Vibration Issues Research Articles

Offline model predictive control approach to micro-slip control in gearshifts of dual clutch transmission

Dual clutch transmission can avoid some noise vibration and harshness issues caused by other transmissions with single clutch. And applying micro-slip control on clutches can further improve the gearshift performance of transmission compared to the lock-up control. Considering the real-time characteristic of vehicle control, an offline model predictive controller designed by multi-parameter quadratic programming was creatively applied in dual clutch transmission to obtain both clutch torque at the same time with optimal control algorithm. In this way, while realizing the micro-slip state of the clutches, the fast response speed can be realized through the off-line controller, which makes it more feasible and practical for transmission control. A six degrees of freedom vehicle powertrain system model was built in MATLAB/Simulink to simulate the proposed control algorithm. The simulation results show that the micro-slip control avoid the negative torque compared to the lock-up control, which leads to a smoother shift process. In addition, compared with the proportional–integral–derivative micro-slip controller, the offline model predictive controller can achieve more stable control effects with less output torque fluctuation and shorter gearshift time.

Drop-In Motors: What You Need to Consider Beyond the Bolt Pattern

The push to improve efficiency and lower costs has impacted electric motors. It is not uncommon to see a reduction in mass for modern medium-voltage machines, and the actual footprint of newer machines is smaller in most cases, too. Many drop-in motors (mechanically interchangeable) perform very well. There are design constraints that may be overlooked when ordering a functional drop-in replacement machine. Depending on the power, size, and speed of a motor, failure to meet the minimum base stiffness requirements can cause severe vibration issues. The combination of a transition base with a machine of a different mass can cause resonance problems, which can cost more than the motor to resolve. Changing from a stiff to a flexible rotor can result in unexpected vibration without an easy solution. The issues described in this article could be experienced by any end user, regardless of the original equipment manufacturer.

Experimental comparison of localised magnetostriction difference under sinusoidal and PWM excitations

The majority of power transformers are usually energized by sinusoidal excitation. However, there is a growing demand for using PWM excitation on power electronics devices for energy savings. As awareness of the environment also increases, the importance of noise and vibration issues becomes more significant. Increasing non-linear loads over time affect the ageing and lifetime of transformers. Such cases also cause to change the nominal values ​​of transformers. It is important that mechanical parameters such as vibration and noise can be accurately measured and examined so that all necessary functions can be entirely performed as other electromagnetic performances. For this reason, it is necessary to analyse the vibration movements of transformers and determine their characteristics, especially locally under changing operating conditions. Magnetostrictive is known as the main source of vibration and noiseof the transformer core. This paper presents localized magnetostriction of transformer core measured by strain gauges under sine and PWM voltage excitations. For validation of the study in this paper, a no-load strain measurement was performed experimentally on a real 20kVA three-phase three-limb T-joint transformer assembled in a laboratory.Localized magnetostriction in the rolling and transverse directions of the lamination under sinusoidal and PWM voltage excitations was carried out. The results of the experiment were compared with each other in terms of the location of the sensors.The Finite Element Analysis (FEA) was used to simulate the magnetic behavior of the transformer based on time-dependent analysis of magnetic field density, force, e.t. distributions under no-load conditions, respectively.In conclusion, evaluating the localized magnetostriction characteristic, especially under PWM voltage excitation, is essential for interlamination electromagnetic and electromechanical behaviors.

An Aspect of Noise, Vibration, and Harshness Issues in Electric Vehicles

An Aspect of Noise, Vibration, and Harshness Issues in Electric Vehicles

Analytical Evaluation of Mobile In Situ Soil Nitrate Infrared Sensor Designs for Precision Agriculture

One approach to improving nitrogen fertilizer use efficiency in crop production is to use infrared (IR) soil nitrate sensors to analyze soil nitrate and then spatially modulate fertilizer application rates. The most commonly used Fourier transform IR (FTIR) spectrometers are sensitive to vibration and hence not suitable for real-time measurements in agricultural fields when mounted on tractors that experience severe vibrations as they are driven across a field. In this paper, we propose IR sensor designs to address the vibration issues currently limiting the use of IR spectroscopy for precision nitrogen fertilizer management in agriculture. We evaluate the performance of different nitrate sensor configurations based on diamond attenuated total reflection (D-ATR) spectrometers, that do not have moving parts and less sensitive to vibrations than FTIRs. We study sensor configurations based on the following infrared light sources: commercially available tunable quantum cascade lasers (QCLs), thermal sources, superluminescent diodes (SLDs), and superlattice light emitting diodes (SLEDs). Performance of the different sensor systems is evaluated and optimized to achieve maximum signal-to-noise ratio (SNR). We also propose a sensing limit variable, S, to characterize different sensor configurations. The work presented in this manuscript provides design options for agricultural nitrate sensors that can be rugged in the field and collect spectral data at fast rates with high SNR.

A corner smoothing algorithm using Trajectory Pattern Method (TPM) for high-speed and high-quality machining

In micro-line segments machining, transition curves with high harmonic components are more prone to causing vibration issues in the feed drive system, which affects machining efficiency and quality severely. To construct low harmonic trajectories, this paper proposes a corner smoothing algorithm that uses the Trajectory Pattern Method (TPM). The transition curve construction and axial motion scheduling are performed with a specified fundamental frequency in one step, which reduces the smoothing process time and avoids excitation of natural modes of vibration of the system. The synthesized trajectories and axial kinematic profiles are all smooth and only contain the selected fundamental frequency and its first two odd harmonics, which minimizes the number of high harmonic components in the required actuation forces/torques and avoids excitation of the system modes of vibration. Linear programming is used to synthesize the trajectories. The proposed algorithm is shown to achieve near time-optimal trajectories. The provided experimental analysis and comparisons demonstrate that the proposed algorithm achieves smooth axial kinematic profiles with low harmonic contents, which would improve machining efficiency and quality.

Simulation of rubber grommets and correlation with test at low frequencies

Residential air conditioning units include several sources which can lead to vibrational and noise issues. The most important structure-borne source is the compressor which controls the noise and vibration in certain frequency ranges. Compressors are mounted on four relatively stiff rubber grommets which partially isolate the basepan from the compressor motion while also ensuring that the compressor does not move too much. In this work, the grommets are simulated using the finite element method and results are correlated with measurement results with good agreement. It is demonstrated that the hyperelastic properties of the grommets should be increased due to the Payne effect to improve correlation.

New Analytical Solution to Predict the Vertical Impedance of a Large-Diameter Pipe Pile in Soil Considering Wave Propagation in Visco-Elastic Continuum

According to the theories of wave propagation in visco-elastic continuum and Rayleigh-Love rod, a simplified model in axisymmetric conditions for the longitudinal vibration of large-diameter pipe pile (LDPP) in radially heterogeneous surrounding soil with viscous damping is presented. The relevant analytical solution for dynamic impedance at pile head is derived by using complex stiffness transfer method, which is also validated via independent comparisons with previous solutions. Besides, parametric analyses are carried out to reveal both the radial heterogeneity of surrounding soil and the lateral inertia effect of pile shaft on the dynamic impedance of LDPP. The obtained analytical solutions are suitable for the longitudinal vibration issues of floating LDPP in visco-elastic surrounding soil with radial heterogeneity, which can be conveniently degenerated to describe the longitudinal vibration of a floating solid pile in soil with radial heterogeneity as well as a floating LDPP or solid pile in radially homogenous soil.

Dynamic load distribution of planetary gear sets subject to both internal and external excitations

Planetary gearsets are widely used in several mechanical systems and have numerous advantages over counter-shaft gears. Despite this, the complex arrangement of components in a planetary gear system makes them susceptible to noise and vibration issues. An exhaustive and rich literature is available on the topic of planetary gear dynamics, but most of these studies consider only the parametric excitation of gear mesh contacts while assuming an ideal power source. But contrary to this popular assumption, realistic power sources (IC Engine, electric motor, wind turbine, etc.) could be subjected to torque fluctuations based on the operating conditions. The current study presents a theoretical investigation on the load distribution and dynamic behavior of planetary gear sets subjected to both internal and external excitations. A three-dimensional dynamic planetary load distribution model that inherently captures the internal excitation due to the elastic gear mesh contacts is employed in this study. The influence of operating conditions on both system-level response and local gear mesh contact stress distribution are explored. Discussed results not only illustrate the potential of the dynamic model but also reinforce the need for such computationally efficient models for design and analysis purposes.

Study on S-shape instabilities and pressure pulsations in reversible pump-turbines: Conflictive mechanisms behind a varying rotor-stator distance and development of a new guide vane design for improving transient behavior during turbine start-up and in case of load-rejection

Increasing demands towards a more flexible and reliable operation of backbone systems for electrical grid stability has been leading to an upsurge of pumped-storage in the last years. As technological requirements concerning reversible pump-turbines have been undergone substantial transformations with respect to operational stability and noise emission, hydraulic designs are prompted to change according to market needs and requirements. One of the main factors threatening the mechanical structure of components represents the unstable operation in pump and turbine mode. Instabilities are typically accompanied by an intense increase in pressure pulsations that can be a main reason for vibration issues and resonance excitations in reversible pump-turbines. Avoiding instabilities during operation is, therefore, one of the major targets for competitive designs. This paper emphasizes the relevance of a thorough analysis of S-shape instabilities and provides an explanation of their underlying mechanisms based on analytical, numerical and experimental methods. It also addresses conflictive mechanisms behind a varying rotor-stator distance that could occur in terms of operational stability and rotor-stator interaction. The introduction of a new 3D-shaped guide vane design represents a further key outcome of this study. With respect to a varying rotor-stator distance, special attention has been paid to the description of influencing factors for turbine stability and pressure pulsations using three rescaled versions of an existing guide vane design. Series of model tests have been conducted on a test rig at ANDRITZ in Linz, Austria, revealing whether a measure is competitive based on the layout of a 2x330MW variable-speed pump-turbines plant.

Validation of Clicking-type Noise and Vibration in Automotive HVAC System

In this study, the characteristics of clicking-type noise and vibration occurring in the automotive heating, ventilation and air conditional (HVAC) systems are investigated. A lab-scale model of HVAC system is developed, and validation is carried out with a vehicle system. A fixed blower speed of 1 (at an airflow of 2.53 m/s) with alternated air conditional (AC) was implied in this study. Three different sensors namely as tachometer, accelerometer, and microphone were used to measure and prove the existing noise in the HVAC system. The study inferred that the compressor contributed significantly to the total vibration and noise in the HVAC system. Other components such as AC pipe, evaporator, and thermal expansion valve (TXV) also contributed to a slight extent. The clicking noise was observed in the operating frequency range of 200 ~ 300 Hz. This noise and vibration issues are partly influenced by the running conditions of the AC and the effect was significant when the AC was turned on. The validation of the findings in the model shows a good agreement with the results obtained in the vehicle system, whereby the clicking noise and vibration can be observed at a similar frequency range.

Implementation of a novel eccentric dog leg reamer in oil well drilling

A high-quality wellbore is generally considered to have a gauge hole, a smooth wellbore and a wellbore with minimum tortuosity. Therefore, dog leg reamers (DLRs) have been recently proposed and implemented to specifically provide a high-quality wellbore which in turn improves the overall drilling performance. These improvements include smoothening the wellbore from high in place dogleg, lowering drag values, improving the tripping performance, increasing the success ratio of wireline logging tools to reach total depths and enhancing the casing and cement jobs. DLRs are an eccentric string reamers which have been recently designed and optimized using modelling software, and a mathematical model has been deduced to specify the weight and torque distribution between the bit and DLR based on mechanical specific energies at bit and DLR with a model accuracy closely matches the field data. A total of twenty five runs all over the world have been performed to date in hole sizes ranging from 12¼″ to 6″. Directional work has also been performed showing good directional control with this system, and no vibration issues have been reported. The development of this down hole tool has added new capability to the industry in the optimization of hole enlargement applications. The benefit is realized in a reduced number of days required to drill the well and in reduced total well cost. In addition, getting casing into the hole sooner reduces the accompanying risks and can contribute to reducing operational nonproductive time. Several case studies from three fields X, Y and Z from Egypt, Oman and Saudi Arabia, respectively, will be discussed to demonstrate the positive economic impact of deploying DLR in not only the deviated holes but also in vertical wells.

Analysis and Modification of Vibration Issue of Condensate Regulating Valve in a Nuclear Power Plant

Regulating valves are widely used in nuclear power plants. The critical application of regulating valves determines whether the unit and system can operate safely, stably and economically. Taking the analysis and modification of the vibration issue of the conventional island condensate regulating valve in a pressurized water nuclear power plant as an example, this paper expounds the essence of the vibration issue of the regulating valve and provides reference for other power plants to deal with the same issue..

Nonlinear free vibration analysis of a bi-directional functionally graded microbeam on nonlinear elastic foundation using modified couple stress theory

In this research, a size-dependent Euler–Bernoulli beam model is proposed for nonlinear free vibration of a bi-directional functionally graded (BFG) based on a three-layered nonlinear elastic foundation within the framework of the modified couple stress (MCS) theory. The nonlinearity due to the stretching effect of the mid-plane of the BFG microbeam is the source of the nonlinearity of the assumed free vibration issues. The motion governing equations and the corresponding boundary conditions are derived by applying the principle which is associated to Hamilton, under the assumption that the axial inertia is negligible. By applying cubic nonlinearity via Galerkin’s method, the partial nonlinear differential equation can be reduced and turned into an ordinary nonlinear equation of the differential. Then, Galerkin’s variational method is used to gain proximate analytical expressions for the nonlinear frequency of microbeams with boundary conditions of pinned–pinned ends and clamped–clamped ends. The precision of the present solution is evaluated through comparing the nonlinear frequency provided by the proposed approach with the results available from previous studies. The influence of changes in some parameters such as amplitude ratio, the material length scale parameter, material gradient parameters, end supports and stiffness coefficients of the foundation with nonlinearity on the normalized fundamental frequency is studied in detail. As a main result, it is observed that the nonlinear vibration frequencies are higher than their linear counterparts.

Harmonic Forcing from Distortion in a Boundary Layer Ingesting Fan

Integrating a fan with a boundary layer ingestion (BLI) configuration into an aircraft fuselage can improve propulsion efficiency by utilizing the lower momentum airflow in the boundary layer developed due to the surface drag of the fuselage. As a consequence, velocity and total pressure variations distort the flow field entering the fan in both the circumferential and radial directions. Such variations can negatively affect fan aerodynamics and give rise to vibration issues. A fan configuration to benefit from BLI needs to allow for distortion without large penalties. Full annulus unsteady computational fluid dynamics (CFD) with all blades and vanes is used to evaluate the effects on aerodynamic loading and forcing on a fan designed to be mounted on an adapted rear fuselage of a Fokker 100 aircraft, i.e., a tail cone thruster. The distortion pattern used as a boundary condition on the fan is taken from a CFD analysis of the whole aircraft with a simplified model of the installed fan. Detailed simulations of the fan are conducted to better understand the relation between ingested distortion and the harmonic forcing. The results suggest that the normalized harmonic forcing spectrum is primarily correlated to the circumferential variation of inlet total pressure. In this study, the evaluated harmonic forces correlate with the total pressure variation at the inlet for the first 12 engine orders, with some exceptions where the response is very low. At higher harmonics, the distortion content as well as the response become very low, with amplitudes in the order of magnitude lower than the principal disturbances. The change in harmonic forcing resulting from raising the working line, thus, increasing the incidence on the fan rotor, increases the forcing moderately. The distortion transfers through the fan resulting in a non-axisymmetric aerodynamic loading of the outlet guide vane (OGV) that has a clear effect on the aerodynamics. The time average aerodynamic load and also the harmonic forcing of the OGV vary strongly around the circumference. In particular, this is the case for some of the vanes at higher back pressure, most likely due to an interaction with separations starting to occur on vanes operating in unfavorable conditions.

Minimization of Torque Deviation of Cylinder Deactivation Engine through 48V Mild-Hybrid Starter-Generator Control.

Cylinder deactivation (CDA) is an effective technique to improve fuel economy in spark ignition (SI) engines. This technique enhances volumetric efficiency and reduces throttling loss. However, practical implementation is restricted due to torque fluctuations between individual cylinders that cause noise, vibration, and harshness (NVH) issues. To ease torque deviation of the CDA, we propose an in-cylinder pressure based 48V mild-hybrid starter-generator (MHSG) control strategy. The target engine realizes CDA with a specialized engine configuration of separated intake manifolds to independently control the airflow into the cylinders. To handle the complexity of the combined CDA and mild-hybrid system, GT-POWER simulation environment was integrated with a SI turbulent combustion model and 48V MHSG model with actual part specifications. The combustion model is essential for in-cylinder pressure-based control; thus, it is calibrated with actual engine experimental data. The modeling results demonstrate the precise accuracy of the engine cylinder pressures and of quantities such as MAF, MAP, BMEP, and IMEP. The proposed control algorithm also showed remarkable control performance, achieved by instantaneous torque calculation and dynamic compensation, with a 99% maximum reduction rate of engine torque deviation under target CDA operations.

Wide Speed Range Noise and Vibration Mitigation in Switched Reluctance Machines With Stator Pole Bridges

Noise, vibration, and harshness (NVH) issue in switched reluctance machines (SRMs), originating from their doubly salient structure and unique principle of operation, is addressed in this work by proposing a structural design modification in the stator, which increases stiffness to mass ratio of the structure. A 24-slot 16-pole (24s/16p) SRM designed with the aim of automotive application is studied here for the NVH optimization, at different target operating points, using stator pole bridges. Stator pole bridges link consecutive stator teeth to provide additional stiffness to the stator structure. Average torque reduction due to flux shorting in stator pole bridges is tackled by proposing a low-permeability material, with considerable stiffness, which has not yet seen its' application in SRM NVH domain. Multiphysics aspects of stator pole bridge design encompassing electromagnetic radial force, mechanical stress, steady-state temperature distribution, and acoustic noise analyses are presented in this article. Possible manufacturing issues are considered during the design phase and appropriate measures are implemented to facilitate easier construction of two 100-kW prototypes. The final design with stator pole bridges and a baseline design without any stator pole bridges are prototyped, after rigorous multiphysics optimization, for extensive testing. Experimental results verify simulation outputs and report a maximum noise reduction of 12.52 dBA in the stator pole bridge model compared to the baseline SRM.

Research on Abnormal Vibration Issue of Car Bodies of EMU Trains and Its Treatment

Research on Abnormal Vibration Issue of Car Bodies of EMU Trains and Its Treatment

Discussion on the Issues of Rotor-Stator Interference in Pump Turbine

There are serious vibration issues of powerhouse in some pumped storage power plants and it affects severely the safe and stable operation of power plant. In order to settle the issues which have troubled the hydropower technology for several decades, extensive researches have been made. The rotor-stationary interference between rotating runner and stationary guide vanes are one of the researched issues concerned most and has the biggest influences. In this paper, the different opinions are presented. Firstly, the characteristics of pressure variations before and after the guide vanes are discussed and it indicates that, the pressure distribution is not uniform due to the turbulent flow around guide vanes but there is no pressure fluctuation with the dominant frequency of rotational frequency multiplying guide vane number. The interference precondition of pressure waves is there are two pressure waves with the same frequency, thus the new opinion, there is no rotor-stationary interference in the vaneless area, is presented. Secondly, equations of rotor-stationary interference presented by Hiroshi Tanaka and its derivation process are introduced. The equation foundation, physical meanings of parameters and equation dimensions are analyzed, and it is concluded that it is wrong to combine the pressure waves from rotating part and stationary part by multiplying the two pressure waves. And also the following mistakes and unreasonable issues are described. The studied objects are not consistent with that in practical application, the pump condition is not considered, the steady operation is taken as unsteady, and the definition of nodes is mistaken. The correct combination method of rotor-stationary interaction are presented.

Principal component analysis technique for early fault detection

Online condition monitoring and predictive maintenance are crucial for the safe operation of equipments. This paper highlights an unsupervised statistical algorithm based on principal component analysis (PCA) for the predictive maintenance of industrial induced draft (ID) fan. The high vibration issues in ID fans cause the failure of the impellers and, sometimes, the complete breakdown of the fan-motor system. The condition monitoring system of the equipment should be reliable and avoid such a sudden breakdown or faults in the equipment. The proposed technique predicts the fault of the ID fan-motor system, being applicable for other rotating industrial equipment, and also for which the failure data, or historical data, is not available. The major problem in the industry is the monitoring of each and every machinery individually. To avoid this problem, three identical ID fans are monitored together using the proposed technique. This helps in the prediction of the faulty part and also the time left for the complete breakdown of the fan-motor system. This helps in forecasting the maintenance schedule for the equipment before breakdown. From the results, it is observed that the PCA-based technique is a good fit for early fault detection and getting alarmed under fault condition as compared with the conventional methods, including signal trend and fast Fourier transform (FFT) analysis.