The Efficacy of Impact-Absorbing Materials during Collision with a Soccer Ball

2013 ◽  
Vol 440 ◽  
pp. 363-368
Author(s):  
Zahari Taha ◽  
Mohd Hasnun Arif Hassan ◽  
Mohd Azri Aris
Keyword(s):  
High Speed ◽  
Impact Force ◽  
Coefficient Of Restitution ◽  
Soccer Ball ◽  
Absorbing Materials ◽  
The Subject ◽  
The Impact ◽  
The Brain ◽  
Peak Impact Force ◽  
Impact Duration

The uniqueness of soccer is that the players are allowed to use their head to pass the ball to a teammate of even try to score goal. Studies have shown that heading in soccer might be dangerous to the brain and could lead to brain trauma. There are headgears available for soccer players to protect their head, but studies have proven that currently available headgears are ineffective in reducing the impact caused by a soccer ball. The objective of this study is to test the efficacy of six different types of impact-absorbing materials in reducing the linear impact force from a soccer ball. The soccer ball was dropped from the height of 2.3 m onto a force platform to measure the impact force. A high-speed camera is used to record the motion and the impact duration, and then the coefficient of restitution for each impact was determined. Polyurethane (PU) comb-gel was found to be the most effective material in reducing the peak impact force and impulse compared with other materials. The reduction in peak force was associated with longer impact duration between the soccer ball and the PU comb-gel. However, the coefficient of restitution was reduced by 21.7%, implying that using the gel alone will reduce the speed of the ball after heading, thus reducing the performance of a player wearing it. A combination of PU gel and another stiffer material is suggested and the effectiveness of the composite will be the subject of future investigation.

scholarly journals Is There a Link between Oropharyngeal Microbiome and Schizophrenia? A Narrative Review

2022 ◽  
Vol 23 (2) ◽  
pp. 846
Author(s):  
Stanislas Martin ◽  
Audrey Foulon ◽  
Wissam El Hage ◽  
Diane Dufour-Rainfray ◽  
Frédéric Denis
Keyword(s):  
Periodontal Disease ◽  
Research Team ◽  
Oral Microbiome ◽  
Oral Microbiota ◽  
Future Studies ◽  
The Subject ◽  
The Moment ◽  
The Impact ◽  
The Brain

The study aimed to examine the impact of the oropharyngeal microbiome in the pathophysiology of schizophrenia and to clarify whether there might be a bidirectional link between the oral microbiota and the brain in a context of dysbiosis-related neuroinflammation. We selected nine articles including three systemic reviews with several articles from the same research team. Different themes emerged, which we grouped into 5 distinct parts concerning the oropharyngeal phageome, the oropharyngeal microbiome, the salivary microbiome and periodontal disease potentially associated with schizophrenia, and the impact of drugs on the microbiome and schizophrenia. We pointed out the presence of phageoma in patients suffering from schizophrenia and that periodontal disease reinforces the role of inflammation in the pathophysiology of schizophrenia. Moreover, saliva could be an interesting substrate to characterize the different stages of schizophrenia. However, the few studies we have on the subject are limited in scope, and some of them are the work of a single team. At this stage of knowledge, it is difficult to conclude on the existence of a bidirectional link between the brain and the oral microbiome. Future studies on the subject will clarify these questions that for the moment remain unresolved.

An experimental and simulation study of the flow pattern characteristics of water jet impingements in boreholes

2021 ◽  
pp. 014459872110520
Author(s):  
Yabin Gao ◽  
Xin Xiang ◽  
Ziwen Li ◽  
Xiaoya Guo ◽  
Peizhuang Han
Keyword(s):  
High Speed ◽  
Impact Force ◽  
Jet Impingement ◽  
Flow Patterns ◽  
Water Jet ◽  
Solid Boundary ◽  
Force Model ◽  
Water Jets ◽  
Contact Surfaces ◽  
The Impact

Hydraulic slotting has become one of the most common technologies adopted to increase permeability in low permeability in coal field seams. There are many factors affecting the rock breaking effects of water jets, among which the impact force cannot be ignored. To study the influencing effects of contact surface shapes on jet flow patterns and impact force, this study carried out experiments involving water jet impingement planes and boreholes under different pressure conditions. The investigations included numerical simulations under solid boundary based on gas–liquid coupling models and indoor experiments under high-speed camera observations. The results indicated that when the water jets impinged on different contact surfaces, obvious reflection flow occurred, and the axial velocity had changed through three stages during the development process. Moreover, the shapes of the contact surfaces, along with the outlet pressure, were found to have impacts on the angles and velocities of the reflected flow. The relevant empirical formulas were summarized according to this study's simulation results. In addition, the flow patterns and shapes of the contact surfaces were observed to have influencing effects on the impact force. An impact force model was established in this study based on the empirical formula, and the model was verified using both the simulation and experimental results. It was confirmed that the proposed model could provide important references for the optimization of the technical parameters water jet systems, which could provide theoretical support for the further intelligent and efficient transformation of coal mine drilling water jet technology.

Dynamic Response and Shear Demand of Reinforced Concrete Beams Subjected to Impact Loading

2019 ◽  
Vol 19 (08) ◽  
pp. 1950091 ◽  
Author(s):  
Wuchao Zhao ◽  
Jiang Qian
Keyword(s):  
Dynamic Response ◽  
Impact Loading ◽  
Parametric Study ◽  
Shear Failure ◽  
Impact Force ◽  
Rc Beams ◽  
Local Response ◽  
Shear Demand ◽  
The Impact ◽  
Peak Impact Force

Reinforced concrete (RC) beams under the impact loading are typically prone to suffer shear failure in the local response phase. In order to enhance the understanding of the mechanical behavior of the RC beams, their dynamic response and shear demand are numerically investigated in this paper. A 3D finite-element model is developed and validated against the experimental data available in the literature. Taking advantage of the above calibrated numerical model, an intensive parametric study is performed to identify the effect of different factors including the impact velocity, impact mass and beam span-to-depth ratio on the impact response of the RC beams. It is found that, due to the inertial effect, a linear relationship exists between the maximum reverse support force and the peak impact force, while negative bending moments also appear in the shear span. In addition, the local response of the RC beams can be divided into a first impact stage and a separation stage. A shear plug is likely to be formed near the impact point at the first impact stage and a shear failure may be triggered near the support by large support forces. Based on the simulation results, simplified methods are proposed for predicting the shear demand for the two failure modes, whereas physical models are also established to illustrate the resistance mechanism of the RC beams at the peak impact force. By comparing with the results of the parametric study, it is concluded that the shear demand of the RC beams under the impact loading can be predicted by the proposed empirical formulas with reasonable accuracy.

scholarly journals Effect of Abrasive Concentration on Impact Performance of Abrasive Water Jet Crushing Concrete

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Xiaohui Liu ◽  
Ping Tang ◽  
Qi Geng ◽  
Xuebin Wang
Keyword(s):  
Internal Energy ◽  
Impact Force ◽  
Abrasive Particle ◽  
Water Jet ◽  
Abrasive Water Jet ◽  
Sph Method ◽  
Impact Performance ◽  
Water Jets ◽  
The Impact ◽  
Peak Impact Force

It has been found that the impact performance of water jets can be changed by its properties, which include pressure, additive, and mode of jet. Thus, an abrasive water jet (AWJ) has been developed as a new method. However, there is little research on the effect of abrasive concentration on the impact performance of abrasive jets. Thus, the SPH method is used to establish an abrasive water jet crushing concrete model to study the effect of abrasive concentration on the impact force, concrete internal energy, abrasive particle distribution, crushing depth, and damage and crushing efficiencies under different concrete compressive strengths and abrasive densities. The results indicate that there is little effect of the abrasive concentration on the peak impact force under different compressive strengths and abrasive densities, while the mean impact force tends to increase linearly with the abrasive concentration. The internal energy of the concrete increases stepwise with the abrasive concentration under different compressive strengths and abrasive densities. The concentration of 10%∼20% is the rapid increasing stage. The crushing depth and damage efficiencies are all maximum at a concentration of 20% under different compressive strengths and abrasive densities. After the concrete was impacted by the water from the water jet, it is divided into rebounding particles and intrusive particles. The more the intrusive particles, the easier the concrete to be crushed and damaged.

scholarly journals The Effect of Pendolino high-speed rail on the structure of buildings located in the proximity of railway tracks

2016 ◽  
Vol 21 (1) ◽  
pp. 231-238
Author(s):  
K. Grębowski ◽  
Z. Ulman
Keyword(s):  
Dynamic Analysis ◽  
High Speed ◽  
Building Structure ◽  
High Speed Train ◽  
High Speed Rail ◽  
Railway Tracks ◽  
High Speed Trains ◽  
Railway System ◽  
The Subject ◽  
The Impact

Abstract The following research focuses on the dynamic analysis of impact of the high-speed train induced vibrations on the structures located near railway tracks. The office complex chosen as the subject of calculations is located in the northern part of Poland, in Gdańsk, in the proximity of Pendolino, the high speed train route. The high speed trains are the response for the growing needs for a more efficient railway system. However, with a higher speed of the train, the railway induced vibrations might cause more harmful resonance in the structures of the nearby buildings. The damage severity depends on many factors such as the duration of said resonance and the presence of additional loads. The studies and analyses helped to determinate the method of evaluating the impact of railway induced vibrations on any building structure. The dynamic analysis presented in the research is an example of a method which allows an effective calculation of the impact of vibrations via SOFISTIK program.

scholarly journals Particle–wall collisions in a viscous fluid

2001 ◽  
Vol 433 ◽  
pp. 329-346 ◽  
Author(s):  
G. G. JOSEPH ◽  
R. ZENIT ◽  
M. L. HUNT ◽  
A. M. ROSENWINKEL
Keyword(s):  
Reynolds Number ◽  
Viscous Fluid ◽  
High Speed ◽  
Particle Density ◽  
Particle Surface ◽  
Density Ratio ◽  
Experimental Studies ◽  
Stokes Number ◽  
Coefficient Of Restitution ◽  
The Impact

This paper presents experimental measurements of the approach and rebound of a particle colliding with a wall in a viscous fluid. The particle's trajectory was controlled by setting the initial inclination angle of a pendulum immersed in a fluid. The resulting collisions were monitored using a high-speed video camera. The diameters of the particles ranged from 3 to 12 mm, and the ratio of the particle density to fluid density varied from 1.2 to 7.8. The experiments were performed using a thick glass or Lucite wall with different mixtures of glycerol and water. With these parameters, the Reynolds number defined using the velocity just prior to impact ranged from 10 to approximately 3000. A coefficient of restitution was defined from the ratio of the velocity just prior to and after impact.The experiments clearly demonstrate that the rebound velocity depends on the impact Stokes number (defined from the Reynolds number and the density ratio) and weakly on the elastic properties of the material. Below a Stokes number of approximately 10, no rebound of the particle occurred. For impact Stokes number above 500 the coefficient of restitution appears to asymptote to the values for dry collisions. The coefficients of restitution were also compared with previous experimental studies. In addition, the approach of the particle to the wall indicated that the particle slowed prior to impacting the surface. The distance at which the particle's trajectory varied due to the presence of the wall was dependent on the impact Stokes number. The particle surface roughness was found to affect the repeatability of some measurements, especially for low impact velocities.

scholarly journals Jumping with adhesion: landing surface incline alters impact force and body kinematics in crested geckos

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Timothy E. Higham ◽  
Mara N. S. Hofmann ◽  
Michelle Modert ◽  
Marc Thielen ◽  
Thomas Speck
Keyword(s):  
High Speed ◽  
Impact Force ◽  
Three Dimensional ◽  
Adhesive System ◽  
Vertical Surface ◽  
High Impact ◽  
Body Movements ◽  
Impact Forces ◽  
Landing Platform ◽  
The Impact

AbstractArboreal habitats are characterized by a complex three-dimensional array of branches that vary in numerous characteristics, including incline, compliance, roughness, and diameter. Gaps must often be crossed, and this is frequently accomplished by leaping. Geckos bearing an adhesive system often jump in arboreal habitats, although few studies have examined their jumping biomechanics. We investigated the biomechanics of landing on smooth surfaces in crested geckos, Correlophus ciliatus, asking whether the incline of the landing platform alters impact forces and mid-air body movements. Using high-speed videography, we examined jumps from a horizontal take-off platform to horizontal, 45° and 90° landing platforms. Take-off velocity was greatest when geckos were jumping to a horizontal platform. Geckos did not modulate their body orientation in the air. Body curvature during landing, and landing duration, were greatest on the vertical platform. Together, these significantly reduced the impact force on the vertical platform. When landing on a smooth vertical surface, the geckos must engage the adhesive system to prevent slipping and falling. In contrast, landing on a horizontal surface requires no adhesion, but incurs high impact forces. Despite a lack of mid-air modulation, geckos appear robust to changing landing conditions.

Impact Response Measurement of Poly-Urethane Sheet Using an Optical Interferometer

2017 ◽  
Vol 29 (3) ◽  
pp. 613-618
Author(s):  
Sa-nga Songmuang ◽  
◽  
Akihiro Takita ◽  
Suphanchai Punthawanunt ◽  
Keyword(s):  
High Speed ◽  
Impact Force ◽  
Inertial Force ◽  
Spherical Body ◽  
The Body ◽  
Impact Response ◽  
Optical Center ◽  
Optical Interferometer ◽  
Cube Corner ◽  
The Impact

[abstFig src='/00290003/16.jpg' width='300' text='The changes impact force to the sheet' ] A method for measuring the impact response of a polyurethane sheet is proposed. In the method, the velocity, acceleration, force, and displacement of a spherical body dropping onto the polyurethane sheet is measured using an optical interferometer. Only the velocity is measured from the Doppler shift of the laser light reflected on the cube corner prism embedded inside the spherical body. The optical center of the cube corner prism is made to coincide with the center of gravity of the whole spherical body to minimize the effect of the attitude change of the body. The acceleration, displacement, and inertial force of the body are calculated from the velocity. The dropping body is also observed using a high-speed camera. The uncertainty in measuring the instantaneous value of the impact force with a sampling interval of approximately 0.1 ms is estimated to be 0.23 N, which corresponds to 0.14% of the maximum force of approximately 1.60×102N. In the experiment, 10 drop measurements are conducted and show good reproducibility of this method.

Numerical study on debris flow in step-pools channel using smoothed particle hydrodynamics method

2020 ◽  
Author(s):  
Shuai Li ◽  
Xiaoqing Chen ◽  
Chong Peng ◽  
Jiangang Chen
Keyword(s):  
Debris Flow ◽  
Smoothed Particle Hydrodynamics ◽  
Debris Flows ◽  
Impact Force ◽  
Numerical Study ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
The Impact ◽  
Peak Impact Force

<p>Drainage channel with step-pool systems are widely used to control debris flow. However, the blocking of debris flow often gives rise to local damage at the steps and baffles. Hence, the estimation of impact force of debris flow is crucial for design step-pools channel. This paper presents a numerical study on the impact behavior of debris flows using SPH (Smoothed Particle Hydrodynamics) method. Some important parameters, such as the baffle shape (square, triangle, and trapezoid) and the densities of debris flows are considered to examine their influence on the impact force. The results show that the largest peak impact force is obtained at the second last baffle, rather than the first baffle. Moreover, the square baffle gives rise to the largest impact force whereas the triangle baffle bears the smallest one among the three baffles. Generally, the peak impact force increases with increasing the inflow density. However, a threshold density, beyond which the peak impact force will decrease, is suggested by the simulations. Based on the numerical results, an improved expression to predict the impact force considering the inclined angle of baffle is proposed.</p>

Impact Indentation Properties and Interfacial Strength of Ceramic Coatings

2010 ◽  
Vol 654-656 ◽  
pp. 1972-1977
Author(s):  
Yi Wang Bao ◽  
Kun Ming Li ◽  
De Tian Wan ◽  
Xue Qiang Cao
Keyword(s):  
Impact Force ◽  
Steel Substrate ◽  
Impact Resistance ◽  
Interfacial Strength ◽  
Ceramic Coatings ◽  
Impact Angle ◽  
Zro2 Coating ◽  
Aluminum Substrates ◽  
The Impact ◽  
Peak Impact Force

Spherical impact indentation tests with different impact angles (90°, 60°, 45°, and 30°) were carried out to understand the impact resistance and interfacial adhesion of zirconia (ZrO2) ceramic coating on steel and aluminum substrates, respectively. A linear rail with an adjustable impact angle was used to guide the slipping impact head to impact the specimen. It is found that the peak impact force for surface damage decreases but the contact indentation becomes longer with decreasing impact angle. Under almost the same peak impact force, the smaller the impact angle, the higher the impulse. The experimental results indicate that the ZrO2 coating on steel substrate has higher impact resistance than that on the aluminum substrate. The cross bonded test results show that ZrO2 coating on both steel and aluminum substrates exhibit excellent interfacial tensile and shear strength.

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