Automobile Comfort Research Articles

Double roller negative stiffness mechanism seat suspension optimization design and vibration analysis

To further improve the vibration isolation performance of automobile seat suspension and the riding comfort of automobiles, this paper uses the double roller negative stiffness mechanism (NSM) to calculate the seat suspension with quasi-zero stiffness (QZS) characteristics. The influence of the structural parameters on the QZS characteristics is simulated and analyzed, and the structural parameters are optimized by the orthogonal design method. The effectiveness of the optimization was verified by analyzing the dynamic response of the seat suspension system. The results show that the natural frequency of the vibration isolation system of the seat suspension decreases, the vibration isolation band widens after the introduction of the double roller NSM, and the vibration isolation effect is improved under low-frequency excitation.

Bidirectional Multi-Spectral Vibration Control: Insights from Automotive Engine Mounting Systems in Two-Dimensional Structures with a Damaged Vertical Active Element

Active mounting systems have become more prevalent in recent years to effectively mitigate structure-induced vibration across the automobile chassis. This trend is particularly evident in engine mounts. Considerable research has been dedicated to this approach owing to its potential to enhance the quietness and travel comfort of automobiles. However, prior research has concentrated on a limited spectrum of specific vibrations and noise control or has been restricted to vertical vibration control. This article describes the modeling, analysis, and control of a source structure employing a multidirectional active mounting system designed to closely simulate the position and direction of an actual automobile engine mount. A piezoelectric stack actuator is connected in series to an elastic (rubber) mount to form an active mount. The calculation of the secondary force required for each active mount is achieved through the application of harmonic excitation forces. The control signal can also reduce vibrations caused by destructive interference with the input signal. Furthermore, horizontal oscillations can be mitigated by manipulating the parameters via dynamic interconnections of the source structure. We specifically examined the level of vibration reduction performance in the absence of a vertical active element operation and determined whether the control is feasible. Simulation outcomes demonstrate that this active mount, which operates in both the vertical and horizontal directions, effectively mitigates excitation vibrations. Furthermore, a simulation was conducted to mitigate the vibrations caused by complex signals (AM and FM signals) and noise. This was achieved by monitoring the system response using an adaptive filter NLMS algorithm. Adaptive filter simulations demonstrate that the control efficacy degrades in response to complex signals and noise, although the overall relaxation trend remains unchanged.

Modelling and simulation of suspension system based on topological structure

The traditional approach of longitudinal cutting in suspension system simplification introduces redundant degrees of freedom, leading to increased system errors. This study focused on a seven degrees of freedom (7DOF) car model and constructed a suspension system topology model based on an across-cutting approach. To emulate road surface excitation, the filtered white noise method was employed. MATLAB/Simulink was used to create simulation models for the across-cutting, traditional longitudinal cutting and the whole car structure. Comparative analysis of these three topologies was conducted in both the time and frequency domains. Simulation results demonstrated that the performance curve of the across-cutting simplified suspension system closely matched that of the whole car model, validating the accuracy of the proposed across-cutting topology. Furthermore, when compared to traditional longitudinal cutting, the across-cutting simplification method reduced the natural frequency error of body pitch vibration by 25% and decreased the root mean square error of body acceleration by 27%. The suspension topology based on across-cutting more closely resembled the actual car structure, offering a theoretical foundation for enhancing overall ride comfort in automobiles.

Sealing strip acoustic performance evaluation using WF-VMD based signal enhancement method

The sealing strip is an essential component that rubs against the sunroof supporting rod when the sunroof is opening or closing. The acoustic performance of the sealing strip, such as sound pressure level (SPL) and psychoacoustic annoyance (PA), is important for automobile comfort. However, no automated equipment is available for evaluating the acoustic performance of the sealing strip. Moreover, the weak sealing strip acoustic signal, under the strong noise of the running vehicle or machinery, is difficult to obtain, making it hard to be accurately evaluated. In this paper, a sealing strip acoustic performance detector is developed to simulate the frictional state between the sealing strip and the supporting rod, and a weak sealing strip acoustic signal enhancement method based on Wiener filtering (WF) and variational mode decomposition (VMD) is proposed. The machinery noise’s spectrum is obtained through multitaper spectrum estimation and wavelet thresholding. The sealing strip acoustic signal’s spectrum is estimated by subtracting the machinery noise’s spectrum from the spectrum of the noisy signal. Therefore, an accurate prior signal-to-noise ratio (SNR) estimation required in WF can be obtained, and distortion in the estimated sealing strip acoustic signal is reduced. The estimated acoustic signal is further decomposed into multiple intrinsic mode functions (IMF), based on which an optimized estimated signal is finally constructed, thus realizing the enhancement of weak sealing strip acoustic signal. The effectiveness and applicability of the proposed method are validated by experiments conducted with different sealing strips and compression levels. The average correlation coefficient between the optimized estimated signal and the actual sealing strip acoustic signal is 94.2 %. Three sealing strips’ acoustic performances under various compression levels and friction speeds are accurately evaluated using SPL and PA.

Acoustic Materials in Automobiles

Automobile comfort and design has had an important impact on the world wide economy during the past century and millions of additional vehicles have been sold because of it. Much research work is being done on automobile interior design in comparison to other industrial designs. However, sound level inside the cabins affects the journey of millions of passengers to a great degree and comfort than many other subjects. Low noise level in the cabins is a comfort parameter of high importance. Therefore an attempt has been made in this paper to review the different acoustic materials being used in various automobiles and also their properties which have impact on noise reduction

Investigation regarding the Replacement of Composite Material Leaf Springs with Spring Steel Leaf Springs in Automotive Vehicles: A Review

Leaf Springs finds vast applications in different types of mechanical systems. In spite of lot of research, spring steel leaf springs finds a lot of applications in all types of heavy vehicle. Composite leaf springs represent some application of composite materials in the field of automotive lightweight materials. However, the composite material finds limited applications in the form of mono leaf but for multi leaf in heavy vehicles, its application is rare due to certain issues including delamination. Stiffness and damping properties are the critical parameter of composite leaf springs and are closely related to the handling stability and ride comfort of automobiles. Composite leaf spring with variable parameters may be used in the automobiles to replace the conventional steel leaf springs, mainly due to the high load-bearing capacity. The optimum structural design of composite leaf spring may be calculated using an effective algorithm. The mechanical properties of composite leaf spring is analyzed with experimental or computational approach or both. This paper investigates addresses various issues regarding the replacement of composite material leaf springs with spring steel leaf springs in light and heavy weight automotive vehicles.

Improvement of transient response of automobiles by analysis based on experimental measurements

In recent years, the demand for improvement of ride comfort in automobiles has been increasing, and the demand for quietness in the vehicle interior also increased. In particular, noise in the low-frequency range is one of the most important interior properties and has been the subject of various studies, but there have been few studies on the transient noise generated in a vehicle cabin when a shock input is applied. In this study, we attempt to improve the transient response to reduce the booming noise in the low frequency range caused by the shock input. First, the vibration characteristics of the test vehicle were determined based on data obtained from experimental measurements. As a result, it was found that ceiling deformation, which adversely affects vibration noise, occurs at a specific frequency. Next, based on the experimental measurements, a sensitivity analysis was performed to determine the appropriate mass addition, and mass addition was actually performed on the test vehicle. As a result, the transient response to shock input was improved as the sensitivity analysis predicted.

Teaching practice research of higher vocational course the inspection and repair of automobile comfort and safety system in moral education

This article aims to study how to integrate the educational goal of cultivating talents through moral cultivation with the theoretical and practical teaching of the professional course. In order to realize a new teaching pattern of education, the study combined the professional course teaching with the ideological and political theory course teaching during the research process. Based on the practical teaching cases, this study followed the principle of combining qualitative and quantitative researches. The paper adopted several effective methods such as observation method, literature research method and case analysis method. It sums up the implementation approach of curriculum ideological and political construction strategy of “three integrations, two innovations and one connection”, so as to fulfill the fundamental task of establishing morality and cultivating talents.

A Development of the Self Shape Adjustment Cushion Mechanism for Improving Sitting Comfort

The seat comfort of automobiles is one of the significant factors for determining the driver’s fatigue, emotional experience, and individual space (which captures their individuality, rather than just a means of transportation in modern society). Conventional automobile seats could not provide seating comfort suitable for all drivers, in the form of seats that fit each driver’s body type and the difficulty of meeting individual needs. This study proposes self-shape adjustable (the SSA seats) seats that improve the sitting comfort, safety, and secure the stability, by adjusting shape fit to the driver’s body type. The SSA seats transforms the seat itself, in a way that improves the distribution of contact pressure and reduces sitting fatigue, with the pneumatic system. The transformed seats provide better sitting comfort and safety than the conventional automobile seat, by providing a seat shape suitable for the body shape of all users. It was verified that the SSA seats, proposed in this paper, have a uniform and improved pressure distribution, compared to the conventional seat, in various sitting postures; the contact area between the seat and user is enlarged, and the pressure concentrated on the ischial bone is lowered. In addition, it was proven (through user evaluation) that quantitative evaluation verification was the same as qualitative evaluation results.

Control of a reversible electric machine included in the vehicle suspension

The relevance of the work is due to the constantly growing requirements for the ride comfort of automobiles. The purpose of the study is a rational choice and combination of principles for constructing an algorithm for controlling an electric machine, replacing a hydraulic damper in the design of a vehicle’s suspension system. The study of the behavior of suspension, depending on the applied control algorithms, was carried out by the method of mathematical modeling. In this work, the control of the suspension of one wheel was considered. The angular and longitudinal oscillations of the body were not the subject of this study. In this regard, the applied design scheme is two-mass. The positive and negative aspects of various principles for calculating the target force generated by an electric machine are considered, and an algorithm for calculating the magnetic flux and armature current of an electric machine necessary for the implementation of the target force under various conditions is developed. It is shown that the calculation of the target force should be based on a combination of several principles, since this allows significant expanding of the suspension operating conditions range.

Stiffness Prediction and Analysis of Composite Leaf Springs

Composite leaf springs represent a key application of composite materials in the field of automotive lightweight materials. Stiffness, as a critical parameter of composite leaf springs, is closely related to the handling stability and ride comfort of automobiles. Therefore, this paper proposes an explicit theoretical model, which can consider the anisotropy of composite materials and detailed structure of the leaf spring, to predict the stiffness based on the law of energy conservation. The obtained results are verified against the results of the finite element method and bench test of basalt/epoxy samples. Moreover, the influence of the relevant design parameters on the stiffness is analyzed to provide guidance for the stiffness matching of composite leaf springs. The thickness of the composite leaf spring considerably influences its stiffness. As a key parameter representing the bearing capacity, the strength is closely related to the reliability of leaf springs. Based on the Tasi-Wu strength failure criterion, the influence of the relevant design parameters on the strength ratio of a composite leaf spring is analyzed under the constraint of stiffness. An increase in the width of the composite leaf spring enhances its bearing capacity when the stiffness is required to be within a certain range.

Study on NVH robustness evaluation method of high-mileage automobile based on systematic sampling

In order to study the Noise Vibration and Harshness (NVH) changing characteristics of high-mileage automobile, master the NVH variation regularity of high-mileage automobile, and improve the riding comfort of automobile, based on the principle of statistical analysis and the adaptability of different sampling methods, a robust evaluation method of NVH of high-mileage automobile based on systematic sampling is proposed. In this paper, the basic principle and system implementation steps of this method are described. An example is provided to illustrate the robustness evaluation process of high-mileage automobile vibration acceleration by using the method proposed, and requirements and precautions in using the method are pointed out. The method proposed in the paper can provide a theoretical basis and guidance for quantitative and qualitative evaluation of automobile NVH robustness.

Study on NVH robustness evaluation method of high-mileage automobile based on systematic sampling

In order to study the Noise Vibration and Harshness (NVH) changing characteristics of high-mileage automobile, master the NVH variation regularity of high-mileage automobile, and improve the riding comfort of automobile, based on the principle of statistical analysis and the adaptability of different sampling methods, a robust evaluation method of NVH of high-mileage automobile based on systematic sampling is proposed. In this paper, the basic principle and system implementation steps of this method are described. An example is provided to illustrate the robustness evaluation process of high-mileage automobile vibration acceleration by using the method proposed, and requirements and precautions in using the method are pointed out. The method proposed in the paper can provide a theoretical basis and guidance for quantitative and qualitative evaluation of automobile NVH robustness.

A theoretical model used for determining the stiffness of composite leaf springs with a main spring and an auxiliary spring

The stiffness characteristics of composite leaf springs with a main spring and an auxiliary spring directly affect the handling stability and riding comfort of automobiles and finally determine its application value. In order to achieve precise calculation for the stiffness characteristics of composite leaf springs with a main spring and an auxiliary spring, a theoretical model, which is verified by finite element simulation and related test results, was established by using the mechanics of composite materials and finite difference method. Then, the design parameters that influence the stiffness of the composite leaf spring with a main spring and an auxiliary spring were analyzed to provide a guide for the stiffness matching and optimization of this kind of composite leaf springs. The proposed theoretical model is suitable for parametric modeling and programming, which not only considers the detail features of the spring and the anisotropy of composite material, but also guarantees the speed and the accuracy of the calculation process. This paper also provides a new numerical method for calculating the stiffness of composite structures with arbitrary section shape or complex material composition.

The Influence of Static Factors on Seating Comfort of Motorcycles: An Initial Investigation.

The aim of the current study is to examine the influence of static factors on overall seating comfort in motorcycles and validate the use of static lab-based setups for evaluating seating comfort in motorcycles. Seating comfort in automobiles has two factors, static and dynamic. Research on seating comfort of passenger cars has shown that when the magnitude of vibration reaching the seat is low, comfort is largely determined by static factors. Studies have also validated the use of static lab-based setups for research on seating comfort in passenger cars. Static lab-based setups are easy to develop, provide a controlled environment, and efficient for experimental research. The riding posture, mass distribution, and dynamics of a motorcycle differ from a passenger car and warrant further investigation to extend the results from the research on passenger cars. The study compares subjective rating of seating comfort and objective measurement of seat interface pressure in two test conditions: a static lab-based setup and actual driving on a flat test track where the magnitude of vibration reaching the seat is low. The vibration at the seat is measured for the driving trial. A group of 18 male volunteers from TVS Motor Company participated in the study, and two motorcycles from the economy/executive segment of India are used in the study. The subjective ratings are analyzed statistically using analysis of variance (ANOVA) and Pearson's correlation. The vibration data are analyzed as per ISO 2631-1 to calculate the frequency-weighted acceleration, aw. The results show that there is no significant difference between the two test conditions either in the objective measurements or in the subjective rating of comfort. There is also a statistically significant correlation between the subjective ratings of seating comfort in static lab-based setup and actual riding (r = .77, p < .01, n = 36). The mean aw at the seat while driving in the test track used in this study is 0.2 m/s2. Static factors have a significant influence on seating comfort in motorcycles. When the vibration reaching the seat is low (aw ≤ 0.2 m/s2), seating comfort is largely determined by the static factors. The use of static lab-based setups for evaluating static factors of seating comfort in motorcycles is validated. The results of this study enable further research to understand the human criterion for seating comfort in motorcycles using static lab-based setups which are easier to develop and provide controlled environment that is essential for any research.

Research on Influence Mechanism of Tire Pressure on the Ride Comfort of Automobile

Factors that affect vehicle vibration and noise are design, material, tire pressure, structure, road condition, etc. the influence of tire inflation pressure on vibration and noise of tire and whole automobile is studied. Through the experimental data and theoretical analysis show that the tire stiffness and the natural frequency increased with tire inflation pressure increase; changes of suspension and automobile vibration characteristics with the tire inflation pressure change; tire pressure has different influence on the pump noise; tire pressure has little effect on the tire noise level; tire damping performance decreased with the increase of tire pressure, increased automobile vibration feeling, reduce automobile ride comfort. Therefore, reasonable tire inflation pressure can not only reduce and improve automobile vibration and noise, but also improve automobile ride comfort.

Review on vibration quality improvement of a passenger seat

Seats are one of the most significant components of vehicles. Customer’s expectations for the comfort in vehicle seats rise continuously. Designing of automobile seats has always been a challenge for engineers as design parameters for automobile seats are complex. When it comes to the design of automobile seats, three design objectives, namely comfort, safety and health need to be fulfilled simultaneously. Vibration analysis plays a major role in engineering including the area of design for automobile comfort. Human structure, as a mechanical system, is immensely complex and the mechanical properties of human body readily undergo change. In addition, the vibration can initiate the development of pressure ulcer and other long-term diseases. Comfort measurement is challenging because of such factors as user subjectivity, seat geometry, occupant anthropometry and amount of time spent sitting. The purpose of this study is to identify the most significant parameters that make vibration in the vehicle seat which reduce passenger comfort and to identify the design parameters that can impact on appropriate seat design. Suspension systems, seat cushion and sitting postures are some of the vital parameters that have huge impacts on comfort analysis. This review could help in design of seat cushions with appropriate material properties and in analysing the comfort levels of human body to reduce the vibration transmissibility at the critical frequency bands.

Numerical analysis on aerodynamic performance of different automobile body shape

Aerodynamic characteristics directly affect the dynamics, economy, control stability and ride comfort of automobiles. In this paper, the FLUENT software is applied to analyse the automobile aerodynamic performance considering the influence of different tire width and ground clearance in order to enhance the automobile fuel economy so as to provide reference for the design of the automobile body shape.

Investigation on Influence of Geometry on Performance of a Cavity-less Pressure Sensor

In recent years the automobile comfort and safety greatly improved by incorporation of specialized sensors. These sensors monitor the satisfactory working of different parts of an automobile by providing timely information to the driver. Tyre inflation pressure sensor is one of the important devices whose satisfactory working will improve tyre life as well fuel economy. The present work is focussed on modeling of a Cavity-Less pressure sensor for sensing inflation tyre pressure. Dielectric soft material for the sensor is taken as Silicone rubber. The sensor is modeled using finite element technique. The influence of width to thickness ratio of dielectric material for square geometry is studied. It is observed that change in capacitance increases with the applied pressure. The highest sensitivity of 4.79 fF/kPa is obtained for a sensor with width to thickness ratio of 100.

Research on microstructure and properties of automobile body steel and its development trend

With the promotion of green sustainable economic development, the study on automobile lightweight to reduce greenhouse gas emissions is one of the important means for reducing air pollution. At present, the most valuable research direction is how to reduce the car’s self-weight in the performance of the safety and comfort of automobiles, so as to achieve the goal of energy saving and emission reduction. Based on the brief introduction of the microstructure and properties of automobile steel from the first generation to the third generation, the paper analyzes the future research and development trend of automobile steel. Compared with the first and second generation automobile steel, the third generation automobile steel has better strength and economic performance, can better meet the current needs of people and is more suitable for a large number of production and application. At present, with the continuous progress of the process (such as hot forming process), the third generation automobile steel has great development research value in reducing the weight of automobile.