Vibration Harshness Research Articles

Optimization of Energy Management Strategy for Series Hybrid Electric Vehicle Equipped with Dual-Mode Combustion Engine Under NVH Constraints

Energy management strategies (EMSs) are a core technology in hybrid electric vehicles (HEVs) and have a significant impact on their fuel economy. Optimal solutions for EMSs in the literature usually focus on improving fuel efficiency by operating the engine within a high efficiency range, without considering the drivability, which is affected by noise–vibration–harshness (NVH) constraints at low vehicle speeds. In this paper, a dual-mode combustion engine was implemented in a plug-in series hybrid electric vehiclethat could operate efficiently either at low loads in homogeneous charge compression ignition (HCCI) mode or at high loads in spark ignition (SI) mode. An equivalent consumption minimization strategy (ECMS) combined with a dual-loop particle swarm optimization (PSO) algorithm was designed to solve the optimal control problem. A MATLAB/Simulink simulation was performed using a well-calibrated model of the target HEV to validate the proposed method, and the results showed that it can achieve a reduction in fuel consumption of around 1.3% to 9.9%, depending on the driving cycle. In addition, the operating power of the battery can be significantly reduced, which benefits the health of the battery. Furthermore, the proposed ECMS-PSO is computationally efficient, which guarantees fast offline optimization and enables real-time applications.

Minimal model identification of drum brake squeal via SINDy

The industrial standard in the design and development process of NVH(Noise Vibration Harshness) characteristic of brakes is the application of Finite Element(FE) models with a high number of degrees of freedom in the range of one or several millions. Nevertheless, parallel experimental investigations are still indispensable. On the other hand, minimal models with, due to the inclusion of the self-excitation process, at least two degrees of freedom are well known to be capable to explain qualitatively phenomena as instability of the desired non-vibrating solution or limit cycle oscillation but are in general very inaccurate in predicting the dynamics of a specific real brake. This is because the underlying physical assumptions are already too restrictive and model parameters (especially those referring to nonlinearities) are widely unknown. To overcome this problem, the data-driven modeling approach SINDy(Sparse Identification of Nonlinear Dynamics) is applied to identify appropriate nonlinear functions for a brake squeal minimal model. A problem thereby is the limited database. It turns out that the naive implementation of the method yielding the lowest possible residuum does not necessarily provide physically meaningful models and results, respectively. Instead, a constrained model that incorporates physical knowledge is used to robustly identify parameters and reproduce realistic dynamic behavior. Thereby, several appropriate models with coexisting limit cycles and stationary equilibrium are identified. In particular, it was found that the angular position of the brake drum has a significant influence on the model parameters and therefore must be taken into account in a model with long-term validity.

Insights on non-exhaust emissions: An approach for the chemical characterization of debris generated during braking

Up to 50 % of total PM2.5 emissions are due to particles derived from the automotive sector, and both exhaust and non-exhaust emissions contribute to the pollution of urban areas. Fuel incomplete combustion, or lubricant degradation due to high temperatures during the combustion process, are responsible for exhaust emissions. The non-exhaust ones concern brakes, tires and road surface-wear emissions and road resuspension contribution. The present study aims to provide a methodological approach for a detailed chemical characterization of wear friction products by means of a large array of techniques including spectroscopic tools, thermogravimetric analysis (TGA), chromatography, morphological and elemental analysis. The dust sample derived from the wear of a brake pad material was collected after a Noise & Vibration Harshness (NVH) test under loads similar to a Worldwide Light vehicle Test Procedure (WLTP) braking cycle. The TGA shows that only a small fraction is burned during the test in an oxidizing environment, testifying that the sample consists mostly of metals (more than 90 %). Fe exhibits the highest concentrations (50–80 %, even in the form of oxides). Also other kinds of metals, such as Zn, Al, Mg, Si, S, Sn, Mn, occur in small quantities (about 1–2% each). This finding is confirmed by X-ray diffraction (XRD) analysis. The organic fraction of the debris, investigated by means of Raman spectroscopy, has an evident aromatic character, probably due to oxidative phenomena occurring during the braking cycle test. Noteworthy, the extraction of the dust sample with organic solvents, revealed for the first time the presence of ultrafine particles (UFPs), even in the range of few nanometers (nanoparticles), and polycyclic aromatic hydrocarbons (PAHs), recognized as highly toxic compounds. The simultaneous presence of toxic organic carbon and metals makes of concern the non-exhaust emissions and mandatory a deep insight on their structure and detailed composition.

Multi-directional active vibration control of 1D smart structure inspired by automotive engine mounting system

Recently, active mounting system is being gradually applied to automotive engine mounts for mitigating structure-borne vibration effectively throughout the whole vehicle chassis. This paper presents modeling, analysis, and control of a source structure with an active mounting system in multi-directions, considering position and direction of actual automotive engine mounts. The active mount consists of a piezoelectric stack actuator in series with an elastomeric (rubber) mount. When harmonic excitation forces are employed, secondary force required for each active mount is calculated mathematically and the control signal can reduce the vibration through the destructive interference with input signal. In addition, the horizontal vibration can also be mitigated by setting a variable parameter through the dynamic relation of source structure. A series of simulation results demonstrate that the excitation vibration could be reduced along with this multi-directional (vertical and horizontal) active mounts. Based on this result, it can be expected that noise vibration harshness(NVH) performance can be improved by controlling the vibration of the actual automotive engine structure with rubber mount and secondary force of actuators in both vertical and horizontal directions.

Study on the Influence of Gear Spoke Hole Numbers on Meshing Noise

Gear meshing stiffness is one of the important causes of noise, and the structure optimization of gears, such as spoke hole structures, has been proven to be an effective method to reduce gear meshing noise. In this paper, the meshing dynamics model of spur gears with spoke structures was established, and the quasi-static dynamics simulation of the meshing process was carried out by ANSYS. The results show that more spoke holes lead to less meshing stiffness and less stiffness fluctuation. The BEM (boundary element method) acoustic simulation of spur gears meshing was accomplished by the LMS Virtual.Lab. It shows that meshing stiffness is the dominate factor for noise and less meshing stiffness will result in louder noise. In summary, having fewer spoke holes causes less noise, and the experiment shows the same trend. This has certain reference significance for gear structure design considering NVH (noise vibration harshness) performance.

Sensitivity Analysis of NVH Simulations with Stochastic Input Parameters for a Car Body

<div class="section abstract"><div class="htmlview paragraph">Uncertainties play a major role in vibroacoustics - especially in car body design in the preliminary development because of the overall spread in the production that should be covered with one simulation model. Therefore, we use uncertain input parameters to determine the stochastically distributed admittance of the car body before each part of the car is fully designed. To gain a stochastic result - the stochastically distributed admittance curve - we calculate a deterministic finite element simulation several times with sets of stochastically distributed input parameter values. To reduce simulation time and cost of the car model with many million degrees of freedom we focus on the uncertain parameters that show a significant influence on the admittance curve. It is therefore necessary to be able to accurately estimate for each parameter if its influence on the admittance of the car body plays a major role for the noise vibration harshness simulation. A sensitivity analysis describes the connection between model input and output and the influence of the input on the output. We conduct a two-step global sensitivity analysis which is based on the generalized polynomial chaos expansion to determine the sensitivity of the parameters. Since the less sensitive parameters hardly influence the admittance curve of the car body, we can simulate them as deterministic values. In the further research, we will focus on the most sensitive parameters.</div></div>

Performance Comparison and Analysis of Different Rotor Structures of Vehicle Permanent Magnet Synchronous Flat Wire Motor

In this paper, we designed flat conductor winding permanent magnet synchronous motors with three different rotor structures under certain boundary conditions. The causes of the noise vibration harshness and abnormal noise of permanent magnet synchronous motors are analyzed by using an analytical method. The causes of 24-order and 48-order abnormal noise are given. Based on the comparison of the performance of three rotor structures, the V+1 rotor structure has the least no-load harmonic content, the minimum cogging torque, the maximum output torque, the lowest temperature rise, and the best motor performance, and the V+1 rotor design consumes less permanent magnet material. The simulation is verified by manufacturing a prototype, and the experimental results verify the correctness of the simulation.

Innovative optimization approach to improve noise vibration harshness and lightweight in lower control arm

This paper presents a multi-material design for a lightweight swing arm of a McPherson suspension. Starting from a stamped steel lower control arm (LCA) of a C-segment vehicle a hybrid arm made of a metal core and two Carbon Fiber Reinforced Plastics covers has been hand sketched, Computer Aided Design designed, and Finite Element Method tested. To fully exploit hybridization potential, it has developed a specific methodology which combines the topological optimization of the metal core, and the 3-phase optimization of the composite covers. Also, an innovative viscoelastic material has been included in the laminates to enhance the damping properties of the arm and a Frequency Response Function analysis has been performed. The results in terms of mass, stiffness and stress distribution have been compared with the original stamped steel LCA and with another hybrid LCA design. The final comparison has shown that with the redesign approach it has been possible to reduce the mass to a greater extent without affecting stiffness performance and stress distribution.

Optimal design of noise reduction and shape modification for traction gears of EMU based on improved BP neural network

Under high-speed operating conditions, the noise caused by the vibration of the traction gear transmission system of the Electric Multiple Units (EMU) will distinctly reduce the comfort of passengers. Therefore, analyzing the dynamic characteristics of traction gears and reducing noise from the root cause through comprehensive modification of gear pairs have become a hot research topic. Taking the G301 traction gear transmission system of the CRH380A high-speed EMU as the research object and then using Romax software to establish a parametric modification model of the gear transmission system, through dynamics, modal and Noise Vibration Harshness (NVH) simulation analysis, the law of howling noise of gear pair changes with modification parameters is studied. In the small sample training environment, the noise prediction model is constructed based on the priority weighted Back Propagation (BP) neural network of small noise samples. Taking the minimum noise of high-speed EMU traction gear transmission as the optimization goal, the simulated annealing (SA) algorithm is introduced to solve the model, and the optimal combination of modification parameters and noise data is obtained. The results show that the prediction accuracy of the prediction model is as high as 98.9%, and it can realize noise prediction under any combination of modification parameters. The optimal modification parameter combination obtained by solving the model through the SA algorithm is imported into the traction gear transmission system model. The vibration acceleration level obtained by the simulation is 89.647 dB, and the amplitude of the vibration acceleration level is reduced by 25%. It is verified that this modification optimization design can effectively reduce the gear transmission.

Research on coupled vibrations of driveshaft–rear axle system based on nonlinear hybrid model

The transmission shaft–rear axle system is consisted of universal joint, hypoid gear pair, tapered roller bearing, and half shaft. In this article, as a combination of system dynamics and structure dynamics, a hybrid dynamic model of the bending–torsional–shaft vibration of the driveshaft main reducer was established to study its noise vibration harshness performance. Through dynamic frequency sweep analysis, it is found that the natural frequency of torsional vibration of the system is 53.96 Hz. Getting the natural frequency of the torsional vibration of the systems being 57 Hz by the bench tests and Adams simulations. The correctness of the nonlinear hybrid model of the driveshaft–rear axle system is proved. This research will be beneficial to the design, monitoring, and fault detection of the automobile transmission system.

Electric vehicles diffusion: changing pavement acoustic design?

Abstract Electric vehicles (EVs) are progressively entering into the current noisy urban ecosystem. Even though EVs are apparently quieter than traditional Internal Combustion Engine Vehicles (ICEVs), they have an impact on noise maps and road pavement designers should take this into consideration when designing future low-noise road pavements. Consequently, the main objective of this study is to define what are the most important aspects that road pavement designers should take into account. For this reason, in this paper, the noise emitted by EVs was analysed, considering parameters (e.g., speed and frequency) and comparisons, in order to identify crucial characteristics. Results show that EV noise could call for the improvement of pavement acoustic design due to the Acoustic Vehicle Alerting System (AVAS), high-frequency peaks, and noise vibration harshness.

Experimental Study on the Performance of an SI Engine Fueled by Waste Plastic Pyrolysis Oil–Gasoline Blends

Pyrolyzed waste plastic-based green fuel has been reported to be used as an alternate fuel for diesel engines. Some of the main challenges for implementing this in current automotive technology include evaluating engine performance, emission, noise vibration harshness (NVH), and knock characteristics of this fuel. This study focuses on the engine performance of poly-ethylene terephthalate (PET)-based waste plastic oil (WPO) at varying engine speed conditions. The pyrolysis of mixed-waste plastic was carried out at 300 °C in a fixed-bed reactor. Physicochemical properties such as viscosity, density, calorific value, sulfur, and research octane number (RON) of the plastic fuel and its blends with gasoline were analyzed using ASTM standard test methods. The WPO was blended with two different types of gasoline (RON88 and RON90) at 10, 20, and 30%, and was tested in a spark-ignition (SI) engine. The experimental results showed that different WPO–gasoline blends can be used in an SI engine without any engine modifications, and the performance indicators for different blends were found to be close to that of pure gasoline. The brake power and brake specific fuel consumption (BSFC) were found to be 4.1 kW and 0.309 kg/kW h, respectively. The 10% WPO and 90% RON90 blend produced optimal engine performance at 3500 rpm.

Modeling and NVH Analysis of a Full Engine Dynamic Model with Valve Train System

The valve train system is an important source of vibration and noise in an engine. An in-depth study on the dynamic model of the valve train is helpful in understanding the dynamic characteristics of the valve train and improving the prediction accuracy of vibration and noise. In the traditional approaches of the dynamic analyses, the simulations of the valve train system and the engine are carried out separately. The disadvantages of these uncoupled approaches are that the impact of the cylinder head deformation to the valve train and the support and constraints of the valve train on the cylinder head are not taken into consideration. In this study, a full engine dynamic model coupled with a valve train system is established and a dynamic simulation and noise vibration harshness (NVH) analysis are carried out. In the coupled approach, the valve train system is simulated simultaneously with the engine, and the complexity of the model has been greatly increased. Compared with the uncoupled approach, more detailed dynamic results of the valve train can be presented, and the subsequent predictions of vibration and noise can also be more accurate. The acoustic results show that the difference from the experimental sound power level is reduced from 1.8 dB(A) to 0.9 dB(A) after applying the coupled approach.

Three cylinder TGDI+CVT equipped driveline torsional vibration mode study over driveline component inertia/torsional stiffness

It is already well known how MT equipped driveline torsional modes are distributed and influenced, and that is successfully applied to MT equipped vehicle noise vibration harshness (NVH) problem solving. However, it is still marginal for systematically continuous variable transmission (CVT) equipped driveline torsional modes sensitivity analysis, hence it is very meaningful to dig out the CVT driveline torsional vibration mode distribution and sensitivity to driveline component inertia/torsional stiffness, hence the right driveline component parameters could be pre-defined from the very start of driveline development or tuned during the refine stage. The aim of this paper is to find out CVT equipped driveline torsional vibration mode sensitivity to driveline component inertia/torsional stiffness and rules to tune the driveline torsional vibration modes to mitigate torsional vibration induced NVH issues.

Design, Production, and Verification of a Switched-Reluctance Wheel Hub Drive Train for Battery Electric Vehicles

This contribution deals with the topic of the consistent further development of a wheel hub motor for battery electric vehicles (BEV) based on the principle of an outer rotor switched reluctance machine (SRM). The research work presented in this paper was founded by the ERDF.NRW program, Investment for Growth and Employment and the European Regional Development Fund. The R&D project was named Switched-Reluctance fo(u)r wheel (SR4Wheel). Based on the experience made by first prototype Evolution 0 (EVO 0), developed in the Laboratory for Automation Engineering, Power Electronics and Electrical Drives of the Cologne University of Applied Sciences (CUAS), the test results of EVO 1, as well as the redesign, EVO 2 is presented in this paper. The prototype EVO 0, a first proof of concept leads to several optimizations and lessons learned for the predecessor model EVO 1. The overall target of developing such a gearless outer rotor wheel hub motor is the full integration of the complete machine including its power electronics into the given space between the original friction brake and the rim. Furthermore, due to the additional integration of the power electronics, great opportunities in terms of new vehicle design as well as retrofitting capabilities of already existing vehicle platforms can be achieved. Thereby, further drive train assembly space like the engine compartment is no longer necessary. The SRM does not require magnets for torque production which leads to independence from the changeable commodity prices on the rare earth element markets. This paper presents the developing process, testing, and verification of the innovative drive train concept starting with the final CAD of EVO 1. During the testing and verification process a machine characteristic mapping is performed on a drive train test bench and subsequently the results of a finite element analysis (FEA) are plausibility checked by the test bench results. The process continues with energy conversion test scenarios of the project demonstrator vehicle on a roller test bench focused on noise vibration harshness (NVH) behavior and efficiency. As a conclusion, the gained knowledge by evaluating two EVO 1 prototypes on the rear axle of the test vehicle, and the design for the front axle drive train EVO 2 will be presented. As a major task on the front axle, the limited space due to the large disc brake can be identified and solved.

Low-Frequency Road Noise of Electric Vehicles Based on Measured Road Surface Morphology

In this paper, the noise vibration harshness (NVH) road surface morphology of a test site is scanned to establish a data processing system for the road surface, which can be used to transform the road surface morphology into the road surface excitation required for the road noise simulation analysis. The road surface morphology of the test site is used as the excitation input of the simulation analysis. The results obtained from the simulation analysis are equivalent to the experimental results. Using the actual scanning road surface morphology to simulate the excitation of a vehicle, the noise, as well as the vibration response of the vehicle under the actual road excitation of NVH in the early stage of vehicle development, can be accurately predicted. In the physical prototype stage, the rectification of vehicle road noise and the optimization to provide the needed excitation for the simulation analysis can be done, which will reduce the labor costs of the relevant experiment. Therefore, this method of road noise research has important engineering significance.

Novel Rotor Design of Wound Field Synchronous Motor for Torque Ripple Reduction in ISG System

This paper describes a method to reduce the torque ripple for the Wound Field Synchronous Motor, which does not use a permanent magnet. When a WFSM is used in an Integrated Starter Generator system, it must have a higher power density than other automotive motors in order to satisfy the size constraints and required power. An increase in the power density creates a magnetic flux saturation in the rotor, and this soon becomes the cause of an increase in the torque ripple of motor. An increase in the torque ripple can degrade the Noise Vibration Harshness characteristics of automotive by creating vibration and noise in the engine start-up mode, in which the maximum torque is generated in an ISG system. This paper proposes a method of reducing the torque ripple via a design that uses a flux barrier model in the WFSM’s rotor. The Response Surface Method is used to optimize the flux barrier model, and Finite Element Method is used to to verify the torque ripple reduction.

Comparing Acquisition and Operation Life Cycle Costs of Powder Metallurgy and Conventional Wrought Steel Gear Manufacturing Techniques

The automotive industry has striven for fuel economy and resource efficiency through the deployment of powder metallurgy (PM) manufacturing processes for few decades. However, PM technology for transmission gears is currently only used at a small scale within the automotive industry. This is mainly due to: its shortcomings in material properties and performance gaps for final parts; lack of advancement in pressing technologies (dimensional limitation); lack of data availability (e.g. on materials, load capacity calculations; gear design experimental confirmation); premature failed attempts on PM gears; economics of scale and large initial capital investments. This article reviews the current state of the art of PM gear manufacturing technology highlighting an important gap in technical and financial data availability for PM gear economic analysis. Thus, this study seeks to give some empirical evidence of the economic aspects of PM gear manufacturing. Data availability is still the major challenge with respect to PM cost calculations thus further studies are needed to quantify both the economic and non-economic benefits e.g., sustainability, noise vibration harshness (NVH) of PM adoption.

Detailed Investigations on the Oil Flow in Dip-Lubricated Gearboxes by the Finite Volume CFD Method

Three main concerns are in the focus of the development of geared transmissions nowadays: load carrying capacity, noise–vibration–harshness (NVH) behavior, and efficiency. Increasing the efficiency of modern gearboxes contributes significantly to the reduction of energy consumption and the saving of resources. Gearboxes are frequently designed conservatively with an oversupply of oil to guarantee operational reliability. An oversupply of oil results in an unnecessarily high amount of oil kept in motion and to high no-load losses. Detailed information on the oil distribution in the early design stages of gearboxes would help to optimize the lubrication and to increase the efficiency. Thereby, CFD (computational fluid dynamics) methods offer a very flexible way to visualize the oil flow inside gearboxes with much fewer restrictions compared to measurements with transparent gearbox designs. In this study, a verified CFD model based on the finite volume method is used to investigate the oil flow in a single-stage gearbox. Different oil viscosities and circumferential speeds are considered. The investigations focus on the oil flow. The gear churning loss, as part of the no-load loss, is additionally considered. Experimental validation is obtained by high-speed camera recordings and measurements at the FZG no-load power loss test rig. The results show very strong agreement between simulation and measurement. The results show that CFD simulations can visualize the oil flow behavior with a very high degree of detail.

Free-Piston Linear Generator and the Development of a Solid Lubrication System

The free-piston linear generator (FPLG) is a new electromechanical generator. It converts chemical energy into electrical energy by means of a combustion process, a linear generator, and a gas spring. The FPLG does not use any crankshaft, which is responsible for a lot of losses. Thereby, the technology aims to have better properties than other electromechanical generators: higher efficiency over wide range of operating points, better noise–vibration–harshness package. This publication deals with the explanation of the concept, the characteristics of a FPLG, and one of the challenges in the development. In order to use a port scavenging, the emission issue is the challenge and has to be solved. One possible solution is the use of solid lubricants to substitute motor oil. On this way, the development methodology and one aspect of the development is explained.