Disc Springs Research Articles

Evaluating the Performance of a Novel Digital Slippage System for Tractor Wheels Across Varied Tillage Methods and Soil Textures

Accurate measurement of slip rate (SR) in agricultural tractors, particularly in Iraq, is essential for optimizing tractive efficiency, fuel economy, and field efficiency. Presently, tractors in Iraq lack sensors for SR detection, posing a challenge. This research addresses the issue by introducing a wireless technology, the novel digital slippage system (NDSS), designed to precisely measure the SR of rear wheels. The NDSS was tested across diverse field conditions, involving six soil textures and various kinds of agricultural tillage equipment (A-TE). Different tillage practices, including conservational tillage (CT) with a chisel plough, traditional tillage (TT) with a moldboard plough and disc plough, and minimum tillage (MT) using disc harrowing and spring tooth harrowing, were examined. Results from the NDSS were compared to traditional techniques, demonstrating the cost effectiveness and overall performance. Silty loam soil exhibited higher SR values, while the silty clay soil showed lower values. SR varied significantly across soil textures, with more cohesive soils leading to reduced SR percentages. Additionally, tillage methods had a marked influence on SR values. The use of CT resulted in higher SR values of 18.35% compared to TT and MT systems, which recorded lower SR values of 13.69% and 6.03%, respectively. SR measurements were also found to be affected by the draft force during the loading of A-TE, emphasizing the role of operational conditions in tractor performance, especially in challenging field environments. Comparison between NDSS and traditional techniques revealed that the NDSS offered high accuracy, flexibility, configurability, and consistent performance. The NDSS demonstrated superior precision, making it an effective tool for assessing SR in agricultural tractors.

Assembled self-centering brace with replaceable friction damper for seismic resilience: Development and mechanical behavior research

A novel seismic resilient brace, integrating a replaceable friction damper mechanism with an assembled self-centering device of combination disc springs, has been developed and investigated through experimental research. This brace can be named as the Assembled Pre-pressed Disc-springs Self-centering Replaceable Energy Dissipation (APD-SRED) brace. The working principles, structural configurations, fabrication process and mechanical behaviors of this bracing system were discussed and analyzed firstly in detail. Subsequently, five brace specimens were designed incorporating different axial pre-compression forces within a combination disc springs system and varying friction forces in the damper device. Test results exhibit a stable and repeatable flag-shaped hysteretic responses with satisfactory energy dissipation, which can be implemented under the low cyclic reversed loading. Additionally, it can be noted that the excellent seismic resilience performance can be obtained by maintaining a relative balance between self-centering and energy dissipation characteristics. The stiffness and strength of this brace can withstand cyclical loading without degradation, making superiorities against sequential design earthquakes without the replacement or repair, and facilitating replacement of the friction energy dissipation components to meet different demands. Moreover, the proposed calculation model can be validated accurately predicting the mechanical behavior of the APD-SRED brace by considering friction effects in disc-springs. This validation was achieved through comparisons with experimental results, and several crucial design factors influencing the brace's behavior were analyzed and discussed for practical application in a parametric design. Finally, drawing upon a combination of experimental and analytical studies, this study ultimately presented practical design recommendations.

Experimental study on acoustic emission damage in precast reinforced concrete interior joints containing disc springs

To address the inferior performance of precast reinforced concrete beam-column joints compared to cast-in-place joints during earthquakes, this study designed a precast concrete frame beam-column interior joint incorporating disc springs. The disc springs, installed based on grouted sleeve connections, aimed to enhance structural ductility and mitigate seismic forces on the joints. Five joints, including one cast-in-place joint, two ordinary precast joints, and two precast joints with disc springs, were tested quasi-statically and monitored using acoustic emission technology. The precast joints had axial compression ratios of 0.2 and 0.4. Parameters such as energy, count, and b-value from acoustic emission monitoring were analyzed. The Gaussian mixture model was employed for the clustering analysis of RA-AF parameters, and a damage model was developed to evaluate performance differences among the joints in the quasi-static tests. The results indicate that precast joints with the same axial compression ratio can achieve performance similar to cast-in-place joints, with more rapid damage development at higher axial compression ratios. Installing disc springs decelerates damage progression in the later stages of loading, maintaining joint integrity for a certain period even after reaching maximum load, thereby demonstrating improved ductility. At higher axial compression ratios, the b-value curve of joints with disc springs more closely resembles that of ordinary joints. Disc springs' positive effect is more pronounced in clustering analysis and damage models, such as their lower proportion of shear fractures.

Engineering considerations for the development of disk spring stacks for vibration isolation

Coned disk springs exhibit significant nonlinear properties including the quasi-zero stiffness regimes that are useful in isolating equipment at the lower frequency vibrations. However, the stroke of a single disk spring is too low for most applications, and thus springs must be stacked to increase the deflection. Development of such isolator stacks then becomes critical for practical uses. The goal of this article is to identify challenges and engineering considerations in developing such stacks within the practical constraints. For instance, how to appropriately contain the stack without affecting the low-frequency isolation performance. Three designs are analyzed: a retaining ring design, tube and shaft design, and zero Poison’s ratio sleeve design. Disk spring stack protypes with each containment method are built, and force-deflection curves are measured and compared with the standalone stacks. Under quasi-static compression testing, each containment method has minimal effect on the standalone stack force-deflection curve. However, significant advantages of certain methods are found including lateral stability, lateral strength, and degrees of freedom. Lastly, advantages, disadvantages, and appropriate applications for each containment method are summarized, and are demonstrated. Salient contribution of this work is the identification of engineering considerations that would lead to robust or versatile containment designs. This has been overlooked in the scientific literature as the stack containment methods are found to be important in the design of isolation devices.

Optimization of Operation Parameters and Performance Prediction of Paddy Field Grader Based on a GA-BP Neural Network

Paddy field leveling is an essential step before rice transplanting. During the operation of a paddy field grader, a common issue is the wrapping of rice straw around the blades, resulting in a low rice straw burial rate. This study focused on analyzing the operating parameters of a disc spring–tooth-combined paddy field grader. A soil–straw mechanism simulation model was created using EDEM 2021 software to simulate the field operation status. Firstly, the single-factor test was carried out, with the working speed, the working depth of the disc cutter roller, and the rotation speed of the cutter roller as the factors and the straw-buried rate (SBR) and the machine forward resistance (MFR) as the test indexes, and the parameter range was optimized. The parameters were optimized by the response surface method (RSM) and machine learning algorithms. The results indicated that the genetic algorithm–back propagation (GA-BP) neural network outperformed other optimization models in terms of prediction accuracy and stability. By utilizing the GA-BP regression model and RSM model for regression fitting, two sets of optimal parameter combinations were obtained. Verification experiments were carried out using two sets of parameter combinations. Taking the average of the experimental results, the simulation results showed that the straw burial rate was 93.47% and the forward resistance was 6487 N for the parameter combinations of RSM, and the straw burial rate was 94.86% and the forward resistance was 6352 N for the parameter combinations of GA-BP; the field experiments showed that the straw burial rate was 92.86% and the forward resistance was 6518 N for the parameter combinations of RSM, and the straw burial rate was 95.17% and the forward resistance was 6249 N for the parameter combinations of GA-BP. The results demonstrated that the GA-BP prediction model exhibited better predictive capabilities compared to the traditional RSM, providing more accurate predictions of the paddy field grader’s field operation performance.

Development of a novel full-scaled self-centering brace with notched steel tubes

A novel self-centering brace with notched steel tubes (SCB-NST) was developed and experimentally studied. The proposed SCB-NST consists of a novel notched steel tube (NST) for energy dissipation and disc springs for self-centering, respectively. Three full-scaled specimens were tested to investigate the hysteresis behavior under cyclic loading. These specimens include a brace with NST only, a brace with disc spring only, and an SCB-NST. The first two tests were specifically conducted to obtain the contributions of the NST and disc springs alone, respectively. The test results illustrate that the first proposed NST displays excellent energy dissipation and deformation capabilities. The proposed SCB-NST exhibits a stable flag-shaped hysteresis behavior, distinguished self-centering, and significant energy dissipation capacity without residual displacement. Furthermore, experimental findings reveal that the disc spring functions as a secondary defense line of the SCB-NST system upon sudden failure of the NST. The cyclic test of the brace with disc spring only shows that the friction between the disc springs should not be neglected, especially when quantities of large-diameter disc springs are stacked. The modular design of the proposed SCB-NST facilitates the replacement of energy-dissipating components, allowing for efficient maintenance and ultimately achieving the design objective of promoting reusability and resource conservation. The SCB-NST, equipped with two NSTs featuring different ultimate displacements, has been confirmed through finite element analysis to have three defense lines, which improves the reliability and redundancy of the SCB-NST system. The parametric finite element analysis results reveal that the thickness of the energy-dissipation ring has the most significant influence on the load-bearing capacity and energy-dissipation capability of the SCB-NST. Concurrently, the pre-pressed force of the disc spring is crucial for eliminating the residual displacement of the SCB-NST.

Seismic Performance of Precast Concrete Exterior Beam-Column Joint with Disc Spring Devices

ABSTRACT To improve the seismic performance of precast concrete reinforced frame structures which are widely used worldwide, and enable a certain repairable function for the precast structure after an earthquake, this paper proposes a new type of precast concrete frame joint using a full grouting sleeve connection with a disc spring device. The disc spring device was connected in series to the longitudinal reinforcement located in the plastic hinge zone at the beam end to provide a restoring force and protect the concrete. Six exterior beam-column joints consisting of one cast-in-situ beam-column joint and five precast concrete frame joints, using a fully grouted sleeve connection equipped with or without a disc spring device, were designed and fabricated. The failure process, hysteretic characteristics, and energy dissipation capacity of the joint specimens were analyzed based on reversed cyclic loading test. The results showed that the energy dissipation and seismic performance of the newly precast concrete joints equipped with the disc spring device were better than those of the precast concrete frame joints connected by ordinary grouting sleeves without a disc spring device. The disc spring device proposed in this study plays a similar role as a damper in the precast joint during loading and has the characteristics of concentrated damage as it transfers part of the damage in the joint core area to the built-in disc spring area at the beam end. Additionally, the deformation of the precast joints under a lateral seismic load was theoretically calculated, the calculated results were in good agreement with the experimental results.

Development and experimental study of disc spring-based negative-positive-uncoupled stiffness devices for structural multi-level seismic fortification

To achieve the structural multi-level seismic fortification objectives, this paper proposes a novel negative-positive-uncoupled stiffness device (NPUSD) based on combined disc springs with multi-linear elasticity characteristics. This device allows for independent variations in the negative stiffness range under small deformations and the positive stiffness range under large deformations. It primarily utilizes the negative stiffness mechanism for seismic mitigation during medium and small seismic events referring to existing research on traditional negative stiffness devices (NSDs) while providing positive stiffness to prevent collapse during major seismic events. The configuration and working principle of the NPUSD are discussed. By replacing the preloaded linear elastic spring of traditional NSDs with multi-linear elastic spring, the NPUSD can effectively and conveniently achieve stiffnesses decoupling. A design algorithm based on the successive area equivalence principle for the multi-linear elastic spring is proposed. Finally, based on a 56-story steel core-outrigger structure, a comparison between NSDs and NPUSDs is made under the four seismic intensity levels. Results show that the novel NPUSDs contribute to achieving structural multi-level seismic fortification objectives.

Pseudo-dynamic tests of steel frame with disc spring self-centering energy dissipation braces under doublet earthquake and mainshock-aftershock sequence

To provide valuable insights into the seismic performance and self-centering behavior of self-centering braced systems, a 1/2-scale 3-story 1-bay steel frame equipped with disc spring self-centering energy dissipation braces (DS-SCBs) was designed, fabricated, and subjected to pseudo-dynamic testing. This testing encompassed various earthquake hazard levels, a doublet earthquake, and a mainshock-aftershock sequence. The experimental findings revealed the stable hysteretic response of the DS-SCB, with no observed degradation in stiffness or activation forces. Additionally, the test frame exhibited outstanding seismic performance, sustaining only confined damage under very rare earthquakes. Due to the presence of the DS-SCBs, the test frame performed commendable self-centering behavior, characterized by minimal residual deformations. Peak story drifts and floor accelerations under two earthquakes of the same hazard level were regarded as equivalent. Furthermore, the subsequent aftershocks exhibited no discernible impact on the seismic performance of the test frame. Floor acceleration spikes were observed at locations where the brace stiffness underwent changes or where adjacent stories moved in opposite directions. The steel frame equipped with DS-SCBs proved to be an attractive, low-damage alternative to conventional steel systems for the development of resilient urban areas.

POWER ACCUMULATOR FOR STABILIZATION OF THE PRESSING PRESSURE OF THE CORE OF A POWERFUL TURBOGENERATOR WITH BUILT-IN METER

In this paper present described features of stabilization and restoration of pressing force of the stator core of a powerful turbogenerator (TG). Weakening of the pressing forces is the cause of a number of negative phenomena, such as increased vibration and loosening of the core sheets with their subsequent destruction (cracking), which is often the cause of generator damage. It is shown that to assess the state of the pressing force in the core of the TG stator, force meters in the clamping prisms of the core, built into the design of the power accumulator (PA) for stabilizing the pressing force of the core, can be used. The design of the package of disc springs used in PA consists of a package of plate springs and allows to stabilize the pressure in the stator core of a powerful TG to a given level without additional control with probes and fixation by tightening the adjustment nuts. Describes the advantages and features of using PA with a package of disc springs for pressure stabilization, installed under the tightening nuts or instead of them on the threaded ends of the tightening prisms. Proposed to use a built-in force measuring transducer, which consists of an elastic sensitive element (ESE) and a capacitive sensor (CS) into PA structure. The purpose of this article is to create a force meter in the clamping prisms of the stator core of a powerful TG using an elastic sensitive element and a capacitive sensor built into the design of a "caseless" power battery to stabilize the pressing pressure of the stator core of a powerful turbogenerator. A number of TG and PA parameters, which should know to calculate the mechanical characteristics of the disc spring unit outlined. The dependence of the force of the spring block on the displacement of the pressure plate of the stator core is determined. Showing that the assessment of the force in the tightening prism performed by measuring the electrical capacity between the potential electrode CS and the grounded element of PA. Measuring the height of the block during planned repairs or operation of the turbogenerator allows you to determine with high accuracy the amount of tension on each tightening prism and therefore the compression force of the core and, if it necessary to adjust the pressing force by tightening the springs. The conversion function of the force converter is determined, taking into account the geometric dimensions of the ESE and CS. The calculation of ESE for mechanical strength was carried out. The use of pressure gauges in tightening prisms allows you to effectively restore and maintain the pressing force of the final packages of the stator core, control the pressure during operation and adjust it without stopping the turbogenerator. The obtained results can be used in systems for stabilizing the pressing force of the stator core with power accumulators and in the system for assessing the current state of the stator core of powerful turbogenerators of the TGV-200 and TGV-300 type. Increasing the accuracy of measurements and reducing operational risks will contribute to the rapid and effective restoration of critical infrastructure and ensure the stable operation of energy facilities.

Effect of disk-to-disk variations on the nonlinear static characteristics and stability regimes of coned disk spring stacks: Experimental and computational studies of quasi-zero-stiffness isolators

In this study, we introduce a novel approach to creating a Quasi-Zero Stiffness (QZS) isolator using off-the-shelf coned disk springs with a unique stack. These springs are affordable, compact, and can be adapted for a broad spectrum of force requirements, enabling the achievement of the QZS effect using a solitary component, thereby eliminating the need to balance the positive and negative stiffness elements. To address the issue of the limited displacement range offered by a single coned spring, the solution involves layering multiple disk springs with rigid spacers. Nonetheless, the nonlinear force–deflection behavior is significantly affected by manufacturing-driven geometric variability due to inherent differences from one disk spring to another. This aspect of variability has been overlooked by previous researchers, who have operated under the assumption that all disks in a stack are identical. This research delves into how variations in the disk springs’ geometry impact the nonlinear static behavior of the QZS stacks, employing both experimental and computational techniques. We illustrate the stability conditions and pinpoint the occurrences of buckling and snap-through events. Computational model for the multi-disk engineered stack is experimentally validated. Finally, we explore the QZS isolator design approaches that would take into account these geometric variations.

Design and Analysis of a Novel Impact- Resistant Electro-Mechanical Actuator With Disc Spring Compression and Hydraulic Buffering Mechanism

Design and Analysis of a Novel Impact- Resistant Electro-Mechanical Actuator With Disc Spring Compression and Hydraulic Buffering Mechanism

Seismic mitigation analysis of three-dimensional base-isolated nuclear structures with soil-dependent isolation system under extreme earthquakes

The Fukushima nuclear accident in March 2011 has raised more stringent requirements for the ability of nuclear power plants (NPPs) to withstand extreme disasters such as extreme earthquakes. To address this challenge, this study proposed a new hybrid multi-dimensional passive control system that combines three-dimensional base isolation and geotechnical seismic isolation. In this system, high-damper rubber bearings were employed to isolate horizontal seismic motions, whereas disc springs, accounting for frictional forces, were used to mitigate vertical seismic motions. Additionally, a geotechnical seismic isolation system arranged under the base mat was leveraged to further reduce the seismic response of the superstructure. Taking a large-scale reactor building in complex layered sites as an example, the effectiveness of the hybrid multi-dimensional isolation system was studied using a wave motion method. The research results indicate that when subjected to extreme earthquakes, hybrid multi-dimensional isolation exhibits superior isolation performance compared with three-dimensional base isolation, which can significantly reduce the three-dimensional dynamic response of nuclear structures without increasing the displacement of the isolation bearings. The proposed hybrid multi-dimensional isolation system offers an effective solution to the challenges faced by three-dimensional isolation systems, thereby enhancing the seismic resistance of nuclear structures against extreme earthquakes.

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.

Effectiveness of displacement compensation units for integral abutment bridges

Integral abutment bridges (IAB) have become increasingly popular in the past few decades due to their design simplicity. UK design rules limit the length of IABs to 60 m, due to the issues associated with thermal strains, settlement, and pressure build-up behind the abutment. A cyclic loading test, representing seasonal thermal fluctuations, was conducted on a 1/12 scaled-down retaining wall of a conventional full-height IAB. The test was then repeated with the inclusion of displacement compensation units (DCU) in the form of conical disc springs (CDS) and hollow rubber cylinders (HRC), which operate in a pre-deformed shape. The results show some remarkable improvements in the IAB performance with DCUs. The soil backfill pressure was reduced to 30% and 47% with CDSs and HRCs, respectively. Furthermore, no settlement was observed, as compared to the conventional IAB test which recorded a 20 mm settlement after 100 cycles. Non-linearity in the force-deflection behaviour of DCUs enables expansion and contraction of the deck to be accommodated with minimal fluctuation of backfill pressure. Finally, a finite element (FE) model of an HRC applied with two temperatures has been analysed and compared with the IAB wall test, which suggests that both analyses showed some correlation.

Analytical and numerical simulation of seismic resilient rocking column with enhanced RC column and pre-pressed disc springs devices

This paper presents a novel self-centering energy dissipating RC rocking column (SCERC) in which a steel tube protects the concrete from spalling and crushing at the column base. It incorporates an easily repairable pre-pressed disc spring self-centering device (SC) to restore the rocking column to its original position and a straightforward slip friction energy dissipation device (ED) to ensure adequate energy dissipation capacity. The working principle of the SC was investigated, and an analytical method was proposed. Subsequently, a theoretical hysteresis model for the SCERC considering different limit states is developed through reliable analyses. Lastly, the preliminary design parameters of the SCERC were determined, with numerical simulations conducted to validate the theoretical model. These simulations aim to explore the hysteresis characteristics, energy dissipation capabilities, and self-centering performance of the SCERC under different axial pressures and self-centering ratios. The results indicate that the theoretical hysteresis model was consistent with the numerical simulations, revealing that the SCERC exhibits a “flag-shaped” hysteresis response. The proposed SCERC displays satisfactory energy dissipation and self-centering characteristics. The SC provide sufficient restoring forces, with the EDs accounting for much of the energy dissipation. Plastic deformation was not observed in the concrete column, except for the unavoidable deformation occurring in the steel tube at the point of rotation. While a rocking column naturally possesses self-centering capabilities under axial forces, it requires SCs to counteract the negative stiffness caused by the P-∆ effect. As the self-centering ratio decreases, both the load capacity and energy dissipation capacity of the SCERC increase, leading to an increase in the residual deformation of the column; hence, the design should balance these two aspects for a suitable self-centering rate.

Modification of friction block connection for improving the tribological behavior of high-speed train braking interface

This work aims to improve interface tribological behavior by modifying the friction block connection. The effectiveness of this approach and its underlying mechanisms are evaluated through friction braking test and finite element analysis (FEA). A finite element model (FEM) was established based on the main structure and material parameters of the high-speed train braking performance simulation test setup. The Achard wear formula was used to adequately run-in the friction block. Using a restart analysis to inherit the model post run-in, complex eigenvalue analysis (CEA) and implicit dynamic analysis (IDA) were conducted. Results indicate that the disc spring deformation significantly affects tribological behavior and friction-induced vibration and noise (FIVN) via regulating the contact state at the braking interface. Inappropriate deformation of the disc spring can lead to severe eccentric wear of the friction block, exacerbating the tribological behavior at the braking interface and inducing the brake system to generate high-intensity FIVN. Therefore, rational design of disc spring connection is an effective strategy for improving interface tribological behavior, but the disc spring connection design must provide it appropriate deformation capability. This is essential to ensure that the braking interface exhibits favorable contact state, thereby improving tribological behavior.

Investigating quench crack susceptibility in disc springs: a microstructural analysis of martensitic evolution and its implications

Investigating quench crack susceptibility in disc springs: a microstructural analysis of martensitic evolution and its implications

Experimental and numerical study of enhanced elongation self-centring beams

An enhanced elongation self-centring beam (ESCB) was developed in this study for use in short-span buildings. Disc springs were inserted into the beam body to provide additional elastic elongation while avoiding unexpected yielding via an overload-protective component. The mechanics of the ESCB in a frame and the equations governing its hysteresis were explained in detail. After the hysteretic behaviours of the ESCB frame were further validated using experimental and numerical approaches, a new hysteretic model was established to accurately reproduce its dynamic behaviours under seismic loads. The dynamic analyses from the established hysteretic model showed that the ESCB systems had smaller mean peak displacements and minimal mean residual displacements than the original self-centring beam systems.

Numerical investigation of three-dimensional isolator and mitigation for single-layer lattice shell structure

Three-dimensional (3D) isolators need to have capabilities to support the dead weight of superstructures and mitigate both horizontal and vertical seismic responses of structures. However, the lack of self-centering capability under horizontal loadings and large stiffness under vertical loadings of the 3D isolators might limit their isolation performance in practical engineering. This study presents a novel 3D isolator (hereinafter referred to as DS-SMA-FS) to achieve self-centering capability under horizontal loadings and quasi-zero stiffness under vertical loadings. The self-centering capability is provided by shape memory alloys U-shaped dampers (SMA-UDs), and the quasi-zero stiffness (QZS) property is realized by the negative stiffness of disc spring (DS) isolator and positive stiffness of SMA-UDs. The working mechanism and analytical model of the DS-SMA-FS isolator were developed first. The finite element model of the DS-SMA-FS isolator was furtherly established. Numerical results revealed that DS-SMA-FS can exhibit SC capability under horizontal loadings and QZS property under vertical loadings. Subsequently, single-layer lattice shells were established to explore the isolation performance of the DS-SMA-FS isolator. Structural analysis results indicated that the DS-SMA-FS isolator can prolong the natural vibration periods of the shell and effectively prevent the shells from tri-directional earthquakes.