Fixed Load Conditions Research Articles

Study on the vibration characteristics of angular contact ball bearing cage under rolling-sliding compound motion

Abstract Cage fracture has become the main form of bearing failure, the study of factors affecting the operating condition of the cage has an important impact on the operating performance and life of bearings. This study takes the angular contact ball bearing H7006C as the object of study and extracts the bearing inner ring and cage speed to analyze the bearing slip rate law. Extract cage vibration data and analyze cage vibration frequency characteristics using the VMD method. The effects of load and speed induced bearing slippage on the vibration characteristics of cages are investigated by varying the induced bearing slippage factors. The effects of load and speed induced bearing slip on the vibration characteristics of cages are investigated separately by varying the induced bearing slip factors. The study found that, at a fixed rotational speed, the bearing slip rate decreases as the axial load increases from 0 to 350N, and then stabilizes beyond 350N. Under fixed load conditions, the bearing slip rate increases with the rotational speed ranging from 1000 to 9000rpm. At a constant speed, the axial load is varied within 50 to 100N, resulting in vibration frequency increases of 72Hz, 43.5Hz, and 24Hz at 1000 rpm, 5000 rpm, and 9000 rpm, respectively. The characteristic frequency of cage vibration rises with increasing load, contributing to smoother cage operation. Nonetheless, as the rotational speed increases, the influence of axial load-induced slippage on the vibration characteristics of the cage diminishes gradually. At a set load of 500N, the amplitudes of the cage vibration eigenfrequencies at 1000rpm, 3000rpm, and 7000rpm are 0.0317, 0.0288, and 0.0174, respectively, decreasing with rotational speed. This indicates that the cage does not operate smoothly. The findings of this study serve as a theoretical foundation for detecting and diagnosing bearing slip and vibration issues in rotating machinery.

High Tracking Control for a New Independent Metering Valve System Using Velocity-Load Feedforward and Position Feedback Methods

The new configuration of independent metering valve (NIMV) system uses three proportional valves that gave been effectively proven to be energy saving compared with a conventional independent metering valve system in the fixed load condition. However, the variable load condition completely affects the accuracy and energy consumption during the operation of excavators. To improve the motion tracking precision and reduce the energy consumption of the NIMV system, a novel control method based on the coordinated control of the pump and the valve is proposed. In detail, the valve is controlled by considering velocity, load force, and position feedback of the cylinder. Meanwhile, velocity feedforward and position feedback methods are used to control the speed of the pump. In addition, a switching mode for the NIMV system is designed to flexibly select the metering modes based on the load and velocity conditions. To confirm the effectiveness of the proposed control method, the co-simulation model is built by using the AMESim and MATLAB software. From the results, the proposed method not only has high trajectory tracking precision with the displacement error of the cylinder at around 3.6% but also achieves up to 6.4% energy saving.

Experimental study on heat transfer characteristics of helix ground heat exchanger coil under dynamic load

In order to study the thermal behavior of helix ground heat exchanger coil when subjected to different thermal load distributions, a full scale helix ground heat exchanger coil system was constructed in this paper. On basis of the system, two kinds of simulated thermal loads were subjected to the full scale helix ground heat exchanger coil. To obtain the actual thermal performance, the temperature response and transient effective heat transfer coefficient were analyzed under the two kinds of simulated thermal loads. The results indicate that under the cyclic dynamic load, the temperature of the inlet and outlet of the helix ground heat exchanger coil also changes periodically. And from the overall trend, the inlet and outlet water temperature of the exchanger increase gradually. In the constant flow rate condition, when the load rate of the helix ground heat exchanger coil is low, the effective heat transfer coefficient is small, thus the load rate of the exchanger should be as high as possible. When the system is under part load, the number of sections of the running helix ground heat exchanger coil should be reduced in order to guarantee a high load value. The accumulated heat rejection from the heat exchanger to ground will affect the effective heat transfer coefficient to a certain extent. The effective heat transfer coefficient under dynamic load condition can be up to 67.4% higher than fixed load condition under the effect of accumulated heat rejection. It is also preliminarily found that rainfall infiltration can effectively strengthen the heat transfer effect of the helix ground heat exchanger coil by 18.4%, which is almost equal to the increase of the effective heat transfer coefficient after the night-time recovery period during intermittent operation.

Finite element (FE) assisted investigation of a compliant mechanism made of various polymeric materials

Compliant mechanisms are flexible devices that can produce useful work through elastic deformations. Compliance is a relatively novel approach, that contrasts with the conventional rigid body approach common in most mechanisms. The advantages of compliant mechanisms over conventional rigid body mechanisms include reduced parts, lower costs due to reduced assembly, reduced inventory storage, ease of manufacturing, improved performance, reduced weight, elimination of lubrication, and the ability to create miniature mechanisms. The present work investigates the finite element analysis of compliant mechanism for plier type device using linear solver in Pre/Post tool available in Siemens NX 12. A computer aided design (CAD) model of the mechanism is recreated through approximate geometry tracing and the model are recorded for optimization. The model parameters are then imported into Pre/Post tool for simulation using the Linear Solver. The model is simulated to understand behaviors of displacement, stress and strains. To achieve this a Finite Element Analysis is conducted on the model and the results of the FEA study are presented in the study under fixed load conditions for Acrylonitrile Butadiene Styrene (ABS), Polylactic Acid (PLA) and Thermoplastic polyurethane (TPU) polymers. From the results of the study, it can be concluded that compliant mechanism can be reliably achieved for the application required using ABS as the desired useful work is achieved within the range of elastic deformation for the material.

A stress distribution modelization of a neat fit pin-loaded hub

PurposePin-loaded hubs with fitted bush are used in industrial connector-type elements. They are subjected to varying radial forces leading to variable stress distribution. The literature provides various pressure distribution expressions adapted essentially for symmetric geometries and fixed load condition (circular hubs, half-infinite geometries, axial load, tangential load, etc.). This study aims to take into account the geometrical conditions of industrial connector-type elements and presents a model for pressure distribution based only on geometric parameters, maximal pressure and contact angle value for the case of fit pin-loaded hub.Design/methodology/approachThe finite element computation for the contact problem shows that the pressure distribution of the pin-loaded hub under various inclined forces (from 0° to 180°) is a parabolic distribution. This distribution can be defined by three parameters which are θA, θB and Pmax. The study assumes that the distribution is symmetric and that Pmax can be modeled using force F, hub radius R, hub thickness b and the half contact angle are θA.FindingsThe new proposal pressure distribution parameters are easy to identify. Even for the non-symmetric pressure distribution, the study denotes that the errors on evaluating θA and θB keep the analytical model still in good agreement with finite element computations.Research limitations/implicationsOnly the neat fit case was studied.Practical/implicationsPin-loaded joints are connector-type elements used in mechanical assemblies to connect any structural components and linkage mechanisms such as connecting rod ends of automotive or shear joints for aircraft structure.Originality/valueThe good correlation between finite element computations and model results shows the validity of the assumptions adopted here. Analytical fatigue models, based on this stress distribution, could be derived in view of a fatigue lifetime calculation on connecting hub. Friction, pin deformation and local plastic effects under pin-loading are the main phenomena to take into account to further enrich this model.

Investigation on a diesel engine’s performance with integration of magnetic flux on the fuel line

ABSTRACTApplication of magnetic flux (MF) on the fuel line of diesel engines is a promising technique to enhance the performance of the engine. In this work, MF was applied by placing neodymium magnet pairs (MP) on the fuel line of a diesel engine test setup. Tests were carried out for different loads in the range of 0–8 kg. In the first stage, performance of the test setup was evaluated without MF for fixed load condition; in the second stage, performance evaluation was done by increasing number of MP on the fuel line – that is, the number of magnetic pairs was increased from 1 to 4. The experimental results confirmed that fuel consumption rate decreases with an increase in magnetic pair from 1 to 3; after employing the fourth magnetic pair, an increase in fuel consumption rate was observed. This clearly gives an idea for the presence of critical magnetic field for fuel savings.

Equivalent energy release rate and crack stability in the End Notched Flexure with inserted roller mixed mode I/II test

The crack propagation performance of the End Notched Flexure with inserted roller test is analyzed. An equivalent energy release rate is proposed taking into account the interaction of the modes I and II, based on the linear failure criterion. Experimental results obtained with specimens of F593/T300 carbon/epoxy unidirectional composite show a good agreement with the proposed approach. The stability condition is theoretically developed based on the derivative of the equivalent energy release rate, under fixed load condition and fixed displacement condition. Experimental tests have been carried out to assess the proposed equivalent energy release rate and to evaluate the crack stability condition. An analysis of the influence of compliance measurement on the crack length and on the equivalent energy release rate is included. Based on the results obtained, test conditions with initial mode ratios between 65% and 75% are recommended.

Investigations on ion transport properties of and battery discharge characteristic studies on hot-pressed Ag+-ion-conducting nano-composite polymer electrolytes: (1–x) [90PEO : 10AgNO3] : xSiO2

Investigations on the ion transport properties of Ag+-ion-conducting nano-composite polymeric electrolytes (NCPEs): (1−x)[90PEO : 10AgNO3] : xSiO2, where x = 0, 1, 2, 3, 5, 10 or 15 (wt%) and PEO is poly(ethylene oxide), are reported here. Films of NCPEs were cast using a novel hot-press/solvent-free/dry technique instead of the usual solution cast method. Nano-size (∼8 nm) SiO2 particles, as the second dispersoid phase, were dispersed into the first-phase conventional solid polymer electrolyte (SPE) host: (90PEO : 10AgNO3). The SPE host, also prepared by hot-pressing the homogeneously mixed composition: PEO : AgNO3 :: 90 : 10 (wt%), has been identified as the film with the highest room temperature conductivity σ∼4×10-6 S cm-1, exhibiting a σ increase of more than three orders of magnitude from that of the pure PEO. Dispersal of SiO2 nano-particles in the SPE host resulted in a 2-fold conductivity enhancement in the NCPE film: 95(90PEO : 10AgNO3) : 5SiO2 (wt%). This has been referred to as the ‘optimum conducting composition (OCC)’. The ion transport behavior in NCPE has been characterized on the basis of experimental studies on some basic ionic parameters, viz. ionic conductivity (σ), ionic mobility (μ), mobile ion concentration (n), ionic transference number (tion), etc. The temperature-dependent measurements on σ, μ and n in the NCPE OCC film provided quantitative information on the energies involved in different thermally activated processes. A thin-film solid-state battery has been fabricated using the NCPE OCC membrane as the electrolyte to test the cell performance under a fixed load condition at temperatures below/above room temperature.

Evolutionary methods for topology optimisation of continuous structures with design dependent loads

Evolutionary structural optimisation (ESO) method is based on the idea that by gradually removing inefficient materials, the structure evolves towards an optimum. Bi-directional ESO (BESO) allows for adding efficient materials in the evolution. This paper investigates the ESO and BESO methods in solving the topology optimisation of continua structures with a constraint on the global stiffness. Based on the work on stiffness optimisation with fixed load conditions, this paper focuses on problems considering design dependent loads. The dependence can be due to transmissible loads, inclusions of structural self weight and surface loads. Sensitivity analysis and evolutionary procedure for problems of fixed load conditions are modified to accommodate the load variation condition. A number of examples are presented for verification. The results demonstrate that ESO and BESO are effective in solving the optimisation with design dependent loads. BESO has the flexibility of balancing solution quality and computing time.

DESIGN OF LATERAL BRACES FOR COLUMNS CONSIDERING CRITICAL IMPERFECTION OF BUCKLING

The present paper discusses the design of column-type structures, which are composed of columns and lateral braces attached perpendicular to the columns. Buckling of the braces of this kind of structures directly leads to global buckling of the columns. The brace-buckling modes are successfully detected by considering higher-order geometrically nonlinear relations and by introducing Green's strain into the total potential energy of the structure. Sensitivity analysis of the eigenvalues of the tangent stiffness matrix under fixed load condition is carried out with respect to imperfections of the nodal locations. Furthermore, the critical imperfection that most drastically reduces the eigenvalues are calculated and buckling loads of the imperfect systems are evaluated. The numerical results show that the second or higher eigenmode of the tangent stiffness matrix of the perfect system should be sometimes used for estimating the buckling load of the imperfect system. Design examples are presented using the proposed method, and they are compared with those in accordance with an allowable-stress design standard. The results show a possibility of reducing the sizes of the brace sections.

Control of Reactive Power in Distribution Systems with an End-Load and Fixed Load Condition

Control of Reactive Power in Distribution Systems with an End-Load and Fixed Load Condition

Control of Reactive Power in Distribution Systems with an End-Load and Fixed Load Condition

Control of Reactive Power in Distribution Systems with an End-Load and Fixed Load Condition

Instability conditions in the development of expressions for [formula omitted

The development of linear fracture toughness, G c and nonlinear energy toughness, G ̃ c is based on the energy balance criterion. The expressions for G c and G ̃ c were derived assuming fixed grip and fixed load conditions at instability. In this paper it is indicated that neither the fixed grip nor the fixed load condition is likely to exist at instability, and the expressions for G c and G ̃ c are derived assuming an arbitrary load-displacement relationship at instability.

Optimized Distribution and Subtransmission System Planning by Digital Computer I-System Philosophy

The principal features of a co-operative planning study by the Arizona Public Service Company and the General Electric Company are described. Objective of the joint study is to determine optimum design of distribution and subtransmission systems to serve a large load area. To accomplish this objective a series of four digital computer programs have been developed. These programs generate the costs and characteristics of systems designed to serve a specified area for fixed load conditions.