Search

This paper proposes a new version of a variable gravity compensation mechanism (CVGC-II) for mobile manipulation robots such as mobile manipulators and exoskeletons. CVGC-II, which incorporated an energy-free variable mechanism in a smaller design space, exhibited improved performance with a wider range of variable torque. These enhancements were achieved by adopting an optimal curved lever and hybrid spring system. First, the mechanism concept and specifications of the CVGC mechanism are described. Next, the contribution of the curved lever and hybrid spring system to the performance enhancement of CVGC-II is explained. Subsequently, the design methodologies for the main mechanical elements, including the lever, hybrid spring, and cam, are introduced. In the lever design, Hermite spline and B-spline curve model based optimization is performed to generate optimal curved shape of the lever. The hybrid spring system, consisting of compression coil springs and layered leaf springs, helps achieve a wider variable range by maximizing the storable energy in a limited design space. Finally, the enhanced performance of CVGC-II is evaluated experimentally. The results showed that CVGC-II exhibited a 6.8 times wider variable range and energy-free variable mechanism under a 1.5 and 1.3 times smaller size and weight, respectively.

A special vibration mode called intrinsic localized mode (ILM) in a dispersed multi mass point-nonlinear spring system has been actively studied in solid-state physics and has a high application potential in engineering. Previous studies have only considered parameter-invariant systems, hence active control of the excited ILM is not possible. Therefore, even though the phenomena are very interesting, there are no applications to devices. In this paper, we propose a new paradigm of ILM by designing a dynamic nonlinear vibration system that can treat nonlinear spring properties in a variable manner depending on the applied current. By using variable spring characteristics, the localized vibration energy of the ILM can be freely transferred in unconventional way than before. The spring properties of the variable spring structure with applied current are investigated using finite element analysis. Then, numerical simulations in MATLAB show that the active control of the ILM is possible in a dynamic vibration system with variable spring characteristics.

The spring system is the key component of linear compressor, which is attractive in the field of household refrigeration due to its high efficiency and compact structure. Inspired by the traditional flexure spring, we proposed a novel cylindrical arm spiral spring for linear compressor with a comprehensive consideration on the cost, compactness and performance requirements. The design method of spring was introduced and different performance can be obtained by adjusting the internal radius, external radius, number of turns and wire diameter. The static displacement of spring was modelled by using FEA (Finite Element Analysis) method for various axial and radial force. And a specific fixture was built to measure the spring stiffness to verify the results obtained from FEA simulation. At last, the dynamic test of the linear compressor equipped with the proposed spring was conducted. The experimental results showed that the resonant frequency of linear compressor can meet the design requirements of 78 Hz without gas compressor, indicating that the application of this type of spring in the linear compressor is feasible.

This paper communicates the observations of the parametric study of a high-speed railway (HSR) system using the conventional mathematical approach. The study investigates the static and dynamic performance of the steel-mass spring system (MSS) and its vibration reduction efficiency by considering the effect of floating slab thickness, the spring rate of the steel spring isolator, and the speed of the train. The study also verifies the fatigue performance of the steel spring isolator. A conventional mathematical approach (Zimmermann Method) is used to solve the governing equations for deflection, vertical loads, stiffness, and accordingly the natural frequency of MSS; hence its vibration attenuation ability is calculated. The fatigue strength of the system has been verified from Goodman’s diagram using DIN EN 13906-1:2013-11. It is observed that MSS is effective in reducing the dynamic responses of the track caused by the vertical axle load. Increasing the slab thickness and reducing the steel spring isolator stiffness increase the vibration reduction ability of the system. However, the increase in vehicle speed reduces the vibration reduction efficiency of the system. The observations of the study revealed that steel-MSS can be successfully used in underground high-speed railway tunnels, because of its global vibration reduction efficiency and good fatigue strength to withstand the long-term dynamic responses. The findings of this study will be useful in obtaining an optimized design of the floating slab track for the HSR systems.

The mechanical properties of tissues are critical design parameters for biomaterials and regenerative therapies seeking to restore functionality after disease or injury. Characterizing the mechanical properties of native tissues and extracellular matrix throughout embryonic development helps us understand the microenvironments that promote growth and remodeling, activities critical for biomaterials to support. The mechanical characterization of small, soft materials like the embryonic tissues of the mouse, an established mammalian model for development, is challenging due to difficulties in handling minute geometries and resolving forces of low magnitude. While uniaxial tensile testing is the physiologically relevant modality to characterize tissues that are loaded in tension in vivo, there are no commercially available instruments that can simultaneously measure sufficiently low tensile force magnitudes, directly measure sample deformation, keep samples hydrated throughout testing, and effectively grip minute geometries to test small tissues. To address this gap, we developed a micromanipulator and spring system that can mechanically characterize small, soft materials under tension. We demonstrate the capability of this system to measure the force contribution of soft materials, silicone, fibronectin sheets, and fibrin gels with a 5 nN - 50 µN force resolution and perform a variety of mechanical tests. Additionally, we investigated murine embryonic tendon mechanics, demonstrating the instrument can measure differences in mechanics of small, soft tissues as a function of developmental stage. This system can be further utilized to mechanically characterize soft biomaterials and small tissues and provide physiologically relevant parameters for designing scaffolds that seek to emulate native tissue mechanics. STATEMENT OF SIGNIFICANCE: The mechanical properties of cellular microenvironments are critical parameters that contribute to the modulation of tissue growth and remodeling. The field of tissue engineering endeavors to recapitulate these microenvironments in order to construct tissues de novo. Therefore, it is crucial to uncover the mechanical properties of the cellular microenvironment during tissue formation. Here, we present a system capable of acquiring microscale forces and optically measuring sample deformation to calculate the stress-strain response of soft, embryonic tissues under tension, and easily adaptable to accommodate biomaterials of various sizes and stiffnesses. Altogether, this modular system enables researchers to probe the unknown mechanical properties of soft tissues throughout development to inform the engineering of physiologically relevant microenvironments.

Advances in automobile technology have led to the dynamic development of various types of active suspension systems to improve passenger riding comfort and maneuverability. This study improved the riding comfort of vehicle passengers by converting a conventional spring into a rotating C-shaped spring system that supports the load of the vehicle and varies its vertical stiffness. The C-shaped spring system rotates the spring in the multi-link suspension structure, utilizing the mechanical properties of the spring itself and the offset effect of the spring seat to vary the wheel rate. Using this effect, the riding comfort of an automobile can be improved to a certain level by altering the motion characteristics of the automobile body as it reacts to road bumps and irregularities. A C-shaped spring, an offset spring seat, and a rotating system were combined and installed on the rear suspension of an SUV. A field test of a vehicle driving over a speed bump was conducted to comparatively analyze the obtained data measurements, which verified the utility of the increased riding comfort when the vehicle was equipped with the proposed rotating C-shaped spring system.

Objective: This article aimed to develop a unique exoskeleton to provide different types of elastic resistances (i.e., resisting flexion, extension, or bidirectionally) to the leg muscles during walking. Methods: We created a completely passive leg exoskeleton, consisting of counteracting springs, pulleys, and clutches, to provide different types of elastic resistance to the knee. We first used a benchtop setting to calibrate the springs and validate the resistive capabilities of the device. We then tested the device's ability to alter gait mechanics, muscle activation, and kinematic aftereffects when walking on a treadmill under the three resistance types. Results: Benchtop testing indicated that the device provided a nearly linear torque profile and could be accurately configured to alter the angle where the spring system was undeformed (i.e., the resting position). Treadmill testing indicated the device could specifically target knee flexors, extensors, or both, and increase eccentric loading at the joint. Additionally, these resistance types elicited different kinematic aftereffects that could be used to target user-specific spatiotemporal gait deficits. Conclusion: These results indicate that the elastic device can provide various types of targeted resistance training during walking. Significance: The proposed elastic device can provide a diverse set of resistance types that could potentially address user-specific muscle weaknesses and gait deficits through functional resistance training.

Tension Leg Platform (TLP) is an offshore platform structure used for deep-sea oil and gas exploration. The main structure of the TLP consists of a deck, pontoon, mooring system, and foundation. TLP operates in a balance of buoyancy, structural weight, and mooring tension. The problem is the construction of TLP in the deep sea, where sometimes extreme waves appear could damage the TLP structure. This paper proposes a new model of TLP that is more stable to extreme waves. The method is to separate the mass of the deck and the mass of the pontoon into two flexible parts, which are connected by a cantilever spring system. Thus the TLP motion becomes two degrees of freedom (TLP 2-DOF). Using the dynamic vibration absorber (DVA) method, the ratio of the deck mass, pontoon mass, and spring stiffness are adjusted so that the primary mass movement is minimal. Furthermore, the ratio of the amplitude of the deck movement as the primary mass to the wave amplitude is analyzed, which is known as the operator response amplitude (RAO). The results showed that the TLP 2-DOF model was more stable. As an illustration, at resonance conditions, this model can reduce RAO to about 67%.

Sway-Rocking (SR) spring system is a foundation modelling method in which a 2 × 2 spring stiffness matrix represents the foundation stiffness at seabed level. Since each individual element of the spring stiffness matrix is a function of a few physical properties of the soil and pile, it is the simplest and computationally cheapest method to estimate the deformation at the seabed level and the natural frequency of an offshore wind turbine structure. Formulae currently available are only applicable to conventional long-flexible piles or perfectly rigid foundations such as footings or caissons. This study aims to extend the application of the SR spring system to a so-called short-rigid pile range, which lays between the two ranges: long-flexible and perfectly rigid. Monopiles, the most commonly selected type of offshore wind foundations, are categorized in the short-rigid pile range. By conducting three-dimensional finite element analyses, the short-rigid pile behaviour is investigated. Based on the results, a new set of formulae of the SR spring stiffness, which is applicable to a wide range (long-flexible, short-rigid and perfectly rigid) of piles, is proposed. The new formulae also improve the accuracy of frequency estimation for practical use cases.

This article presents the design of a tuned mass damper with a conical spring to enable tuning to the natural frequency of the system at multiple values, as may be convenient in case of a system with fluctuations in the mass. The principle and design procedure of the conical spring in the context of a varying mass system are presented. A passive feedback control mechanism based on a simple pulley-mass system is devised to cater to the multi-tuning requirements. A design example of an elevated water tank with fluctuating water content, subjected to ground excitation, is considered to numerically illustrate the efficiency of such a tuned mass damper associated with the conical spring. The conical spring is designed based on the tuning requirements at different mass conditions of the elevated water tank by satisfying the allowable load bearing capacity of the spring. Comparisons are made with the conventional passive tuned mass damper with a linear spring tuned to the full tank condition. Results from time history analysis reveal that the conical spring-tuned mass damper can be successfully designed to remain tuned and thereby achieve significant response reductions under stiffening conditions of the primary structure, whereas the linear spring-tuned mass damper suffers performance degradation because of detuning, whenever there is any fluctuation in the system mass.

An undulator generating a magnetic field whose longitudinal profile is arbitrarily varied has been developed, which is one of the key components in a number of proposed new concepts in free-electron lasers. The undulator is composed of magnet modules, each of which corresponds to a single undulator period, and is driven by a linear actuator to change the magnetic gap independently. To relax the requirement on the actuator, the mechanical load on each module due to magnetic force acting from opponent and adjacent modules is reduced by means of two kinds of spring systems. The performance of the constructed undulator has been successfully demonstrated by magnetic measurement and characterization of synchrotron radiation.

In order to assess the performance of a vehicle in the conceptual design stage, a square box model was proposed to predict the torsional stiffness and the first-order torsional frequency of Body-in-White. The structure of Body-in-White was decomposed into eight simple structural surfaces, from which a square box model was constructed. Based on the finite element method, modified shear stiffness of each simple structure surface was calculated and the torsional stiffness was obtained. Then, simple structural surfaces of Body-in-White were constructed into an eight degree-of-freedom series spring system to calculate the first-order torsional frequency. Furthermore, a multiobjective genetic algorithm was used to determine the thickness and structural reinforcement of panels with small stiffness, so as to achieve the goal of increasing the stiffness while reducing the mass of the panel. The result shows that the optimal values of thickness are reduced by around 9.9 percent without affecting their performance by the proposed method. Compared to the prediction results obtained with the complicated numerical simulation, the relative error of the square box model in predicting the torsional stiffness is 6.04 percent and in predicting the first-order torsional frequency is 0.95 percent, indicating that the prediction model is effective.

The gecko effect is famous for its smart adhesion, which is achieved by its fractal-like hierarchy from nano scale spatulas to micro scale seta. This paper designs a gecko-inspired receptor system for a three-dimensional printing technology. A fractal oscillator is established and solved for the fractal-like spring system, the experimental results show that any printed objects can be received smoothly without any morphology change.

HighlightsA spring buffering system was added to a longitudinal vibration picking mechanism for berry shrub fruits.Vibration models of the picking part and side branch were established to obtain the vibration relationship.Blueberry picking experiments were conducted to verify the performance of the picking mechanism.Abstract. Current berry shrub picking mechanisms are generally rigid structures, which can easily cause the mechanism to jam and produce rigid impacts, damaging the berry shrub branches. In view of this situation, a longitudinal vibratory picking mechanism for berry shrub fruits is proposed in this study with a spring system added to provide a buffering effect. Vibration models were established for the picking part and for the berry shrub side branch, and analysis was performed to obtain the vibration relationships. Using blueberry as an example, suitable parameters were determined through calculation and then used in blueberry picking experiments with a prototype of the picking mechanism. The experiments verified that the vibration frequency calculated with the vibration relationships can meet the requirements for picking, and the performance of the longitudinal vibratory picking mechanism for berry shrub fruits was verified. Keywords: Berry shrub picking, Buffer, Longitudinal vibration, Vibration analysis.

Technological advancements are growing at a rapid rate for comforting mankind. Every sector including manufacturing, aerospace, and automobile are growing in terms of technical enhancements, material development and design innovations. An attempt has been made in this investigation to design the spring system used in the suspension system. A suspension system or shock absorber is a mechanical device designed to smooth out or damp shock impulse, and dissipate kinetic energy. In a vehicle, it reduces the effect of travelling over the rough ground, leading to improved ride quality, and increase in comfort due to substantially reduced amplitude of disturbances. Hence, the design of spring in suspension system forms the vital designing component. Here, a spring is designed for which material consideration formed the basis of analysis owing to the impact loads the spring experiences during the working cycle. The spring design combines two basic designs i.e. variable pitch and cylindrical designs to amalgamate the advantages and eliminate the drawbacks of individual designs. A 3D model was generated using SolidWorks software which was further imported in another software i.e. ANSYS to analyze various mechanical parameters. A material study was carried out in terms of mechanical properties for the selection of spring material. The selected material were alloy steel (vanadium chrome spring steel) and high carbon steel (music wire spring steel) which is commonly used. The analysis was carried out by varying the applied load on the spring and it was recorded in term of stress and deformation. It can be inferred that the results of analysis showed spring was designed successfully and fulfilled the motives of two basic spring designs in a single combined spring structure. The result was also in accordance to the previous research which showed alloy steel as a promising material for the springs in the suspension system of the vehicle.

Izvorišno područje potoka Vrapčaka na jugozapadnome dijelu Medvednice obuhvaća područje površine 3,37 km2 . Terenskim istraživanjima utvrđena je pojava 95 izvora, na petrološki raznolikoj, pretežno vapnenačkoj ili pješčenjačkoj podlozi. Izvori Vrapčaka pojavljuju se u visinskom rasponu od 100 do 660 m, u području umjereno raščlanjena reljefa, uglavnom na znatno nagnutim padinama različitih usmjerenja. Općenito, izvorišno područje pokazuje odlike fluviodenudacijskoga tipa reljefa. Za 87 izvora određena je izdašnost, po kojoj najveći broj izvora pripada VII., a potom VIII. razredu izdašnosti po Meinzeru. Prema obliku staništa koje tvore, najviše je reokrenih i helokrenih, a od kombiniranih stanišnih tipova heloreokrenih izvora. Za 57 izvora izmjerena je električna provodnost, temperatura vode, vrijednost pH i količina otopljenih krutih tvari (TDS-a). Prosječna električna provodnost Vrapčakovih izvora iznosi oko 500 μScm-1 , temperatura oko 10 °C, vrijednost pH oko 7,5, a količina TDS-a oko 250 ppm. Za moguća sustavnija i obuhvatnija istraživanja u budućnosti potrebno je dugotrajnije daljnje praćenje većega broja hidroloških pokazatelja izvora, ali i provedba fizičko-geografskih, geoloških, geokemijskih i ekoloških istraživanja izvorišnoga područja potoka Vrapčaka. Spring area of the Vrapčak Stream in the southwestern part of Medvednica Mt. covers an area of approximately 3.37 km2 . Field researches revealed occurrence of 95 springs on a petrologically diverse, predominantly limestone or sandstone bedrock. The springs of Vrapčak appear in the height range from 100 to 660 m, in an area with moderate vertical dissection, mostly on significantly inclined slopes of various expositions. In general, Vrapčak's spring area shows characteristics of fluviodenudation relief. Discharge was measured for 87 springs, most of which belongs to categories VII and VIII according to Meinzer. According to the type of habitat formed by the spring, the biggest number of springs are rheocrene and helocrene, and helorheocrene among combined types. Electrical conductivity, water temperature, pH value and total dissolved solids (TDS) were measured for 57 springs. The average measured values of selected basic hydrological parameters of Vrapčak springs were: electroconductivity 500 μScm-1 , water temperature 10 °C, pH value 7.5 and TDS 250 ppm. For more systematic and comprehensive research in the future, longerterm further monitoring of a larger number of hydrological indicators of springs is required, as well as implementation of physical-geographical, geological, geochemical and ecological researches of Vrapčak Stream's spring area.

Colormap is a visualization tool to realize the mapping from data to colors. The data patterns can be revealed by color distribution, and the data details can be explored by the mapping. Most colormaps use a linear mapping between data and colors. When the data are unevenly distributed, most data samples are encoded in very few colors, so that the patterns hidden in these huge amount of data samples encoded by very small range of colors cannot be explored. Every data sample is equally important, it should map to the exclusive color in the colormap. Inspired by force-directed model-based node layout in network visualization, we propose a novel colormap optimization algorithm with data equality, called spring model-based colormap. It formulates the proposed proportionality rule and data ink rule by a dynamically balanced spring system. The proportionality rule is that the color perception difference is proportional to the values of data samples for better identification of data values. The data ink rule lets the spring system make colors associated with data samples as separate as possible in the color space for better data distribution reveal. To accelerate the colormap generation, a fast solution for the colormap optimization algorithm is proposed. The effectiveness of our method is evaluated by eye tracking experiments. The results show that the fixations on both our colormap and the encoded visualization are more dispersed, which indicates that our method is better at both data distribution reveal and identification of data values.

The dual mass flywheel especially used in diesel engines has a structure in which the single- mass flywheel is divided into two parts and these two parts are combined with a curved helical spring. The flywheel is a part that reduces the speed fluctuations in the crankshaft of the internal combustion engines. In addition to this function, the dual mass flywheel dampens the torsional vibrations better than the clutch disc springs thanks to the spring system found in its structure. There are no torsional springs in the disc of the clutch system where dual mass flywheel is used. The dual mass flywheel is used with a rigid clutch disc without torsion springs. From this point of view, it is thought that the clutch dynamics of both systems are different. For this purpose, mathematical models of both systems were formed. The obtained models were solved after the appropriate transformations. As a result, it was seen the clutch engagement times are almost same in both systems. However in the clutch system where the dual mass flywheel is used the clutching process is performed more smoothly.

The most common disorders of the musculoskeletal system are low back disorders. They cause significant direct and indirect costs to different societies especially in lifting occupations. To reduce the risk of low back disorders, mechanical lifting aids have been used to decrease low back muscle forces. But there are very few direct ways to calculate muscle forces and examine the effect of personal lift-assist devices, so biomechanical models ought to be used to examine the quality of these devices for assisting back muscles in lifting tasks. The purpose of this study is to examine the effect of a designed wearable lift-assist vest (WLAV) in the reduction of erector spinae muscle forces during symmetric squat lifting tasks. Two techniques of muscle calculation were used, the electromyography-based method and the optimization-based model. The first uses electromyography data of erector spinae muscles and its linear relationship with muscle force to estimate their forces, and the second uses a developed musculoskeletal model to calculate back muscle forces using an optimization-based method. The results show that these techniques reduce the average value of erector spinae muscle forces by 45.38 (± 4.80) % and 42.03 (± 8.24) % respectively. Also, both methods indicated approximately the same behaviour in changing muscle forces during 10 to 60 degrees of trunk flexion using WLAV. The use of WLAV can help to reduce the activity of low back muscles in lifting tasks by transferring the external load effect to the assistive spring system utilized in it, so this device may help people lift for longer.

To avoid too large exciting force in traditional linear vibrating screen and unstable working state in resonance screen, the disc spring system is applied in the linear vibration screen. The model of the disc spring system in vibration screen is established by simulation and experiment. The characteristics of modal and amplitude of the disc spring system in vibration screen are studied. We found that the disc spring system vibrates in vertical direction at the third-order natural frequency, which is consistent with the direction of the vibration screen when screening particles. Moreover, the third-order natural frequencies in simulation and experiment are basically consistent. Furthermore, the maximum amplitude of the disc spring system appears at 960 r/min (16 Hz), which is in accord with the third-order natural frequency. Meanwhile, the amplitude increases proportionally with the increase of exciting force, while the amplification factors are the same under three different exciting forces. This indicates that the disc spring system has excellent linearity. The results of research provide guidance for design and application of elastic components on the vibration screen.

The stalk of Vorticella convallaria, a sessile ciliated protozoan, contracts in a few milliseconds at a maximum speed of ~ 10 mm/s and generates a contractile force of ~ 10 nN. After powerful contraction, the stalk slowly returns to its extended state, and this relaxation process completes and resets the contraction cycle. The stalk relaxation needs to be better characterized because it is indispensable to the contraction-relaxation cycle of V. convallaria. In contrast to the spasmoneme-based contraction force, the driving force for the stalk relaxation is thought to be the elastic restoring force of the coiled stalk. In this study, relaxing V. convallaria was modeled as the damped spring system to estimate the effective spring constant of the relaxing stalk in different viscous media. In the order of 0.1 pN/μm, the effective spring constant was found to increase with the medium viscosity, which suggests that the stalk relaxation is affected by the final status of the contraction phase.

This paper proposes a multi-frequency controller design scheme for Markov jump systems (MJSs) based on the self-triggered strategy in a resource-aware way. Firstly, a derandomization technique is introduced to make sure the transition probability information is included in the finite frequency specification analysis. Then, a self-triggered policy is developed to update the control input of the system via the history measurement. Finally, sufficient conditions are deduced that guarantee the multiple range frequency performances and the reduction of computation and communication occupation for the controlled MJSs, simultanously. The cart- spring system is employed to illustrate the effectiveness of the proposed approach.

Introduction. Rubber bushings are important parts of the spring systems of modern vehicles. The properties determine not only the comfort of car movement, but also affect the elastic suspension characteristics. When a bushing is deformed, linear sections appear in characteristics. It is advisable to describe such characteristics using a mathematical model based on the classical elements of Hooke and Saint-Venant. The paper presents a mathematical description of the bushing simulation functioning results, accuracy of approach, areas of application of the mathematical model.Materials and methods. The initial data was the experimental characteristic of a cylindrical automobile rubber bushing, obtained in harmonic mode at the 0.03 to 51 Hz frequency and the 0.4 to 10 mm amplitude. The force balance of the two Hooke elements and one Saint-Venant element interacting with each other determined the mathematical model description. The authors carried out the calculations using numerical and optimization methods.Results. As a result, the authors determined functions characterizing the change in the parameters of the Hooke and Saint-Venant elements from the rubber bushings’ deformation amplitude. Moreover, the authors calculated power characteristics in the form of dependences of the rubber bushing effort and also found quantitative indicators of the reliability of the experimental data approximation by the developed mathematical model.Discussion and conclusions. The analysis of the operating modes shows the possibility of the model application to describe the rubber bushing functioning in a stationary harmonic mode with small and medium strain amplitudes. The simulation results of the Hooke’s and Saint-Venant’s parameters reveals the theoretical prerequisites for the possibility of using the model to calculate the bushing force in an unsteady mode.The authors have read and approved the final manuscript. Financial transparency: the authors have no financial interest in the presented materials or methods. There is no conflict of interest.

In this paper we displayed the problematic of spring design, with usage of CAD/CAE (Computer Aided Design/Computer Aided Engineering) methods. Spring 3D (Three-dimensional) parametric modeling is performed in CATIA (Computer Aided Three-dimensional Interactive Application) software for purposes of achieving fast manipulation of spring geometry, so various spring variants can be made. Using the same software, FEM (Finite Element Method) analysis is used to determine maximum stresses and deflections. Utility of developed parametrized spring system is best reflected for cases of new spring design, where new geometric and FEM models are created with simple parameter application and update feature. This research resulted in spring prototyping with utilization of 3D printing techniques and spring manufacturing.

Flexible robotics are capable of achieving various functionalities by shape morphing, benefiting from their compliant bodies and reconfigurable structures. In this study, we construct and study a class of origami springs generalized from the known interleaved origami spring, as promising candidates for shape morphing in flexible robotics. These springs are found to exhibit nonlinear stretch-twist coupling and linear/nonlinear mechanical response in the compression/tension region, analyzed by the demonstrated continuum mechanics models, experiments, and finite element simulations. To improve the mechanical performance such as the damage resistance, we establish an origami rigidization method by adding additional creases to the spring system. Guided by the theoretical framework, we experimentally realize three types of flexible robotics-origami spring ejectors, crawlers, and transformers. These robots show the desired functionality and outstanding mechanical performance. The proposed concept of origami-aided design is expected to pave the way to facilitate the diverse shape morphing of flexible robotics.

A simplified fluid–structure interaction model is presented, consisting of a cylinder tethered by a spring system interacting dynamically with the two-dimensional and incompressible lid-driven cavity flow. The fluid–structure interaction was solved in a partitioned way, having separate solvers for the fluid flow equations and the structural equations. The influence of the Reynolds number and spring constants on the cylinder motion and fluid flow was analyzed. Results show that as the Reynolds number increases, the secondary eddies grow in size and the primary eddy adapts to this change, shifting toward the center of the cavity. When the values of the spring constants are small $$(k=0.01\,{\text {N/m}})$$ , such that the spring forces are weaker than the fluid drag force, the springs stretch freely and the cylinder motion is the direct result of the fluid dynamics action. For higher values of spring constants $$(k>0.01 \,{\text {N/m}})$$ , the cylinder motion reaches a maximum displacement, and the spring forces induce the cylinder to an oscillatory movement damped by the viscous fluid force; subsequently, the amplitude of the displacements decreases. As the Reynolds number increases, the cylinder motion is restricted within the mainstream fluid flow (considered the more energized region), having smaller displacements.

This study aims to obtain an effective solar panel tracking mechanism using energy-efficient electric actuators. Furthermore, we designed and implemented a semi-active solar tracking system. A tracking system is proposed to control solar panel orientation using a moving mass, a spring system, and an actuator. The weight of the moving mass and the spring constant are optimized to reduce actuator size. A stepper motor was used for this case. This electric drive is not the prime mover of the solar tracker; hence, it works against mass elements lighter than solar panel weight as used in the active solar tracker. Experimental results suggest that the average power required by the stepper motor is 0.21% of the energy generated by the solar tracking system. The results indicate that the proposed solar panel tracker works satisfactorily to control solar panel orientation.

Force sensing and control functions are very important for flip chip bonding systems for the reason of purchasing high-quality chip interconnection. But it is regrettable that, using the existing commercial technology and equipment, the bonding interconnection procedure is hard to be performed perfectly, specifically in the aspects of efficiency, accuracy and quality. There are many processes involved in the bonding interconnection procedure, so as to say, we need to take as far as possible every step and aspect into consideration. This paper proposed a highspeed flip-chip bonding system with force control, which can make the chips after alignment be bonded on substrate well as soon as possible. In the first place, benefited from the work of our predecessors, the active soft-landing (ASL) interconnection is realized by using the advantages of the monolithic force integrated flexible bonding device. However, the adopted flexure bonder is not enough to satisfy the high-efficiency flip-chip bonding requirement. Because the lightly-damping second-order spring system characteristic caused by the force detective part of the adopted flexure bonder. Secondly, based on the flip-chip bonding process, a flexure-based switch is designed to change the unidirectional stiffness of the bonder with the property of force detection for the purpose of reducing the vibration caused by the linear motor braking in the process. Thirdly, a novel closed-loop control strategy which can accommodate the requirements of position and force, namely hybrid position/force closed-loop (HPFC) control, with integrator composed of inertial filter (ICIF) is proposed to realize the high-efficiency force control under high-dynamic working conditions. By adopting these methods above, the bonding system can go through each step of chip bonding after alignment fleetest, and provide high-quality chip interconnection at the same time.

This report presents some experimental results of the effect of the Coulomb friction on the resonant frequency of the two-mass system connected by a nonlinear leaf spring. The experimental apparatus designed and built has an ability to vary the excitation frequency, the excitation force and friction force. Experimental data show that the resonance frequency of the system tends to decrease when increasing the friction force. The resonant frequency of the system can be expressed as the functions depending both on the amplitude of excitation force and on the Coulomb friction force. The experimental results serve as the basic premise for the development of studies applied in self-movement structure operating under different resistant environments.

INTRODUCTION AND OBJECTIVE:The Zenflow Spring System (Zenflow, Inc., South San Francisco, CA, USA) is a minimally-invasive treatment for LUTS secondary to BPH, delivered transurethrally to the pros...

A rectangular thin elastic sheet is deformed by forcing a contact between two points at the middle of its length. A transition to buckling with stress focusing is reported for the sheets sufficiently narrow with a critical width proportional to the sheet length with an exponent 2/3 in the small thickness limit. Additionally, a spring network model is solved to explore the thick sheet limit and to validate the scaling behaviour of the transition in the thin sheet limit. The numerical results reveal that buckling does not exist for the thickest sheets and a stability criterion is established for the buckling of a curved sheet., Comment: 10 pages, 15 figures