Spring Component Research Articles

Amplifying the power density in thermoacoustic systems using a spring component.

This paper deals with the introduction of a spring component into a thermoacoustic system to increase the power density. This enables more compact and cheaper thermoacoustic systems. A theoretical and experimental study is presented to demonstrate the effect of the introduction of a spring component to amplify the thermal power in a thermoacoustic heat pump. The required spring constant is determined using an electrical circuit analogy model and a DeltaEC model of an existing heat pump. This is calculated for two locations in the system at the cold and hot side of the regenerator. The theory of the deflection of an elastic membrane loaded by a uniform pressure differential is used to calculate the required pretension of an elastic membrane used as spring to obtain the required spring constant. Elastic membranes are prepared and tested in the heat pump. The experimental results show that the insertion of the membrane at the hot side of the regenerator increases the power density by about 20%. The implementation of the membrane at the cold side of the regenerator increases the thermal power by about 100%. For both cases the improvement in the coefficient of performance is about 10%.

Influence of fractal-based contact friction coefficient on the stiffness of disc springs: Experimental and numerical studies

In order to study the influence of friction coefficient on the stiffness of disc spring, A series of disc springs ( D = 71 mm) were selected in this paper. The tension and compression experiments of disc spring components were carried out by universal testing machine. The load-displacement characteristic curves of disc springs with different friction surfaces were obtained. The results show that in the loading process, the friction effect hinders the increase of the deformation of the disc spring, so that the actual stiffness of the disc spring is improved and the actual compensation amount is reduced, so this result is worthy of attention. In order to further study the influence of friction coefficient on the loading process of disc spring, according to the load-deformation formula of disc spring in A-L method, the tangential stress caused by friction is added, and the stiffness calculation model of corresponding disc spring is established by Workbench finite element software. The coefficients of different friction surfaces are used as variables for numerical calculation. The results show that the theoretical calculation, numerical calculation and experimental results of stiffness increase with the increase of friction coefficient under 0.55 h (the compensation displacement of A71 disc spring under the working displacement of corrugated tube ±10 mm). Among them, the numerical calculation results are close to the experimental results, and the error value is less than 1%. The numerical calculation results are corrected by using the experimental data, and the corrected model calculation results are in good agreement with the measured results.

Hydrodynamic analysis of a floating platform integrated with buoys and spring components for energy conversion

Hydrodynamic analysis of a floating platform integrated with buoys and spring components for energy conversion

On the Automated Unit Tests Generation for Java Applications using Spring Framework

This paper considers the automated unit tests generation for programs written in Java using the Spring framework. Although several test generation tools for “pure” Java applications have been developed in recent decades, the features of this framework are mostly not taken into account. However, Spring is used to develop many industrial Java applications. At the same time, the presence of Spring components in the application for which the tests are generated imposes additional requirements not only on the code analysis approaches, but also on the structure of the generated tests. The main source of the information about object types and their properties is the Spring application context. The paper proposes an instrument for analyzing the application context, that in some cases allows generating test scenarios corresponding to real program executions and avoiding excessive mocking. The full initialization of the application context does not occur during this analysis. It makes the test generation safe for user data. The proposed instrument for analyzing the Spring context has been integrated into the UnitTestBot Java automatic test generation tool. We also provide examples of tests generated for real open-source projects.

Design and Finite Element Analysis of an Automatic Electromechanical Overload Detecting System for Trucks

This paper presents a simple design, low‐cost, electromechanical overloading system, which is easy to use and install and suitable for all types of truck chassis and suspension. This design can detect an overload, signal the driver, and also interrupt ignition when the truck is overloaded. The system was modelled using CAD software, and FEA was performed on the spring component to verify analytical solutions. Components of the overload detection system include a load carrying springs, an electrical relay, ignition system, an LED for signaling overload, and an electrical circuit. Results showed that, for a 3‐axle trucks, the allowable pay load was 15.125 tonnes, and each spring in the design supports a minimum weight of 74.183 kN. A spring index of 4.009 was achieved in line with safe design conforming to 4 ≤ C ≤ 12 with a spring rate of 1464305.5 N/m. The spring displacement needed to actuate the overloading system was 51 mm. FEA which was performed validated analytical solutions in that the induced von Mises stress which was 69.92 MPa was below the yield strength of the material (200 MPa) and the factor of safety obtained was 1.24 signifying safe design. The designed electromechanical system is capable of detecting an overloadand also interrupting the truck ignition. Installation can be installed on new trucks or by retrofitting onto old trucks.

Finite element dynamic modeling and vibration reduction analysis of the double-lap bolted thin plate with partially attached constrained layer damping

The double-lap bolted thin plate is widely used, but it is easy to produce vibration. In this paper, the method of attaching H-shaped constrained layer damping (CLD) is adopted to reduce vibration, and the finite element dynamic model of the double-lap bolted thin plate with H-shaped CLD is investigated. The innovations of the modeling method are described as follows. A composite element with four nodes and 28 degrees of freedom (DOFs) is produced by taking into account the interlaminar shear deformation of the CLD structure and employing complex modulus to quantify the damping characteristics of the viscoelastic layer. A series of transition elements are constructed to conduct the assembly of elements with inconsistent dimensions. Complex stiffness spring components and mass elements are presented to simulate the stiffness, damping, and mass characteristics of the double-lap bolt joint based on the crock-shaped stress distribution in the double-lap bolt joint and taking the bolt effect region into account. Finally, a case study is carried out, and the rationality of the finite element model of the bolted structure in solving the natural characteristics and vibration response parameters is verified by the established experimental tests. At the same time, the test and modeling results show that the H-shaped CLD reduces vibration on the double-lap bolted thin plate. Furthermore, based on the established finite element model, the influence of the attaching position of the H-shaped CLD, thicknesses of the viscoelastic layer, and the constraining layer on the vibration characteristics of the bolted structure are analyzed.

Numerical investigation of a proposed multidimensional isolator applied to large-scale domes subjected to earthquakes

A three-dimensional seismic isolation device that is effective in isolating both horizontal and vertical earthquake components has drawn the interest of researchers in recent years. This paper proposes a new three-dimensional isolator for large-scale dome structures, which is composed of a quintuple friction pendulum component and a stacked disc spring component in series in the vertical direction. The complex working characteristics of these components are investigated in detail. Numerical modeling methods are proposed to simulate this isolator for engineering application purposes, and the model accuracy is validated based on theory and experiments. Thus, the isolator is applied to a large-scale dome structure subjected to near- and far-fault ground motions. Numerical analysis shows that the proposed modeling methods can efficiently analyze the isolation performance of the isolator in a large-scale structure. The numerical results demonstrate that the isolator has excellent isolation performance not only for displacement and axial force demands but also for velocity and acceleration demands in all three directions. In addition, according to the comparative study of this paper, the isolation performance of the proposed isolator is better than that of other types of isolators under major earthquakes due to the adaptive sliding characteristics of the quintuple friction pendulum component and the flexibility of the stacked disc spring component prolonging the structural periods.

The spectral resolution of DOM in urban rivers affected by different non-point source intensities using self-organizing maps.

UV-Vis, three-dimensional excitation-emission matrix fluorescence spectroscopy (EEMs) and a self-organizing map (SOM) were used to study changes in the composition and constituent concentrations of dissolved organic matter (DOM) in the water column of two urban rivers with different non-point source inputs during spring and summer. The level of humification and the relative molecular mass of DOM were remarkably higher in the summer than in the spring (P < 0.01) in both rivers. The SOM model showed that the fluorescence intensity of the spring component was lower than in summer in water bodies with higher levels of non-point source inputs, while the opposite was true for water bodies with lower levels of non-point source inputs. Principal component analysis (PCA) showed that nutrients like nitrogen and phosphorus promoted autogenous processes in these water bodies. Seasonal variations and differing intensities of non-point source inputs had remarkable effects on urban river waters (R2 = 0.775, P < 0.001). Non-point source inputs increased the concentrations of humus-like fractions and promoted autogenesis in the water bodies.

Fabrication of metal–polymer matching layers to improve some ultrasonic transducers for NDT and calibration

This paper investigates the impact of different matching layers on the ultrasonic transducers’ performance. Matching layers are mostly used to solve the acoustic impedance matching problem between the piezoelectric element and the test specimen. To design good matching layers, we merged the metal–polymer and mass–spring systems. Their thickness was also optimized using the quarter-wavelength approach. Silver, alumina, and copper served as mass components, while parylene served as the polymer spring component. This was the first time to use such matching materials with lead zirconate titanate (PZT) transducers. The transducers’ sensitivity increased, the beam diameter broadened, the signal-to-noise ratio reduced, and the echo-height increased. According to the findings, the developed matching layers were extremely efficient in upgrading PZT transducers, making them ideal for a variety of non-destructive ultrasonic applications such as identifying defects in various materials. In addition, the new developed transducers may be useful in calibration.

Optimal design of compliant displacement magnification mechanisms using stress-constrained topology optimization based on effective energy

In this paper, stress-constrained topology optimization is applied to the design of compliant displacement magnification mechanisms. By formulating the objective function based on the concept of effective energy, it is not necessary to place artificial spring components at the boundaries of the output and input ports as in previous methods. This makes it possible to design mechanisms that do not receive a reaction force at the output port, such as sensors. Furthermore, by imposing a constraint on the maximum stress evaluated in terms of the p-norm of the von Mises equivalent stress, problems such as stress concentration can be avoided. Several numerical examples of displacement magnification mechanisms are provided to demonstrate the effectiveness of the proposed method.

An Empirical Study on Log Level Prediction for Multi-Component Systems

Logging statements are used to trace the execution of a software system. Practitioners leverage different logging information (e.g., the content of a log message) to decide for each logging statement an appropriate log level, which is leveraged to adjust the verbosity of logs so that only important log messages are traced. Deciding for the log level can be done differently from one to another component of a multi-component system, such as OpenStack and its 28 components. For example, a component might aim for increasing the verbosity of its log messages, while another component for the same multi-component system might aim at decreasing such a verbosity. Such different logging strategies can exist since each component can be developed and maintained by a different team. While a prior work leveraged an ordinal regression model to recommend the appropriate log level for a new logging statement, their evaluation did not consider the particularities that each component can have within a multi-component system. For instance, their model might not perform well at each component level of a multi-component system. The same model’s interpretability can mislead the developers of each component that has its unique logging strategy. In this paper, we quantify the impact of the particularities of each component of a multi-component system on the performance and interpretability of the log level prediction model of prior work. We observe that the performance of the log level prediction models that are trained at the whole project level (aka., global models) have lower performances (AUC) on 72% to 100% of the components of our five evaluated multi-component systems, compared to the same models when evaluated on the whole multi-component system. We observe that the models that are trained at the component level (aka., local models) statistically outperform the global model on 33% to 77% of the components of our evaluated multi-component systems. Furthermore, we observe that the rankings of the most important features that are obtained from the global models are statistically different from the feature importance rankings of 50% to 87% of the local models of our evaluated multi-component systems. Finally, we observe that 60% and 35% of the Spring and OpenStack components do not have enough data points to train their own local models (aka., data lacking components). Leveraging a peer-local model for such type of components is more promising than using the global model.

Vibration of a metaplate made of an acoustic black hole and local resonators

In recent years, acoustic black holes (ABHs) exhibit fascinating damping effects at mid-to-high frequencies. However, flexural waves having long wavelength cannot be trapped in the ABH pit when there is a residual thickness at the ABH tip, therefore below the cut-on frequency the ABH effect fails to work. While locally resonant acoustic metamaterials allows mitigating vibrations in subwavelength scale, usually in a narrow band. In this paper we combine the advantages of the metamaterials and ABHs (MMABH) to control vibrations in the whole frequency band. The designed MMABH plate remains the same weight to the reference uniform plate. To characterize the MMABH performance, an artificial spring component mode synthesis (GECMS) method is suggested, based on the modal coupling between the resonators and the ABH plate via springs. The band gap for the infinite periodic MMABH and the modes for the finite MMABH have been accurately predicted with the GECMS, compared to a reference FEM model. Numerical results show that the low-frequency peaks of the ABH plate can be substantially suppressed when the resonators with proper loss factor are set at its first resonant frequency. The proposed MMABH shows great potentials for light-weight and whole-band vibration reduction.

Prediksi Usia Kelelahan Pegas Ulir dan Lower Suspension Arm Berdasarkan Pendekatan Strain Life Berdasarkan Bentuk Permukaan Jalan

This study aims to determine the effect of road surface contours on fatigue life of coil springs and lower suspension arm. In this study, strain gauge was affixed to the critical point of the minibus front suspension coil springs based on stress distribution. Strain signal obtained was analyzed using the Coffin-Manson, Morrow, and SWT approaches. From the results of the chemical composition test, it was found that the coil springs were made of SAE 5160 and lower suspension arm made of AISI 1513. From the results of this study it can be concluded that when the vehicle drive on the damaged road, coil spring and lower suspension arm received greater stress so that provide shorter fatigue life. Fatigue life of coil spring on rough roads is 16% lower than city roads and 7% lower than flat roads. Whereas fatigue life of lower suspension arm on rough roads is 27% lower than city roads and 0.03% lower than flat roads. So that the coil spring components fail faster than the lower suspension arm. This is because the contour of the road surface provides a vertical load so that it is in accordance with the function of the coil spring which works to reduce the load vertically while the lower suspension arm function holds the load when turning.

An artificial spring component mode synthesis method for built-up structures

In this paper, we develop a component mode synthesis method that relies on artificial springs to connect the subsystems of a built-up structure. The modal behaviour of the subsystems can be computed using different approaches, from analytical to numerical methods, depending on their complexity. The advantage of using artificial springs to link the subsystems is that one can model them with the Rayleigh–Ritz method, which is problematic in component mode synthesis. As known, the approximating functions must satisfy the system boundary conditions and the use of artificial springs avoids this difficulty. Moreover, and as in other component mode synthesis approaches, one can build reduced-order models at the subsystem level to significantly diminish the dimensions of the entire built-up structure, resulting in substantial reduction of the computational cost when performing numerical simulations. The method is first presented for the simple case of two axially connected beams. Two more complex cases are then addressed. The first one deals with two beams connected at right angles and the second one deals with an internal floor attached to a cylindrical shell, which reminds of some aeronautical structures. The performance of the method is carefully analysed and validated against finite element simulations.

MATERIAL SELECTION AND MECHANICAL PROPERTIES IN LEAF SPRING APPLICATION: A REVIEW

In the industrial world, leaf springs are an important component of vehicles. Therefore, material selection is very influential in producing good mechanical properties that can affect leaf spring performance. In this review article, the author aims to review and compile articles on relevant previous studies to compare the best alternative materials other than steel that meet the criteria for the application of leaf springs. The review method used in this article is to search for articles that are relevant to the keyword material, leaf springs, and mechanical properties. After that, the author will collect articles and choose articles that have the criteria to be reviewed. Then the articles that meet the criteria will be reviewed by extracting the data to the review table. As a result, 24 articles will be reviewed. Then the author will extract data on each article, namely material, tensile strength, and flexure. Flexural and tensile strength are used as quality criteria for each material. The conclusion of the review article obtained is that carbon/epoxy has the potential as an alternative steel material because carbon/epoxy has the highest tensile strength with a value of 1841MPa, and flexural strength with a value of 1646.7MPa is close to steel as shown in the review table. However, further research is needed, such as proper design and more efficient manufacturing methods to produce innovative leaf spring components with high quality and acceptable quality in the industry.

Non-linear Isolator for Vibration and Force Transmission Control of Unbalanced Rotating Machines

PurposeThe objective of this paper is to investigate with simulations how non-linear spring and non-linear damper components of isolators can be employed to effectively reduce both the oscillations and the force transmitted to ground in the whole spinning range of unbalanced rotating machines.MethodsThe principal goal of this paper is twofold. First, to present a concise and consistent formulation based on the harmonic balance approach for the vibration response of spinning machines mounted on linear/non-linear, softening/hardening, un-tensioned/pre-tensioned springs and linear/non-linear dampers. Second, to provide a comprehensive overview of the vibration and force transmission control with non-linear isolators specifically tailored to unbalanced machines.ResultsThe study has shown that, the best vibration isolation is provided by a pre-tensioned linear and cubic softening spring combined with a linear and negative quadratic damper. The pre-tensioned spring should be designed in such a way as it holds the weight of the machine and thus produces on the vibrating machine a symmetric elastic restoring force proportional to the linear and cubic powers of the displacement. The cubic softening stiffness should then be tuned to minimise the frequency, and thus the amplitude, of the resonant response of the fundamental mode of the machine and elastic suspension system, while preserving stability and a desired static deflection. In parallel, to reduce the force transmission to ground above the fundamental resonance frequency, the negative quadratic damping effect should be tailored to maximize the energy absorption at higher frequencies.ConclusionThe study has shown that non-linear spring and non-linear damper components can be effectively employed to control the vibration and force transmission in the whole spinning range of the machine. In particular, a pre-tensioned softening cubic non-linear spring can be used to mitigate the vibration and force transmission at low frequencies, close to the fundamental natural frequencies of the elastically suspended machine. Also, a negative quadratic non-linear damper can be used to tailor the energy dissipation of the isolator in such a way as to have high damping at low frequencies and low damping at higher frequencies, which enhances the vibration and force transmission control at low frequencies and, rather importantly, mitigates the force transmission at higher frequencies.

A Novel Nonlinear Dynamic Model for Predicting Contact Bounce of Electromagnetic Relays With Flexible Spring Components

Contact bounce is a common phenomenon in the closing process of electromagnetic relays, which seriously affects the electrical contact reliability of the system. The whole closing process of flexible spring components consists of the free movement stage and the contact bounce stage, which increases the complexity of analyzing the electrical contact behaviors of electromagnetic relays. In this study, a novel nonlinear dynamic model of the flexible spring components in electromagnetic relays is established to analyze the physical mechanism of the electrical contact bounce. Considering the electromagnetic effect, flexible deformation, contact collision, and welding force, the proposed mathematical model can capture the dynamic closing process accurately and collect bounce parameters efficiently. The Kelvin–Voigt viscoelastic contact model is employed to evaluate the nonlinear contact force between the static and movable contacts. Based on the Galerkin method, the nonlinear equations of motion for the movable spring within electromagnetic relays are formulated. A series of experimental work are designed to measure the typical waveforms of displacements of the movable contact and currents in the coil during the closing process of the movable spring. Furthermore, the theoretical results are validated by comparing with the experimental data. The dependences of some key factors, including the structural, material, and electrical contact parameters on the contact bounce characteristics, are investigated explicitly. The theoretical results attest that the proposed model can accurately predict the dynamic behaviors of the movable spring, and the contact bounce can be effectively suppressed by adjusting the parameters of the flexible spring component.

Investigating the influence of the viscoelastic material as a heart muscle simulator on the powering leadless pacemaker from heartbeats by using a piezoelectric beam.

This paper studies experimentally and analytically the influence of the viscoelastic cardiac muscle on the energy harvesting from heartbeats for powering the leadless pacemakers by using a piezoelectric beam. An appropriate representative gel-type viscoelastic material that mimics the heart tissue is used in the tests. The piezoelectric beam coupled with a gel-type material is analytically modeled, and experimentally tested. By considering a combination of the translational standard linear solid model and a rotational spring component for the gel-type material, the analytical model of the coupled system is developed utilizing the generalized Hamilton's principle. The system is attached on top of a shaker and excited harmonically, and the time history of output voltage and accelerations are measured. The analytical model is verified by experimental results for the tip displacement, voltage, generated power, phase-portraits histories, and voltage FRF with harmonic base excitations. Transmissibility analysis by the analytical model shows that for excitation frequencies beyond a specific frequency, the viscoelastic material can magnify the amplitude of the excitation and incredibly improve the power generation. Experimental results demonstrate that by coupling the gel into the harvester, oscillations of the tip are increased into high energy orbits and large tip deflections around the resonance frequency. The significantly widened frequency bandwidth and the increased power output at specific input frequencies are the other results of considering the viscoelastic characteristics of the heart wall in the dynamic investigations. By simulating the response of the energy harvesting system to the heartbeat impulsive rhythm, when the energy harvesting system is attached to the viscoelastic material, the output power is increased from 18 to 55 µW. The obtained results reveal that influence of the viscoelastic properties of the heart muscle is crucial in the accurate design of the energy harvesting system for the self-powered medical leadless pacemaker.

Controller-extensible hybrid simulation platform for viscoelastically damped frame structures based on Matlab-Opensees frameworks

Most of hybrid simulation platforms (HSPs) that use OpenSees for structural hybrid testing research are developed based on OpenFresco framework software. Although OpenFresco is mature and reliable, it can only communicate with specific hydraulic servo actuator control systems, which limits the diversity and flexibility of HSP development. Matlab has powerful independent development functions, and has a wide range of communication interface advantages with many finite element software and actuator control systems. Therefore, Matlab can be used as the communication medium between OpenSees and actuator control system in this study. Firstly, the controller-extensible HSP based on Matlab-OpenSees frameworks is developed. Then, the core establishment details of HSP, including core architecture, hardware system, and DELTA-Matlab-OpenSees system, are analyzed and described in detail. Next, the dynamic loading tests on the spring components are carried out when the HSP is subjected to continuously changing working conditions in the wide frequency domain and displacement amplitude domain. The comparative analysis results on the target displacement curve and the measured displacement curve verify the accuracy and robustness of the inner control loop of HSP. Next, the hybrid tests on a three-story reinforced concrete frame structure with linear springs are implemented under different seismic wave excitations. The comparative research on the hybrid test results and time-history analysis results verifies the accuracy and robustness of the developed HSP (outer control loop) in this study. Lastly, on this basis, a series of hybrid tests on viscoelastically damped frame structures are conducted under different seismic wave excitations. The test results truly reveal the control rule on the seismic response of reinforced concrete frame structures affected by viscoelastic dampers.

Influence of vehicle acceleration intensity on dual-mass flywheel elements and transmission load

Modern high-torque low-speed internal combustion engines (ICEs) generate torsional vibrations close in disturbance frequency to gearboxes natural oscillation frequencies. Effective absorption of such oscillations requires a new torsional vibration damper between the internal combustion engine and gearbox design, which is implemented in the form of a dual-mass flywheel (DMF). One of the main reasons for DMF failure is its spring components destruction. The article develops mathematical and simulation (in MATLAB Simulink environment) model of a car with DMF in the period of starting, which takes into account the dependence of torque and power of the internal combustion engine on the number of the crankshaft revolutions and uneven rotation, car inertial and stiffness parameters, road resistance. It is established that when the car starts in first gear, the maximum load on spring components of DMF and transmission occurs at the initial moment of clutch engagement and exceeds the maximum effective torque of the internal combustion engine 1.6 times, has a pronounced oscillatory character and stabilizes as the car accelerates. With smooth acceleration of a car, when torque of internal combustion engine reaches, but does not exceed its maximum value of 250 N‧m, elastic moment in transmission components is stabilized at 230 N‧m. During intensive acceleration and transition through the extremum on torque curve of internal combustion engine on number of crankshaft revolution, the maximum DMF spring components and transmission load initially doesn’t change significantly, but reduces the duration of oscillatory processes and elastic moment of 160 N·m after attenuation of oscillations. A similar nature of stress changes is observed in the elastic links of DMF, which eventually leads to their fatigue failure and DMF failure. To increase a DMF service life, it is advisable to accelerate a car when moving intensively, bringing a number of revolutions to a value that is located at the extreme of torque of internal combustion engine on its performance characteristic, followed by switching to the next gear.