Spring Structure Research Articles

Integration of Flexible Loads and Electric Spring Using a Three-Phase Inverter

In this article, a new structure of the electric spring (ES) system using a three-phase inverter is proposed. Noncritical or flexible loads associated with ES can be turned into a smart load. The smart load consumes power adaptively to achieve quick demand response in the future smart grid. Compared to previous ES topologies, the new structure of ES eliminates the battery storage and isolation transformer. The benefit of size and weight reduction results in further improvement on power density of the system. The control strategy is developed and the optimal operating condition for the new ES system is explicitly studied. Power inverter prototype has been built and tested to demonstrate not only the functionality but also the practicality of the new proposal. At the end of the article, the power capability of the new ES system is investigated and compared with previous ES to highlight its features.

Design and application of spectacle frame for eye moxibustion

The new style spectacle frame for eye moxibustion is designed, which is characterized by adjustable direction, constant temperature and smoke absorption. Combined with mechanical structure design and physical and chemical technology, a new style of moxibustion spectacle frame is designed by means of spring mechanism, damping bearing, filter cotton, etc. The moxibustion spectacle frame includes the right and left eye frames, spectacle legs, nose mask, eye mask, slide rod, screw rod, spring structure, damping bearing, support rod and pin. The eye mask can prevent from the risks induced by the burning moxa stick. A ventilate hole is designed in the lower part of the nose mask to keep breathing unobstructed. In the upper end of the ventilate hole, a filter cotton is placed to prevent from moxa smoke penetrating to the nasal cavity. The spring structure can keep relatively the fixed distance between the combustion area and the acupoints. Such device ensures the safety of eye moxibustion, reduces the complexity of operation and is suitable for moxibustion treatment for all kinds of eye diseases.

Simulation analysis of control system for six degrees of freedom damping platform based on MATLAB

On the basis of relevant mathematical theory inference and the observability analysis of sensor arrangement and the controllability analysis of actuator arrangement, the simplified model of the six-degree-of-freedom air spring active vibration isolation system is established. Considering the structure of the air spring damping platform and the environment interference around the vibration isolation platform, we use the simulation software named MATLAB to establish three control models: PID control, Fuzzy control and Fuzzy PID control. The simulation analysis results show that the Fuzzy PID control consequent is obviously benefit to the damping platform, in addition, the composite feedback can also greatly promote the control consequent.

Empirical High Cycle Fatigue Assessment Model of MEMS Devices

Abstract Many microelectromechanical systems (MEMS) devices generate large deflections and stresses under some severe loads, and this cumulative stress often causes structural fatigue when applying high cyclic loads. It affects the reliability and quality of the product and can easily damage structures in harsh environments. For example, accelerometers and gyroscopes in motion sensors always combine a movable mass component with a bending or torsion spring, which can severely deform their structure at some large accelerations or angular accelerations. After this high cycle of deformation, the spring structure will be damaged and cause device failure, we call this failure mode high cycle fatigue (HCF). This is very common for MEMS products, but it is difficult for designers to predict it at design stage. To prevent early fatigue problems and reduce product development time, we developed a simulation process and empirical prediction model to help designers predict HCF and improve fatigue strength of moving structures used in MEMS devices. In this study, a bending and a torsion beam are used as test vehicles. A combination of dynamic and electromechanical coupling simulations was developed and applied to analyze the effects of frequency under HCF testing. The test structures were fabricated using silicon-on-insulator (SOI) MEMS technique and these test structures were used to validate empirical life prediction equation developed in this research. The frequency effect of HCF was also to be included in the developed prediction model. Based on the test results, the accuracy of the empirical prediction equation is improved by including frequency effect.

Comparison of ice‐on and ice‐off abiotic and biotic parameters in three eutrophic lakes

AbstractThe structure and abundance of winter planktonic communities are limited by environmental conditions that are unfavorable to life, but do not stop biological processes. The aim of the study was to test the hypothesis that the abundance of planktonic groups of organisms in temperate lakes can be higher during winter under ice cover than during the ice‐free seasons. Physical (ice/snow cover, temperature), chemical (organic carbon, chlorophyll a, phosphorus, nitrogen) and biological parameters (phytoplankton, protozooplankton, zooplankton) were investigated in three eutrophic lakes during two consecutive years in winter, spring, summer and autumn. The results of this study showed that in all lakes chlorophyll a concentrations were usually lower in winter than in other seasons, while total nitrogen concentrations were higher in winter than in autumn. All groups of planktonic organisms were able to reach similar or even higher abundances in winter under‐ice than in other ice‐free periods, depending on the lake morphometry and the year of the study. Winter taxonomic structure of phytoplankton was similar to the spring (medium‐sized Lake Dgał Wielki with the dominance of cryptophytes), summer (small‐sized Lake Dgał Mały with cyanobacteria as a dominant group) or autumn (the shallow lake with the dominance of diatoms) structure, depending on the lake. In all lakes, the structure of the ciliate community was the most similar to that of the spring with the clear dominance of Oligotrichida. Our results show that some species among all the studied groups of organisms can lead an active and dynamic life under the ice cover.

Design and experimental study of zero-compensation steering gear load simulator with double torsion springs

As one of the main actuators of the missile guidance control system, the steering gear is used to change the missile flight direction. In order to improve the accuracy of the load simulator used to test missile steering gears, a mechanical servo load simulator design, based on torsion springs, is presented. In the design process, in order to avoid the zero hysteresis portion of the torsion spring characteristic curve, the innovative method of zero-compensation using the reverse arrangement of the double torsion spring is proposed. Finally, by using the process servo calibration test and the actual test of the steering gear, the zero error is effectively reduced while the load gradient is satisfied, and the accuracy of the load platform is improved. The results obtained strongly indicate the feasibility of the proposed method. The zero error of the double torsion spring structure is less than the required 1%.

Structure, design, and mechanics of a paper spring.

A paper spring is a simple paper craft popular with children. It can be constructed by interfolding and gluing two long strips of paper of equal sizes, with the simplest possible crease patterns. In addition to its curious springy response, this origami-based composite exhibits a twist deformation during its extension. Although its interlocking structure is expected to underly the strong stretch-twist coupling, a detailed understanding of it remains elusive. Here we quantify the kinematics and mechanics of a paper spring during its extensional actuation by combining experimental, numerical, and analytical approaches. We directly link the nonlinear mechanics of a paper spring with its structural design and the sheet elasticity. We show that the unique interlocking provides an enhanced structural rigidity because the thin sheets suffer from geometric frustrations and must locally bend and stretch during extension. This structural design allows for a reversible transformation between the rotatory and linear motions solely by controlling forces and moments applied at the ends of the structure. Such deployment kinematics could provide a unique avenue of the mode conversion for potential applications and will broaden the possibilities of future designs of origami-based springs with tunable functionalities.

Electromechanical Decoupling by Porous Aerogel Conducting Polymer

In the field of biointerface electronics, electromechanical decoupling—electrical performance independent of mechanical deformation—can ensure reliability of measured signals, which is critical in stable electrode. Herein, Chen et al. report such a decoupled and stretchable conductive polymer foam.

A Study on the Element Technologies in Flame Arrester of End Line

An end-line flame arrester allows free venting in combination with flame protection for vertical vent applications. End-line flame arresters are employed in various fields, especially in shipping. In flame arresters, springs are essential parts because the spring load and the spring's elasticity determine the hood opening moment. In addition, the spring has to work under a high-temperature condition because of the burning gas flame. Therefore, it is necessary to analyze the mechanical load and elasticity of the spring when the flame starts to appear. Based on simulations of the working process of a specific end-line flame arrester, a thermal and structural analysis of the spring is performed. A three-dimensional model of a burned spring is built using computational fluid dynamics (CFD) simulation. Results of the CFD analysis are input into a finite element method simulation to analyze the spring structure. The research team focused on three cases of spring loads: 43, 93, and 56 kg, correspondingly, at 150 mm of spring deflection. Consequently, the spring load was reduced by 10 kg after 5 min under a 1,000 oC heat condition. The simulation results can be used to predict and estimate the spring’s load and elasticity at the burning time variation. Moreover, the obtained outcome can provide the industry with references to optimize the design of the spring as well as that of the flame arrester.

Abnormal wave propagation behaviors in two-dimensional mass–spring structures with nonlocal effect

This paper considers the propagation of elastic waves in periodic two-dimensional mass–spring structures with diagonal springs. The second-neighbor interactions in non-diagonal directions are included to account for the nonlocal effect. The influences of the spring stiffness in the diagonal directions and the nonlocal effect on the propagation characteristics of elastic waves are then scrutinized. Through the dispersion relation curve and the equi-frequency contours, it is seen that when the diagonal spring stiffness increases, the slope of the second curve in the –M direction will not always be positive, meaning that the negative group velocity occurs. Therefore, an incident wavevector with a chosen angle to the negative group velocity can lead to the negative refraction phenomenon in the two-dimensional mass–spring structure. Another interesting phenomenon called directional radiation of elastic waves can also be achieved by adjusting the nonlocal effect. Within a certain range, the stronger the nonlocal effect in a specific direction is, the more obviously the elastic waves propagate along this direction. In this paper, we theoretically analyze and numerically simulate the phenomena of negative refraction and directional wave propagation by choosing a proper set of parameters of the two-dimensional mass–spring structure.

Influence of Leaf Spring Structure Milling Tool on Chipping Resistance in Titanium Alloy Milling Process

Influence of Leaf Spring Structure Milling Tool on Chipping Resistance in Titanium Alloy Milling Process

Analysis of vibration isolation performance of parallel air spring system for precision equipment transportation

Precision equipment is usually accompanied with vibrations during road or railway transportation. Sometimes the vibration exceeds the given limit, leading to the damage of the equipment. It is necessary to control the vibration during the transportation. However, it is still difficult to adjust the parameters of a designed vibration isolation system for the transportation of different precision equipment under various road conditions. Aiming at satisfying the vibration isolation requirements of different precision equipment, this paper proposes a parallel air spring vibration isolation system based on the principle of limiting lateral deflection. According to the measured parameters, a rigid-body dynamics simulation model of parallel air spring vibration isolation system is established. Then its feasibility is verified, and the optimal parameters of the vibration isolation system are obtained by a simulation. Finally, the vibration isolation system is built and installed in the equipment to carry out the real vehicle transportation test. The test results show that the transportation vibration isolation system based on the parallel air spring structure has not only excellent vibration isolation efficiency but also acceptable lateral stability. The research results in this paper can provide a reference for the design of the vibration isolation system for the large precision equipment transportation.

Design and Optimization for a New Compliant Planar Spring of Upper Limb Assistive Device Using Hybrid Approach of RSM–FEM and MOGA

This study develops a new multi-objective optimization design for a compliant planar spring that is used for upper limb assistive device for disabled people. The structure of spring is designed by arranging the leaf springs in a zigzag shape to permit a large deformation. The spring is a key element of the gravity-balanced mechanism (GBM) in the upper limb assistive device, exoskeleton and upper limb assistive robot. Static equilibration of the GBM is utilized to eliminate the working effort of the disable forearm. The spring is therefore used to adjust the stiffness and to maintain the equilibrium condition. To improve static performances, an effective hybrid approach of the response surface method, finite element method, and multi-objective genetic algorithm is developed. In comparison with common types of surrogates, the Kriging metamodel was found as a prefer black-box to approximate the objective functions. Subsequently, the multi-objective genetic algorithm is adopted to find out the Pareto-optimal set for the spring. The sensitivity of each design variables is then analyzed, and their significant contributions are conducted using the analysis of variance. The predicted results give a good agreement with the validation ones. It eliminates the modeling errors of the analytical method for synthesis and analysis of compliant mechanisms. The results facilitate an optimization design for the intelligent robotics systems for the assistive devices.

A Single Polymer Artificial Muscle Having Dual‐Mode Contractibility, Temperature Sensibility, and Trainability through Enthalpy Change

AbstractArtificial muscles (AMs) have high demand in many fields like robotics, medical devices, sensors, and actuators as well as prosthesis. To achieve what a natural muscle can do for humans in AMs, an ideal material should be cheap, soft, and have both isotonic and isometric contractions, high energy density, sensibility, and trainability. However, only a single function of AM, isotonic contraction, is considered in most existing studies, while other critical functions are always neglected. Moreover, current AMs are normally made of either hard metals or polymer composites, or special structures typically twisted coils of thermal expansion polymers. Here a single polymer artificial muscle (SPAM) with natural muscle molecular structures is reported to perform both isotonic and isometric contractions (dual‐mode), where spring structure is similar to titin and semicrystal likes actin. This SPAM can sense the surrounding temperature due to a crystal phase where enthalpy‐battery is installed. Then the trainability is proved by structural evolution which leads to contraction responsive to stimulated conditions with longitudinal strokes higher than 29%, and a specific work up to 473 J kg−1, respectively. This single soft polymer realizes significant multifunctions of an AM without any complicated structure design and composite system.

Development of a Conductive Polymer Based Novel 1-DOF Tactile Sensor with Cylindrical Arch Spring Structure Using 3D Printing Technology.

Under this research, a novel tactile sensor has been developed using a conductive polymer-based sensing element. The incorporated sensing element is manufactured by polymer press moulding, where the compound is based on silicone rubber and has enhancements by silica and carbon black, with Silane-69 as the coupling agent. Characteristics of the sensing element have been observed using its sensitivity and range, where its results pose an inherent nonlinearity of conductive polymers. For the force scaling purpose, a novel 3D printed cylindrical arch spring structure was developed for this highly customizable tactile sensor by adopting commonly available ABSplus material in 3D printing technology. By considering critical dimensions of the structure, finite element analysis was carried out to achieve nearly optimized results. A special electrical routing arrangement was also designed to reduce the routing complexities. The optimized structure was fabricated using the 3D printing technology. A microcontroller-based signal conditioning circuit was introduced to the system for the purpose of acquiring data. The sensor has been tested up to the maximum load condition using a force indenter. This sensor has a maximum applicable range of 90 N with a maximum structural deflection of 4 mm. The sensor assembly weighs 155 g and the outer dimensions are 85 mm in diameter and 83 mm in height.

Enhanced Metaheuristic Optimization: Wind-Driven Flower Pollination Algorithm

The flower pollination algorithm is a new metaheuristic optimization technique that simulates the pollination behavior of flowers in nature. The global and local search processes of the algorithm are performed by simulating the self-pollination and cross-pollination of flowers. However, the conventional flower pollination algorithm has several limitations. To overcome the problem of slow convergence and prevent the algorithm from becoming stuck around local optimum, this paper describes an enhanced metaheuristic wind-driven flower pollination algorithm (WDFPA). Experiments are conducted using 29 benchmark test functions and two engineering design problems, and the proposed WDFPA is compared against other metaheuristic optimization algorithms and several classical optimization approaches. The results show that WDFPA achieves better performance than the conventional flower pollination algorithm, especially in high-dimensional optimization problems. The convergence speed and accuracy of WDFPA exhibit significant improvements over other metaheuristic algorithms in many of the test cases. Additionally, WDFPA produces optimal results for engineering design problems involving a welded beam and a spring structure.

Road-killed toads as a non-invasive source to study age structure of spring migrating population

Development of road system causes worldwide barriers to wildlife movement and leads to mass road mortality which is a serious threat to the biodiversity, especially globally endangered amphibians. Animal carcasses, however, constitute an important non-invasive material for further research including species life history traits, but there is little known whether the road-killed animals are a representative sample of entire population. The aim of our research was to compare the age structures between road-killed and live individuals which crossed the road successfully during the breeding migration. As a model species, we used the common toad Bufo bufo which is a main amphibian traffic victim in Europe. We collected toe clips of dead and live toads during their breeding migration in four sampling sites located in the lowlands of western Poland. Phalanges were used for age determination by the skeletochronology. There were no significant differences in age distribution between live and dead individuals of the same sex in all populations studied. In compared groups, medians and mean ages were the same or differed marginally and confidence intervals for the mean age almost completely overlapped. Our results suggest that toads are killed on roads regardless of individual age, thus skeletochronological analysis of dead individuals is useful to study age structure of a live population. Our approach allows to avoid mutilation of amphibians and can be used to increase the knowledge of age structure of a given species living near the road as well as to study long-term road effect on amphibian demography. However, further comparative research on different species is required.

Electric impulse spring-assisted contact separation mode triboelectric nanogenerator fabricated from polyaniline emeraldine salt and woven carbon fibers

In this article, we used modified woven carbon fiber mat (wCF-COOH), as one of the contact-electrification Triboelectric Nanogenerator (TENG) friction layer to generate high open circuit voltage (Voc) and short circuit current (Isc). We designed the contact-separation mode TENG which is functional using spring structure. The oxidation of wCF into wCF-COOH by Piranha solution followed by coupling of aniline through electrostatic interactions and in-situ oxidative polymerization to get woven carbon fiber-polyaniline emeraldine salt (wCF.PANI.ES) composite is a novel approach. The wCF-PANI.ES composite displays the surface resistivity of 0.324 Ω m and serves as a friction layer to generate charges by harvesting energy through vertical contact-separation mode TENG against PVDF membrane. The dynamic interactions of novel wCF-PANI.ES and PVDF membrane produced high Voc of 95 V, and Isc of 180 μA, respectively. In particular, wCF-PANI.ES-TENG has shown an enhancement of 498% of Voc with respect to wCF-COOH-TENG due to availability of PANI layer. In addition, it was observed that the proposed wCF-PANI.ES-TENG has shown the output power of 12.4 mW at 5 Hz, and the rectified current upto 180 μA. The novel wCF-PANI.ES is the potential candidate for fulfilling the need of optimized energy harvesting device as an alternate material option for contact-separation mode TENGs.

A novel energy sink with piecewise linear stiffness

In this paper, a nonlinear energy sink with piecewise linear stiffness spring is proposed, and the fundamental characteristics of the nonlinear energy sink are investigated. Firstly, the structure of the piecewise linear stiffness spring is proposed and nonlinearity of the spring is analyzed. Then, the dynamic model of the primary vibration system with the nonlinear energy sink is built, and the responses and vibration suppression effects are studied by numerical simulations. Finally, the effectiveness of the NES is proved by experiment. The results show that the piecewise linear stiffness spring is effective; its structure is simple, compact and adjustable; the vibration attenuation performance of nonlinear energy sink is very good under moderate exciting force.

Performance improvement of bilateral control systems using derivative of force

SUMMARYThis paper proposes a bilateral control structure with a realization of the force derivative in the control loop. Due to the inherent noisy nature of the force signal, most teleoperation schemes can make use of only a proportional (P) control structure in the force channel of the bilateral controllers. In the proposed scheme, an α–β–γ filter is designed to smoothly differentiate the force signal obtained from a reaction force observer integrated to both of the master and slave plants. The differentiated force signal is then used in a proportional-derivative (PD) force controller working together with a disturbance observer. In order to design the overall bilateral controller, an environment model based on pure spring structure is assumed. The controller is designed to enforce an exponentially decaying tracking error for both position and force signals. With the presented controller design approach, one can independently tune the controller gains of the force and the position control channels. The proposed approach is experimentally tested in a platform consisted of direct drive linear motors. As illustrated by the experiment results, the contribution of the PD control in the force channel improves the teleoperation performance especially under hard-contact motion scenarios by attenuating the oscillations, hence, improving the transparency when compared to the structures using only a P force control.