretting-fatigue tests of steel wires at different contact loads were conducted using a fretting-fatigue test rig. The fretting regime, normalized tangential force and fretting-fatigue life were studied. The morphologies of fretting contact scars and fracture surfaces were observed by scanning electron microscopy and optical microscopy to examine wear and failure mechanisms.

Dynamic tension changes from 0 to 30,900 N. In outer strand layer, contact loads between steel wires in certain wire layers are 60.5 and 38.3 N compared with 378 and 102.7 N between wire layers; relative displacements between wires are 62.5 and 113.2 μm, respectively. Mixed fretting regimes develop in all cases. Increasing contact load decreases the stabilized relative slip and normalized tangential force, reduces the fretting fatigue life, induces accelerated adhesive wear and fatigue wear and results in rougher fracture surface topographies. In all cases, fretting zone induces crack initiation; crack propagation and rupture zones present brittle cleavage and longitudinal splitting, respectively.

This paper presents the systemic study on determination of fretting parameters of hoisting rope according to the hoisting parameters in coalmine and the fretting-fatigue behavior of its internal steel wires. The results of fretting-fatigue tests show that the increase of contact load decreases the stabilized relative slip in mixed fretting regime and normalized tangential force, reduces the fretting fatigue life, induces accelerated adhesive wear and fatigue wear and results in rougher fracture surface topographies.

The authors warrant that the paper is original submission and is not being submitted to any other journal. And the research does not involve confidentiality, copyright infringement, leaks and other issues, all the responsibilities that the authors will take.

The purpose of this paper is to demonstrate the application of analytical decision making during the selection of engineering entities in an engineering design setting.

The paper develops a quantitative method for wire rope selection and uses handbook data to demonstrate the use of the method in selecting a suitable type and size of wire rope for the hoisting/hauling mechanism of a hypothetical manual winch.

Wire rope data can be processed into forms that are more readily useable in a quantitative selection method. Moreover, computer software such as Microsoft Excel may be used in the selection process, so long as the data are in suitable form.

The selection of engineering entities often occurs in engineering design processes. An information processing approach to wire rope selection has been developed and demonstrated. The method demonstrated in this paper should be applicable in other situations in which a need for the selection of engineering entities arises.

WIRE ropes are found in almost every industry. Short lengths are used on many fork lift trucks, cranes, and other hoisting machinery, long lengths, up to several miles, are used for aerial ropeways, in collieries, and on many kinds of hoisting and transporting equipment. In many cases long aerial ropeways provide the only means of transport across water, deserts, bogs and even mountains. They are costly to buy and replace and their breakdown can cause serious loss of production in addition to possible injury to personnel.

The purpose of this paper was to create conditions for the correct decision concerning an exchange of the used rope for a new one. A cognitive goal was to indicate the causes of its wear and determining its mechanism reliability and durability.

The magnetic, organoleptic and strength standard tests of lifting triangle-strand ropes of a mining hoist were carried out. This way the current state of the tested rope was defined.

On the basis of an analysis of the results of the performed tests: magnetic, organoleptic and fatigue tests, it can be said that the magnetic one is accurate enough only to indicate the place of the rope’s biggest weakening, though the degree of weakening is not defined precisely – with significant excess. The accurate rope’s destruction degree is indicated by the strength tests.

The results of described investigations can improve safety of the mining rope mechanisms operation, even for an increased resource.

The elementary wear processes, which are the basic reason for the destruction of the rope, are indicated. Rope destruction is caused mainly by tribological factors: abrasion, corrosion and fatigue wear. Magnetic tests are accurate enough only to indicate the place of the rope’s biggest weakening (qualitative index). Most precisely, the rope’s destruction degree (quantitative index) can be found by the strength tests.

Part One in this series appeared in our June issue and dealt with early and more recent investigations which have proved the importance of wire rope lubrication. Part Two (July issue) covered the duties and properties of wire rope lubricants.

In our previous article, we stressed the importance of lubricating wire ropes, both during manufacture and during subsequent service. We also pointed out that ropes having fibre cores need both internal and external lubrication. Most manufacturers lubricate their ropes, with or without fibre cores, at every stage of manufacture.

The main aim of this paper is to explain how numerical magnetic field analysis can be adopted for the simulation of the effects generated when a rope fault occurs. In particular, some important aspects are examined regarding the magnetic flaw generated by internal and external rope faults and the capability of 2D and 3D magnetic field solutions to detect the magnetic flaws.

After a first explanation of the non‐destructive approach from the point of view of the many different methods that can be used to perform a test, an introduction about magnetic systems is provided. Then a 3D magnetic simulation, based on finite integrate technique, of the system is performed and the results compared with those obtained by a simpler 2D magnetic finite element analysis. In the 3D simulation real local damage to the rope is considered and the leakage fluxes around it plotted. A parametric simulation was performed by considering variations of the main geometrical parameters that in a real test can affect the results, such as the airgap between the rope and the measuring point (the position of the field sensors) and the radial position of the sensor itself. Finally, experimental results on the real prototype on many different commercial ropes are provided. In this last section an original method to evaluate the signal to noise ratio of the device is presented.

At first, a really good correspondence between 2D and 3D numerical results was observed. Then it was shown that the difference among the sensing capabilities of field probes placed around the rope is reduced when the position of the damage is higher than 90° in respect of the sensor itself. Moreover, when the angular distance between a sensor and a surface damage is higher than 90°, the damage signal provided by the sensor does not practically change.

Although the development method is always the same, the presented results are valid only for the configuration considered here. The experimental results of the signal to noise ratio are reported only for a reduced number of ropes.

The design procedure can be adopted to develop real devices and to identify the best position of the field sensing system. In particular, the paper shows the difference between radial and axial components of the leakage fluxes around the damage and their variation when the defect moves along the device.

The paper shows a methodology based on 2D and 3D numerical magnetic field analysis for the design of a non‐destructive device for metallic ropes with particular attention being given to the influence of field sensor and damage positions.