Design Of Bellows Research Articles

Study on axial and bending stiffness characteristics of reinforced S-shaped bellows

PurposeReinforced S-shape bellows are novel metal bellows with high pressure resistance. Displacement compensation ability is a key index in the design of metal bellows. Axial-tension-compression deformation and bending deformation are two typical displacement compensation forms. Thus, analysis of axial and bending stiffness is important in structure design.Design/methodology/approachIn this study, theory analytics of axial tension and compression stiffness of reinforced S-shaped bellows structure is derived, and the load-displacement relationship during axial deformation is obtained by correcting the geometric parameters of waveform during axial tension and compression deformations. On the basis of them, the relationships of bending stiffness with axial tensile and compression stiffness under the action of bending loading are constructed, and thus, the theory analytics of bending stiffness is realized for S-shaped bellows.FindingsThis theory analytics is verified by comparing the results of theory analytics with those of numerical simulation for a few typical examples. An investigation on the axial and bending non-linear mechanical behaviors of multi-layer-reinforced S-shaped bellows was also carried out by numerical simulation and experiment, and the experimental results verified the reliability of the analysis method.Originality/valueIt is found that non-linearity behavior occurs greatly during the first loading course of reinforced S-shaped bellows, and the structure is strain-strengthened due to plastic deformation; however, stable stiffness characteristic is exhibited during the succeeding cyclic-loading course.

Development of double-walled bellows for ITER VUV spectrometer systems

This study describes the design and development of double-walled bellows used in ITER's vacuum ultra-violet (VUV) spectrometer systems. These bellows were designed to accommodate port plug displacement resulting from the thermal expansion of the ITER vacuum vessel and other interface loads. The three VUV spectrometer systems under development—the VUV core survey spectrometer, divertor-VUV spectrometer, and VUV-edge spectrometer—are intended to measure the VUV spectrum to monitor impurity species in the plasma. While the ex-vessel components of ITER VUV spectrometers in the interspace and port cell areas, are fixed to the tokamak building, the closure plate of the port plugs, to which the sight pipes are attached, is expected to move by several centimeters both vertically and radially owing to the vacuum vessel's thermal expansion. As a result, the structural integrity of the system requires a flexible structure that can compensate for displacement caused by thermal expansion. To address this need, two types of double-walled bellows were developed, gimbal bellows for lateral displacement and axial bellows for axial displacement. These were developed in accordance with the ASME SEC.VIII code and EJMA standard to meet ITER's safety and vacuum requirements. A double wall is mandated for vacuum bellows due to their vulnerability in terms of vacuum safety. The structural integrity and functionality of the designed bellows were confirmed through functional tests on the manufactured prototype.

A Forward Sensitivity Analysis and Design of U-Shaped Bellows Considering the Radial Compensation Capability Under Internal Pressure

Abstract Bellows serve as integral component within a piping system, which withstand radial displacement loads and internal pressure loads. This study investigates the sensitivity analysis of structure design parameters, such as convolution height, convolution pitch, ply thickness, and convolution number, on radial compensation capability of U-shaped bellows under internal pressure. The influences of the geometric parameters on the strength performance of U-shaped bellows under internal pressure and radial displacement loads are also investigated. A forward design process considering the sensitivity of the structural parameters of the bellows to the bending stiffness and strength is provided. In order to improve the radial displacement compensation ability and to obtain better pressure resistance performance, a mathematical model is established to describe the performance of bellows, and multi-object optimization of bellows is conducted. The results show that the ply thickness has the greatest impact on bending stiffness and strength, and the optimized model has lower stiffness and higher strength compared to the initial model.

Structural assumption on design of rounded rectangular bellows under pressure

Bellows is a flexible component whose volume can be changed by compression or expansion under pressure. Rounded rectangular type bellows is most applied where the internal space of application is strict. The Expansion Joint Manufacturers Association (EJMA) code is world-recognized code for design by formulas method. However, the calculation formulas of stress and deformation in EJMA code does not consider the shape of corner. Therefore, this study proposed a structural assumption of curved beam model to calculate the stress and deformation for rounded rectangular bellows under pressure load by formula calculation method. A parametric study by means of finite element analysis (FEA) was performed to assess the impact of different structural parameters and the applicable scope was investigated. The experimental and numerical results showed that the proposed method can obtain a suitable precision and safe result when ratio of wave height to corner radius is lower than 35 % and the ratio of length of short side length to corner radius is in range 5–20. This study will enrich existing bellows design code and help industry designers to accelerate the optimization iteration in preliminary design stage instead of FEA.

Key parameters that affect the fatigue life of metal bellows-type expansion joint: Another look

Identifying and understanding the key parameters that influence the fatigue life of metal bellows-type expansion joints (metal bellows) enable designers and manufacturers to optimize performance, durability, and reliability and to develop design guidelines and manufacturing processes that could enhance fatigue resistance and ensure their reliable operation in real-world applications. The parameters that influence the fatigue life of metal bellows include the type of material and its properties, operating environment, type of expansion joint, temperature, stress/pressure, manufacturing/forming processes, geometry/construction, proper design, loading history, movement/deflection, vibration, and seismic activity. This comprehensive review covers the fatigue life literature, including concepts, guidelines, standards, assumptions, and the evolution of each parameter. Uniquely classifying parameters through thematic analysis, it guides manufacturers and users in optimizing metal bellows design, assessment, and risk mitigation. The review highlights overlooked insights in a user-friendly manner, prioritizing practical, easily fixable aspects for immediate application in the industrial setting.

Analytical and finite element analyses on axial tensile behaviour of origami bellows with polygonal cross-section

The mechanical behaviour and energy absorption (EA) of origami bellows with polygonal cross-sections under quasi-static axial tension were numerically and theoretically investigated. The finite element analysis results showed that the plateau force increased with the number of polygon sides N, leading to increases in the mean tensile force (Pm) and specific energy absorption (SEA). Two types of basic deployment elements during the tensile process of hexagonal cross-section bellows were defined based on two corresponding deployment modes, namely non-rigid deployment mode I and non-rigid deployment mode II. The bellows exhibiting deployment mode II had approximately 60 % greater SEA and Pm than those exhibiting mode I. Theoretical predictions of the mean tensile force for each mode were derived based on a rigid, perfectly plastic material model and superfolding elements. The predicted results showed reasonable agreement with the finite element analysis results in terms of force – displacement history and Pm. This work reveals the fundamental mechanics involved and can facilitate design of origami bellows with optimized geometric and material parameters for desired EA behaviour.

An Optimized Design of the Soft Bellow Actuator Based on the Box–Behnken Response Surface Design

Soft actuator technology is extensively utilized in robotic manipulation applications. However, several existing designs of soft actuators suffer from drawbacks such as a complex casting process, a multi-air chamber configuration, and insufficient grasping force. In this study, we propose a novel soft bellow design featuring a single air chamber, which simplifies the fabrication process of the actual model. To enhance the performance of the proposed design, we employ the Box–Behnken response surface design to generate a design matrix for implementing different levels of design factors in the finite element model. The FEA response is then subjected to an analysis of variance to identify significant factors and establish a regression model for deformation and stress response prediction. Among the considered responses, the wall thickness emerges as the most influential factor, followed by the divided ratio of radians and the number of bellows. Validation of the optimized soft bellow actuator’s deformation response is performed through comparison with experimental data. Moreover, the soft bellow actuator is capable of exerting a pulling force of 8.16 N when used in conjunction with a simple gripper structure design, enabling effective object manipulation. Additionally, the soft bellow design boasts cost-effectiveness and easy moldability, facilitating seamless integration with different gripper frames for diverse applications. Its simplicity and versatility make it a promising choice for various robotic manipulation tasks.

A finite element based parametric study to assess the suitability of factors used in EJMA for estimation of the meridional stresses in bellows

Bellows are highly engineered components. In general, the design of bellows is carried out as per the standards of the expansion joints manufacturer’s association (EJMA). In EJMA, the basic form of the expressions for estimation of stresses was derived by considering the half convolution of the bellows as a strip beam. Since axisymmetric shell theory leads to a more realistic response of the bellows, EJMA had introduced factors Cp, Cd and Cf for estimation of the meridional stress in the bellows due to pressure and deflection. These factors in EJMA are plotted as a function of two parameters viz. QW and QDT, which are dependent on bellows geometry and ply thickness. This paper discusses the suitability of the above-mentioned factors considering various configurations of the bellows. A finite element based parametric study was carried out and meridional stresses in the bellows were calculated due to pressure and deflection loading for various values of the QW and QDT. Around 36 bellows geometries with different ranges of QW and QDT were analysed numerically. Based on FE analysis, the EJMA factors Cp, Cd and Cf values were estimated and compared with the corresponding values given in EJMA. It was observed that for both shallow (QW approaching 1) and deeper convolutions (QW approaching 0.2), the EJMA solutions lead to an under prediction of membrane stress due to deflection loading and over-prediction of meridional bending stress due to deflection and pressure loading. The effect of geometric nonlinearities on elastically calculated stresses bellows was quantified for various geometries.

The Bellows Designing Method of Divided Working Conditions for Launch Vehicle

The working environment of the pipeline system of the launch vehicle is very complex. Bellows in piping system should endure high temperature, corrosive medium, vibration and other conditions, which require for high reliability. However, due to the restrictions of fixed location, weight reduce requirement, the number and location of bellows are strictly required. There is a great difference for the bellows design method between the launch vehicle and the ground pipeline. In this paper, a bellows designing method for launch vehicle is introduced in detail. The method calculates the compensation amount of bellows under divided working conditions, and checks the fatigue damage coefficient as the main failure judgement basis. It has been proved by practice that the designing method of divided working conditions can solve the design problems of the bellows of launch vehicles effectively.

Mechanism of Mechanical Analysis on Torsional Buckling of U-Shaped Bellows in FLNG Cryogenic Hoses

Floating liquefied natural gas (FLNG) cryogenic hoses can be employed for the transmission of liquefied natural gas (LNG). Usually, U-shaped metal bellows can be applied as the inner lining of FLNG cryogenic hoses. In installation, positioning and other working conditions, torsion is one of the main loads, and torsional buckling instability is a major failure mode of U-shaped metal bellows of FLNG cryogenic hoses. In the current research, the buckling instability of bellows under torsional loads has been investigated in detail, the mechanical mechanism of deformation in torsional buckling mode of bellows has been analyzed and the influence of the structural design parameters on the stability performance has been summarized. It was seen that the axis of the bellows was presented as a spiral line shape during the torsional buckling stage. At the same time, the torsional buckling properties of toroid and spiral bellows were analyzed. The obtained results showed that the torsional buckling stability of the spiral bellows was weaker than that of the toroid bellows and increase of the spiral angle of the spiral bellows intensified this trend. In addition, the post-buckling analysis of U-shaped bellows under torsional loads was carried out by means of experiments and finite element simulation. It was shown that the results obtained from finite element (FE) analysis in this research presented a relatively accurate critical torque value and a consistent buckling instability mode, compared with the experimental results. On this basis, the effects of common defects such as thickness thinning on the torsional stability of bellows were investigated. Considering the geometric defect of thickness thinning, the error of FE analysis was reduced further, and it was found that the defect could significantly decrease the stability of the bellows. The above analysis results could provide a reference for structural design and post-buckling analysis of bellows.

TECHNICAL ISSUE & SERVICE SUPPORT OF 7000 ANESTHESIA VENTILATOR MULTI-VOLTAGE ELECTRONIC

Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classication of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston conguration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modication done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benets provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room.

The optimization of bellows convolutions in bellows pump for better stress distribution

Bellows pump has been widely used for chemical transportation with excellent elasticity and seal ability of the core component bellows. Nevertheless, for repeated alternating compression and expansion, bellows convolutions, that is, the maximum stress points, are at risk of fatigue rupture, which leaves a safety hazard for practical applications. Though a special bellows shape with non-constant wall thickness was proposed as an effective method to strengthen the convolutions, it also affects other characteristics of bellows, such as stiffness, single-stroke displacement, and size, which are equally important for the bellows pump. This article designs a fine-tuned convolution structure on the premise of avoiding its effect on volume properties of bellows. Limiting the value of variables by the stability of bellows stiffness, the structure parameters are optimized with the combination of the finite element method (FEM) and whale optimization algorithm. To ensure the accuracy of the FEM, the stress–strain curve of bellows material and the bellows axial stiffness is measured. Finally, digital image correlation is employed to obtain the strain at convolutions before and after the optimization, and the significant reduction of the strain verifies the effectiveness of the optimization. We believe that this method is valuable for optimizing stress distribution and guiding the design of longer-life pump bellows.

Design and Preliminary Validation of Grasp Assistive Device for an Industrial Environment

Abstract Carpal tunnel syndrome and tendonitis are two common upper extremity cumulative trauma disorders (CTD) related to repetitive and forceful activities in industrial environments. Reducing the muscular force during activities such as the operation of a pistol grip hand tool could result in lower incidence of CTDs. The objective of this research was to reduce the muscular contribution to the grip force using an active grasp assist orthosis system. A novel soft, pneumatic grasp assistive device was designed to augment the users' strength during operation of pistol grip hand tool. The optimized design was fabricated using rapid prototyping. Device effectiveness was quantified by measuring muscle activity and grip force during an in vivo study of a common industrial activity. Nine subjects experienced with power tools employed by an automobile manufacturer installed 18 fasteners using a pistol grip DC tool with and without the grasp assistive device. Surface electromyography (sEMG) was used to measure the activity of four muscles commonly associated with grasping. The grasp assist significantly reduced the mean, combined, normalized muscle activity by 18% (p<0.05). Muscle activation results were contextualized using the revised strain index (RSI). The grasp assistive device trial yielded a significantly lower mean RSI value than the typical trial by 13% (p<0.05). Using an active grasp assist orthosis could reduce the incidence of CTDs in able bodied industrial workers using DC hand tools. The device used a unique design of sinusoidal bellows oriented at 45 deg to the plane of symmetry that yielded higher force output and a lower bending ratio and lower input pressure with acceptable device rigidity and strength.

Design, analysis and experimental qualification of gripper bellows for FBTR control rod drive mechanism

The design of welded-disc bellows is not addressed in any design codes or standards. This paper discusses the design, analysis and experimental validation of the gripper bellows used in the control rod drive mechanisms of fast breeder test reactor. The material of construction of the bellows is 0.125 mm thick AM350-SCT1000. The design fatigue curve of the material at 803 K is not available in open literature. The fatigue curve of the material (Coffin-Manson's relation) was generated from the tensile testing data using four-point correlation method and universal slopes method. Elasto-plastic finite element analysis of the bellows was carried out and fatigue life of the bellows was estimated numerically. A factor of safety of 20 on number of cycles was used as suggested in codes such as ASME section-III and RCC-MR. Experimental qualification of the bellows as per ASME section-III, appendix-II was carried by testing of the bellows in sodium at 803 K.

Experience of various materials for design and manufacture of bellows for nuclear industry

Bellows find wide applications in reactor systems such as in bellows sealed valves as primary leak tight barriers and in piping systems to absorb differential thermal expansions. Reliable operation of bellows is strongly dependent of proper material selection. Various candidates for material of the bellows are austenitic stainless steels (such as SS316, SS304, SS316Ti, SS304L etc.), precipitation hardened stainless steels (such as AM350) and Nickel base alloys such as Inconel-718 and Inconel-625. This paper presents the review of the operating experience, mechanical & neutronic properties of various materials for bellows in nuclear industry. In this work, it is observed that Inconel alloys have superior mechanical properties than austenitic stainless steels but exhibit neutron embrittlement. Hence, use of Inconel bellows is limited to low neutron fluence applications. Precipitation hardened steels such as AM350 have high mechanical strength but lesser ductility. Though AM350 is not suitable for formed bellows, it has excellent operating experience for welded disc bellows in nuclear applications. Austenitic stainless steels have large operating experience. Variants of SS316 are used for high temperature and variants of SS304 are used for temperatures below creep range. ‘L’ grades or stabilized grades are used for resistance to sensitization during welding. Based on the present review work, guidelines for selection of material for bellows are drawn, satisfying the selection criterion. Copyright © 2017 VBRI Press.

Design and Analysis of Metal Expansion bellows under Axial and Transverse loadsusing CATIA V5 R21 software

Bellow is a versatile seal/expansion joint, whose convoluted element is designed to flex even as thermal moves get up in the piping machine. The form of convolutions relies upon the amount of movement the bellows should accommodate or the stress that want to be used to perform this deflection. The convoluted elements have to be strong circumferentially to face up to the contraction and thermal growth of the device. This strength with flexibility is a totally specific design problem that isn’t often positioned in other additives in commercial machine. Bellows are regularly used in the pressure vessels or piping device, aerospace, and so forth. It has the characteristic to soak up ordinary or irregular enlargement and contraction inside the device. Because of the reality bellows require excessive strength in addition to properly flexibility, we determine upon SS 316 L alloy to layout and manufacture a bellow. The design, manufacturing and evaluation of bellows are extra complex than different contemporary tubes. A magazine associated with layout and production of bellows may be noted. On this study, we bear in mind to format, modelling and detailing of bellows under axial and transverse loading the usage of Expansion Joint Manufacturer’s Association(EJMA) code using CATIA V5 R21 software. With the aid of the use of this EJMA code one can anticipate the circumferential membrane strain, meridional membrane pressure, motion in keeping with convolution and fatigue life cycle of the bellows.

Design, analysis and experimental validation of Inconel-625 bellows for critical applications

This paper presents the methodology for design, analysis and experimental validation of Inconel-625 bellows for critical applications. By conducting a series of fatigue tests on Inconel-625 bellows, a curve representing the variation of fatigue life with equivalent stress range was generated. For critical applications such as in nuclear systems, the design of bellows needs to comply with the standard nuclear design codes such as ASME section-III. A design curve was generated by incorporating a factor of safety (FOS) on the experimental data. The experimental stress analysis approach given in ASME section-III/appendix-II was used to obtain the FOS. Design of the Inconel-625 bellows as per the generated fatigue design curve in the present work is simple and can be adopted by bellows suppliers. Also, the proposed method has required compliance with design codes such as ASME section-III. This paper also presents the design by analysis approach for design of nuclear bellows as per ASME section-III/NB).

Stress analysis and design of the waveguide bellows for EAST ECRH system

A 140GHz 4MW long pulse ECRH system for the experimental advanced superconducting tokamak (EAST) has launched in 2011. The waveguide (WG) bellows is an important component in transmission lines, which can absorbs the axial deformation caused by thermal expansion. The flexible WG inside WG bellows dominates bellows performance. In this paper the mechanical analysis including stress analysis and error analysis for flexible WG is presented in detail. A prototype of the WG bellows has been designed and fabricated.

Numerical and experimental estimation of creep-fatigue life of Inconel 625 bellows at 570°C

Methodology for creep-fatigue design of bellows is not covered in design codes such as Expansion Joint Manufacturer's Association (EJMA). This paper presents the analysis and experimental validation of the creep-fatigue design of Inconel-625 bellows at 570°C. Creep-fatigue testing of the bellows was carried out in INSTRON servo electrical fatigue testing system, which is used in general for testing of cylindrical specimens for fatigue loading. Conceptual design and manufacturing of the bellows creep-fatigue testing specimen were carried out. Testing of the bellows was carried out at 3bar pressure and ±10mm movement at 570°C. Finite element analysis of the bellows was carried out using both linear elastic and inelastic approaches. The method suggested in RCC-MR was used for creep-fatigue design of the bellows using LE analysis. Chaboche and Rousselier visco-plastic constitutive model was used for inelastic analysis of the bellows. It was found that the design by analysis was conservative.

Numerical and experimental estimation of creep-fatigue life of Inconel 625 bellows at 570°C

Methodology for creep-fatigue design of bellows is not covered in design codes such as Expansion Joint Manufacturer's Association (EJMA). This paper presents the analysis and experimental validatio...