Showing papers on "Bellows published in 2022"

Delicate memory structure of origami switches

Abstract: While memory effects emerge from systems of wildly varying lengthscales and timescales, the reduction of a complex system with many interacting elements into one simple enough to be understood without also losing the complex behavior continues to be a challenge. Here, we investigate how bistable cylindrical origamis provide such a reduction via tunably interactive memory behaviors. We base our investigation on folded sheets of Kresling patterns that function as two-state memory units. By linking several units, each with a selected activation energy, we construct a one-dimensional material that exhibits return-point memory. After a comprehensive experimental analysis of the relation between the geometry of the pattern and the mechanical response for a single bit, we study the memory of a bellows composed of four bits arranged in series. Since these bits are decoupled, the system reduces to the Preisach model, and we can drive the bellows to any of its 16 allowable states by following a prescribed sequence of compression and extension. We show how to reasonably discriminate between states by measuring the system's total height and stiffness near equilibrium. Furthermore, we establish the existence of geometrically disallowed defective stable configurations that expand the configuration space to 64 states with a more complex transition pattern. Using empirical considerations of the mechanics, we analyze the hierarchical structure of the corresponding diagram, which includes Garden of Eden states and subgraphs. We highlight two irreversible transformations, namely shifting and erasure of defects, leading to memory behaviors reminiscent of those observed with more complex glassy systems.3 MoreReceived 29 June 2021Revised 4 November 2021Accepted 21 January 2022DOI:https://doi.org/10.1103/PhysRevResearch.4.013128Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFunctional materialsMechanical metamaterialsOrigami & KirigamiShape memory effectTechniquesGeometryGraph theoryMechanical testingCondensed Matter, Materials & Applied PhysicsGeneral PhysicsPolymers & Soft MatterStatistical Physics

Design, fabrication, and characterization of dielectric elastomer actuator enabled cuff compression device

Abstract: Wearable dielectric elastomer actuators (DEAs) have been greatly considered for development of biomedical devices. In particular, a DEA cuff device has the capability of minimizing venous system disorders that occur in the lower limbs such as orthostatic intolerance (OI) and deep-vein thrombosis which are a result of substantial blood pooling. Recent works have shown that DEAs could regulate and even enhance venous blood flow return. This wearable technology orders a new light, low-cost, compliant, and simple countermeasure which could be safely and comfortably worn that includes mobility. In addition, it may supplement or even provide an alternative solution to exercise and medication. This work presents the design, model, and characterization of the DEA cuff device design that is capable of generating significant pressure change. A rolled DEA strip was actuated over a simulated muscle-artery apparatus using a periodic voltage input, and fluid pressure change was directly observed. A force sensitive resistor sensor was used to achieve a more precise pressure measurement. Performance analysis was conducted through frequency response analysis. The results provide a framework for implementing dynamic modelling and control to allow various forms of actuation input.

Design, Computational Modelling and Experimental Characterization of Bistable Hybrid Soft Actuators for a Controllable-Compliance Joint of an Exoskeleton Rehabilitation Robot

Abstract: This paper presents the mechatronic design of a biorobotic joint with controllable compliance, for innovative applications of “assist-as-needed” robotic rehabilitation mediated by a wearable and soft exoskeleton. The soft actuation of robotic exoskeletons can provide some relevant advantages in terms of controllable compliance, adaptivity and intrinsic safety of the control performance of the robot during the interaction with the patient. Pneumatic Artificial Muscles (PAMs), which belong to the class of soft actuators, can be arranged in antagonistic configuration in order to exploit the variability of their mechanical compliance for the optimal adaptation of the robot performance during therapy. The coupling of an antagonistic configuration of PAMs with a regulation mechanism can achieve, under a customized control strategy, the optimal tuning of the mechanical compliance of the exoskeleton joint over full ranges of actuation pressure and joint rotation. This work presents a novel mechanism, for the optimal regulation of the compliance of the biorobotic joint, which is characterized by a soft and hybrid actuation exploiting the storage/release of the elastic energy by bistable Von Mises elastic trusses. The contribution from elastic Von Mises structure can improve both the mechanical response of the soft pneumatic bellows actuating the regulation mechanism and the intrinsic safety of the whole mechanism. A comprehensive set of design steps is presented here, including the optimization of the geometry of the pneumatic bellows, the fabrication process through 3D printing of the mechanism and some experimental tests devoted to the characterization of the hybrid soft actuation. The experimental tests replicated the main operating conditions of the regulation mechanism; the advantages arising from the bistable hybrid soft actuation were evaluated in terms of static and dynamic performance, e.g., pressure and force transition thresholds of the bistable mechanism, linearity and hysteresis of the actuator response.

A Novel Inchworm-Inspired Soft Robotic Colonoscope Based on a Rubber Bellows

Abstract: Colorectal cancer is a serious threat to human health. Colonoscopy is the most effective procedure for the inspection of colorectal cancer. However, traditional colonoscopy may cause pain, which can lead to the patient’s fear of colonoscopy. The use of active-motion colonoscopy robots is expected to replace traditional colonoscopy procedures for colorectal cancer screening, without causing pain to patients. This paper proposes an inchworm-like soft colonoscopy robot based on a rubber spring. The motion mechanism of the robot consists of two anchoring units and an elongation unit. The elongation unit of the robot is driven by 3 cables during contraction and by its inherent elasticity during extension. The balloon is selected as the anchoring mechanism of the robot. It has soft contact with the colon and will not damage the colon wall, which means no discomfort is caused. The elastic force test of the rubber spring shows that the elongation unit of the robot has sufficient restorative force to drive the robot to move forward and backward. The influence of the balloon’s expansion size on the dexterity of the robot head is analyzed, and the functions of the balloons are expounded. The balloon can not only assist the robot in its locomotion but also assist the robot to perform a better inspection. The robot can move successfully in a horizontal, straight, and inclined isolated pig colon, showing great clinical application potential.

Experimental Study on the Closed-Loop Control of a Soft Ring-Shaped Actuator for Gastric Simulator<i />

Abstract: In-vitro gastric simulators are soft robotic systems that reproduce the change of the food or drug by emulating the stomach's motility functions. The control of gastric simulators traditionally lies in tuning the actuators via open-loop approaches. However, the lack of precise position control, external disturbances, sensitivity to model uncertainties, and continues retuning are solid motivations for employing closed-loop methods to control gastric simulators. A bellows-driven viscoelastic soft ring-shaped pneumatic actuator (RiSPA), including five spring-like bellows, was developed for stomach simulators’ primary actuation system. This article studies the implementation of closed-loop methods equipped with the online feedback system on the RiSPA for the first time. All technical aspects for implementing the closed-loop control and the sensor-actuator integration are discussed in detail. A model-based closed-loop method has been implemented and compared with a classic model-free method to show the closed-loop system's ability to reject model uncertainties. The experimental results in both the tracking trajectory and the regulation performances are thoroughly compared to the open-loop approach, where the superiority of closed-loop techniques is demonstrated. A mechanical setup is designed to show the ability of the closed-loop approach in dealing with the disturbances and external loads as well.

Development of a near-5-Kelvin, cryogen-free, pulse-tube refrigerator-based scanning probe microscope.

Abstract: We report the design and performance of a cryogen-free, pulse-tube refrigerator (PTR)-based scanning probe microscopy (SPM) system capable of operating at a base temperature of near 5 K. We achieve this by combining a home-made interface design between the PTR cold head and the SPM head, with an automatic gas-handling system. The interface design isolates the PTR vibrations by a combination of polytetrafluoroethylene and stainless-steel bellows and by placing the SPM head on a passive vibration isolation table via two cold stages that are connected to thermal radiation shields using copper heat links. The gas-handling system regulates the helium heat-exchange gas pressures, facilitating both the cooldown to and maintenance of the base temperature. We discuss the effects of each component using measured vibration, current-noise, temperature, and pressure data. We demonstrate that our SPM system performance is comparable to known liquid-helium-based systems with the measurements of the superconducting gap spectrum of Pb, atomic-resolution scanning tunneling microscopy image and quasiparticle interference pattern of Au(111) surface, and non-contact atomic force microscopy image of NaCl(100) surface. Without the need for cryogen refills, the present SPM system enables uninterrupted low-temperature measurements.

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

Abstract: 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.

A new apparatus for measurement of the critical p-ρ-T properties based on the variable-volume method

Abstract: • A new variable-volume method for measuring critical pρT properties was designed with a mental-bellows volumeter. • The device can measure the critical pρT properties by filling the fluid only once. • All the experimental pρT data compare well with the data in the open literature. In the present study, a new variable-volume apparatus equipped with a metal-bellows volumeter is designed to measure the critical pressure-density-temperature ( p-ρ-T ) properties by charging the device only once. The expanded uncertainties of the temperature, pressure and density measurements are assessed to be less than 20 mK, 4.2 kPa, and 1.6% ( k = 2, 95%), respectively. Moreover, the combined expanded uncertainty of the respective critical quantities is lower than 0.084 K, 10.2 kPa, and 2.4% ( k = 2, 95%). The average relative absolute deviation (ARAD) between the experimental p-ρ-T data and those calculated by the Refprop for the nitrogen is evaluated to be 0.18%. The p-ρ-T data and the critical properties of the 1,1,1,2-tetrafluoroethane and difluoromethane are measured by the apparatus for verification. All the critical p-ρ-T data agree well with the accessible experimental data from the literature. The ARAD is evaluated to be 0.67% and 0.28% for the density of 1,1,1,2-tetrafluoroethane at the vapor and liquid phases, respectively.

Impedance modelling and collective effects in the Future Circular e+e− Collider with 4 IPs

Abstract: Abstract The FCC-ee impedance model is being constantly updated closely following the vacuum chamber design and parameters evolution. In particular, at present, a thicker NEG coating of 150 nm (instead of previous 100 nm) has been suggested by the vacuum experts, and a more realistic impedance model of the bellows has been investigated. Moreover, also the transverse impedance has been updated by considering the same sources as for the longitudinal case. Therefore, the FCC-ee impedance database is getting more complete and the impedance model is being refined. In this paper we describe the presently available machine coupling impedance in both longitudinal and transverse planes, and study the impedance-driven single bunch instabilities (with and without beam-beam interaction) for the new FCC-ee parameter set with 4 interaction points (IPs). The results are compared with the previously obtained ones and a further possible mitigation of the beam-beam head-tail instability (X-Z instability) is proposed.

Lightweight Dual-Mode Soft Actuator Fabricated from Bellows and Foam Material

Abstract: Foam-based soft actuators are lightweight and highly compressible, which make them an attractive option for soft robotics. A negative pressure drive would complement the advantages of foam actuators and improve the durability of the soft robotic system. In this study, a foam actuator was designed with a negative pressure pneumatic drive comprising bellows air chambers, a polyurethane foam body, and sealing layers at the head and tail. Experiments were performed to test the bending and contraction performances of the actuator with the foaming multiplier and air chamber length as variables. At air pressures of 0–90 kPa, the bending angle and contraction of the actuator increased with the foaming multiplier and number of air chamber sections. The designed actuator achieved a bending angle of 56.2° and contraction distance of 34 mm (47.9% of the total length) at 90 kPa, and the bending and contraction output forces were 3.5 and 7.2 N, respectively. A control system was built, and four soft robots were constructed with different numbers of actuators. In experiments, the robots successfully completed operations such as lifting, gripping, walking, and gesturing. The designed actuator is potentially applicable to debris capture, field rescue, and teaching in classrooms.

Wireless Micro Soft Actuator without Payloads Using 3D Helical Coils

Abstract: To receive a greater power and to demonstrate the soft bellows-shaped actuator’s wireless actuation, micro inductors were built for wireless power transfer and realized in a three-dimensional helical structure, which have previously been built in two-dimensional spiral structures. Although the three-dimensional helical inductor has the advantage of acquiring more magnetic flux linkage than the two-dimensional spiral inductor, the existing microfabrication technique produces a device on a two-dimensional plane, as it has a limit to building a complete three-dimensional structure. In this study, by using a three-dimensional printed soluble mold technique, a three-dimensional heater with helical coils, which have a larger heating area than a two-dimensional heater, was fabricated with three-dimensional receiving inductors for enhanced wireless power transfer. The three-dimensional heater connected to the three-dimensional helical inductor increased the temperature of the liquid and gas inside the bellows-shaped actuator while reaching 176.1% higher temperature than the heater connected to the two-dimensional spiral inductor. Thereby it enables a stroke of the actuator up to 522% longer than when it is connected to the spiral inductor. Therefore, three-dimensional micro coils can offer a significant approach to the development of wireless micro soft robots without incurring heavy and bulky parts such as batteries.

Movement of Free-Ranging Koalas in Response to Male Vocalisation Playbacks

Abstract: Simple Summary Conservation management is critical for threatened wildlife species and an effective conservation approach relies on good understanding of animal behaviour in natural habitat. Currently, koalas are listed as vulnerable to extinction in Australia with declining populations, but their social and breeding system remains unclear. Male koala vocalisations, known as bellows, are believed to be closely related to their breeding behaviour. Bellows incorporate callers’ body size information which can be perceived by other koalas. In this study, we tested the behavioural responses of 20 GPS-collared free ranging koalas to bellow recordings collected from small (<6 kg) and large (>8.5 kg) adult male koalas. We report evidence of intra-male competition, with adult males approaching bellow playbacks, particularly those from small-sized males. In contrast, juvenile males under three years of age showed avoidance of the playbacks. No patterns in the response of females were detected. Our results provide the strongest evidence yet that bellows are primarily a means by which males occupy and control habitat space during the breeding season. Future studies are required to see if female response to bellows depends on their reproductive status. Abstract Effective conservation strategies rely on knowledge of seasonal and social drivers of animal behaviour. Koalas are generally solitary and their social arrangement appears to rely on vocal and chemical signalling. Male koala vocalisations, known as bellows, are believed to be closely related to their breeding behaviour. Previous research suggests that oestrous female koalas use bellows to locate unique males to mate with, and that males can similarly use bellows to evaluate the physical attributes of their peers. We tested the behavioural responses of 20 free ranging koalas to bellow recordings collected from small (<6 kg) and large (>8.5 kg) adult male koalas. Individual koala movement was reported by hourly-uploaded GPS coordinates. We report evidence of intra-male competition, with adult males approaching bellow playbacks, particularly those from small-sized males. In contrast, males under three years of age were averse to the playbacks. No patterns in the response of females were detected. Our results provide the strongest evidence yet that bellows are primarily a means by which males occupy and control space during the breeding season. Future studies are required to see if female response to bellows depends on their reproductive status.

Modeling the Soft Bellows of the Bionic Soft Arm

Abstract: Conventional robots are strong, fast and rigid. Although these properties make them useful for industrial applications, for human machine collaborations they pose a threat. An alternative is provided by soft robots. However, model-based control algorithms for soft robots are not yet at the same level as for conventional robots. Their performance is often limited by their soft materials, which are difficult to model. The goal of this paper is to extend and increase the quality of the existing model for the bionic soft arm while ensuring real-time feasibility. In particular, the focus is on the soft bellows of the manipulator that actuates the robot. In this work, the three-dimensional geometrical problem of the inflating bellows is reduced to a two-dimensional problem that can be efficiently solved in real-time. The solution approximates the nonlinear behavior of the hyperelastic material and is part of a regressor, which then models the driving torque. In comparison to the existing model, the new developed model is able to describe hysteresis effects caused by the material. This increases the overall accuracy of the model. The results are backed up by experimental data.

3D-Printed Soft Pneumatic Robotic Digit Based on Parametric Kinematic Model for Finger Action Mimicking

Abstract: A robotic digit with shape modulation, allowing personalized and adaptable finger motions, can be used to restore finger functions after finger trauma or neurological impairment. A soft pneumatic robotic digit consisting of pneumatic bellows actuators as biomimetic artificial joints is proposed in this study to achieve specific finger motions. A parametric kinematic model is employed to describe the tip motion trajectory of the soft pneumatic robotic digit and guide the actuator parameter design (i.e., the pressure supply, actuator material properties, and structure requirements of the adopted pneumatic bellows actuators). The direct 3D printing technique is adopted in the fabrication process of the soft pneumatic robotic digit using the smart material of thermoplastic polyurethane. Each digit joint achieves different ranges of motion (ROM; bending angles of distal, proximal, and metacarpal joint are 107°, 101°, and 97°, respectively) under a low pressure of 30 kPa, which are consistent with the functional ROM of a human finger for performing daily activities. Theoretical model analysis and experiment tests are performed to validate the effectiveness of the digit parametric kinematic model, thereby providing evidence-based technical parameters for the precise control of dynamic pressure dosages to achieve the required motions.

Hybrid Robotic Manipulator Using Sensorized Articulated Segment Joints With Soft Inflatable Rubber Bellows

Abstract: Robotic manipulators have been used inindustry for decades. However, their heavy mass and rigidity make them unsuitable for environments where they may coexist with humans. This has spurred interest in robotic arms with compliance in their joints using methods, such as impedance control. However, inherent compliance is safer, less computationally expensive, and does not require complex sensing solutions. In this article, the design of a sensorized hybrid hard-soft articulated joint using inflatable soft rubber bellows for actuation and simple angular potentiometers for angular position sensing is presented. The joint is hybrid in the sense that it combines rigid motion with soft actuation. This design allows for a simple yet effective solution that combines the precise sensing of rigid manipulators with the compliance of soft ones. Closed-loop control of this joint was implemented and it was capable of following a given trajectory while rejecting disturbances. This design was then extended to a two degrees of freedom (DOFs) joint with the path following capability, and then, integrated with a rigid base joint to form a 6-DOFs hybrid robotic manipulator for use in small retail businesses. This manipulator can handle payloads up to 1 kg over a large work area and was tested for pick-and-place operations.

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

Abstract: 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.

Structural Integrity Assessment of the Compensators Used in the Heat Exchangers Under Combined Angular Movement and Lateral Offset

Abstract: Process industries typically utilize bellows expansion joints (compensators), which offer both axial flexibility and circumferential strength on convolutions. These components are utilized in pipe structures as well as their connections to vital process equipment’s, such as boilers, fixed tube heat exchangers, pressure vessels, pressure relief equipment, pulsation dampeners, etc. The expansion-contraction operation of the compensators attached to the pipes produces different thrusts and stresses, rendering process equipment vulnerable to catastrophic failure if there is an axial misalignment or lateral offset in connection. For the purpose of maintaining structural integrity, it is essential to determine the meridian stresses generated on bellows compensator under various operating conditions. This study examines the quantitative effects of combined lateral shift and angular rotational misalignment on meridional stress levels for the heat exchanger shell bellows. Mainly the generation of the stresses on the U-shaped convolution profile is multifaceted and difficult to evaluate. An experimental setup has been designed to make it easier to see the combined angular rotation and offset at various levels and to improve evaluating the stress levels for analysis purposes. The paper presents the results pertaining to meridional deflection-based stresses. The analysis process signifies the assessment of structural integrity to enable designers to implement mitigating measures regarding the installation of bellows compensators and adequate support conditions.

Development of Coil Spring Suspension System with Air Bellows

Abstract: Abstract 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.

An Experimental Study on Seismic Performance Evaluation of Multi-Ply Bellows Type Expansion Joint for Piping Systems

Abstract: Piping systems are a representative social infrastructure to provide oil, gas, and water. Damage to piping systems may cause serious consequences, such as fire, water outage, and environmental pollution. Therefore, piping systems need to be protected from natural disasters, such as earthquakes. Earthquakes may cause deformation that exceeds piping design criteria. For example, large relative displacements and liquefaction of the ground resulting in loss of strength and ground subsidence, and the side-sway of primary structures subjected to a strong ground motion may cause critical damage to piping systems. Therefore, expansion joints to maintain flexibility can be applied to locations where excessive deformation is expected to improve the seismic performance of piping systems. Metal bellows, a type of expansion joints, are flexible, so they are highly durable against deformation and fatigue loads. This indicates that metal bellows can be used as seismic separation joints for piping. In this study, experimental research was conducted to analyze the seismic performance of multi-ply bellows type expansion joints, a type of metal bellows. Monotonic loading tests and cyclic loading tests were conducted on 2-ply bellows and 3-ply bellows, and the results were compared. In the cyclic loading tests, multi-step increasing amplitude cyclic loading, which used the displacement history amplified in stages, and constant amplitude cycling loading with various magnitudes were considered. The test results showed no significant difference in bending performance for monotonic loading between the two types of multi-ply bellows. The 3-ply bellows, however, showed higher performance for low-cycle fatigue than 2-ply bellows.

A Method for Calculating the Reliability of Welded Metal Bellows for Mechanical Seals

Abstract: Welded metal bellows are an elastic element widely used in the field of mechanical seals. The main objective of the present study was to investigate the reliability of welded metal bellows in mechanical seals under specified working conditions. To this end, a stress relaxation test bench was built to obtain the residual elastic force data of welded metal bellows under different compression loads in high-temperature environments. Then, the elastic force loss equation of the bellows was fitted. Moreover, a failure judgment form of welded metal bellows in the mechanical seal is proposed. According to the calculation relationship between the seal face pressure and the welded metal bellows’ elastic force, the elasticity force loss range of the bellows was 556–708 N. Finally, according to the elastic force loss equation, elastic force loss was determined. The maintenance time of the welded metal bellows, and the bellow’s failure limit state equation were determined, and the limit state equation was substituted into the center point method. The reliability of the welded metal bellows was 0.9958. The results show that the new failure criterion and the center point reliability calculation method proposed in this paper have certain practical value for the rapid reliability prediction of welded metal bellows.

Reliability Analysis of the Welded Bellows for Mechanical Seals Based on Six Sigma

Abstract: This paper investigates the reliability of welded metal bellows used in mechanical seals under specified working conditions. Firstly, considering the working environment of mechanical seals and the structural characteristics of welded metal bellows, a stress relaxation test bench was developed to obtain projectile loss data of welded metal bellows under different compression loads at elevated temperatures. The creep constants for a stress relaxation simulation were derived from the experimental data, and a stress relaxation finite element analysis (FEA) of the bellows was conducted using Workbench under different compression loads. We found that the stress relaxation simulation of welded metal bellows can accurately simulate the relaxation characteristics of welded metal bellows. The reliability of the welded metal bellows was calculated using Six Sigma response surface reliability by taking the material properties and compression load as variable parameters and the residual elasticity of the bellows as the objective function. We concluded that the reliability calculation method of welded metal bellows promotes reliability research into welded metal bellows for mechanical seals.

Origami-Type Flexible Thermoelectric Generator Fabricated by Self-Folding Using Linkage Mechanism

Abstract: We proposed an “origami-TEG” which is a thermoelectric generator (TEG) with flexibility using an origami structure fabricated by self-folding. The micro bellows-folded origami structure was formed by self-folding using a linkage mechanism after mounting the thermoelectric elements. We confirmed the fabricated origami-TEG showed almost the same internal resistances and maximum output powers when attached to a heat source with a flat and curved surface.