Shaft Housing Research Articles

A New Latin Hypercube Sampling with Maximum Diversity Factor for Reliability-Based Design Optimization of HLM

This research paper presents a new Latin hypercube sampling method, aimed at enhancing its performance in quantifying uncertainty and reducing computation time. The new Latin hypercube sampling (LHS) method serves as a tool in reliability-based design optimization (RBDO). The quantification technique is termed LHSMDF (LHS with maximum diversity factor). The quantification techniques, such as Latin hypercube sampling (LHS), optimum Latin hypercube sampling (OLHS), and Latin hypercube sampling with maximum diversity factor (LHSMDF), are tested against mechanical components, including a circular shaft housing, a connecting rod, and a cantilever beam, to evaluate its comparative performance. Subsequently, the new method is employed as the basis of RBDO in the synthesis of a six-bar high-lift mechanism (HLM) example to enhance the reliability of the resulting mechanism compared to Monte Carlo simulation (MCS). The design problem of this mechanism is classified as a motion generation problem, incorporating angle and position of the flap as an objective function. The six-bar linkage is first adapted to be a high-lift mechanism (HLM), which is a symmetrical device of the aircraft. Furthermore, a deterministic design, without consideration of uncertainty, may lead to unacceptable performance during the manufacturing step due to link length tolerances. The techniques are combined with an efficient metaheuristic known as teaching–learning-based optimization with a diversity archive (ATLBO-DA) to identify a reliable HLM. Performance testing of the new LHSMDF reveals that it outperforms the original LHS and OLHS. The HLM problem test results demonstrate that achieving optimum HLM with high reliability necessitates precision without sacrificing accuracy in the manufacturing process. Moreover, it is suggested that the six-bar HLM could emerge as a viable option for developing a new high-lift device in aircraft mechanisms for the future.

Modern Methods of Strengthening and Sealing Salt Mines

In order to ensure safe working conditions for miners underground, many works are carried out in mines to strengthen and seal mining excavations. This article presents the successfully applied technology for removing water inflow from the unique Salt Mine. Failure to take such action may ultimately lead to the flooding of the “Wieliczka” Salt Mine (KSW). On the basis of the authors’ research studies, some of the implemented works at the “Wieliczka” Salt Mine are presented, the purpose of which is to better protect the mine against the risk of flooding with water. Thanks to this, the mine can safely survive for many more years. This article presents two innovative technologies in salt mines: (1) sealing of the rock mass surrounding the Kościuszko shaft casing in the “Wieliczka” Salt Mine, where jet injection was used as the basic method of making an anti-filter screen outside the shaft casing and classic injection as a supplementary method for sealing the anthropogenic embankment; (2) reconstruction of the internal pillar of safety by implementing a patented technology called “pipeline injection” on the example of the Mina cross-section, in which a catastrophic water inflow was previously created that threatened the existence of the “Wieliczka” Salt Mine. The first method consists of making an anti-filter screen, which is located outside the shaft housing. Unfortunately, it is not possible to perform injection works from inside the shaft housing, because the Kosciuszko shaft, as a ventilation shaft, must be open constantly. To solve this problem, it is designed as the main technology known as jet grouting, which is supplemented by pressure injection at a depth of up to several meters with continuous monitoring of the condition of the casing during injection works. The second example concerns the reconstruction of the internal pillar of mine safety in the area of the northern border of the salt deposit. In this case, the catastrophic hazard is documented, as evidenced by the inflow to the Mina transverse, which is located on the fourth level of the mine. This task was successfully completed by the implementation of a patented technological solution called pipeline injection, the details of which are discussed in this article.

손 글씨 프린터의 부품개선에 따른 소음저감 연구

The noise generated by a small printer that simulates handwriting is noticeable when it operates in a quiet environment. In this study, analytical experiments were conducted prior to upgrading the printer design. The printer head, linear shaft and printer housing were considered as candidate components affecting the noise characteristics and thereby the noise level of the printer. The results obtained from the conducted computer simulations indicate that printer head’s design is a key factor in reducing the overall noise level. Hence, to maintain the stiffness while reducing the mass, a new design for the printer head was implemented. Furthermore, modifications in the printer components resulted in achieving noise reduction.

Experimental investigation on the machinability of nodular ductile iron with cubic boron nitride and tungsten carbide inserts

The nodular irons have more ductility which is demanded by mechanical components like crankshaft, cam shaft, bearing cap and clutch housing, offering fatigue resistance for their intended performance. The impact of various process parameters like depth of cut (D), cutting speed (S) and feed (F) on the cutting force of nodular iron was studied and optimized by using the RSM model. The nodular iron was turned at dry condition with two different types of cutting tools, namely CBN and coated tungsten carbide tool (TiCN + Al2O3 + TiN) to evaluate the influence of cutting parameters. The cutting speed employed for these tests are 102,174 and 245 m/min with feed rates of 0.051, 0.102 and 0.143 mm/rev together with the depth of cuts as 0.5, 0.75 and 1 mm. The tungsten carbide coated tool performed well as compared to CBN tool while machining with nodular iron in terms of getting lower cutting force and better surface roughness.

Turbulence effect on dynamic performance of non-circular floating ring bearing

The current work scrutinizes the impact of turbulence on the dynamic performance of the novel variation of hydrodynamic bearing, especially “Non-Circular Floating Ring Bearing”. A bearing comprises of a shaft, floating ring, and non-circular outer housing. The journal and floating ring are cylindrical, whilst the outer housing is noncircular. The noncircular designs of journal bearing provide better stiffness characteristics. The well-established Navier–Stokes and continuity equations (cylindrical coordinates) have been adequately utilized with the linear turbulence lubrication theory. Dynamic characteristics of modified floating ring bearing have been scrutinized at different numerical values of film eccentricity ratio (outer) and Reynolds numbers up to 9000. The current analytical work envisages satisfactorily well performance of modified floating ring bearing in the regime of turbulence.

Effects of lightweight gear blank on noise, vibration and harshness for electric drive system in electric vehicles

In this paper, effects of lightweight gear blank on static and dynamic behavior for electric drive system in electric vehicles are studied. First, a hybrid finite element-analytical method is proposed in this paper to establish gear load contact analysis model considering the structure of lightweight gear blank, which can balance the computing speed and numerical accuracy. Second, this paper establishes a rigid-flexible coupled dynamic model of electric drive system considering shaft elasticity, bearing stiffness, and housing flexibility. Finally, aiming at the noise, vibration, and harshness problem of an electric drive system equipped on electric vehicles, effects of gear web and gear rim thickness on noise, vibration, and harshness excitation source such as static transmission error and dynamic meshing force as well as dynamic response at bearings and housing are analyzed. The results show that changing gear web and gear rim thickness can significantly reduce dynamic meshing force and dynamic response. Compared with solid gear, dynamic meshing force is reduced by 68.50%, and dynamic response is reduced by 66.70% after optimization, thereby significantly improving the noise, vibration, and harshness performance of gear transmission system in electric vehicles.

Transient Thermal Modeling of Ball Bearing Using Finite Element Method

Gas turbines are fitted with rolling element bearings, which transfer loads and supports the shafts. The interaction between the rotating and stationary parts in the bearing causes a conversion of some of the power into heat, influencing the thermal behavior of the entire bearing chamber. To improve thermal modeling of bearing chambers, this work focused on modeling of the heat generated and dissipated around the bearings, in terms of magnitude and location, and the interaction with the components/systems in the bearing chamber. A thermal network (TN) model and a finite element (FE) model of an experimental high-pressure shaft ball bearing and housing were generated and a comparison to test rig results have been conducted. Nevertheless, the purpose of the thermal matching process that focused on the FE model and experimental data is to provide a template for predicting temperatures and heat transfers for other bearing models. The result of the analysis shows that the predictions of the TN are considerate, despite the simplifications. However, lower relative errors were obtained in the FE model compared to the TN model. For both methods, the highest relative error is seen to occur during transient (acceleration and deceleration). This observation highlights the importance of boundary conditions and definitions: surrounding temperatures, heat split and the oil flow, influencing both the heat transfer and heat generation. These aspects, incorporated in the modeling and benchmarked with experimental data, can help facilitate other related cases where there is limited or no experimental data for validation.

Fault Detection of Tripod Shaft using Dual Strain Sensor

Tripod shafts used in high-speed trains transmit power of motor reduction unit to axle reduction unit. Since the load applied to the reduction units is very large during operation, it is designed as the shaft with a fuse to protect gears of reduction units. Failure of the fuse can lead to accidents and economic loss such as train service interruption and repair problem in accident site. However, it is difficult to inspect the fuse covered by the tripod shaft housing. So, it is necessary to detect the fuse of the tripod shaft in advance. In this study, torsion fatigue tests considering failure mode were carried out and strain data were collected by strain sensors at around weak point of that. Thresholds for the damage detection of the tripod shaft fuse were defined by feature extraction from sensor data. We evaluated the detection performance of the thresholds.

An efficient modeling method for coupled vibration analysis of double-helical gear reduction

A modeling method of double-helical gear reduction for analysis of bending-torsional-axial-swinging coupled vibration is introduced in this study. Using integrating theories of system dynamics and structural dynamics, the model proposed is of sufficient simulation accuracy as well as high computational efficiency according to the modal verification. Based on hybrid user-defined element method (HUELM) combining TCA and LTCA methods, the model consists of four special finite elements: double-helical engagement element, bearing element, 3Dflexible shaft element and housing element. Models for each element are developed in FORTRAN language with precise mathematical representation. Frequency extraction by Lanczos method is applied to the model to predict free vibrations of the example system. Simulation results show that the predictions by HUELM in terms of the same order frequency and mode shape match well with the ones by 3D FEM. However, the efficiency comparison reveals that CPU time of the latter is nearly eight times longer than the time of HUELM. An experimental study on modal analysis of support box is also exhibited. It is demonstrated that maximum error of frequency between measured data and housing element simulation is less than 8%

Przegląd technik inwentaryzacji rury szybowej

Nadrzędnym celem pomiarów i obserwacji wykonywanych w szybach jest zapewnienie ich bezpiecznej pracy. Wiąże się to nie tylko z określeniem aktualnego stanu technicznego szybu, lecz również z określeniem przyczyn i źródeł powstawania zmian. Wraz z rozwojem technik laserowych i cyfrowych pojawiają się nowe możliwości prowadzenia bezpiecznej inspekcji i inwentaryzacji wyrobisk szybowych. W celu zachowania sprawności szybu wykonuje się szereg prac inwentaryzacyjnych, opisanych szczegółowo w Rozporządzeniu Ministra Gospodarki z dnia 28 czerwca 2002 i jego załączniku (nr 4) [1,2]. Artykuł przedstawia przegląd technik pomiarowych stosowanych obecnie do pomiarów deformacji rury szybowej, ze szczególnym uwzględnieniem ciągłych telemetrycznych metod pomiarowych.Szczegółowo opisano zaprojektowany dla Kopalni Soli ‘Wieliczka’ system monitoringu wykorzystany w latach 2014 i 2015 podczas wykonywania iniekcji usztywniających i uszczelniających szyb Kościuszko. W celu uniknięcia uszkodzeń konstrukcji szybu oraz awarii krytycznych skonstruowano i zainstalowano mobilny system monitorowania stanu szybu. Wyniki jego pomiarów pozwoliły wskazywać w czasie rzeczywistym zmiany, a w razie konieczności dokonywać modyfikacji przebiegu iniekcji i w sytuacjach awaryjnych wstrzymać proces. Analiza rezultatów wykazała niewielkie deformacje obudowy szybu podczas iniekcji oraz jednoznacznie potwierdziła zalety wykonanego systemu monitoringu i nowatorskiego sposobu iniekcji wysokociśnieniowych.

The usage of telemetry measurements methods to determine shaft tube deformations caused by natural and antrophogenic rock mass movements [abstract

Mining shaft is the most important element of the underground mine. It determines mine’s ability to work efficiently. Mining shaft is used for transporting employees, equipment and dirt or output. It also allows to perform fast rescue operation and ensures that employees in danger can be quickly evacuated. Last but not least it allows ventilation and functioning underground. Mining shaft and especially the shaft tube are subject to influences, both geological and anthropogenic. In details: local geological structure (deposit tectonic structure), mass rock movements due to exploitation inside and outside of safety shaft pillar, underground watercourses and leakages of shaft or voids around the shaft (especially dangerous in case of salt exploitation). Ensuring shaft’s safe operation is the primary aim of measurements and observations performed in mining shafts. This involves not only determining the current technical condition of the mining shaft, but also determining causes of observed changes (Szczerbowski & Joźwik 2002). In order to preserve the efficiency of every shafts several inventory works have been performed, described in details in Ordinance (Regulation of the Minister of Economy from 28 th of June 2002) and its appendix (Appendix nr 4 to Regulation of the Minister of Economy from 28 th of June 2002) (Jaśkowski 2013). The report presents an overview of measurements techniques which are in use in order to perform shift tube’s inventory, with particular emphasis on telemetric measurement methods. Monitoring system designed for ‘Wieliczka’ Salt Mine has been described in details. The system was used in 2014 and 2015 to monitor deformations during sealing and stiffening the shaft housing. Material, injected under considerable pressure (up to 30 MPa) to 92 boreholes located few meters from the shaft, could damage the reinforcement and cause critical failures of the shaft. In order to prevent such situations, mobile system for monitoring the condition of the structure of the shaft was mounted. Its indications allowed to define in the current time the value of deformation occurring in the shaft, and if necessary immediately modify the schedule and course of injection works. Analysis of the results shows a slight deformation of the shaft housing during the injection, and demonstrates the advantages of the monitoring system and a novel method of high-pressure injections (Jaśkowski, Lipecki & Jablonski 2016). The system and implemented software was created within the project Developing technologies of sealing mine shafts by Salt Mine ‘Wieliczka’, co-financed by the European Regional Development Fund. Research for the article was funded by statutory research of the Department of Mining Areas Protection, Geoinformatics and Mining Surveying (AGH University of Science and Technology) number 11.11.150.195.

Simulated Annealing Algorithm for Minimising the Surplus Parts in Selective Assembly-A Software Approach

Selective assembly is a precision assembly making process from wider tolerance components in which products are produced from randomly assembling the measured components from portioned bins. Very few papers were discussed in literature regarding cost aspects of manufacturing products in selective assembly techniques. Only procedural algorithms were used to calculate the cost of a product in these techniques. Moreover, tolerance cost curves and selection of tolerance for a component with alternative process were also not considered in most of the papers found in literature. The best combination of bins to make less scrap was computed only based on component's tolerance and not by considering the original dimension of the components. None of the paper used simulated annealing algorithm to compute the best bin combinations to make more number of assemblies in turn to reduce surplus parts. In this paper, these problems were removed using Power Builder, an optional programming language with Sybase SQL Anywhere as a database and Matlab software. Shaft housing assembly is considered as an example product to illustrate the effectiveness of the proposed method. Tolerance cost curves can be viewed within no time for individual process or together with a good number of processes. Moreover, for the same process and tolerance value, the best nominal dimension of the product can also be selected in this work and for the given tolerance of a component with alternative processes; the minimum cost process can be visualized and calculated.

A Methodology for Protective Vibration Monitoring of Hydropower Units Based on the Mechanical Properties

It is important to monitor the radial loads in hydropower units in order to protect the machine from harmful radial loads. Existing recommendations in the standards regarding the radial movements of the shaft and bearing housing in hydropower units, ISO-7919-5 (International Organization for Standardization, 2005, "ISO 7919-5: Mechanical Vibration-Evaluation of Machine Vibration by Measurements on Rotating Shafts-Part 5: Machine Sets in Hydraulic Power Generating and Pumping Plants," Geneva, Switzerland) and ISO-10816-5 (International Organization for Standardization, 2000, "ISO 10816-5: Mechanical Vibration-Evaluation of Machine Vibration by Measurements on Non-Rotating Parts-Part 5: Machine Sets in Hydraulic Power Generating and Pumping Plants," Geneva, Switzerland), have alarm levels based on statistical data and do not consider the mechanical properties of the machine. The synchronous speed of the unit determines the maximum recommended shaft displacement and housing acceleration, according to these standards. This paper presents a methodology for the alarm and trip levels based on the design criteria of the hydropower unit and the measured radial loads in the machine during operation. When a hydropower unit is designed, one of its design criteria is to withstand certain loads spectra without the occurrence of fatigue in the mechanical components. These calculated limits for fatigue are used to set limits for the maximum radial loads allowed in the machine before it shuts down in order to protect itself from damage due to high radial loads. Radial loads in hydropower units are caused by unbalance, shape deviations, dynamic flow properties in the turbine, etc. Standards exist for balancing and manufacturers (and power plant owners) have recommendations for maximum allowed shape deviations in generators. These standards and recommendations determine which loads, at a maximum, should be allowed before an alarm is sent that the machine needs maintenance. The radial bearing load can be determined using load cells, bearing properties multiplied by shaft displacement, or bearing bracket stiffness multiplied by housing compression or movement. Different load measurement methods should be used depending on the design of the machine and accuracy demands in the load measurement. The methodology presented in the paper is applied to a 40 MW hydropower unit; suggestions are presented for the alarm and trip levels for the machine based on the mechanical properties and radial loads.

Piezoelectric Rotary Mechanism for Precise Positioning

A new piezoelectric rotary mechanism for precise positioning was proposed. It was designed in asymmetrically configuration of two sets of cantilever bimorphs with end-mass. And the frictional force between the revolving shaft and axle housing can be adjusted within potential range. The rotary actuator can run silently and smoothly on sine wave electric voltage. The dynamic characteristics have been tested on assembled prototype. The rotary actuator is desired to used in micromachining or micro-assembly etc.

Demonstration of a Palm-Sized 30 W Air-to-Power Turbine Generator

A compact, high power density turbo-generator system was conceived, designed, and experimentally tested. The air-to-power (A2P) device with a nominal design point of 50 W electric power output operates on high pressure air such as from a plant pneumatic system or from a portable bottle of pressurized air. A concept design study was first carried out to explore the design space for a range of output power at cost efficiency levels specified in collaboration with industry. The cost efficiency is defined as the cost of electrical power over the cost of pressurized air. The key challenge in the design is the relatively low power demand of 50 W while operating at high supply pressures of nominally 5–6 bars. To meet the cost efficiency goal under these conditions, a high-speed turbine and generator (∼450,000 rpm) are required with small blade span (∼200 μm), minimizing the mass flow while achieving the highest possible turbine performance. Since turbines with such small turbomachinery blading are not commercially available, a silicon-based micro electro mechanical systems (MEMS) turbine was designed using 2D and 3D computational fluid dynamics (CFD) computations. To reduce the development time, existing and previously demonstrated custom-made generator and ceramic ball bearing technology were used, resulting in a compact A2P proof-of-concept demonstration. The cylindrical device of 35 mm diameter resembles a tube fitting with a standard M24 adapter. Without load, a top turbine speed of 475,000 rpm was demonstrated, exceeding the design specification. Using load resistors, the proof-of-concept A2P device achieved 30 W of electrical power at 360,000 rpm and a turbine efficiency of 47%, meeting the cost efficiency goal. Higher speeds under load could not be achieved due to thrust load limitations of the off-shelf ball bearings. The demonstrated performance is in good agreement with the projected CFD based predictions. To the authors’ knowledge, this is the first successful demonstration of a self-contained, 50 W class turbo-generator of hybrid architecture where a MEMS turbine disk is joined with a precision machined titanium shaft and aluminum housing.

Variant design for mechanical parts based on extensible logic theory

A new variant design method of mechanical part is proposed based on extensible logic theory, to support design knowledge reuse more efficiently in computer aided conceptual design. In this method, matter-element, event-element and relation-element are used to characterize the feature information, connection constraint relations and topology variant operations of mechanical conceptual structures respectively. Extensible composite-element model of product part is established sequentially based on the above three basic-element models (matter-element, event-element and relation-element). Moreover, five types of variant operations are defined in order to realize structure variations and shape design of mechanical parts. Finally, an example of shaft housing part in grinder component is taken to explain the part variant design process in details, in which the efficiency and effectiveness of this method are illustrated simultaneously.

Characterization of a Foil Bearing Structure at Increasing Temperatures: Static Load and Dynamic Force Performance

Oil-free turbomachinery relies on gas bearing supports for reduced power losses and enhanced rotordynamic stability. Gas foil bearings (GFBs) with bump-strip compliant layers can sustain large loads, both static and dynamic, and provide damping to reduce shaft vibrations. The ultimate load capacity of GFBs depends on the material properties and configuration of the underlying bump-strip structures. In high temperature applications, thermal effects, which change the operating clearances and material properties, can considerably affect the performance of the GFB structure. This paper presents experiments conducted to estimate the structural stiffness of a test GFB for increasing shaft temperatures. A 38.17 mm inner diameter GFB is mounted on a nonrotating hollow shaft affixed to a rigid structure. A cartridge heater inserted into the shaft provides a controllable heat source and thermocouples record the temperatures on the shaft and GFB housing. For increasing shaft temperatures (up to 188°C), increasing static loads (0–133 N) are applied to the bearing and its deflection recorded. In the test configuration, thermal expansion of the GFB housing, larger than that of the shaft, nets a significant increase in radial clearance, which produces a significant reduction in the bearing’s structural stiffness. A simple physical model, which assembles the individual bump stiffnesses, predicts well the measured GFB structural stiffness. Single frequency periodic loads (40–200 Hz) are exerted on the test bearing to identify its dynamic structural stiffness and equivalent viscous damping or a dry-friction coefficient. The GFB dynamic stiffness increases by as much as 50% with dynamic load amplitudes increasing from 13 N to 31 N. The stiffness nearly doubles from low to high frequencies, and most importantly, it decreases by a third as the shaft temperature rises to 188°C. In general, the GFB dynamic stiffness is lower than its static magnitude at low excitation frequencies, while it becomes larger with increasing excitation frequency due apparently to a bump slip-stick phenomenon. The GFB viscous damping is inversely proportional to the amplitude of the dynamic load, excitation frequency, and shaft temperature. The GFB dry-friction coefficient decreases with increasing amplitude of the applied load and shaft temperature, and increases with increasing excitation frequency.

Effect of Rarefaction, Dissipation, and Accommodation Coefficients on Heat Transfer in Microcylindrical Couette Flow

This paper examines the effects of rarefaction, dissipation, curvature, and accommodation coefficients on flow and heat transfer characteristics in rotating microdevices. The problem is modeled as a cylindrical Couette flow with a rotating shaft and stationary housing. The housing is maintained at uniform temperature while the rotating shaft is insulated. Thus, heat transfer is due to viscous dissipation only. An analytic solution is obtained for the temperature distribution in the gas filled concentric clearance between the rotating shaft and its stationary housing. The solution is valid in the slip flow and temperature jump domain defined by the Knudsen number range of 0.001<Kn<0.1. The important effect of the momentum accommodation coefficient on velocity reversal and its impact on heat transfer is determined. The Nusselt number was found to depend on four parameters: the momentum accommodation coefficient of the stationary surface σuo, Knudsen number Kn, ratio of housing to shaft radius ro∕ri, and the dimensionless group [γ∕(γ+1)](2σto−1)∕(σtoPr). Results indicate that curvature, Knudsen number, and the accommodation coefficients have significant effects on temperature distribution, heat transfer, and Nusselt number.

Modelling of Gearbox Vibration and Noise

AbstractThe paper presents the methodology intended to the vibration and noise analysis of gearboxes or generally of large rotating systems. These systems are considered including their interior rotating shaft system and housing joined together by rollingelement bearings and gear couplings. The new developed bearing model respects real number of rolling bodies and roller contact forces acting between the journals and the outer housing. The model of a complete gearbox is created using the modal synthesis method. Steady state dynamic response of the whole gearbox excited by gear kinematic transmission errors is investigated. A noise radiated by the housing is calculated on the basis of the acoustic power density evaluation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Numerical model of spindle/disks assembly–shaft–housing system for vibro-acoustic analysis of HDD in idle mode

This paper presents the mathematical models of the spindle/disks–shaft–housing system for vibro-acoustic analysis of hard disk drives operating in idle mode. A complete model of a spindle/disks assembly–shaft–housing system is developed using a multi-body system Lagrangian formulation. The transfer functions between source excitations and induced vibration on the housing are derived. The effect of adding flexibility to the non-spinning components (i.e. housing and shaft) is examined and the model capabilities are demonstrated through parameter studies.