Showing papers on "Bellows published in 2020"

An origami-inspired dynamically actuated binary switch

Abstract: Origami, the ancient Japanese art of folding paper to create esthetic sculptures, has recently emerged in the scientific literature as an innovative means to build mechanical structures with tailorable properties. Along those lines, the Kresling origami pattern has been used to design and construct bi-stable bellows with tailorable stiffness. In this work, we exploit the inter-well dynamic behavior of such bellows to develop and characterize a cluster of mechanical binary switches that can be selectively operated using a single input. This input is in the form of a harmonic resonant excitation with a pre-selected frequency and magnitude applied at the base of the switch. Using a phenomenological model of the switch, we study its nonlinear dynamic behavior and approximate its activation frequency bandwidth. We also demonstrate that multiple binary switches of different geometric characteristics can be combined to create a mechanical memory board of multiple bits placed on a single harmonically excited platform.

Parametric design analysis of meridional deflection stresses in metal expansion bellows using gray relational grade

Abstract: Unpredictable and uncertain failure of the bellows needs the attention of the designer toward maximum meridional deflection stresses generated on the U-shaped convolutions. Evaluation of these maximum stress points on the flexible convolutions is multifaceted. This paper deals with the identification of these stresses induced on the bellows convolutions by analytical and experimental methods. Further, the influence of the pivotal design parameters on meridional deflection stresses is studied mainly in two aspects: (1) effect of number of convolutions (N) and pitch diameter (dp) on the meridional deflection stresses and (2) the determination of the optimized design parameters to reduce the stress levels using effective multi-response gray relational grade (GRG) optimization technique. Three bellows of stainless steel material (Grade SS321) are used for the experimentation with a different number of convolutions (N) and pitch diameters (dp). The optimal design parameter setting is found by using GRG analysis through ANOVA and regression mathematical model. The effect of design factors on GRG is analyzed. Besides, using GRG, the regression model enhances to give alternative optimal solutions; in turn, it increases the designer’s choice for the selection of the parametric levels. In the confirmation test, it is seen that the average improvement in GRG for all selected Taguchi orthogonal runs is 23%.

Suction pad unit using a bellows pneumatic actuator as a support mechanism for an end effector of depalletizing robots

Abstract: This paper describes a vacuum suction-type end effector for depalletizing robots in distribution centers. The developed end effector has multiple suction pad units to which a bellows pneumatic actuator is applied as the support mechanism. Load-bearing capacity is improved due to a high-strength wire provided inside the bellows, and the contraction force is improved due to ring members placed inside of the ridges of the rubber bellows. The developed end effector is attached to the arm of a linear motion-type depalletizing robot, and its real-world performance is verified. Verification results confirm that the suction pad units tolerate cardboard box inclination and differences in box height by a simple lowering motion of the arm, and multiple cardboard boxes can be simultaneously unloaded. Moreover, as compared with conventional end effectors, the developed end effector achieves large expansion and contraction in a thin structure. The developed end effector is expected to broaden applications for depalletizing robots.

Design and development of a soft robotic manipulator

Abstract: Soft robotic manipulator, which has advantages of low-weight, flexibility, safe physical interaction, shows a wide prospect in both industry and family application. In this paper, a design of pneumatic soft manipulator, in which the modularization concept is adopted, is presented. The soft manipulator is made up of three pneumatic soft actuators stacked in series. The soft actuator is composed of three inflatable bellows, which are connected and constrained by a series of thin rigid plates. The bellows is stretched by the actuation of pressured gas. The cooperation of the bellows and the rigid constraints effect the soft actuator’s directional move. The stacking connection of several soft actuators can have a large coverage in space. Based on this design, the kinematic models of the soft actuator as well as the soft manipulator are proposed using piecewise constant curvature method. The elastic coefficient of the actuator, which is necessary in the numerical calculation of the proposed model, is determined experimentally. Finally, the prototype and experimental set up of the soft manipulator are designed and developed. The correctness of the proposed model and the end-repeat positioning accuracy are validated experimentally.

An experimental study of bellows-type fluidic soft bending actuators under external water pressure

Abstract: Soft actuators which are composed of low-modulus material have broad application prospects in marine exploration tasks such as biological sampling due to their inherent compliance and adaptability. However, the influence of underwater pressure on the soft actuators remains to be studied. In this work, an experimental study of bellows-type fluidic soft bending actuators fabricated with 3D printing technology is implemented. Deep sea test environment is simulated by adjustable external water pressure. The response of the soft actuator to the input pressure under different external pressure (from 1 atm to 15 MPa) is presented and discussed. The results show that the external water pressure can cause the actuator to bend more in both static and dynamic conditions. Moreover, the increase of the bending angle is positively related with the environment pressure. In general, the feasibility of the soft actuators and the fluid power system for underwater applications are verified. This work can provide experimental reference for the design and control of soft manipulators in marine operation.

Wireless Soft Actuator Based on Liquid-Gas Phase Transition Controlled by Millimeter-Wave Irradiation

Abstract: We propose a wireless soft actuator controlled thermally by millimeter-wave irradiation. The actuator is composed of low boiling point liquid sealed in a soft bellows. By irradiating high-power millimeter-waves, the liquid can be evaporated to generate a strong mechanical force. We characterize the force and work extracted from the bellows as a function of the liquid volume and temperature. We then demonstrate the wireless actuation by irradiating a millimeter-wave on the bellows. We also evaluate its dynamic response by modulating the millimeter-wave. Our approach provides novel usage and design space of soft actuators.

Research on dynamic stiffness of the damping element in bellows-type fluid viscous damper by a simplified model

Abstract: Bellows-type fluid viscous damper can be used to isolate micro vibration in high-precision satellites. The conventional model cannot describe hydraulic stiffness in the medium- and high-frequency domain of this damper. A simplified analytical model needs to be established to analyze hydraulic stiffness of the damping element in this damper.,In this paper, a bellows-type fluid viscous damper is researched, and a simplified model of the damping element in this damper is proposed. Based on this model, the hydraulic stiffness and damping of this damper in the medium- and high-frequency domains are studied, and a comparison is made between the analytical model and a finite element model to verify the analytical model.,The results show that when silicone oil has low viscosity, a model that considers the influence of the initial segment of the damping orifice is more reasonable. In the low-frequency domain, hydraulic stiffness increases quickly with frequency and remains stable when the frequency increases to a certain value; the stable stiffness can reach 106 N/m, which is much higher than the main stiffness. Excessive dynamic stiffness in the high-frequency domain will cause poor vibration isolation performance. Adding compensation bellows to the end of the original isolator may be an effective solution.,A model of the isolator containing the compensation bellows can be derived based on this analytical model. This research can also be used for dynamic modeling and vibration isolation performance analysis of a vibration isolation platform based on this bellows-type fluid viscous damper.,This paper proposed a simplified model of damping element in bellows-type fluid viscous damper, which can be used to analyze hydraulic stiffness in this damper and it was found that this damper showed stable hydraulic stiffness in the medium- and high-frequency domains.

Multi-response design optimisation of convolution stresses of metal bellows using integrated PCA-GRA approach

Abstract: This paper presents the parametric design optimisation of the bellows multi-response convolution stresses using multiple attribute decision making (MADM) technique. Grey Relational Analysis (GRA) i...

Influence of process parameters on thinning ratio and fittability of bellows hydroforming

Abstract: Metal bellows are widely used in piping systems, aerospace, automobile and other industries due to their favourable properties including absorption of expansion, light weight and flexibility. In this paper, the fittability was presented to evaluate the convolution shape precision of the metal bellows. By establishing a finite element model of bellows hydroforming process during the bulging and forming stages, the influence of internal pressure, axial feeding and feeding loading path on the wall thickness variation and fittability of one-convolution bellows was investigated. On that basis, the hydroforming process of multi-convolution bellows was studied, and an experiment was carried out. The results showed that with the increase in internal pressure, the wall thickness of the bellows thinned overall, and the fittability of the root zone of the bellows gradually deteriorated. Some region near the crown zone did not fit the dies well when the internal pressure is small. To improve the fittability of the bellows, the actual axial feeding should be a bit less than the theoretical axial feeding. It is of importance in developing the hydroforming technique and improving the hydroforming quality of bellows.

A Piezoelectric Bellows Round-Window Driver (PBRD) for Middle-Ear Implants

Abstract: We describe a new implantable hearing-aid output device, a piezoelectric bellows round-window driver (PBRD), which is expected to be unaffected by external magnetic fields. The core elements of the PBRD are a piezoelectric element and a gold-coated copper bellows of low stiffness that transmits piezoelectric displacements, without significant attenuation, to the round window (RW). We analyzed structural and mechanical vibrations when confirming bellows transmission efficiency using a finite element model simulation. The PBRD was bench-tested under no-load conditions to determine its frequency response characteristics. We compared the outputs of the PBRD and a commercial floating-mass transducer in situ in human cadaveric temporal bones with responses measured using a laser Doppler vibrometer. PBRD outputs were excellent at both low (0.1–0.7 kHz) and high (2–16 kHz) frequencies; thus, the PBRD has the potential to compensate for conductive and/or sensorineural hearing loss. The frequency-response performance of the PBRD is better than that of conventional RW drivers (actuators or transducers).

Concentric Precurved Bellows: New Bending Actuators for Soft Robots

Abstract: We present a new mechanical bending actuator for soft and continuum robots based on a pair of concentric precurved bellows. Each bellows is rotated axially at its base, allowing independent control of the curvature and bending plane of the concentric bellows pair. Rotation of precurved nested tubes is a well-known principle by which needle-sized concentric-tube robots operate, but the concept has never been scaled up to large diameters due to the trade-offs of increased actuation forces, decreased range of motion, strain limits, and torsional windup. In this letter, we show that using bellows structures instead of tubes allows two important breakthroughs: (1) actuation by rotation of precurved concentric elements can be achieved at much larger scales, and (2) torsional lag (i.e. when the relative tube angle at the tip differs from that at the base) and torsional instability are virtually eliminated due to the high ratio of torsional rigidity to flexural rigidity endowed by the bellows geometry. We discuss the development of two types of 3D printed concentric precurved bellows prototypes (revolute and helical), perform model parameter identification, and experimentally verify a torsionless mechanics model which accounts for direction-dependent rigidities.

Movable Die and Loading Path Design in Tube Hydroforming of Irregular Bellows

Abstract: Manufacturing of irregular bellows with small corner radii and sharp angles is a challenge in tube hydroforming processes. Design of movable dies with an appropriate loading path is an alternative solution to obtain products with required geometrical and dimensional specifications. In this paper, a tube hydroforming process using a novel movable die design is developed to decrease the internal pressure and the maximal thinning ratio in the formed product. Two kinds of feeding types are proposed to make the maximal thinning ratio in the formed bellows as small as possible. A finite element simulation software “DEFORM 3D” is used to analyze the plastic deformation of the tube within the die cavity using the proposed movable die design. Forming windows for sound products using different feeding types are also investigated. Finally, tube hydroforming experiments of irregular bellows are conducted and experimental thickness distributions of the products are compared with the simulation results to validate the analytical modeling with the proposed movable die concept.

Study of Various International Codes and Standards for Flanged and Flued Type Expansion Bellows Design

Abstract: Differential longitudinal thermal expansion between the shell and the tube bundle is a well-known problem in fixed tubesheet heat exchanger design. An expansion bellows provide flexibility for thermal expansion and also function as a pressure retaining part. In this paper, guidelines for design of flanged and flued type (thick wall) expansion bellows available in international codes and standards including ASME VIII-1 and 2, EN-13445, and TEMA and EJMA codes are presented. These codes and standards are compared in terms of information available for thick wall expansion bellows design with regard to condition of applicability of design formula, spring rate determination, parameter to define the initial geometry, stress determination, and fatigue evaluation. Inherent limitations of these codes with respect to expansion bellows design, research gape, and recommendations for effective design are also presented in this paper. Brief history and information provided in various codes and standards related to unreinforced thin wall expansion bellows (bellows expansion joints) are also presented to understand evaluation of expansion bellows design.

Experimental Research on the Detection of Inner Defects of Bellows Based on Ground Penetrating Radar

Abstract: With the development of science and technology, the development of non-destructive testing is more and more mature, and Ground penetrating radar (GPR) has been widely used because of its advantages of fast detection speed, continuous detection process, high resolution, convenient and flexible operation, and low detection cost. However, it is rarely used in the detection of bellows defects. Therefore, the validity and applicability of GPR needs to be verified for detecting grouting defects of bellows in box girders. The box girder slab is simulated by placing bellows in the reinforced concrete slab. Ground penetrating radar (GPR) profiling method is used to detect grouting defects of bellows in reinforced concrete slabs. The two-dimensional and three-dimensional images of ground penetrating radar detection results are analysed. The results show that: Combining the X and Y direction detection images of ground penetrating radar, the specific location of the cavity defects in the bellows can be known. The three-dimensional slice of ground penetrating radar can roughly reflect the size of the internal cavity defect in the bellows. The two-dimensional and three-dimensional images of ground penetrating radar (GPR) can verify each other and complement each other when detecting the internal void defects of reinforced concrete plate corrugated pipe, which is helpful to grasp the internal defects of corrugated pipe in depth. The experiment proves that the ground penetrating radar is effective and promising for the detection of reinforced concrete plate bellows, and can be used for the detection of box girders in bridge engineering.

Development of Pneumatically Driven Hand Capable of Grasping Flexible Objects

Abstract: Industrial robots equipped with various grippers have been introduced in production sites and most of them are electrically driven. Because of the electric actuator’s characteristics, they have no back drivability, making it difficult for them to grasp flexible objects. In this study, therefore, we propose a pneumatically driven robot hand capable of grasping flexible objects by effectively employing the compressibility and back drivability of air.

Study on Mechanical Model of Balance and Stiffness Characteristics of Fiber Reinforced Bellows Type Rubber Hose

Abstract: The mechanical model related to the balance and stiffness characteristics of the bellows type rubber hose under internal pressure was studied. Based on the thin shell theory without considering bending moments and shear force, the equilibrium equation of the bellows type hose was established to obtain the mechanical equilibrium angle under different mechanical environments. Considering the deformation characteristics of the rope structure and the mechanical equilibrium angle of the hose, the deformation of the bellows type rubber hose was divided into two stages, including winding angle deflection and tensile deformation of fiber. Then the constitutive model of anisotropic material was introduced, and the physical equation of the bellows type hose was established to obtain the mechanical model of the balance and stiffness characteristics. According to the mechanical model, the influence of initial fiber winding angle, fiber layer thickness, the radius at the two ends of the hose, the length of hose, the curvature radius and internal pressure of hose on the balance and stiffness characteristics of hose was studied. Eventually, the structure of the hose was designed based on the mechanical model, to optimize the balance and stiffness characteristics of hose. The balance and stiffness characteristics of the optimized hose were verified by experiments. The theoretical and experimental results indicated that, the mechanical model of the balance and stiffness characteristics of the hose can be the theoretical basis for the optimization of structural parameters.

A Model-Based Cascaded Control Concept for the Bionic Motion Robot

Abstract: The applications, modeling and control of continuum manipulators have been strongly developing over the past years. In this contribution, we present a model-based control concept for the Bionic Motion Robot - a quasi-continuum robot with six actuator degrees of freedom driven by compressed air. The model is based on a constant curvature approach for the mechanics also being used for the feed-back control, and a dynamic representation of the bellows pressures. The control law itself consists of a cascaded concept, where an underlying pressure control compensates for the compressibility of the driving fluid. With measurements, the working principle of the proposed methods are illustrated and the effectiveness of the control is demonstrated.

Hydroforming of Toroidal Bellows: Process Simulation and Quality Control.

Abstract: Having higher capacity to undertake pressures and larger compensation ability compared with the U-shape bellows, toroidal or Ω-shape bellows are being more and more widely used in engineering. The wave-shape and wall thickness reduction of bellows are the most important parameters for measuring the hydroforming quality of the bellows. In order to provide references for actual manufacturing, it is valuable to study the factors influencing the hydroforming process and quality of the bellows. In this paper, finite element simulations of the hydroforming process of a monolayer and single-wave toroidal bellows and a two-layer and four-wave toroidal bellows were carried out. Stress and strain distributions before and after unloading were analyzed and the wave height and wall thickness reduction were examined. The numerical results were verified by the actual hydroforming measurements. In addition, ranges of the significant structural or operating factors for producing better bellows were studied and a formula to compute the wall thickness reduction was fitted based on the sufficient numerical results of the hydroforming simulations.

Design and Thermal-Structural Analyses of Ancillary Components for the Optical Steering Mirror (M4) for the ITER ECH Upper Launcher

Abstract: Each of the four ITER Electron Cyclotron Heating Upper Launcher (ECHUL) features eight transmission lines (TLs) that are used to inject 170-GHz microwave power into the plasma at a level of up to 1.31 MW (at the TL diamond window) per line. The millimeter waves are guided through a quasi-optical section consisting of three fixed mirror sets (M1, M2, and M3) and one front steering mirror set (M4), with a steering range of [−7, +7]°. The M4 mirror assembly (upper and lower) will each reflect nearly four Gaussian beams at the correct location in the plasma for suppression of the ${q}\,\,=3$ /2 and ${q}\,\,=2$ /1 NTMs. EPFL-SPC has developed a novel steering mirror assembly (SMA) actuator system, which is based on four pressure-controlled, helium-filled bellows working against six helicoidally machined, preloaded, compressive springs, that rotate around two frictionless flexure pivots. This article will outline the design and thermal–mechanical analysis of such bellows, springs, housing (stator), and the remote-handling compatible support frame.

Experiment Investigate on the Effectiveness of Flexible Pipes to Isolate Sea-Water Pump Generated Vibration

Abstract: Vibration control is important in maintaining the silence of the underwater vehicle. Among the many methods of vibration control, isolation is by far the most efficient approach. However, as one of the major vibration sources in underwater vehicle, the vibration isolation of the sea-water pump has not been well explored. The sea-water pipe is the primary vibration transmit path from the sea-water pump to the housing. In order to realize the vibration isolation of the sea-water pump, the sea-water pipe must have certain flexibility and damping. In this study, scaled model tests were carried out to investigate the isolation effectiveness of flexible pipes in isolated sea-water pump. Specifically, three types of flexible pipes, i.e., double layer metal bellows (DLMB), rubber pipes (RP) and bellows coated rubber (BCR) were designed and tested. Tests were carried out under the operation rotate speeds of the sea-water pump. Our results show that compared with single layer metal bellows (SLMB), the isolation effectiveness of DLMB and BCR were significant and stable in high frequency regions. The optimal pipe can be chosen for different vibration reduction requirements in practical engineering.

Failure Analysis and Salvaging of Bellow-Sealed Sodium Valve

Abstract: Valves with conventional gland packing seals are not suitable in high-temperature sodium systems. Bellow-sealed valves are used in sodium systems in which bellows are used as primary leak tight barrier. Bellows are made up of very thin gauge material, and hence, most of the failures in the bellow-sealed valves are due to failure of the bellows. The cost of the bellows is typically < 20% of overall cost of the valve. This paper discusses the failure analysis of the bellows in a failed bellow-sealed sodium valve and reconditioning of the same by replacing the failed bellow with new and improved bellows. Initially, sticking sodium from the internal surfaces of the valve was cleaned using alcohol. Subsequently, the failed bellows were disassembled from the valve and a detailed failure analysis was carried out. New and improved bellows were designed initially as per Expansion Joint Manufacturer’s Association (EJMA). The geometry arrived as per EJMA was further analyzed using visco-plastic constitutive model to obtain the creep–fatigue life of the bellows. The inputs from the failure analysis were considered while evolving the new and improved design of the bellows. The bellows were tested and qualified at high temperature and installed in the bellow-sealed valve. Integral testing of the valve was carried out using pressure hold testing and helium leak testing. The valve was reconditioned for further use in sodium services.

Prototyping soft origami quad-bellows robots from single-bellows characterization

Abstract: Developing soft robots is an important research area for biomedical applications due to the advantages of soft robots over conventional hard or rigid-bodied robots, such as compliance, biocompatibility, and biomimicry This project aims to design and prototype biomimetic soft origami robots that can navigate in transluminal applications Starting from a single-bellows robot conceptualization, we characterized variations in actuation among prototypes made with materials of different thickness folded into a simple octagonal bellows design The quad-bellows prototype utilized four-bellows units with the inclusion of a scope This prototype achieved successful navigation of an 8 mm borescope placed between 9 mm bellows units through a lumen model The soft robot was able to interact with the environment safely and adaptable for maneuvering through a compliant and torturous environment These traits will allow the soft robot to be applicable in the field of colonoscopy, in which critical areas of improvement include minimizing patient discomfort and achieving skilled navigation of the colonoscope The prototype could also be suitable for future applications that require in-pipe navigations around luminal environments

Drift Reduction of a 4-DOF Measurement System Caused by Unstable Air Refractive Index

Abstract: Laser beam drift greatly influences the accuracy of a four degrees of freedom (4-DOF) measurement system during the detection of machine tool errors, especially for long-distance measurement. A novel method was proposed using bellows to serve as a laser beam shield and air pumps to stabilize the refractive index of air. The inner diameter of the bellows and the control mode of the pumps were optimized through theoretical analysis and simulation. An experimental setup was established to verify the feasibility of the method under the temperature interference condition. The results indicated that the position stability of the laser beam spot can be improved by more than 79% under the action of pumping and inflating. The proposed scheme provides a cost-effective method to reduce the laser beam drift, which can be applied to improve the detection accuracy of a 4-DOF measurement system.

Deformable radio frequency interference shield

Abstract: A deformable shield for mitigating radio frequency interference with a male coaxial connector includes a flexible hollow body having opposed front and rear ends, a concave section of the body proximate the front end, defining an open mouth of the shield configured to receive a female coaxial port, and a bellows section of the body behind the concave section. The bellows section terminates at the rear end with another mouth configured to be fit upon the male coaxial connector.

A Vision-Based Fuzzy Control to Adjust Compression Speed for a Semi-Dieless Bellows-Forming

Abstract: A novel semi-dieless bellows forming process with a local heating technique and axial compression has been initiated for the past years. However, this technique requires a high difficulty in maintaining the output quality due to its sensitivity to the processing conditions. The product quality mainly depends on not only the temperature distribution in the radial and axial direction but also the compression ratio during the semi-dieless bellows process. A finite element model has clarified that a variety of temperature produced by unstable heating or cooling will promote an unstable bellows formation. An adjustment to the compression speed is adequate to compensate for the effect of the variety of temperatures in the bellows formation. Therefore, it is necessary to apply a real-time process for this process to obtain accurate and precise bellows. In this paper, we are proposing a vision-based fuzzy control to control bellows formation. Since semi-dieless bellows forming is an unsteady and complex deformation process, the application of image processing technology is suitable for sensing the process because of the possible wide analysis area afforded by applying the multi-sectional measuring. A vision sensing algorithm is developed to monitor the bellows height from the captured images. An adaptive fuzzy has been verified to control bellows formation from 5 mm stainless steel tube in to bellows profile up to 7 mm bellows height, processing speed up to 0.66 mm/s. The adaptive fuzzy control system is capable of appropriately adjusting the compression speed by evaluating the bellows formation progress. Appropriate compression speed paths guide bellows formation following deformation references. The results show that the bellows shape accuracy between target and experiment increase become 99.5% under given processing ranges.

Method for producing filter bellows

Abstract: The invention relates to a method for producing at least two filter bellows (12) from a bellows (15) having a filter medium (14) which has folding edges (26) and runs in a running direction (80). The filter bellows (12) are produced in parallel in that a cutting path (82, 84) is made in the bellows (15) between end edge surfaces (20a, 20b) and/or side surfaces (36, 38) of the filter bellows (12), in a direction transverse to the folding edges (26) at least in certain regions, such that the filter bellows (12) are formed one beside the other, and symmetrically or point-symmetrically in relation to one another, as seen in the running direction (80) and/or in a direction transverse to the running direction (80). The invention also relates to a filter element (10) having such a filter bellows (12) and to the use of the filter element (10) as a flat air filter, in particular as a flat air filter of an internal combustion engine, and to a filter system having such an interchangeable filter element (12).