scholarly journals Effect of Increasing Running Cadence on Peak Impact Force in an Outdoor Environment

2021 ◽  
Author(s):  
Taylor Musgjerd ◽  
Jacob Anason ◽  
Drew Rutherford ◽  
Thomas W Kernozek
Keyword(s):  
Impact Force ◽  
Outdoor Environment ◽  
Peak Impact Force

Evaluation on anti-collision performance of multi-level bumper type anti-collision device

2019 ◽  
Author(s):  
Haoxin Guo ◽  
Junjie Wang ◽  
Chengdong Liu
Keyword(s):  
Impact Force ◽  
Superior Performance ◽  
Corrosion Resistant Steel ◽  
Resistant Steel ◽  
Oblique Collision ◽  
Corrosion Resistant ◽  
Multi Level ◽  
Ship Collision ◽  
Energy Absorbing ◽  
Peak Impact Force

<p>An innovative Multi-level bumper and energy-consuming system (MBES) with corrosion-resistant steel floating caisson is proposed as protective structures for bridge piers against ship collision in this paper. MBES is provided with a three-level anti-collision module which consists of a corrugated-type energy-absorbing base, rubber fender, corrosion-resistant steel box filled with pre-compressed rubber tire. MBES is assembled in segments, exhibiting good energy absorbing and highly designable properties. This paper aims to evaluate the effectiveness of MBES adopted in a continuous beam bridge using finite element models. Based on the numerical model, the oblique collision situation at different positions were studied. Numerical results indicate the obvious advantages of the device by comparing peak impact force and impact duration. Significantly decrement of the peak impact force and effectively prolonged impact process indicate the superior performance of the device. Multi-level anti-collision fortification, the modular fabrication and replacement, simple maintenance, strong self-floating ability and excellent corrosion resistance make MBES very effective as a bridge protection structure in ship collision.</p>

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.

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 Determination of Peak Impact Force for Buildings Exposed to Structural Pounding during Earthquakes

Geosciences ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 18 ◽  
Author(s):  
Seyed Mohammad Khatami ◽  
Hosein Naderpour ◽  
Rui Carneiro Barros ◽  
Anna Jakubczyk-Gałczyńska ◽  
Robert Jankowski
Keyword(s):  
Ground Motion ◽  
Parametric Study ◽  
Structural Damage ◽  
Impact Force ◽  
Structural Parameters ◽  
Seismic Excitations ◽  
Ground Acceleration ◽  
Structural Pounding ◽  
Peak Impact Force

Structural pounding between adjacent, insufficiently separated buildings, or bridge segments, has been repeatedly observed during seismic excitations. Such earthquake-induced collisions may cause severe structural damage or even lead to the collapse of colliding structures. The aim of the present paper was to show the results of the study focused on determination of peak impact forces during collisions between buildings exposed to different seismic excitations. A set of different ground motion records, with various peak ground acceleration (PGA) values and frequency contents, were considered. First, pounding-involved numerical analysis was conducted for the basic parameters of colliding buildings. Then, the parametric study was carried out for different structural natural periods, structural damping ratios, gap sizes between buildings and coefficients of restitution. The results of the analysis conducted for the basic structural parameters indicate that the largest response of the analysed buildings was observed for the Duzce earthquake. The parametric study showed that the pounding-involved structural response depended substantially on all parameters considered in the analysis, and the largest response was observed for different ground motions. The results of the study presented in this paper indicate that the value of the peak impact force expected during the time of the earthquake does not depend on the PGA value of ground motion, but rather on the frequency contents of excitation and pounding scenario. It is therefore recommended that the peak impact force for buildings exposed to structural pounding during earthquakes should be determined individually for the specific structural configuration taking into account the design ground motion.

Potential for head injuries in infants from low-height falls

2008 ◽  
Vol 2 (5) ◽  
pp. 321-330 ◽  
Author(s):  
Brittany Coats ◽  
Susan S. Margulies
Keyword(s):  
Child Abuse ◽  
Impact Force ◽  
Head Injuries ◽  
Skull Fracture ◽  
Angular Acceleration ◽  
Objective Data ◽  
Time Duration ◽  
Impact Forces ◽  
Force Data ◽  
Peak Impact Force

Object Falls are the most common accident scenario in young children as well as the most common history provided in child abuse cases. Understanding the biomechanics of falls provides clinicians with objective data to aid in their diagnosis of accidental or inflicted trauma. The objective of this study was to determine impact forces and angular accelerations associated with low-height falls in infants. Methods An instrumented anthropomorphic infant surrogate was created to measure the forces and 3D angular accelerations associated with falls from low heights (0.3–0.9 m) onto a mattress, carpet pad, or concrete. Results Although height significantly increased peak angular acceleration (αp), change in peak-to-peak angular velocity, time duration associated with the change in velocity, and peak impact force (Fp) for head-first drops onto a carpet pad or concrete, none of these variables were significantly affected by height when dropped onto a mattress. The αp was not significantly different for drops onto a carpet pad and concrete from 0.6 or 0.9 m due to compression of the carpet pad. Surprisingly, sagittal αp was equaled or surpassed by axial αp. Conclusions These are the first 3D angular acceleration and impact force data available for head impact in infants from low-height falls. A future study involving a computational model of the infant head will use the loads measured in this study to predict the probability of occipital skull fracture on impact from head-first low-height falls. Together, these studies will provide data that will aid clinicians in the evaluation of accidental and inflicted head injuries, and will contribute to the design of safer environments for children.

The Correlation of Segment Accelerations and Impact Forces with Knee Angle in Jump Landing

2007 ◽  
Vol 23 (3) ◽  
pp. 203-212 ◽  
Author(s):  
Niell G. Elvin ◽  
Alex A. Elvin ◽  
Steven P. Arnoczky ◽  
Michael R. Torry
Keyword(s):  
Contact Angle ◽  
Ground Reaction Force ◽  
Knee Flexion ◽  
Impact Force ◽  
Reaction Force ◽  
Least Square ◽  
Jump Height ◽  
Impact Forces ◽  
Axial Acceleration ◽  
Peak Impact Force

Impact forces and shock deceleration during jumping and running have been associated with various knee injury etiologies. This study investigates the influence of jump height and knee contact angle on peak ground reaction force and segment axial accelerations. Ground reaction force, segment axial acceleration, and knee angles were measured for 6 male subjects during vertical jumping. A simple spring-mass model is used to predict the landing stiffness at impact as a function of (1) jump height, (2) peak impact force, (3) peak tibial axial acceleration, (4) peak thigh axial acceleration, and (5) peak trunk axial acceleration. Using a nonlinear least square fit, a strong (r= 0.86) and significant (p≤ 0.05) correlation was found between knee contact angle and stiffness calculated using the peak impact force and jump height. The same model also showed that the correlation was strong (r= 0.81) and significant (p≤ 0.05) between knee contact angle and stiffness calculated from the peak trunk axial accelerations. The correlation was weaker for the peak thigh (r= 0.71) and tibial (r= 0.45) axial accelerations. Using the peak force but neglecting jump height in the model, produces significantly worse correlation (r= 0.58). It was concluded that knee contact angle significantly influences both peak ground reaction forces and segment accelerations. However, owing to the nonlinear relationship, peak forces and segment accelerations change more rapidly at smaller knee flexion angles (i.e., close to full extension) than at greater knee flexion angles.

The Development of a Custom-Built Portable Impact-testing Device for Assessing the Cushioning Properties of Athletic Socks

2013 ◽  
Vol 29 (6) ◽  
pp. 824-831 ◽  
Author(s):  
Tim Blackmore ◽  
David Jessop ◽  
Stewart Bruce-Low ◽  
Joanna Scurr
Keyword(s):  
Coefficient Of Variation ◽  
Loading Rate ◽  
Impact Force ◽  
Impact Testing ◽  
Reliability Coefficient ◽  
Systematic Bias ◽  
Testing Device ◽  
Confidence Limits ◽  
Time To Peak ◽  
Peak Impact Force

Despite manufacturer claims that athletic socks attenuate force during exercise, no device exists to assess this. Therefore, this study outlines the development of a custom-built impact-testing device for assessing the cushioning properties of socks. The device used a gravity-driven impact striker (8.5 kg), released from 0.05 m, which impacted a no-sock, sock or a basic shoe/sock condition in the vertical axis. A load cell (10,000 Hz) assessed peak impact force, time to peak impact force and loading rate. Reliability was investigated between day, between trial and within trial. Excellent reliability (coefficient of variation < 5% adjusted for 95% confidence limits) was reported for peak impact force in all conditions, with no evidence of systematic bias. Good reliability (coefficient of variation < 10% adjusted for 68% confidence limits) was reported for time to peak impact force and loading rate with some evidence of systematic bias. It was concluded that the custom-built impact-testing device was reliable and sensitive for the measurement of peak impact force on socks.

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