Air Bellows Research Articles

Novel Design of Variable Stiffness Pneumatic Flexible Shaft Coupling: Determining the Mathematical-Physical Model and Potential Benefits

Presently, mechanical system vibroisolation is becoming increasingly important. One of the new approaches is semi-active vibroisolation using elements capable of changing a selected mechanical property. These include, among others, pneumatic flexible shaft couplings capable of changing torsional stiffness during operation. The main goal of the article is to examine the potential advantages of a newly patented pneumatic coupling over a current type with the same pneumatic element arrangement. For comparison, parameters determinable from static load characteristics were selected. These parameters are maximum twist angle and torque, average torsional stiffness, and the percentage of torque transmitted by the bellows rubber shell. In all cases, the new coupling had better properties. Since the prototype of the new coupling has not yet been produced, its parameters were determined from its mathematical-physical model. The article contains a full procedure to obtain the static load characteristic of a new coupling type, beginning with the determination of air bellows force/height and volume/height characteristics, then optimum sizes of coupling with regards to the operating range of elements, the dependency of element height on the coupling’s twist angle, and finally the computation of the static load characteristic considering isothermal gas compression. The presented procedure can be applied to any pneumatic bellows where the force/height characteristics of different pressures are given.

Design and Fatigue Life Analysis of Air Suspension Z Type Leaf Springs Used in Heavy Commercial Vehicle

Leaf springs are used as suspension elements in the front and rear axles of vehicles in the automotive industry, especially in heavy commercial vehicles. Leaf springs working all road conditions and under load, it provides damping of the loads transmitted from the wheel and from the ground to the chassis. In this way, it ensures the safety and working comfort in the vehicle. Mechanical suspension systems have been replaced by air suspension systems in new generation vehicles. In air suspension systems; Z type parabolic leaf springs, especially used in heavy commercial vehicles, is a type of leaf spring that provides spring back with air bellows. In this study; Z type parabolic leaf spring design and finite element model of this leaf spring were prepared and form and stress analyzes were performed on the model. By using finite element analysis, high-tension regions of this leaf spring were determined and the appropriate design was selected. Finally, the fatigue life of this spring was obtained in the N-Code program and physical test.

Research and Verification on the Solution of Pressure Fluctuation of the Fan Air Inlet of Civil Aircraft Pneumatic System

The cold side bleeds air of the precooler in the pneumatic system of civil aircraft is usually drawn out from the external bypass of the engine fan and enters the precooler for heat exchange through the fan air inlet, bellows, and fan air valve. When the fan air valve is closed, a closed dead cavity is formed in the fan air inlet. When the airflow passes through the mouth at high speed, the pressure of the fan air inlet into the mouth will oscillate at high frequency, resulting in pressure fluctuation, which will lead to the damage of the bellows and the loss of bleed air function. CFD is proposed in this paper. The method of dynamic simulation combined with limited test parameters successfully located the root causes of the fan air inlet pressure fluctuations, solved the fan air inlet pressure fluctuation phenomenon, and creatively put forward the fan air inlet with hat, fan air inlet with ventilation branch 2 broad categories, and 8 kinds of potential solution design train of thought. CFD simulation method is used to analyze and compare each potential solution in detail. Finally, the solution was selected according to the test results and applied to the aircraft.

Development of Coil Spring Suspension System with Air Bellows

Most of the mass production cars use only coil springs in their suspension systems. We have developed a combination of coil spring suspension with air bellows to reduce the vibrations of the vehicle in mass production cars. Our design proposes and successfully implemented the use of coil springs and the air bellows that will reduce the vehicle’s vibrations and provide some amount of cushioning effect to the passengers and Driver. The coil spring is placed on the top of air bellows only in the rear suspension. And calculated the vibration using I Dynamics app.

Investigation on the ballistic performance of rubber-aluminum (AA7075-T651) laminated plates reinforced with borosilicate glass balls

In this study, the ballistic behavior of protective armor plates (PaP) obtained by curing between high structural strength AA7075-T651 aluminum plates by reinforcing with glass balls of two different rubber mixtures whose damping properties were developed with carbon nanotube and glass bubbles fillers were investigated. A total of six PaPs at 27, 30, and 35 mm heights were prepared using two different matrix damping rubbers. High-strength liner rubber used in air bellows is vulcanized on the front and back surfaces of PaPs. Between the PaPs, Ø15.875 and Ø6.747 mm, borosilicate glass balls were placed in a particular arrangement that coincides with the middle of the matrix rubber and does not have any gaps. Liner rubber cured on the front face has managed to hold the energy by forming a layer like clothing around the bullet cores. Glass balls between PAPs play an essential role in the energy absorption of GB-filled mixtures. In contrast, in MWCNT-filled mixtures, they act as a second damping element. The ballistic performance of PAPs prepared with multiwalled carbon nanotubes was determined to be better than those prepared with Glass Bubbles. Thanks to the superior mechanical properties and high aspect ratio of MWCNTs, the penetration and swelling heights of the matrix damping rubbers prepared to have excellent results compared to glass bubbles. With the increase in the thickness of the PaPs prepared with MWCNTs, the deformation effect of the penetration depth and bulging height created by the bullet on the anterior and posterior surfaces decreased. As the thickness of PaP increased from 27 mm to 35 mm, penetration depth decreased by 38%, and bulging height reduced by 35%. The amount of penetration and swelling increased in PaPs using rubber filled with glass bubbles. As the plate thickness increased, the damping feature decreased and the glass balls were activated, and the bullet was stopped.

The Air Suspension Synthesis for the Single-axle Transport and Technological Module

The present paper contains a theoretical justification of composition (assembly of elements or structure) and design of an air suspension of a single-axle transport and technological module. Application of mathematical simulation proves the feasibility of using an independent suspension with air bellows, but without any antivibration devices (shock absorbers). The feasibility concerns the transport and technological module of the proposed design.

Analytical approach for the design of convoluted air suspension and experimental validation

An improved analytical design to investigate the static stiffness of a convoluted air spring is developed and presented in this article. An air spring provides improved ride comfort by achieving variable volume at various strokes of the suspension. An analytical relation is derived to calculate the volume and the rate of change in the volume of the convoluted bellow with respect to various suspension heights. This expression is used in the equation to calculate the variable stiffness of the bellow. The obtained analytical characteristics are validated with a detailed experiment to test the static vertical stiffness of the air spring. The convoluted air bellow is tested in an Avery spring-testing apparatus for various loads. The bellow is modeled in the ABAQUS environment to perform finite element analysis (FEA) to understand and visualize the deflection of the bellow at various elevated internal pressures and external loads. The proposed air spring model is a fiber-reinforced rubber bellow enclosed between two metal plates. The Mooney–Rivlin material model was used to model the hyperelastic rubber material for FEA. From the results, it is observed that the experimental and analytical results match with a minor error of 7.54%. The derived relations and validations would provide design guidance at the developmental stage of air bellows. These expressions would also play a major role in designing an effective active air suspension system by accurately calculating the required stiffness at various loads.

Basic principles of vehicle suspension control

The paper is devoted to the description of the basic operation principles of control systems over suspension (cushioning) system elements of a vehicle. The basic operation algorithms, as well as the basic principles of change of properties of suspension or cushioning components under different vehicle driving conditions, are presented. The list of sensors and signals, which shall be present in the system to ensure its effective operation, is proposed. The results of experimental analysis of the pneumatic elastic element (air bellows) stiffness and the results of computer simulation of the vehicle behavior when turning are additionally presented.

Development of an Oculopressor to Evaluate the Efficiency of Glaucoma Drainage Devices

Evaluation of the long-term efficiency of MIGS implants is still challenging, due to the lack of standardized clinical studies of stand-alone procedures. Moreover, the different mechanisms of the various glaucoma drainage devices are not adequately considered. The current study focusses on the development of a method for oculopression to evaluate the efficiency of glaucoma drainage devices. Explanted porcine eyes were subjected to pressure or weight load using three oculopressors with different modi operandi. The time-dependent intraocular pressure was measured using an anterior chamber maintainer. The Honan Balloon exerts variable pressure onto the eye via an air bellows, whereas the Taylor oculopressor applies a defined weight loading on the eye. A novel oculopressor with a weight loading of 60 g was developed and manufactured by means of 3-D-printing. The intraocular pressure changes observed during the experiments were similar for all tested oculopression devices, varying only in the absolute pressure values. The Honan Balloon was not suitable for the intended purpose, due to poor standardisation of the applied pressure. Oculopression using a defined weight appeared more suitable. The Taylor oculopressor, however, created intraocular pressure values of up to 203.3 ± 38.4 mmHg, which precludes its use with glaucoma patients. On the basis of these data, the new oculopression device was used in a preliminary trial with healthy human subjects, thereby preparing its use in a clinical trial. Oculopression represents a potentially suitable tool to analyse the efficiency of glaucoma drainage devices. Commercially available oculopression devices are not directly applicable for this task. Difficult handling, high intraocular pressure, and lack of standardisation complicate the use for glaucoma patients. These difficulties were overcome with the newly designed oculopressor that facilitates a well defined increase in intraocular pressure. The device is currently being used in a clinical study to evaluate the efficiency of MIGS implants.

Transient Torsional Analysis of a Belt Conveyor Drive with Pneumatic Flexible Shaft Coupling

Abstract Development and application of pneumatic flexible shaft couplings have been in the center of our department research activities for a long time. These couplings are able to change torsional stiffness by changing pressure in their flexible elements – air bellows. Until now we have dealt with the use of pneumatic flexible shaft couplings for tuning mechanical systems working with periodically alternating load torque at steady state. Some mechanical systems, however, operate with a static load torque at constant speed (e.g. hoists, elevators, etc.), where it is necessary to consider the suitability of shaft coupling in terms of load torque at transient conditions (run-up and braking). Therefore we decided to analyze the use of pneumatic flexible shaft couplings also in this type of mechanical systems on an example of conveyor belt drive.

Interactive monitoring system for visual respiratory biofeedback

Abstract In almost any medical procedure respiratory motion is an issue and may result in image degradation. Most currently available devices and systems, which are intended to reduce respiratory influences do not come into operation however in clinics due to their high cost and complex operation. In our paper we evaluated an interactive breath hold control system that helps flat breathing to subsequently reduce respiratory motion during signal acquisitions or procedure treatments. With that the human subjects are enabled to regulate their own breath by following visual feedback via a specially designed display. That display shows biofeedback information about the respiratory excursion through air pressure deviations measured inside an air bellows belt. The system was assessed quantitatively in a laboratory setup and qualitatively by applications in real clinical procedures. The obtained results are very promising and can be further improved with additional developments to provide an easy to use and relatively inexpensive solution for respiratory motion related imaging problems.

Robust breathing signal extraction from cone beam CT projections based on adaptive and global optimization techniques

We present a study of extracting respiratory signals from cone beam computed tomography (CBCT) projections within the framework of the Amsterdam Shroud (AS) technique. Acquired prior to the radiotherapy treatment, CBCT projections were preprocessed for contrast enhancement by converting the original intensity images to attenuation images with which the AS image was created. An adaptive robust z-normalization filtering was applied to further augment the weak oscillating structures locally. From the enhanced AS image, the respiratory signal was extracted using a two-step optimization approach to effectively reveal the large-scale regularity of the breathing signals. CBCT projection images from five patients acquired with the Varian Onboard Imager on the Clinac iX System Linear Accelerator (Varian Medical Systems, Palo Alto, CA) were employed to assess the proposed technique. Stable breathing signals can be reliably extracted using the proposed algorithm. Reference waveforms obtained using an air bellows belt (Philips Medical Systems, Cleveland, OH) were exported and compared to those with the AS based signals. The average errors for the enrolled patients between the estimated breath per minute (bpm) and the reference waveform bpm can be as low as −0.07 with the standard deviation 1.58. The new algorithm outperformed the original AS technique for all patients by 8.5% to 30%. The impact of gantry rotation on the breathing signal was assessed with data acquired with a Quasar phantom (Modus Medical Devices Inc., London, Canada) and found to be minimal on the signal frequency. The new technique developed in this work will provide a practical solution to rendering markerless breathing signal using the CBCT projections for thoracic and abdominal patients.

TORSIONAL NATURAL FREQUENCY TUNING BY MEANS OF PNEUMATIC FLEXIBLE SHAFT COUPLINGS

This article deals with the use of pneumatic flexible shaft couplings as device for tuning torsional natural frequencies of mechanical systems. These couplings are using air bellows as flexible elements. Their torsional stiffness can be changed by air pressure change, the natural frequencies of whole mechanical system may be adjusted on desired value.

Pressure distributions on prism-shaped buildings in experimentally simulated downburst

Wind loading is one of the most significant factors in civil engineering that influences the structural design considerably. In this paper, a group of manufacturing equipments for downburst simulation based on impinging jet model was developed for investigating the wind loads on structures: including the centrifugal air bellows to generate airflow, a movable platform to realize multiple locations of the building and a freely rotatable turntable to implement alterable building angles. Hundreds of transducers were used to measure the wind action on all surfaces of the building. The pressure coefficients calculated from the observed data were utilized to evaluate the downburst wind load. Pressure distributions on three prism-shaped building models with different placements and angles were investigated to obtain the maximum wind action and mean pressure coefficients. The results showed that the maximum pressure coefficient would reach 1.0 on the top surface if the downburst just broke out over the edifice. Considering that the building was in the developing field of the downburst, the top and the front surfaces would be under high wind pressure and only the back surface would endure wind suction. When the downdraft happens away from the prismatic building, all surfaces, except the front surface, would subject to suction with different degrees. It was also found that the pressure coefficient on the right surface would get its negative peak at first and then go straight up to 0.6 as the angle changed from 0° to 45° and the wind pressure on the front surface would decrease slightly through the whole process. The assertive results provide elemental data for structural wind-resistant design in civil engineering for the downburst-prone areas.

FEM Analysis on a Rear Axle Housing Oil-Leakage Prediction of Four-Wheel Farm Transporters Based on COSMOS

A finite element method (FEM) analysis based on COSMOS study with the aim to find the causes and effects of deformations in the interface between the rear axle housing and the central gear house of the four-wheel farm transporters during operation has been performed. The present design is analyzed with the aid of a mixed-fidelity, or mixed-grain, FE-model. Boundary conditions are defined on the bushings in front of the rear axle and on the air bellows behind the rear axle. The different load scenarios are represented by forces either on the wheels, the central gear or on the rear axle housing. The simulated results showed that with the worst combined load case for the different proposed design solutions suggested that modified design with a thicker flange and a removed stiffener would be significantly better than the present design; the simulated max displacement is about 0.5 mm and satisfied the design requirement. It indicated that the proposed method of finite element analysis was a good and efficient method predicts the oil leakage of rear axle housing, which can increased the knowledge of how oil leakage from the rear axle central gearbox can be controlled by design measures.

Characteristic Analysis and Experimental Evaluation of Fluidic Muscle Cylinder

The fluidic muscle cylinder consists of an air bellows tube, flanges and lock nuts. Its features are softness of material and motion, simplicity of structure, low production cost and high power efficiency. Recently, unlike the pneumatic cylinder, the fluidic muscle cylinder without air leakage, stick slip, friction or seals was developed as a new concept actuator. It has characteristics such as light weight, low price, high response, durable design, long life, high power and high contraction. In this study, we carried out finite element modeling and analysis on the main design variables such as contraction ratio and force, and diameter increment of the fluidic muscle cylinder. On the basis of finite element analysis, the prototype fluidic muscle cylinder was fabricated and tested. Finally, we compared the test results with the finite element analysis.

공기압 근육 구동기의 유한요소 해석 및 성능시험

The pneumatic muscle actuator consists of an air bellows tube with two end-flanges. The air bellows tube is made from rubber layers and flexible sheathing formed from nylon 6 fibers. This structure can be stretched or compressed to convert the radial expansive forces into contractile forces. We performed the finite element analysis and the performance test of pneumatic muscle actuator. Also, the pneumatic muscle actuator was manufactured and tested by home-made tester. The results of FEA was similar with performance test below the maximum error of 42 %.

An Experimental Study of Static and Dynamic Characteristics of a 580mm(22.8in.) Diameter Direct Lubrication Tilting Pad Journal Bearing

Abstract Direct lubrication tilting pad journal bearings (DLTPJ bearings) have rarely been applied to large-scale rotating machinery, such as turbines or generators, whose journal diameters are more than 500mm. In this paper, static and dynamic characteristics of a 580mm(22.8in.) diameter DLTPJ bearing were studied experimentally using a full-scale bearing test rig. In the static test, distribution of metal temperature, oil film pressure, and bearing loss were measured in changing oil flow rate, with mean bearing pressure ranging up to 2.9MPa. The maximum metal temperature of the DLTPJ bearing was compared to that of a conventional flood lubrication bearing, and it was confirmed that the direct lubrication could increase load capacity. In the dynamic test, spring and damping coefficients of oil film were obtained by exciting the bearing casing that was floated by air bellows. These data will be used for analysis and design of steam turbine rotors and their bearing systems. Also, vibration of pads was investigated because metal failure on upper pads due to vibration has been found in some actual machines. In order to generate oil film pressure on the surface of upper pads, a Rayleigh-step was machined there, and it was confirmed that vibration was reduced by the Rayleigh-step.

An Characteristics Analysis of the Fluidic Muscle Cylinder

The fluidic muscle cylinder consists of an air bellows tube, flanges and lock nuts. It's fbatures are softness of materialand motion, simplicity of structure, low production cost and high power efficiency. Recently, unlikely the pneumaticcylinder, the fluidic muscle cylinder without air leakage, stick slip, friction, and seal was developed as a new conceptactuator. In this study, we carried out the finite element modeling and analysis about the main design variables such ascontraction ration and force, diameter increment of fluidic muscle cylinder. On the basis of finite element analysis, theprototype of fluidic muscle cylinder was manufactured and tested. Finally, we compared the results between the test andthe finite element analysis.

Means for attenuating the jarring and vibration of a trucktractor

Stabilization of a truck or tractor for a semi-trailer to eliminate or at least minimize, jarring and vibration of the truck or tractor frame and cab during its operation without load is accomplished by securing a transverse member preferably over a differential housing, to each of the longitudinal truck frame members to bridge the same, and by interposing between the center point on this bridging element, and the top of the differential housing an expandable and contractable air bellows. The truck's pressurized air is connected to this bellows through a manual control valve, preferably in line with an air gauge. A warning indicator may also be connected with the valve to indicate to the truck operator when the air bellows is inflated. Inflation of the air bellows is normally only to be effected when the truck is being operated without load.