Air Spring Research Articles

Studies of properties of the seat suspension system with air spring

This article presents issues related to the study of the seat vibration isolating properties of the working machine. The spring force of the suspension system is realized by means of a pneumatic spring. The mathematical model of the air spring is presented. The results of research presented in the form of power spectral density of the vibration acceleration of the suspension system.

СЕЗОННА ДИНАМІКА ТЕМПЕРАТУРНОГО РЕЖИМУ БІЛООЗЕРСЬКОГО МАСИВУ РІВНЕНСЬКОГО ПРИРОДНОГО ЗАПОВІДНИКА

Purpose. The purpose of the research is to analyze the temperature regime of the Biloozerskyi massive of Rivne Nature Reserve according to the data of the three nearest meteorological stations and to identify its dynamics and patterns. Methods. In the work are used the results of observations of the air temperature of the meteorological stations in Sarny, Lyubeshiv and Manevychi for the period of 2006-2018, which are freely available on the Internet: http://www.pogodaiklimat.ru. Climatological information was analyzed during the research. Mathematical statistics calculations have been applied to determine the decade air temperatures. Techniques for building graphical models (Excel software) for the annual course of air temperature were used. Graphic models set the date of transition of air temperature across thresholds, the length of periods with different temperatures and the length of periods with winter thaw and high summer temperatures. The work is based on statistical, analytical, comparative, graphic and descriptive research methods. Results. The daily, ten-day, monthly, annual, and long-term values of air temperature were analyzed and the date of steady transition of average daily air temperature across thresholds was established. The dynamics of starting and ending dates of different seasons and their duration are investigated. It is established that the duration of different seasons varies and varies significantly over the years. The cold season covers the winter and is characterized by alternation of cold and warm periods: the flow of cold air masses is accompanied by a decrease in air temperature, and the flow of warm air masses is accompanied by short or long thaws. In general, most of the winter is thawed days. The warm season covers spring, summer and autumn. Spring is the least longest and most dynamic period of the year. According to the peculiarities of the development of circulation processes and the rate of change of air temperature, spring and autumn are divided into several periods. The division of the transitional seasons into periods is conditioned by the beginning and the end of the warm period and the periods of vegetation and active vegetation. Summer is the longest period of the year. The summer is characterized by periods with high temperatures, when maximum temperatures are recorded in different grades. Scientific novelty. The research of the temperature regime of the protected area under the conditions of modern climate change is carried out. The dates of beginning and ending of different seasons, their duration and dynamics are established and regularities are formed. The practical significance. The materials of the research can be used for further meteorological research of nature reserves, for the needs of recreation, agrometeorology and in the educational process in the study of regional disciplines.

Fault Diagnosis of High-speed Train Bogie Based on Deep Neural Network

As an important part of high-speed train (HST), the performance of bogie has a direct impact on the safety of train. Real-time monitoring and evaluation of the operating state of bogie are of great significance for the safe operation of the train. The traditional signal processing methods are difficult to analyze the complex vibration signals of bogie which are collected during train operation. Deep Neural Network (DNN) has been widely used in the field of fault diagnosis due to its good performance in feature extraction of complex data. In this paper, DNN is taken as the overall framework. Failure modes include four states: air springs completely fail, anti-yaw dampers completely fail, lateral dampers completely fail and normal operation. In these four states, HST is running at the speed of 200km/h. Using the data collected in one hour of simulation as the input signal of DNN, the diagnostic accuracy of the four working conditions reached 92.5%. Experimental result shows that DNN has a good performance in multi-class fault diagnosis of bogie.

Finite Element Modeling and Static Strength Analysis on Structure Strength of the High-Speed Maglev Bogie

Maglev train with no mechanical contact of the innovative technology, as well as a series of excellent economic and environmental advantages came into being. More and more people pay attention to it, and it has become one of the most promising transportation means in the new century. According to the actual operation of maglev train, a boundary constraint method is proposed in this paper. On the basis of the actual operation of maglev train, a method of boundary constraint is proposed, and the finite element model is established by using HyperMesh software. Afterwards using ANSYS analysis software to analyzed the statics performance of levitation chassis under the four working conditions of maglev vehicle, and static strength of the levitation chassis based on von Mises stress was assessed. In accordance with the results, the parts with high stress are optimized. The result showed that the stress intensity on the back of the air spring mounting base is relatively high. This situation can be improved by changing the radius to 40 mm fillets. The strength of other parts meets the standard requirement and provided the basis for further optimization calculation. The results have laid a foundation for the fatigue strength test of the suspension chassis of high-speed maglev train.

Diskretna Furijeova transformacija i cepstrum analiza pojave vibracija kod kamiona sa poluprikolicom

The aim of this paper is to present a novel technique to analyse the vibration signals during transportation in order to give new information to engineers to better understand these physical events. One of the primary sources of damages during transportation is the permanent vibration transmitted from the platform of semi-trailer to the cargo. The nature of this vibration depends on the road conditions and the features of the vehicle. In this study, a 2-axle-truck with a 3-axle-semi-trailer equipped with air spring suspension was observed to analyse the vibration circumstances. The affecting factors during the transportation were the type of the road (motorway, primary road, secondary road, tertiary road), and different vehicle speed levels. The vibration events were measured and registered on the platform of the trailer, then these values were evaluated in MATLAB environment. The presence of the harmonic vibrational components, the stationarity of the mode shapes, the characteristic frequency narrow-bands of the RMS and PSD values were primarily studied. The applied methods that were used are: discrete Fourier transformation, autocorrelation-, cross-correlation functions and cepstrum analysis.

Study on Vertical Vibration Reduction of High Speed Railway Vehicle by Controlling Internal Pressure of Air Spring using <i>μ</i> - Synthesis

Study on Vertical Vibration Reduction of High Speed Railway Vehicle by Controlling Internal Pressure of Air Spring using <i>μ</i> - Synthesis

Study on FuzzPID control of Shared Chamber Air Suspension for ride comfort

In order to study a new type of air suspension system, the quarter dynamic model of semi-active suspension system is established based on FuzzPID control theory; At the same time, a test bench is established. Through analyzing the data which got in simulation and test, the result show that the performance of air spring parameters has obvious improvement on the acceleration of the vehicle body. Butthe performance on the deflection of the suspension and the dynamic tire load is not the same. By changing the frequency of sinusoidal excitation, the specific performance of ride comfort parameters in different sinusoidal excitation has been studied

A Dual-Observer Design for Nonlinear Suspension System Based on Feedback Linearization

A novel approach to estimate suspension state information and payload condition was developed in this article. A nonlinear quarter car model with air spring and damper was built. After verification of system observability and solvability, a certain coordinate transform was built to transform the nonlinear system into a linear one. Then a Kalman filter observer was applied. A sprung mass observer, which works cooperatively with suspension state information observer, was also designed. Designed dual-observer was verified under typical road profile and sprung mass disturbance. Compared with extended Kalman filter, the dual-observer showed better accuracy and robustness.

High-performance icephobic droplet rebound surface with nanoscale doubly reentrant structure

A bioinspired superomniphobic surface integrating doubly reentrant nanostructures with microcavities is proposed for simultaneously increasing static repellency and dynamic pressure resistance. Novel micro/nano fabrication techniques were developed for fabricating 15 μm doubly reentrant micro-cavities, which is the smallest in the world. Static and dynamic wetting experiments were conducted on pillared, doubly reentrant, cavity and the newly developed surfaces under different surface temperatures. It is found that the newly fabricated surface has the shortest contact time in comparison with other superhydrophobic surfaces, which depressed the ice nucleation on the surface below freezing temperature and, therefore, enhance the ability of icephobic. The experimental results show that the newly developed surface can not only successfully suspend the liquid with extremely low surface tension but also can repel droplets with an impact Weber number as high as 103 under a room temperature condition which is twice higher than previous research. Especially, even at −5 °C surface temperature, the newly developed surface can still repel droplets under Weber number of 335 while conventional cavity surface failed to repel droplets under the same Weber number at surface temperature −2 °C. The mechanism behind the excellent performance of the newly developed surface is analyzed utilizing “air spring effect”, and micro wetting behavior of Laplace Breakthrough on nanostructures. Breakthrough pressure on the novel surface was three times larger than that of the cavity design. It is suggested that this kind nanostructured doubly reentrant cavity surface is promising which has potential applications in anti-icing and biofluid resistance.

The SOFIA Telescope in Full Operation

The SOFIA telescope is a 2.5[Formula: see text]m class Cassegrain telescope with Nasmyth focus. It is the largest telescope ever integrated into an aircraft. The telescope is exposed to the stratospheric environment during the observations and the fact that the telescope’s foundation, which is a Boeing 747 SP, is vibrating and moving in all degrees of freedom (DoF) requires a highly specialized and sophisticated design. Based on the telescope of its predecessor, the Kuiper Airborne Observatory (KAO), the SOFIA telescope design had to evolve to accommodate a telescope 2.5 times the size of KAO. In several hundred successful observation flights, the telescope proved that it performs not only as specified, but is also extremely reliable. Nevertheless, the telescope’s software and hardware are continuously upgraded to optimize its performance without interfering with the observation schedules to reach even more ambitious image size and pointing jitter goals to enable additional science cases. In addition, manufacturing of the line-replaceable units is in process to ensure that the SOFIA telescope can perform without any major interruptions for the envisioned 20 year lifetime. Some of the main features of the SOFIA telescope are its suspension assembly (SUA), which decouples the telescope from SOFIA’s fuselage with air springs and a spherical oil bearing, the extremely stiff Nasmyth tube (NT), which connects cavity and cabin mounted components of the dumbbell design, and the Secondary Mirror Assembly (SMA), which is used for chopping and fast pointing corrections. This paper aims to give an overview of these and all other major telescope subsystems in operation today. In addition, some of the upgrades, either implemented recently or slated for implementation shortly, are introduced.

Crimping Profile Optimization on the Air Spring Using Finite Element Method

Abstract Due to the fact that the requirements of the industry aim to improve the dynamics, the safety and the comfort during the use of the vehicles, it is recommended to use the finite element method for component quality optimization. The purpose of this paper is to provide an overview of the current state of analysis through the finite element method of the crimping process used to assemble air springs produced in the automotive industry. Starting from the prototype of an air spring, the researches are focused on the study of the assembly of the piston with the bellow and the crimping ring through the crimping process. After analysis with the finite element method and static tests, improvements were made to the piston, the results of the tests revealing an improvement as opposed the original variant of the piston.

Marine Vibrator Concepts for Modern Seismic Challenges

Aside from historical issues of mechanical durability and efficiency, the design of marine vibrators (MVs) for towed streamer operations are confronted by several practical challenges to their different possible applications: 1. Alternatives to conventional air gun arrays for flexible and creative acquisition geometries, 2. Low power alternatives to air gun arrays for environmentally sensitive applications, and 3. High power ultra-low frequency sources specific to Full Waveform Inversion (FWI) optimization. One relevant consideration to MV operations is the volume of water that must be displaced per cycle to achieve a desired Sound Pressure Level (SPL); increasing exponentially as the frequency of interest decreases, and becoming significant at frequencies less than about 5 Hz. This is particularly relevant for FWI optimization as the frequencies of interest are in the range of 1-6 Hz. Another consideration is that ultra-low frequency output theoretically benefits from deeper towing enhanced by the well-known free-surface ghost effect, but in practice, deeper towing is confronted by an air spring effect that increases the force required per cycle to generate a desired SPL, and is due to the surrounding hydrostatic pressure at depth. Environmental motivations to develop low power vibrator concepts are driven by regulatory restrictions upon received SPL and Sound Exposure Level (SEL), and we demonstrate how low power MVs can be configured to yield low SPL and SEL metrics without compromising geophysical performance—in contrast to the use of air gun arrays with few elements. MVs enable independence from large compressors and may be more easily deployed in spatially distributed geometries than air gun arrays. We present examples of flextensional MV development verified by numerical modelling, tow tank testing, and field verification; collectively supporting the principles discussed herein.

Changes in Magnitude and Timing of High Flows in Large Rain-Dominated Watersheds in the Cold Region of North-Eastern China

Global warming-induced earlier streamflow timing and changes in flood risk have been widely reported in snow-dominated regions where the land surface hydrology is dominated by winter snow accumulation and spring melt. However, impacts of climate warming on flow regime in the cold regions dominated by monsoonal rain during the warm season have received little attention in the literature. In this study, the responses of magnitude and timing of high flows to climate warming were analyzed by using a paired-year approach based on the hydrometeorological data of two large rain-dominated watersheds in the cold region of north-eastern China in the past approximately four decades (1975–2013). The results indicated that high flow timings of two watersheds both exhibited significant negative trends associated with the significant increasing trends in air temperature and spring rain over the study period. The results from paired-year approach indicated average timings of high flows in the warming years were significantly advanced by 21 and 25 days in Upper Huma River (UHR) and Ganhe River (GR) watersheds, respectively, which was at least partly attributed to the more frequent occurrence of spring snowmelt/rain generated high flows because of climate warming-induced earlier snowmelt and increased spring rain. The average magnitude of high flows decreased by 13.7% and 14.0% in the warming years compared with those in the reference years in the UHR and GR watersheds, respectively. These findings have implications for water resource management in the study region and similar rain-dominated cold regions across the globe.

Resilient Product Development - A New Approach for Controlling Uncertainty

By combining the established development method according to VDI guideline 2206 and the new approach of resilience, resilient product development makes it possible to control uncertainty in the early development phases. Based on the uncertainty that can occur in a classical product development process, such as uncertainty due to (i) the transition from function to building structure, (ii) interaction of modules and (iii) planning uncertainty, we first discuss the limits of existing product development guidelines and introduce the concept of resilience. The basic idea is that a resilient process can control uncertainty through the four resilience functions (i) monitoring, (ii) responding, (iii) learning and (iv) anticipating. We apply this new approach to the product development of the actuators of the active airspring of the TU Darmstadt. The active air spring can be used to increase driving comfort in a vehicle or, for example, to minimize kinetosis during autonomous driving.

Concept of a Resilient Process Chain to Control Uncertainty of a Hydraulic Actuator

Narrow tolerances are commonly used to control uncertainty in the production of technicalcomponents. However, narrow tolerances lead to financial expense and limit flexibility. In this paperthe concept of a resilient process chain is presented. This concept covers the product life cycle phases ofproduction and usage. It is enabled by the digitalization in mechanical engineering and offers access tovariable process windows instead of rigid tolerances. First steps of this concept are then applied to the TU Darmstadt active air spring. The active air spring can be used to increase the driving comfort in avehicle or, for instance, to minimize kinetosis during autonomous driving. The focus hereby is toidentify possible production influences on the behaviour of the components usage. For this purpose, theactuator of the active air spring is specifically manufactured with typical uncertainty of high precisionmachining of the bore and characterized experimentally in a test rig. The results show an influenceof the production on the efficiency of the actuator. The measurements are fundamental to establish aresilient process chain on the active air spring.

A new hybrid mount actuator consisting of air spring and magneto-rheological damper for vibration control of a heavy precision stage

In this study, a hybrid mount actuator featuring both the air sprung and magneto-rheological (MR) damper is devised for the vibration control of precision manufacturing or inspection stages. After briefly describing the structural configuration of the precision stage, both static and dynamic stress analyses are carried out to determine the appropriate size and weight of the hybrid actuator. The air spring is designed considering the static load of the stage and assuming adiabatic process conditions between the actuator and the surrounding space. The MR damper is designed considering the controllable range of the field-dependent damping force based on the Bingham model of MR fluid. Then, four hybrid mount actuators are manufactured followed by the identification of the field-dependent damping force characteristics. Subsequently, four actuators are installed into the precision semi-conductor inspection stage to evaluate the vibration control performances. In this study, a simple but very effective proportional-integral-derivative (PID) controller is designed and empirically realized in order to drive the hybrid mount actuators. It is demonstrated that by activating the proposed hybrid actuators, the unwanted vibrations of the precision stage are substantially reduced in the operating frequency (up to 30 Hz) and fast settling time is achieved in the transient vibration.

Design and control of active vibration isolation system with an active dynamic vibration absorber operating as accelerometer

This paper exhibits the development of a vibration isolation system using an active dynamic vibration absorber (ADVA) as an accelerometer in a low-frequency range; whereas, it operates as a vibration control device in a high-frequency range. The control signal of the ADVA gives an information of the low-frequency acceleration. At the same time, in the active vibration isolation system, an air spring is employed as a low-frequency control device and an inexpensive MEMS-type accelerometer is used to measure the acceleration of the vibration in a high-frequency range. The sensor fusion technique is applied to integrate the output of the MEMS-type accelerometer and the acceleration estimated from the ADVA. The motions of the vibration isolation table and the absorber mass of the ADVA are controlled by PID control. The integrated acceleration by the sensor fusion is transmitted through a low-pass filter to the air spring and through a high-pass filter into the ADVA to attain additional acceleration and velocity feedback to the PID controls. Several experimentations and observations are conducted to measure the transmissibility and compliance. The experimental and simulation results demonstrate that the performance and operative precision of the developed active vibration isolation system are improved by the additional absolute acceleration and velocity feedbacks in terms of compliance as well as transmissibility characteristics.

Optimization of Geometric Parameters of Longitudinal-Connected Air Suspension Based on a Double-Loop Multi-Objective Particle Swarm Optimization Algorithm

Longitudinal-connected air suspension has been proven to have desirable dynamic load-sharing performances for multi-axle heavy vehicles. However, optimization approaches towards the improvement of comprehensive vehicle performance through the geometric design of longitudinal-connected air suspension have been considerably lacking. To address this, based on a 5-degrees-of-freedom nonlinear model of a three-axle semi-trailer with longitudinal air suspension, taking the changes of driving conditions (road roughness, speed, and load) into account, a height control strategy of the longitudinal-connected air suspension was proposed. Then, in view of the height of the air spring under various driving conditions, the support vector regression method was employed to fit the relationship models between the performance indices and the driving conditions, as well as the suspension geometric parameters (inside diameters of the air line and the connectors). Finally, to tackle the uncertainties of driving conditions in the optimization of suspension geometric parameters, a double-loop multi-objective particle swarm optimization algorithm (DL-MOPSO) was put forward based on the interval uncertainty theory. The simulation results indicate that compared with the longitudinal-connected air suspension using two traditional geometric parameters, the optimization ratios for dynamic load sharing coefficient and root-mean-square acceleration at various spring heights are between −1.04% and 20.75%, and 1.44% and 35.1%, respectively. Therefore, based on the signals measured from the suspension height sensors, through integrated control of inflation/deflation valves of air suspensions, as well as the valves’ inside connectors and air lines, the proposed DL-MOPSO algorithm can improve the comprehensive driving performance of the longitudinal-connected three-axle semi-trailer effectively, and in response to changes in driving conditions.

Continuous fatigue damage prediction of a rubber fibre composite structure using multiaxial energy‐based approach

AbstractThis paper details an advanced method of continuous fatigue damage prediction of rubber fibre composite structures. A novel multiaxial energy‐based approach incorporating a mean stress correction is presented and also used to predict the fatigue life of a commercial vehicle air spring. The variations of elastic strain and complementary energies are joined to form the energy damage parameter. Material parameter α is introduced to adapt for any observed mean stress effect as well as being able to reproduce the well‐known Smith‐Watson‐Topper criterion. Since integration to calculate the energies is simplified, the approach can be employed regardless of the complexity of the thermo‐mechanical load history. Several numerical simulations and experimental tests were performed in order to obtain the required stress‐strain tensors and the corresponding fatigue lives, respectively. In simulations, the rubber material of the air spring was simulated as nonlinear elastic. The mean stress parameter α, which controls the influence of the mean stress on fatigue life, was adjusted with respect to those energy life curves obtained experimentally. The predicted fatigue life and the location of failure are in very good agreement with experimental observations.

Determining influential factors for an air spring fatigue life

AbstractThis paper presents an analysis of factors essential to air spring and undercarriage design to determine their influence on air spring fatigue life. Two sets of factors were chosen for the investigation: those relating to the design of the air spring itself (cord angle, diameter difference) and those relating to the design of the undercarriage (lever length, eccentricity, lever eccentricity, inclination). A full factorial experiment, whereby interactions between all the factors are investigated, would demand 729 experiments. Using Taguchi methods, the number of experiments required is dramatically reduced, using only 27 experiments to determine the influence of 6 factors and 3 interactions. Taguchi analysis shows here that factors inherent to air spring design have a much greater influence on fatigue life than those factors inherent to undercarriage design. Interaction between these factors has also revealed that there is no optimal cord angle for all air springs.