Behavior Of Balls Research Articles

Design of a Guided Inquiry Classroom Activity to Investigate Effects of Chemistry on Physical Properties of Elastomers

Typical organization of science and mathematics K12 education divides subjects into discrete courses. However, science and engineering are highly interdisciplinary fields. To better equip students to engage in the interdisciplinary nature of real-world STEM research and practice, projects can be used to highlight the interconnectivity of core subjects. Here, we present an exploratory, guided inquiry classroom research project. This work details student-led experiments combining physics and chemistry principles to fabricate silicone bouncy balls and analyze resulting mechanochemical relationships in these elastomeric materials. In this project, students embodied researchers to uncover foundational relationships among chemistry, physics, and mathematics. To do this, students used silicone kits to design an array of polymer formulations resulting in bouncy balls of varying stiffnesses. Students aimed to answer a physics-based research question using chemistry and mathematics. The resulting data was used to discuss the effect of polymer chemistry on the behavior of the bouncy balls. This exercise serves to combine hands-on fabrication methods with quantitative analysis, using experimental methods of varying costs and complexities that can be tailored to instructor time and budget. The project presented here is appropriate for upper-level high school students or first-year undergraduates. The pedagogical goal of the work is to empower students to realize and use connections between chemistry, physics, polymer science, and engineering to understand the process of material design and selection.

Dependence of the dissipated energy of particles on the sizes and numbers of particles and balls in a planetary ball mill

The dissipated energy received by the particles during collisions in a high-energy ball-milling can vary due to the breakage and/or aggregation of the particles, that is, a change in the particle size. To investigate the energy variations, a numerical analysis of the behavior of particles and balls in a planetary ball mill was carried out under various conditions, considering different sizes and numbers of particles and balls using the discrete element method (DEM). The variable sizes and numbers of particles and balls affected the contact force, collision frequency, and types of particle collisions, resulting in variations in the dissipated energy distribution and specific dissipated power, even at a constant ball-to-particle filling mass ratio (BPR). The variation in specific dissipated power was expressed as a function of the sizes of the particles and balls and the BPR. According to the obtained empirical formula, the particle-to-ball size ratio strongly affects the specific dissipated power rather than the BPR. The results suggest that based on the energy variations with particle size and number, using balls of appropriate size and number can control the dissipated energy of particles, which may lead to the designing of energy-efficient milling processes.

The effect of lubricant temperature on dynamic behavior in angular contact ball bearings

The dynamic behaviors of rolling bearing are influenced by various factors, such as the lubricant temperature and lubricants used, which is especially desirable for the high-speed conditions. In this paper, the dynamic model of angular contact ball bearing with considering the interactions between balls and raceways, cage and guiding surface is built firstly, and then effects of temperature and lubricant type on the dynamic characteristic are investigated. The five-parameter rheological model is applied to determine the traction coefficients, which considers the effect of lubricant temperatures. The results show that both the lubricant temperatures and lubricant types significantly affect the skidding behavior of balls and the impact force between ball and cage.

A feasibility study on behavior of balls in a bearing using Discrete Element Method

A feasibility study on behavior of balls in a bearing using Discrete Element Method

Ball bearing turbocharger vibration management: application on high speed balancer

Today's modern internal combustion engines are increasingly focused on downsizing, high fuel efficiency and low emissions, which requires appropriate design and technology of turbocharger bearing systems. Automotive turbochargers operate faster and with strong engine excitation; vibration management is becoming a challenge and manufacturers are increasingly focusing on the design of low vibration and high-performance balancing technology. This paper discusses the synchronous vibration management of the ball bearing cartridge turbocharger on high-speed balancer and it is a continuation of papers [1–3]. In a first step, the synchronous rotordynamics behavior is identified. A prediction code is developed to calculate the static and dynamic performance of “ball bearing cartridge-squeeze film damper”. The dynamic behavior of balls is modeled by a spring with stiffness calculated from Tedric Harris formulas and the damping is considered null. The squeeze film damper model is derived from the Osborne Reynolds equation for incompressible and synchronous fluid loading; the stiffness and damping coefficients are calculated assuming that the bearing is infinitely short, and the oil film pressure is modeled as a cavitated π film model. The stiffness and damping coefficients are integrated on a rotordynamics code and the bearing loads are calculated by converging with the bearing eccentricity ratio. In a second step, a finite element structural dynamics model is built for the system “turbocharger housing-high speed balancer fixture” and validated by experimental frequency response functions. In the last step, the rotating dynamic bearing loads on the squeeze film damper are coupled with transfer functions and the vibration on the housings is predicted. The vibration response under single and multi-plane unbalances correlates very well with test data from turbocharger unbalance masters. The prediction model allows a thorough understanding of ball bearing turbocharger vibration on a high speed balancer, thus optimizing the dynamic behavior of the “turbocharger-high speed balancer” structural system for better rotordynamics performance identification and selection of the appropriate balancing process at the development stage of the turbocharger.

Clinical pattern of fungal balls in the paranasal sinuses: our experience with 70 patients.

Many physicians recommend endoscopic sinus surgery (ESS) even when an asymptomatic paranasal sinus (PNS) fungal ball is detected incidentally. The aim of this study was to investigate the natural behavior of PNS fungal balls via sinus imaging techniques. A follow-up study of 74 pathologically confirmed fungus balls was conducted in 70 patients who underwent multiple head and neck computed tomography (CT) scans or magnetic resonance imaging (MRI). We investigated the changes in symptoms and lesion size, as well as any new occurrences. Of the 74 fungus balls detected in 70 patients, we observed the renewed formation of a fungal ball in 21 patients, which was not present on initial imaging conducted over a period of 2-162 months. The fungal ball was already present in 53 patients on the initial screening, and the longest follow-up was 197 months (range 1-197 months). Of these 53 lesions, 29 lesions showed an increase in size (29/53, 54.7%), whereas 12 lesions were not associated with any clinical symptoms (12/53, 22.6%). In the 21 newly formed fungal balls, further development was observed in 10 lesions, with 4 lesions showing an increase in size. Thus, size increment occurred in 33 of the 57 fungus balls. The fungal balls can exist without local tissue invasion for up to 17years and new formation of the fungal balls was observed even within 2 months, especially when accompanied by initial clinical symptoms of sinusitis.

Aerodynamic characteristics and flow field analysis by PIV on peculiar flight behavior of soft tennis balls

Aerodynamic characteristics and flow field analysis by PIV on peculiar flight behavior of soft tennis balls

Effect of Aging Time on Deformation Behavior of Lead-Free and Lead Base Solders Alloys

The effect of aging time on the deformation behavior of lead-free and lead- based sub-mm solder alloys were investigated. Experimental results showed that the aging time (less than 4 hours) did not have any effect on the anisotropy behavior of Tin solder balls during compression processes but that is clear in other intervals time specially when the aging time increased, and the microstructure images show different grain growth in high temperature longer time and the Tin anisotropic behavior in lead-free solder alloys

Friction and Wear Behavior of AlTiN-Coated Carbide Balls Against SKD11 Hardened Steel at Elevated Temperatures

In this study, AlTiN coatings were deposited on YT14 cemented carbide balls by arc ion plating technique. The friction and wear behavior of the AlTiN-coated balls against SKD11 hardened steel was investigated by sliding tests using a ball-on-disk tribometer at various temperatures from 25 to 700 °C in air. The results showed that the friction and wear behavior was significantly influenced by the testing temperature. Obvious fluctuations were observed in the friction curves at elevated temperatures, which could be attributed to the formation and rupture of unstable Fe and Cr oxide layers. As the temperature increased from 25 to 500 °C, the wear rate of the coated balls increased from the scale of 10−21–10−20 m3/N m, and then decreased to 10−22 m3/N m as the temperature further increased to 700 °C. It was also found that the friction and wear behavior of the coated balls was directly dependent on the counterpart materials. As the temperature increased, the main wear mechanism of the coated balls changed from mild abrasive wear and adhesive wear to abrasive wear failure at 500 °C, and then transferred to adhesive wear and mild oxidation wear at 700 °C. For SKD11 hardened steel, the primary wear mechanism changed from delamination wear to abrasive wear and then transferred to plastic deformation and fatigue wear, accompanied by adhesive wear and tribo-oxidation wear.

Sensitivity analysis on the fatigue life of solid state drive solder joints by the finite element method and Monte Carlo simulation

We proposed a method to determine the probabilistic fatigue-life distribution of solid state drives (SSDs) due under thermal cycling through finite element method and Monte Carlo simulation and the effect of their design and operating variables on failure through sensitivity analysis. In the developed finite element model, we utilized the Anand model to represent the viscoplastic behavior of solder balls and utilized the Prony series to represent the viscoelastic behavior of a polymer material in the underfill. In order to verify the developed finite element model, we compared the simulated strain with that measured in a thermal chamber. Using the developed finite element model, thermal cycling analysis was performed to determine the fatigue life of the SSD using the simulated results and Morrow’s energy-based fatigue model. The finite element analysis results showed that the outermost solder ball at the corner of the dynamic random access memory (DRAM), was the most vulnerable component under thermal cycling. Monte Carlo simulation was performed to analyze the fatigue life distribution according to the manufacturing tolerances of the design and operating variables of the SSD. Sensitivity analysis was also performed to determine the effects of variables on number of cycles to failure. The analysis results showed that the minimum temperature of the thermal cycling profile condition and the diameter of the DRAM solder balls dominantly affected the fatigue life of the SSD.

Simulation within simulation for agent decision-making: Theoretical foundations from cognitive science to operational computer model

This article deals with artificial intelligence models inspired from cognitive science. The scope of this paper is the simulation of the decision-making process for virtual entities. The theoretical framework consists of concepts from the use of internal behavioral simulation for human decision-making. Inspired from such cognitive concepts, the contribution consists in a computational framework that enables a virtual entity to possess an autonomous world of simulation within the simulation. It can simulate itself (using its own model of behavior) and simulate its environment (using its representation of other entities). The entity has the ability to anticipate using internal simulations, in complex environments where it would be extremely difficult to use formal proof methods. Comparing the prediction and the original simulation, its predictive models are improved through a learning process. Illustrations of this model are provided through two implementations. First illustration is an example showing a shepherd, his herd and dogs. The dog simulates the sheep’s behavior in order to make predictions testing different strategies. Second, an artificial 3D juggler plays in interaction with virtual jugglers, humans and robots. For this application, the juggler predicts the behavior of balls in the air and uses prediction to coordinate its behavior in order to juggle.

A Study of Aerodynamic Drag of Contemporary Footballs

Most modern footballs possess varied surface characteristics which can affect the flight trajectory of the football. Although the aerodynamic behavior of other sports balls have been studied well, little information is available about the aerodynamic behavior of newly introduced footballs with varied seam configurations and number of panels. Therefore, the primary objective of this study is to understand the surface characteristics mainly the seam depth and seam height and their effects on aerodynamic of a range of new generation balls. Four new generation footballs: Kapanya, Cafusa, Tango and Brazuca were selected for this study. Seam length and depth of seam for each ball were measured using 3D scanning technology and also manual measurement. Additionally, the aerodynamic drag forces were measured using wind tunnel over a range of wind speeds for two positions of each ball. It was found that the seam length and depth of seam have influence on the aerodynamic drag of these modern footballs. Results also indicate that the sideway variation of aerodynamic drag is minimal for the Brazuca ball. As a result, this ball may have better stability in flight. The lowest aerodynamic drag was found for the Cafusa ball at high speeds which indicates that this ball is suitable for long distance pass. However, it has highest sideway drag variation that may cause instability in flight.

Investigation on the phase transformation of electroless Ni–B coating after dry sliding against alumina ball

The purpose of the work was to evaluate the possibility of tribochemical reactions during dry sliding of electroless Ni–B coating against an alumina ball. The effect of probable tribochemical products on the tribological behavior of Ni–B/Al2O3 tribosystem was investigated. Wear experiments were performed in a ball-on-disc configuration pressing alumina balls towards rotating disc specimens. Wear tests were carried out at normal loads of 5, 20, 40 and 60 N at the sliding distance of 100 m. Electroless Ni–B coatings with a mean thickness of 50–60 μm were applied on the mild carbon steel substrates. The worn surfaces of Ni–B coatings were studied with Scanning Electron Microscope (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), X-Ray Diffractometer (XRD) and X-ray Photoelectron Spectrometer (XPS). The results showed that the structure of the worn surfaces of the coatings changed from amorphous to the crystalline. The dominant wear mechanism in the present tribosystem was combination of adhesive and abrasive wear. As the load was increased the friction coefficient and its fluctuations were decreased. The wear rate of alumina balls changed from increasing to decreasing at the load of 40 N. XPS and XRD analysis revealed the phase transformation and production of Ni–Al compounds on the worn surface of electroless Ni–B coating. It was elucidated that tribochemical reactions between the mating surfaces were responsible for tribological behavior of Ni–B coating and unexpected wear behavior of alumina balls.

Measurement of the mechanical properties of the handball, volleyball, and basketball using DIC method: a combination of experimental, constitutive, and viscoelastic models

Many players and audiences nowadays are involved with hand sports, such as handball, volleyball, and basketball. The most important equipment of these games is ball. Each ball has its own characteristics and has to be made according to the rules of its federation. Many characteristics were defined for an approved handball, volleyball, and basketball by IHF, FIBA, and FIVB, respectively. These are including material properties, mass, pressure, etc. These characteristics so far have been well defined by many researchers to get the most efficient performance from a ball. Nonetheless, the mechanical properties of these balls so far have not been comprehensively studied. Therefore, this study was aimed to experimentally measure the compressive mechanical properties, including linear elastic, nonlinear hyperelastic, and viscoelastic (Prony series), of the handball, volleyball, and basketball using digital image correlation technique. To do this, 26 of each approved balls were mounted on a testing machine, and a set of quasi-static compressive and stress-relaxation loading were applied to them. The stress–strain and reduced relaxation function of the samples were calculated and compared. The results revealed the highest elastic modulus for the basketball (591 kPa), while the lowest one was observed for the handball (17 kPa). In addition, volleyball showed to be able to bear 5.941 and 1.615 times more stress compared to the handball and basketball, respectively. The hyperelastic material models, namely Mooney-Rivlin and Ogden, were employed to address the nonlinear mechanical behavior of the soccer balls. Finite element model of each ball was established as well and the obtained numerical data were found to be in good agreement with that of experimental ones. Many injuries to the human head have been attributed to these games due to the balls’ high speed. However, so far these injuries to the human eye have not been studied. The findings of this study, therefore, may have implications not only for understanding the mechanical properties of the balls, but also for providing raw data to investigate the injury that can be occurred for the human body by these balls, especially the eye.

A COMBINATION OF EXPERIMENTAL AND NUMERICAL ANALYSES TO MEASURE THE COMPRESSIVE MECHANICAL PROPERTIES OF TENNIS BALL

Tennis is almost a newly born sport (1859) that can be played individually against a single opponent (singles) or between two teams of two players each, namely doubles. Materially, tennis balls were made of cloth strips stitched together from thread. They have also been made of hollow rubber with a felt coating appearing in different colors from traditionally white to yellow in the recent years to permit their visibility. Although the most common injuries associated with tennis have been reported to be related to rotator cuff, elbow, wrist, anterior knee pain, and ankle, the injury that a tennis ball can cause, for example, for eye is still not clear. However, as the tennis ball can reach to a speed of 260 km/h, it seems vital to understand its mechanical properties to have a deep insight into the injury that can happen during playing. Therefore, this study aimed to perform an experimental study to evaluate the linear elastic and nonlinear hyperelastic mechanical properties of the tennis ball under compressive loading. To do this, 40 numbers of approved tennis balls by international tennis federation (ITF) were prepared and subjected to a series of compressive loadings. The strain of the balls was measured via a pair of CCD cameras using digital image correlation (DIC) technique. The results revealed the mean elastic modulus, maximum stress, and strain of 336.69 kPa, 410.15 kPa, and 66%, for the tennis balls, respectively. The nonlinear mechanical behavior of the tennis balls were also computationally investigated through a hyperelastic material model, namely Ogden. Finally, a finite element (FE) model was executed to verify the hyperelastic data with that of experimental and, interestingly, the numerical data were in good agreement with experimental ones. The findings of this study may have implications not only for understanding the compressive mechanical properties of the tennis ball, but also for investigating the injury that can occur in the human body by tennis ball, especially the eye.

Evaluation and Description of Friction between an Electro-Deposited Coating and a Ceramic Ball under Fretting Condition.

This article describes fretting behavior of zirconia and silicon nitride balls on an electro-deposited coating. Fretting tests are performed using a ball-on-flat configuration. The evolution of the kinetic friction coefficient is determined, along with slip ratio. Experimental results show that the steady-state friction coefficient between ceramic balls (Si3N4 and ZrO2) and an electro-deposited coating is about 0.06, lower than the value between AISI 52100 ball and the coating. After a steady-state sliding, the transition of the friction coefficient is varied with a ball. The friction coefficient for ZrO2 balls became a critical value after higher fretting cycles than those for Si3N4 and AISI 52100 balls. In addition, it is identified that two parameters can describe the transition of the friction coefficient. Finally, the evolution of the friction coefficient is expressed as an exponential or a power-law form.

Effects of Internal Stress of Electroless Nickel Plating on Solder Joining Strength

Nickel/gold electroless plating is commonly used for surface finish of printed circuit boards due to its environmental stability and good solder wettability. However, since deposition of electroless gold plating is a substitution reaction, local corrosion of nickel surface sometimes occurs and it deteriorates joining reliability of solders or wire bonding. In this study, we focused on internal stress of nickel-plating layer. Gold electroless plating was performed on several deferent internal stress level of nickel plating layers, and local corrosion behavior and shear strengths of solder balls were investigated. As a result, it became clear that tensile strength of nickel layer increases occurrence of local corrosion and accordingly it results in deteriorate of solder joining strength.

Direct observation of electron-beam-induced densification and hardening of silica nanoballs by in situ transmission electron microscopy and finite element method simulations

We report on the use of in situ transmission electron microscopy techniques and finite element method simulations to study the influence of electron beam irradiation on the deformation behavior and mechanical properties of nanoscale amorphous silica balls. We show that, on the nanometer scale, electron beam irradiation of silica results in athermal densification and simultaneous material hardening. It is demonstrated how the amount of densification can be controlled via the irradiation dose, using specific beam current densities inside a transmission electron microscope. The electron-beam-induced densification is interpreted as the direct reason for the observed hardening effect. Finite element method simulations are used to model the mechanical response of the silica balls, confirming that the intrinsic properties (such as the Young’s modulus) of amorphous silica can be tailored with the electron beam on the nanoscale.

Tribological Mechanisms of Steels with Respect to Diamond-Like Carbon in Terms of Energy Input

The wear behavior of a carbon steel (SUJ2, ASTM E52100 or similar) and a stainless steel (SUS440C, ASTM 440C or similar) with respect to diamond-like carbon (DLC) was evaluated based on the energy input. The conventional wear equation (Holm-Archard equation) was derived based on the friction force. The wear–energy equation was transformed from the Holm-Archard equation. The measurement method of the energy input induced by a tribometer is proposed, and the equation describing the relationship between the friction coefficient and energy input is introduced. The tribology functions derived from the energy equations are proposed. The wear behavior of the steel balls against the DLC is discussed in terms of tribology functions.

Impact behavior of hollow balls

Measurements are presented of the force acting on ping-pong and squash balls impacting on a force plate. Both ball types are hollow and have the same diameter but deform in very different ways. Ping pong balls are relatively stiff and buckle inwards at high impact speeds, while squash balls are softer and tend to squash or flatten. The buckling process generates a large-amplitude, high-frequency oscillation of the force acting on a ping-pong ball. Squash balls are initially very stiff before they soften, with the result that the force on the ball rises to about half its maximum value in the first 20 μs. Ping-pong balls have a high coefficient of restitution (COR), while squash balls have a low COR. Results for both ball types are interpreted in terms of additional experimental observations.