Impact forces at improvised via ferrata

Impact forces analysis in heel-toe running is often used to examine the reduction of impact forces for different running shoes and/or running techniques. Body mass is reported to be a dominant predictor of vertical impact force peaks. However, it is not evident whether this finding is only true for the real body mass or whether it is also true for additional masses attached to the body (e.g., running with additional weight or heavy shoes). The purpose of this study was to determine the effect of additional mass on vertical impact force peaks and running style. Nineteen subjects (9 males, 10 females) with a mean mass of 74.2 kg/56.2 kg (SD = 10.0 kg and 6.0 kg) volunteered to participate in this study. Additional masses were attached to the shoe (.05 and .1 kg), the tibia (.2, .4, .6 kg), and the hip (5.9 and 10.7 kg). Force plate measurements and high-speed film data were analyzed. In this study the vertical impact force peaks, Fzi, were not affected by additional masses, the vertical active force peaks, Fza, were only affected by additional masses greater than 6 kg, and the movement was only different in the knee angle at touchdown, ϵ0, for additional masses greater than .6 kg. The results of this study did not support findings reported earlier in the literature that body mass is a dominant predictor of external vertical impact force peaks.

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Postural influence on Stand-to-Sit leg load sharing strategies and sitting impact forces in stroke patients

Gait & Posture ◽

10.1016/j.gaitpost.2010.08.005 ◽

2010 ◽

Vol 32 (4) ◽

pp. 576-580 ◽

Cited By ~ 13

Author(s):

Hung-Bin Chen ◽

Ta-Sen Wei ◽

Liang-Wey Chang

Keyword(s):

Load Sharing ◽

Stroke Patients ◽

Impact Forces

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Parametric investigation of the effects of deadrise angle and demi-hull separation on impact forces and spray characteristics of catamaran water entry

Journal of the Brazilian Society of Mechanical Sciences and Engineering ◽

10.1007/s40430-016-0679-3 ◽

2016 ◽

Vol 39 (6) ◽

pp. 1989-1999 ◽

Cited By ~ 8

Author(s):

Roya Shademani ◽

Parviz Ghadimi

Keyword(s):

Water Entry ◽

Spray Characteristics ◽

Parametric Investigation ◽

Impact Forces

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Considerations Concerning Vehicle Collisions Through Simplified Calculations of the Impact Forces

10.4271/962324 ◽

1996 ◽

Cited By ~ 1

Author(s):

Helcio Onusic ◽

José Augusto P. Campos ◽

Paulo Sergio P. dos Santos

Keyword(s):

Vehicle Collisions ◽

Impact Forces ◽

The Impact

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The effect of the descent technique and truck cabin layout on the landing impact forces

Applied Ergonomics ◽

10.1016/s0003-6870(01)00032-1 ◽

2001 ◽

Vol 32 (6) ◽

pp. 573-582 ◽

Cited By ~ 6

Author(s):

Stéphane Patenaude ◽

Denis Marchand ◽

Sabina Samperi ◽

Marc Bélanger

Keyword(s):

Impact Forces ◽

Landing Impact

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Rattlesnake strike behavior: kinematics

Journal of Experimental Biology ◽

10.1242/jeb.201.6.837 ◽

1998 ◽

Vol 201 (6) ◽

pp. 837-850 ◽

Cited By ~ 9

Author(s):

K V Kardong ◽

V L Bels

Keyword(s):

High Speed ◽

Predatory Behavior ◽

The Body ◽

Body Postures ◽

Body Segments ◽

Impact Forces ◽

Tactile Stimuli ◽

High Speed Film ◽

Rodent Prey ◽

Subsequent Loss

The predatory behavior of rattlesnakes includes many distinctive preparatory phases leading to an extremely rapid strike, during which venom is injected. The rodent prey is then rapidly released, removing the snake's head from retaliation by the prey. The quick action of the venom makes possible the recovery of the dispatched prey during the ensuing poststrike period. The strike is usually completed in less than 0.5 s, placing a premium on an accurate strike that produces no significant errors in fang placement that could result in poor envenomation and subsequent loss of the prey. To clarify the basis for effective strike performance, we examined the basic kinematics of the rapid strike using high-speed film analysis. We scored numerous strike variables. Four major results were obtained. (1) Neurosensory control of the strike is based primarily upon sensory inputs via the eyes and facial pits to launch the strike, and upon tactile stimuli after contact. Correction for errors in targeting occurs not by a change in strike trajectory, but by fang repositioning after the jaws have made contact with the prey. (2) The rattlesnake strike is based upon great versatility and variation in recruitment of body segments and body postures. (3) Forces generated during acceleration of the head are transferred to posterior body sections to decelerate the head before contact with the prey, thereby reducing impact forces upon the snake's jaws. (4) Body acceleration is based on two patterns of body displacement, one in which acute sections of the body open like a gate, the other in which body segments flow around postural curves similar to movements seen during locomotion. There is one major implication of these results: recruitment of body segments, launch postures and kinematic features of the strike may be quite varied from strike to strike, but the overall predatory success of each strike by a rattlesnake is very consistent.

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The Effects of Upstream Flexible Barrier on the Debris Flow Entrainment and Impact Dynamics on a Terminal Barrier

Canadian Geotechnical Journal ◽

10.1139/cgj-2021-0119 ◽

2021 ◽

Author(s):

Hervé Vicari ◽

C.W.W. Ng ◽

Steinar Nordal ◽

Vikas Thakur ◽

W.A. Roanga K. De Silva ◽

...

Keyword(s):

Debris Flow ◽

Debris Flows ◽

Impact Force ◽

Dynamic Pressure ◽

Pressure Coefficient ◽

Flexible Barrier ◽

Impact Forces ◽

Flexible Barriers ◽

The Impact ◽

Bed Entrainment

The destructive nature of debris flows is mainly caused by flow bulking from entrainment of an erodible channel bed. To arrest these flows, multiple flexible barriers are commonly installed along the predicted flow path. Despite the importance of an erodible bed, its effects are generally ignored when designing barriers. In this study, three unique experiments were carried out in a 28 m-long flume to investigate the impact of a debris flow on both single and dual flexible barriers installed in a channel with a 6 m-long erodible soil bed. Initial debris volumes of 2.5 m3 and 6 m3 were modelled. For the test setting adopted, a small upstream flexible barrier before the erodible bed separates the flow into several surges via overflow. The smaller surges reduce bed entrainment by 70% and impact force on the terminal barrier by 94% compared to the case without an upstream flexible barrier. However, debris overflowing the deformed flexible upstream barrier induces a centrifugal force that results in a dynamic pressure coefficient that is up to 2.2 times higher than those recommended in guidelines. This suggests that although compact upstream flexible barriers can be effective for controlling bed entrainment, they should be carefully designed to withstand higher impact forces.

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Point mass impulse-momentum model of the equine rotational fall

Comparative Exercise Physiology ◽

10.3920/cep190018 ◽

2019 ◽

Vol 15 (3) ◽

pp. 157-165

Author(s):

M.H. Foreman ◽

J.R. Engsberg ◽

J.H. Foreman

Keyword(s):

Point Mass ◽

Future Research ◽

Collision Time ◽

Mass Model ◽

Impact Forces ◽

Force Transfer ◽

Reference Curves ◽

Key Variables ◽

Cross Country ◽

Input Variables

Rotational falls are a serious cause of injury and death to horse and rider, particularly in the cross-country phase of eventing. The forces involved when horses galloping cross-country strike an immovable fence are unknown. The objective of this study was to mathematically model those forces using existing kinematic data measured from jumping horses. Data were obtained from published research using motion capture to measure mechanics about the center of gravity of the jumping horse at take-off. A convenience method from video evidence of rotational falls was used to estimate time of collision (Δt). A point mass model using equations of impulse-momentum and incorporating key variables was systematically implemented in Matlab (r2016a). The mean collision time (Δt=0.79s) produced horizontal, vertical, and resultant impact forces of 8,580, 8,245, and 12,158 N, respectively. Reference curves of impact forces were created for ranges of relevant input variables including collision time. Proportional relationships showed that shorter impact duration led to higher magnitude of force transfer between horse and obstacle. This study presents a preliminary range of collision forces based on a simplified model and numerous assumptions related to input variables. Future research should work to build upon these estimates through more complex modelling and data collection to enhance applicability for the design of cross-country safety devices.

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