scholarly journals Biomechanical assessment of various punching techniques

2020 ◽  
Author(s):  
Jiri Adamec ◽  
Peter Hofer ◽  
Stefan Pittner ◽  
Fabio Monticelli ◽  
Matthias Graw ◽  
...  
Keyword(s):  
High Speed ◽  
Vertical Wall ◽  
Force Plate ◽  
Physical Parameters ◽  
Time Curve ◽  
Biomechanical Assessment ◽  
Sports Science ◽  
General Terms ◽  
Force Time ◽  
The Impact

Abstract Punches without the use of instruments/objects are a common type of body violence and as such a frequent subject of medicolegal analyses. The assessment of the injuries occurred as well as of the potential of the assault to produce severe body harm is based on objective traces (especially the documented injuries of both parties involved) as well as the—often divergent—descriptions of the event. Quantitative data regarding the punching characteristics that could be used for the assessment are rare and originate mostly in sports science. The aim of this study was to provide physical data enabling/facilitating the assessment of various punching techniques. A total of 50 volunteers took part in our study (29 males and 21 females) and performed severe punches with the fist, with the small finger edge of the hand (karate chop), and with the open hand with both the dominant and the non-dominant hands in randomized order. The strikes were performed on a boxing pad attached to a KISTLER force plate (sampling frequency 10,000 Hz) mounted on a vertical wall. The punching velocity was defined as the hand velocity over the last 10 cm prior to the contact to the pad and ascertained by using a high-speed camera (2000 Hz). Apart from the strike velocity, the maximum force, the impulse (the integral of the force-time curve), the impact duration, and the effective mass of the punch (the ratio between the impulse and the strike velocity) were measured/calculated. The results show a various degree of dependence of the physical parameters of the strikes on the punching technique, gender, hand used, body weight, and other factors. On the other hand, a high degree of variability was observed that is likely attributable to individual punching capabilities. In a follow-up study, we plan to compare the “ordinary” persons with highly trained (boxers etc.) individuals. Even though the results must be interpreted with great caution and a direct transfer of the quantitative parameters to real-world situations is in general terms not possible, the study offers valuable insights and a solid basis for a qualified forensic medical/biomechanical assessment.

Modeling a Viscoelastic Gymnastics Landing Mat during Impact

2006 ◽  
Vol 22 (2) ◽  
pp. 103-111 ◽  
Author(s):  
Chris Mills ◽  
Matthew T.G. Pain ◽  
Maurice R. Yeadon
Keyword(s):  
High Speed ◽  
Force Plate ◽  
System Model ◽  
Video Cameras ◽  
Key Characteristics ◽  
Single Mass ◽  
Force Time ◽  
Mass Spring ◽  
The Impact ◽  
Landing Mat

Landing mats that can undergo a large amount of area deformation are now essential for the safe completion of landings in gymnastics. The objective of this study was to develop an analytical model of a landing mat that reproduces the key characteristics of the mat-ground force during impact with minimal simulation run time. A force plate and two high-speed video cameras were used to record the mat deformation during vertical drop testing of a 24-kg impactor. Four increasingly complex point mass spring-damper models, from a single mass spring-damper system, Model 1, to a 3-layer mass spring-damper system, Model 4, were constructed using Matlab to model the mat's behavior during impact. A fifth model composed of a 3-layer mass spring-damper system was developed using visual Nastran 4D. The results showed that Models 4 and 5 were able to match the loading phase of the impact with simulation times of less than 1 second for Model 4 and 28 seconds for Model 5. Both Models 4 and 5 successfully reproduced the key force-time characteristics of the mat-ground interface, such as peak forces, time of peak forces, interpeak minima and initial rates of loading, and could be incorporated into a gymnast-mat model.

scholarly journals Research on Blade-Casing Rub-Impact Mechanism by Experiment and Simulation in Aeroengines

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Jie Hong ◽  
Tianrang Li ◽  
Zhichao Liang ◽  
Dayi Zhang ◽  
Yanhong Ma
Keyword(s):  
High Speed ◽  
High Performance ◽  
Element Model ◽  
Physical Parameters ◽  
Test Rig ◽  
Calculation Results ◽  
Rotor Support ◽  
Blade Tip ◽  
Set Up ◽  
The Impact

Aeroengines pursue high performance, and compressing blade-casing clearance has become one of the main ways to improve turbomachinery efficiency. Rub-impact faults occur frequently with clearance decreasing. A high-speed rotor-support-casing test rig was set up, and the mechanism tests of light and heavy rub-impact were carried out. A finite element model of the test rig was established, and the calculation results were in good agreement with the experimental results under both kinds of rub-impact conditions. Based on the actual blade-casing structure model, the effects of the major physical parameters including imbalance and material characteristics were investigated. During the rub-impact, the highest stress occurs at the blade tip first and then it is transmitted to the blade root. Deformation on the impact blade tip generates easily with decreased yield strength, and stress concentration at the blade tip occurs obviously with weaker stiffness. The agreement of the computation results with the experimental data indicates the method could be used to estimate rub-impact characteristics and is effective in design and analyses process.

Numerical Simulation Analysis of Collision between Ship and Steel Sheet Pile Quay-Wall

2015 ◽  
Vol 744-746 ◽  
pp. 1175-1179 ◽  
Author(s):  
Peng Liu ◽  
Hong Wang ◽  
Chao Zhu
Keyword(s):  
Numerical Simulation ◽  
Steel Sheet ◽  
Impact Force ◽  
Simulation Analysis ◽  
Sheet Pile ◽  
Time Curve ◽  
Finite Element Software ◽  
Quay Wall ◽  
Force Time ◽  
The Impact

The impact process of 50000t ship and steel sheet pile bulkhead is simulated by finite element software ANSYS/LS-DYNA. This article acquires the impact force-time curve, equivalent force-time curve of steel sheet pile and the pressure-time curve of breast wall. Comparing the impact force of numerical simulation with the result of ship-bridge collision specifications, and general rules and characteristics are obtained. At the same time, put forward some measures to prevent the damage of wharf structure under the ship of large velocity impact, which provide theoretical references during the design, maintenance, and transformation of similar wharf.

Investigations of Reduction Effect of Vertical Wall on Dam-Break-Simulated Tsunami Surge Exerted on Wharf Piles

2018 ◽  
Vol 12 (02) ◽  
pp. 1840006 ◽  
Author(s):  
Cheng Chen ◽  
Bruce W. Melville ◽  
N. A. K. Nandasena
Keyword(s):  
High Speed ◽  
Preliminary Investigation ◽  
Vertical Wall ◽  
Pressure Sensors ◽  
Time History ◽  
Dam Break ◽  
Reservoir System ◽  
Reduction Effect ◽  
The Impact ◽  
Surge Height

For a preliminary investigation of the impact of a tsunami surge on wharf piles, a tsunami flume was built in a laboratory, and a dam break flow was generated by a gate-reservoir system to simulate a tsunami surge. In addition, a vertical wall was installed in front of the wharf model so that its effect in reducing tsunami load could be studied. Five different tsunami surge strengths were generated by this gate-reservoir system. Wave transducers were used in the test flume to capture surge heights and velocities, and hence the surge front profiles, for different surge strengths. High-speed video cameras (210 frames per second) were used to record the flow motion of the tsunami surge, and pressure sensors (1000[Formula: see text]Hz in frequency) were used to capture the time histories of the tsunami pressure on the wharf piles. Four stages of tsunami surge motions were observed by this high-speed camera. Accordingly, the pressure time history can be divided into three phases. In our experimental range, pressures were influenced by surge height and wall height, but not by the wall position. Based on the dimensionless experimental data (pile heights, surge heights, vertical wall heights, and surge pressures), equations for estimating tsunami loads on wharf pile are proposed, expressing surge front (peak impact) pressure and quasi-steady pressure as functions of surge height, wall height, and pile height.

EFFECT OF THE FLUID ON THE IMPACT FORCE OF THE WET MISSILE

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Duc-Kien Thai ◽  
Seung-Eock Kim
Keyword(s):  
Impact Force ◽  
Force Plate ◽  
Time History ◽  
Research Centre ◽  
Element Analysis ◽  
Time Histories ◽  
Target Wall ◽  
Force Time ◽  
Missile Test ◽  
The Impact

In this paper, the force-time histories of soft missiles, with and without filled water, impacting the target wall were investigated using finite element analysis. The force plate tests, with a dry missile (test FP8) and a wet missile (test FP16) carried out by Technical Research Centre of Finland (VTT), were used. The numerical analysis results were verified by comparing with those of experiments. A parametric analysis with different missile velocities was also performed to investigate the force-time history and impulse of the missile impact on target plate. Based on a comparison with the Riera approach, the coefficients were proposed to modify the Riera function. The analysis results show that, the Riera function accurately predicted the impact force time history in the case of the dry missile. However, in the case of the wet missile, the coefficients α from 1.24 to 1.45 are recommended to be added to the second term of the Riera function in the case in which the impact velocity is in the range of 70 m/s to 200 m/s.

scholarly journals Human-Structure Dynamic Interaction during Short-Distance Free Falls

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
E. Shahabpoor ◽  
A. Pavic
Keyword(s):  
Force Plate ◽  
Free Fall ◽  
Physical Contact ◽  
Contact Model ◽  
Dynamic Interactions ◽  
Agent Based ◽  
Sports Science ◽  
Impact Biomechanics ◽  
Contact Models ◽  
The Impact

The dynamic interactions of falling human bodies with civil structures, regardless of their potentially critical effects, have sparsely been researched in contact biomechanics. The physical contact models suggested in the existing literature, particularly for short-distant falls in home settings, assume the human body falls on a “rigid” (not vibrating) ground. A similar assumption is usually made during laboratory-based fall tests, including force platforms. Based on observations from a set of pediatric head-first free fall tests, the present paper shows that the dynamics of the grounded force plate are not always negligible when doing fall test in a laboratory setting. By using a similar analogy for lightweight floor structures, it is shown that ignoring the dynamics of floors in the contact model can result in an up to 35% overestimation of the peak force experienced by a falling human. A nonlinear contact model is suggested, featuring an agent-based modelling approach, where the dynamics of the falling human and the impact object (force plate or a floor structure here) are each modelled using a single-degree-of-freedom model to simulate their dynamic interactions. The findings of this research can have wide applications in areas such as impact biomechanics and sports science.

An Experimental Surface-Wave Method for Recording Force-Time Curves in Elastic Impacts

1959 ◽  
Vol 26 (1) ◽  
pp. 3-7
Author(s):  
J. N. Goodier ◽  
W. E. Jahsman ◽  
E. A. Ripperger
Keyword(s):  
Surface Wave ◽  
Plane Surface ◽  
Hopkinson Pressure Bar ◽  
Time Curve ◽  
Experimental Surface ◽  
Force Time ◽  
Steel Balls ◽  
Pressure Bar ◽  
Surface Wave Method ◽  
The Impact

Abstract The recording of impacts by means of the longitudinal strain wave generated in a Hopkinson pressure bar is no longer possible when the impact is very brief, on account of dispersive effects. The Rayleigh surface wave generated on the plane surface of a block is nondispersive. A method is given for deducing the force-time curve of the impact from the oscilloscope record of the surface wave, and applied to impacts of small steel balls on a block.

Power-Time, Force-Time, and Velocity-Time Curve Analysis during the Jump Squat: Impact of Load

2008 ◽  
Vol 24 (2) ◽  
pp. 112-120 ◽  
Author(s):  
Prue Cormie ◽  
Jeffrey M. McBride ◽  
Grant O. McCaulley
Keyword(s):  
Body Mass ◽  
Power Output ◽  
Peak Power ◽  
Peak Power Output ◽  
Power Development ◽  
Time Curve ◽  
Force Time ◽  
The Impact ◽  
External Loads ◽  
Male Subjects

The purpose of this investigation was to examine the impact of load on the power-, force- and velocity-time curves during the jump squat. The analysis of these curves for the entire movement at a sampling frequency of 200–500 Hz averaged across 18 untrained male subjects is the most novel aspect of this study. Jump squat performance was assessed in a randomized fashion across five different external loads: 0, 20, 40, 60, and 80 kg (equivalent to 0 ± 0, 18 ± 4, 37 ± 8, 55 ± 12, 74 ± 15% of 1RM, respectively). The 0-kg loading condition (i.e., body mass only) was the load that maximized peak power output, displaying a significantly (p≤ .05) greater value than the 40, 60, and 80 kg loads. The shape of the force-, power-, and velocity-time curves changed significantly as the load applied to the jump squat increased. There was a significantly greater rate of power development in the 0 kg load in comparison with all other loads examined. As the first comprehensive illustration of how the entire power-, force-, and velocity-time curves change across various loading conditions, this study provides extensive evidence that a load equaling an individuals body mass (i.e., external load = 0 kg) maximizes power output in untrained individuals during the jump squat.

The Behaviour of the Impact Damper

1965 ◽  
Vol 180 (1) ◽  
pp. 895-906 ◽  
Author(s):  
M. M. Sadek
Keyword(s):  
Differential Equation ◽  
Impact Force ◽  
Equation Of Motion ◽  
Dynamic Equations ◽  
Vibrational Amplitude ◽  
Time Curve ◽  
Impact Damper ◽  
Rectangular Shape ◽  
Force Time ◽  
The Impact

In this investigation a theory is developed relating to the behaviour of the impact damper. The analysis is based on the assumptions that (1) two un-equispaced impacts per cycle occur in the steady state, and (2) the impact force-time curve is of rectangular shape and of infinitesimal duration. Fourier series are used to represent the impact cycle and the differential equation of motion is derived. This is solved using the dynamic equations of impact to determine the boundary conditions. Three equations are developed to determine the variation of impulse, phase angle and vibrational amplitude with the change of the damper parameters. Resonance curves are obtained and the theory is examined experimentally. The regions of validity of the above assumptions are studied both theoretically and experimentally. Non-linearity in the behaviour of this damper is very clear, especially in the range of its optimum behaviour. Two design curves are developed which can be used to determine the damper parameters necessary for a certain amplitude reduction.

scholarly journals Squat Jump Movement Onset Thresholds Influence on Kinetics and Kinematics

2021 ◽  
Vol 9 (3) ◽  
pp. 1
Author(s):  
Paul T Donahue ◽  
Christopher M Hill ◽  
Samuel J Wilson ◽  
Charles C Williams ◽  
John C Garner
Keyword(s):  
Intraclass Correlation ◽  
Force Platform ◽  
Vertical Force ◽  
Time Data ◽  
Movement Onset ◽  
Time Curve ◽  
Squat Jump ◽  
Force Velocity ◽  
Force Time ◽  
The Impact

Background of Study: Differing movement onset thresholds have been used when analyzing the squat jump movement from force-time data obtained from a force platform. This makes comparisons difficult between investigations as this will impact the amount of the force-time curve that is analyzed. Objective: Thus, study examined the effect onset threshold had on kinetic and kinematic variables used in the assessment of the squat jump. Methods: Using a within-subject study design, fifteen recreational trained males performed three trials of squat jumps on a force platform. Each trial was analyzed using one of five different onset thresholds (2.5% SW, 5% SW, 10% SW, 20N, 5SD). Force, velocity, and power, as well as time to peak force, velocity, power and jump height were calculated using the vertical force data obtain from the force plate. Reliability was assessed using intraclass correlation coefficients and coefficients of variation. A one-way ANOVA was used to examine the impact of onset thresholds on all variables of interest. Results: The use of 10% SW and 5SD met minimum reliability criteria for all variables. Temporal related variables were impact to the greatest extent by differing thresholds with large (d > 1.20) significant differences. 10% SW showed the highest mean values of force, velocity, and power. Conclusions: The use of 5SD of the weighting phase is recommended as this showed high level of both absolute and relative reliability in addition to preserving a large portion of the force – time curve to be used in the analysis.

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