Rolling Sphere Research Articles

Investigating the time-distance relationship: an innovative approach to Galileo’s inclined plane experiment using Arduino

Abstract In this paper, we present an innovative approach to hands-on scientific inquiry, for classroom use, by integrating modern tools such as reflective photointerrupter sensors and sound emitters into an experimental setup. Inspired by Galileo’s pioneering work, our proposed experiments investigate the relationship between sound intervals and the motion of an object along an inclined U-shaped profile. Using different sensor arrangements, we explore the quadratic relationship between distance and time for spheres rolling on the inclined plane. Additionally, we discuss a simplified theoretical framework facilitating comparison between theoretical and experimental acceleration values. Our findings demonstrated a close correspondence between experimental distance-time data and theoretical predictions, validating the effectiveness of our approach.

Metoda poboljšanja potresno izoliranih mostova novim V-MG uređajima: dinamička ispitivanja modela

A method for enhancing the seismic performance of isolated bridges was developed using innovative vertical multigap (V-MG) devices based on extensive experimental and analytical research. Significant improvements in seismic performance were achieved by creating a unique type of uniform V-MG energy-dissipation device for a vertical-gaped bridge protection system (VG bridge system) that included double spherical rolling seismic bearings for seismic isolation as a complete set. Seismic shaking table tests on large-scale bridge models, which simulated real earthquake conditions, confirmed that the VG bridge system could significantly modify seismic response and enhance the seismic safety of isolated bridges under very strong earthquakes.

Lightning Strike Danger Zone Detector System Integrated with Smartphone

The potential for direct hits and bounces from buildings during thunderstorms can endanger pedestrians in the open area of the Faculty of Engineering Untirta campus. So far, there has been no danger warning in the open area so that pedestrians in the area are not prepared if unwanted things happen, especially when there is rain and lightning. Direct lightning strikes are one of the hydrometeorological events that need to be watched out for. Because of its impact that can cause damage to objects and casualties if exposed to humans. The campus area has a fairly large open area, making the threat of lightning strikes can occur at any time, especially during the rainy season. The purpose of this research is to design and implement a direct lightning strike hazard zone detection device in the campus area of the Faculty of Engineering UNTIRTA located in the city of Cilegon. The stages of research carried out include analyzing the open area of the FT campus using the Rolling sphere method. After that, plotting the area of the analysis results. Then an area detection tool was created which is categorized as a direct lightning strike danger zone that is integrated with Smartphone notifications.

Adaptive Seismic Upgrading of Isolated Bridges with C-Gapped Devices: Model Testing

The seismic safety margins of seismically isolated bridges have not been thoroughly studied or comprehended due to a lack of actual on-site data observations. This study introduces a newly validated method for the efficient seismic protection of bridges that may be exposed to extremely strong, multidirectional near-source and critical far-source earthquakes. The isolated system was improved by incorporating innovative adaptive horizontal C-multigapped (HC-MG) energy dissipation devices to overcome the safety limitations associated with solely using isolated bridges under seismic loads. The newly developed adaptive C-gapped (ACG) bridge system was systematically validated through extensive experimental seismic tests on bridge models and additional analytical studies. The new ACG bridge system represents an advanced technical solution that integrates the benefits of seismic isolation and energy dissipation. The seismic isolation system for the large-scale ACG bridge prototype was designed using double spherical rolling seismic bearings (DSRSB). The seismic performance of the system was enhanced with adaptive HC-MG energy dissipation devices. The improved seismic performance of the system was demonstrated through extensive seismic shaking-table tests on the ACG bridge prototype, simulating selected seismic inputs characteristic of typical near- and far-source earthquakes. Doi: 10.28991/CEJ-2024-010-09-01 Full Text: PDF

A multi-stable rotational energy harvester for arbitrary bi-directional horizontal excitation at ultra-low frequencies for self-powered sensing

A rotational multi-stable energy harvester has been presented in this paper for harnessing broadband ultra-low frequency vibrations. The novel design adopts a toroidal-shaped housing to contain a rolling sphere magnet which absorbs mechanical energy from bidirectional base excitations and performs continuous rotational movement to transfer the energy using electromagnetic transduction. Eight alternating tethering magnets are placed underneath its rolling path to induce multi-stable nonlinearity in the system, to capture low-frequency broadband vibrations. Electromagnetic transduction mechanism has been employed by mounting eight series connected coils aligned with the stable regions in the rolling path of the sphere magnet, aiming to achieve greater power generation due to optimized rate of change of magnetic flux. A theoretical model has been established to explore the multi-stable dynamics under varying low-frequency excitation up to 5 Hz and 3 g acceleration amplitudes. An experimental prototype has been fabricated and tested under low frequency excitation conditions. The harvester is capable of operating in intra-well, cross-well, and continuous rotation mode depending on the input excitation, and the validated physical device can generate a peak power of 5.78 mW with 1.4 Hz and 0.8 g sinusoidal base excitation when connected to a 405 Ω external load. The physical prototype is also employed as a part of a self-powered sensing node and it can power a temperature sensor to get readings every 13 s on average from human motion, successfully demonstrating its effectiveness in practical wireless sensing applications.

Terminal velocity and drag coefficient of a smooth steel sphere moving in the water-filled vertical and inclined glass pipe (Newton regime)

This paper aimed to determine new data on terminal velocities and drag coefficients of single spheres moving inside a vertical and inclined glass pipe filled with water using the Particle Image Shadowgraph technique in the range of Reynolds numbers from 1420 to 12,740. The inclination angle α of the pipe varied from 0° to 30° relative to the vertical position. In the experiment, smooth steel spheres with diameters ranging from 3 to 9.5 mm were used, and the pipe had a fixed inner diameter of 40 mm. For verification, the experimental results of the drag coefficients were compared with known data from other authors for a free-settling sphere and a sphere rolling down a pipe wall or plane. Finally, the paper presents a new regression model describing the relationship between the sphere drag coefficient and Reynolds number when the cosine of the pipe inclination angle is varied.

Open On-Limb Robot Locomotion Mechanism with Spherical Rollers and Diameter Adaptation

Open On-Limb Robot Locomotion Mechanism with Spherical Rollers and Diameter Adaptation

An experiment for the study of projectile motion

The classic demonstration experiment of the motion of a point mass thrown at an angle to the horizon is studied. Several measurements of the range of a projectile launched sphere are carried out and compared with the results that were obtained by an analytical approach. The sphere’s motion can be treated as two independent movements, a linear uniform movement in the horizontal direction and a uniformly accelerated motion in the vertical direction. The value of launching velocity obtained by kinematics is compared with those predicted by the law of mechanical energy conservation. The conclusion is that the model of a frictionless sliding sphere is far from explaining the experimental result. The model could be improved proposing that the sphere rolls without sliding (pure rolling) on the platform including the rotational kinetic energy. Finally, the fact that the sphere does not settle completely on the launch rail was considered using an effective radius of rotation. Observed from the three proposed models, the last one is the closest to the obtained experimental value. These activities can also improve students’ understanding of the concept of projectile motion.

Integration of electromagnetic and mechanical models for effective lightning protection in buildings

The study focused on the design of an advanced algorithm for the optimal sizing of protection systems against atmospheric discharges in architectural structures, applying the rolling sphere method. This technique facilitated the incorporation of user-specified parameters through an advanced graphical interface. The methodology began with the exhaustive accumulation of data relevant to the project. Risk indices were estimated through sophisticated risk analysis software applications. If adjustments were required, the process continued; If not, the building was considered to be adequately secured. The ground resistivity was evaluated according to IEEE Std. 81, and the rolling sphere method was implemented according to IEC 662305-3. The grounding systems were configured in accordance with IEEE Std. 142 and IEEE Std. 80. To analyze the interaction of electrical discharges with the protected building, the electrical equivalents of elements such as meshes, fused copper rods were computed. , and conductors positioned horizontally and vertically. Using these data, a model was built in ATPDraw, interconnected with Python for the generation of graphical representations of the current waves in the different protection subsystems. To conclude and corroborate the effectiveness of the process, the risk indices were reevaluated. The validation of the algorithm was achieved by minimizing the margin of error to insignificant levels by incorporating standardized data proposed by organizations such as IEC and IEEE, thus confirming the precision of the designed algorithm

Fenomena Back Flashover Akibat Sambaran Petir Pada SUTT 150 kV Haurgeulis–Sukamandi#2

Lightning disturbances on the 150 kV High Voltage Overhead Transmission Line (SUTT) Haurgeulis-Sukamandi #2 were analyzed to understand their causes and impacts. This study aims to identify and analyze lightning-induced disturbances using data from Fault Locator, Digital Fault Recorder, and Lightning Detection System. The methods used include calculating the protection angle, analyzing the maximum current before shield failure, and applying the Rolling Sphere method. The analysis results showed that the lightning current of -22 kA exceeded the tower's shielding capacity, causing a Back Flash Over phenomenon that led to system disruption. This finding was confirmed by comparing the measured voltage with the breakdown voltage of the insulator. The implications of this study highlight the importance of enhancing lightning protection systems, such as reducing tower grounding resistance and installing inductance reducers, to prevent similar disturbances in the future. This research provides valuable insights for improving the reliability and safety of power transmission networks in lightning-prone areas.

Simulation analysis of microstructure development of tricalcium silicate using the needle model of calcium silicate hydrate

This study proposes a two-scale model for tricalcium silicate (C3S) hydration to examine the microstructure of hydrated C3S paste. The needle-like morphology of a calcium silicate hydrate (C-S-H) layer, as observed in many studies, was constructed using this model based on the assumption of C-S-H needles. The boundary nucleation and growth pattern of the C-S-H needles were illustrated, and the impingement among C-S-H needles and particles was considered. The pore size distribution was calculated using the rolling sphere method for the hydrated particle system and C-S-H layer. The simulation results were compared with existing experimental data, revealing consistency for the C3S paste with different hydration times. The shape and growth parameters of the C-S-H needles were studied to model their microstructure. The microstructure constructed using this model was found to be more reasonable and could provide a more accurate description of the C-S-H morphology.

Comparative Analysis of External Lightning Protection Systems Using Protective Angle and Rolling Sphere Method in Areas That Have High Lightning Intensity

Indonesia is a tropical country with a geographical condition where 71% of its area is water. This is what coueses Indonesia is considered a country with a high density of lightning strikes. This results in buildings in Indonesia being at a high risk of damage caused by lightning strikes. According to data from BMKG, the city of Malang has a high lightning intensity, with 108 thunderstorm days per year, posing a serious threat to the Electrical Engineering Building of the Faculty of Engineering at the University of Malang. Considering the building's age and expansion on the building's side, it is necessary to evaluate the lightning protection system to determine whether the existing system is still working effectively and efficiently. Improving the system's performance against lightning disturbances can be done by analyzing the previous external lightning protection system and then evaluating it using the angle of protection and rolling sphere methods. The analysis and evaluation of the external protection system are based on PUIPP, PUIL, SNI, and IEEE standards.

Research on die-less spinning by spherical roller of different radius

Research on die-less spinning by spherical roller of different radius

PERENCANAAN SISTEM PENYALUR PETIR PADA GEDUNG - A UNIVERSITAS MPU TANTULAR CIPINANG

Mpu Tantular University is one of the leading Universities in Indonesia and has three buildings to support learing/teaching activities. Bulding-A Mpu Tantular University has 8 floors. As a vital place and has a potential for lightning strikes, because it is classified as a building with a risk of lightning strikes, Building-A need to be calculated and planned for an external lightning conductor, so that the electronic equipment inside is safe if there is a lightning strike. In determining whether or not a lightning protectionsystem is necessary, a comparative study should be carried out using the reference to the Indonesian National Standart SNI 03-7015-2004 concerning Lightning Protetion System in Buildings. The design of this lightning protection system uses the Rolling Sphere method on the Air Termination System and Multiple Rod on Earthing Termination System, so that the condition of Building-A is safe and in accordance with applicable regulation in building planing

A simplified spherical roller bearing model and its application in the wind turbine main bearing system finite element modeling

Different from most bearing design guidelines, deformation of bearing rings and supporting structures usually influences the bearing performance significantly. Finite element analysis (FEA) can be used in bearing system design considering the structure deformation, but the contact region between rolling elements and raceways modeling is very complex and usually causes non-convergent problems. As to a spherical roller bearing (SRB), the model must also consider both its misalignment ability and roller contact stiffness. This paper presents a simplified SRB model considering the angular misalignment ability. In order to define the SRB roller raceway load deformation relationship, a lamina model is developed. And this simplified model is validated by solid roller model of a bearing sector. A wind turbine main bearing system is analyzed using the developed SRB model. Load distribution considering the system deformation and angular misalignment are discussed. With the help of fine meshed solid elements roller raceway contact model, the raceway contact pressure and subsurface stress distribution can also be obtained.

Effects of surface roughness on the drag coefficient of spheres freely rolling on an inclined plane

An experimental investigation identifying the effects of surface roughness on the drag coefficient ( $C_{D}$ ) of freely rolling spheres is reported. Although lubrication theory predicts an infinite drag force for an ideally smooth sphere in contact with a smooth wall, finite drag coefficients are obtained in experiments. It is proposed that surface roughness provides a finite effective gap ( $G$ ) between the sphere and panel, resulting in a finite drag force while also allowing physical contact between the sphere and plane. The measured surface roughnesses of both the sphere and panel are combined to give a total relative roughness ( $\xi$ ). The measured $C_{D}$ increases with decreasing $\xi$ , in agreement with analytical predictions. Furthermore, the measured $C_{D}$ is also in good agreement with the combined analytical and numerical predictions for a smooth sphere and wall, with a gap approximately equal to the root-mean-square roughness ( $R_q$ ). The accuracy of these predictions decreases for low mean Reynolds numbers ( $\overline {Re}$ ), due to the existence of multiple scales of surface roughness that are not effectively captured by $R_{q}$ . Experimental flow visualisations have been used to identify critical flow transitions that have been previously predicted numerically. Path tracking of spheres rolling on two panels with different surface roughnesses indicates that surface roughness does not significantly affect the sphere path or oscillations. Analysis of sphere Strouhal number ( $St$ ) highlights that wake shedding and sphere oscillations are coupled at low $\overline {Re}$ but with increasing $\overline {Re}$ , the influence of wake shedding on the sphere path diminishes.

Recent Advancements in Fault Diagnosis of Spherical Roller Bearing: A Short Review

Recent Advancements in Fault Diagnosis of Spherical Roller Bearing: A Short Review

Roundness error stacking in assembled spherical roller bearings and its impact on rotor subcritical vibration

In industrial processes, large rotors are commonly operated below the critical speed, where bearings can be an important source of subcritical vibration. This paper presents a complete study and analysis of the roundness error stacking in rotor-bearing systems. The investigation on how the roundness error of tapered shafts is transferred through the bearing inner ring to the raceways during the assembly process allows to evaluate the final roundness profile of the raceways as the sum of the shaft roundness profile plus the inner ring thickness variation. The method’s validity is verified for relative orientations and mounting conditions between the components.A test case is presented in which 3D conical grinding is applied to a shaft tapered bearing installation seats, reducing the roundness error of installed bearings when compared to previous research results. The relevance of the study was proven with rotordynamic measurements, which show that minimized roundness error reduces vibrations.

Effect of sand particle shape on micromechanical modeling in direct shear testing

Soil representation in discrete element method (DEM) simulations is a complex process due to the intrinsic variability in grain shape. Many methods have been proposed to include shape effects in DEM, from rolling friction to aspherical particle representations such as ellipsoids or polyhedra. In this paper the micromechanical differences between two commonly used methods of shape representation, rolling friction applied to spherical particles and ellipsoids, are investigated for direct shear testing. This simulation study is supported by dry direct shear tests in the laboratory using a poorly graded sand and three vertical confining pressures: 50, 100 and 200 kPa. While the bulk behavior observed in the laboratory can be matched using both shape representation approaches, the micromechanics show significant differences. The average cumulative rotation of the ellipsoidal particles is an order of magnitude lower than for the spheres with rolling friction. The addition of rolling friction significantly affects the mechanical redundancy of the system, making the spherical-particle samples more hyperstatic than their ellipsoidal equivalents. Although using ellipsoids enables a better representation of the micromechanical behavior, this increases the computational cost five-fold compared to using rolling friction and spheres.

Spherical rolling robots—Design, modeling, and control: A systematic literature review

Spherical robots have garnered increasing interest for their applications in exploration, tunnel inspection, and extraterrestrial missions. Diverse designs have emerged, including barycentric configurations, pendulum-based mechanisms, etc. In addition, a wide spectrum of control strategies has been proposed, ranging from traditional PID approaches to cutting-edge neural networks. Our systematic review aims to comprehensively identify and categorize locomotion systems and control schemes employed by spherical robots, spanning the years 1996 to 2023. A meticulous search across five databases yielded a dataset of 3199 records. As a result of our exhaustive analysis, we identified a collection of novel designs and control strategies. Leveraging the insights garnered, we provide valuable recommendations for optimizing the design and control aspects of spherical robots, supporting both novel design endeavors and the advancement of field deployments. Furthermore, we illuminate key research directions that hold the potential to unlock the full capabilities of spherical robots.