Vertical Impact Forces Research Articles

Field Measurement of Wheel-Rail Impact Force at Insulated Rail Joint

When wheels pass over insulated rail joints (IRJs) a vertical impact force is generated. The ability to measure the impact force is valuable as the force signature helps understand the behaviour of the IRJs, in particular their potential for failure. The impact forces are thought to be one of the main factors that cause damage to the IRJ and track components. Study of the deterioration mechanism helps finding new methods to improve the service life of IRJs in track. In this research, the strain-gage-based wheel load detector, for the first time, is employed to measure the wheel–rail contact-impact force at an IRJ in a heavy haul rail line. In this technique, the strain gages are installed within the IRJ assembly without disturbing the structural integrity of IRJ and arranged in a full wheatstone bridge to form a wheel load detector. The instrumented IRJ is first tested and calibrated in the lab and then installed in the field. For comparison purposes, a reference rail section is also instrumented with the same strain gage pattern as the IRJ. In this paper the measurement technique, the process of instrumentation, and tests as well as some typical data obtained from the field and the inferences are presented.

Theoretical development of a simplified wheelset model to evaluate collision-induced derailments of rolling stock

A theoretical method is proposed to predict and evaluate collision-induced derailments of rolling stock by using a simplified wheelset model and is verified with dynamic simulations. Because the impact forces occurring during collision are transmitted from the car body to the bogies and axles through suspensions, rolling stock leads to derailment as a result of the combination of horizontal and vertical impact forces applied to the axle and a simplified wheelset model enforced at the axle can be used to theoretically formulate derailment behaviors. The derailment type depends on the combination of the horizontal and vertical forces, the flange angle and the friction coefficient. According to collision conditions, wheel-climb, wheel-lift or roll-over derailment can occur between the wheel and the rail. In this theoretical derailment model of a simplified wheelset, the derailment types are classified as Slip-up, Slip/roll-over, Climb-up, Climb/roll-over and pure Roll-over according to the derailment mechanisms between the wheel and the rail and the theoretical conditions needed to generate each derailment mechanism are proposed. The theoretical wheelset model is verified by dynamic simulation and its applicability is demonstrated by comparing the simulation results of the theoretical wheelset model with those of an actual wheelset model. The theoretical derailment wheelset model is in good agreement with the virtual testing model simulation for a collision-induced derailment of rolling stock.

Reliability of Impact Forces, Hip Angles and Velocities during Simulated Forward Falls Using a Novel Propelled Upper Limb Fall ARrest Impact System (PULARIS)

Previous forward fall simulation methods have provided good kinematic and kinetic data, but are limited in that they have started the falls from a stationary position and have primarily simulated uni-directional motion. Therefore, a novel Propelled Upper Limb fall ARest Impact System (PULARIS) was designed to address these issues during assessments of a variety of fall scenarios. The purpose of this study was to present PULARIS and evaluate its ability to impact the upper extremities of participants with repeatable velocities, hand forces and hip angles in postures and with vertical and horizontal motion consistent with forward fall arrest. PULARIS consists of four steel tubing crossbars in a scissor-like arrangement that ride on metal trolleys within c-channel tracks in the ceiling. Participants are suspended beneath PULARIS by the legs and torso in a prone position and propelled horizontally via a motor and chain drive until they are quick released, and then impact floor-mounted force platforms with both hands. PULARIS velocity, hip angles and velocities and impact hand forces of ten participants (five male, five female) were collected during three fall types (straight-arm, self-selected and bent-arm) and two fall heights (0.05 m and 0.10 m) to assess the reliability of the impact conditions provided by the system. PULARIS and participant hip velocities were found to be quite repeatable (mean ICC = 0.81) with small between trial errors (mean = 0.03 m/s). The ratio of horizontal to vertical hip velocity components (~0.75) agreed well with previously reported data (0.70-0.80). Peak vertical hand impact forces were also found to be relatively consistent between trials with a mean ICC of 0.73 and mean between trial error of 13.4 N. Up to 83% of the horizontal hand impact forces displayed good to excellent reliability (ICC > 0.6) with small between trial differences. Finally, the ICCs for between trial hip angles were all classified as good to excellent. Overall, PULARIS is a reliable method and is appropriate for studying the response of the distal upper extremity to impact loading during non-stationary, multi-directional movements indicative of a forward fall. This system performed well at different fall heights, and allows for a variety of upper and lower extremity, and hip postures to be tested successfully in different landing scenarios consistent with elderly and sport-related falls.

開口を有する建築物を対象とした三次元津波荷重解析と転倒判定法の提案

A numerical simulation using VOF method was carried out to investigate the tsunami forces acting on building with apertures. Large vertical impact forces acting on the ceiling and floor of the building, which had not been considered in previous studies and guidelines, were found due to the invasion of tsunami flow through apertures. Next, formulae of horizontal and vertical forces were proposed in two steps of impact flow and translational flow, respectively. These formulae were then evaluated in comparison with the numerical results to clarify their performances. Finally, the scouring and liquefaction on the foundation were discussed to take note of the adverse condition of building in falling damages.

B6 シューズ-人体連成モデルを利用したシューズの機能抽出(シューズおよびサーフェス)

The purpose of this study was to quantify the functional role of compressive characteristics of shoes sole by combining a fmite-truss-element shoes model and equation of whole-body motion. The equation of the shoes sole deformation was developed by modeling shoes sole as a construction of truss elements with nonlinear spring and damper properties. The coefficients of the properties were identified from impact test by using an impact device consisting of accelerometer and arm with impactor. The equation of whole-body motion was derived by modeling the human body as a system of 15-rigid linked segments. Dynamic contributions of the support leg joint torques, which were caused by the elastic and viscous property of the shoes sole, to the generation of whole-body CG's acceleration were calculated under constant running speed condition. The results in this study indicate that 1) the plantar flexion torque about the ankle caused by the elastic property of the forepart of shoes sole contributes to the acceleration of whole-body CG, and 2) the flexion torque of the knee caused by the viscous property of shoe sole contributes to the absorption of the vertical impact force occurred at foot contact.

Construction Site Measurement of High or Large-Span Form Strut System

Design theory of high or large-span form strut system cann’t meet the engineering requirement and deficiencies were pointed out. In this paper, variation rule of axial force of the strut with the whole course of concrete pouring had been studied by measuring on three sites. The result discovered that pouring method and floor modes have significant effect on axial force of high or large-span form strut system. Compared to manual pouring, pumping lead to not only horizontal impact force but also vertical impact force. Compared to flat roof, axial force of avertical strut in sloping roof form strut system were more uneven and the maximal difference reached to 2 times. Axial force between bottom part and top part at avertical strut are different due to the influence of horizontal strut and crossing strut. Due to analysis result, some corresponding advices were put out in the end.

Active Synthetic-Wheel Biped With Torso

The design of a new biped robot is proposed. Based on the concept of a self-propelled wheel, the design eliminates vertical impact forces from the ground during walking. The biped comprises a torso and two legs. With arc-shaped feet, each leg is constrained to move in a manner that allows the robot to walk by rolling alternately on its two feet. The purpose of the torso is to generate motion through unbalance. The mathematical model of the robot is developed, and constraints are imposed to generate simple walking gaits. A hardware prototype of the biped was fabricated, and a controller was designed to generate one specific gait. This gait results in horizontal impulsive forces at the time of touchdown of the swing leg and the effect of these forces is studied through experiments. The experimental results of the biped successfully walking down a hallway are presented.

The Calculation of Wheel Impact Force Due to the Interaction between Vehicle and a Turnout

It is known that railway turnouts demand more maintenance than other parts of the railway track network because of large impact loads generated by the variation of wheel-rail contact conditions along the turnout and through the crossing. A method using VAMPIRE® modelling to determine the wheel impact forces due to passing turnout has been developed and presented in this article. The simulation shows that both turnout curve and crossing have significant effect on the wheel impact forces; the vertical impact forces from the turnout case are not significantly different from the wheels travelling straight through.

과도한 회내 동작을 보이는 병사들의 군장 착용이 지면반력에 미치는 영향

The purpose of this study was to examine the effects of over pronation on GRF when military marching. It were Selected Four volunteers with normal foot and six volunteers with excessive pronation foot. The kinematic data were collected with ground reaction forces device during walking. The walk was performed with a speed of 4.5 km/h. The experiment was to examine vertical impact force, maximum loading rate and total impulse between normal foot and excessive pronator foot during march. The analyzed results were compared by one-way ANOVA method of SPSS(windows version 15.0). The result of the study were on over pronator foot tend to increase during march but a statistically significant increase in vertical impact force, maximum loading rate and total impulse. It was mean the change which ground reaction force is not quantitative but to degree of shock being difference. Clinically, When will be accomplish the same task It will be able to forecast the increase fatique and injury which is the soldiers with excessive pronation foot compare to soldiers with normal foot.

Model tests on anomalous low friction and pendulum-type wave phenomena

The anomalous low friction (ALF) and pendulum-type wave ( μ wave) phenomena were two typical, nonlinear, geo-mechanical, and dynamic responses in deep-block rock mass discovered from in situ observations, which occurred from the movement of the geo-blocks under the impact of external pulses, such as deep confined explosion, earthquake, and rock bursts. With the aim to confirm the existence of the above two phenomena and study the variation laws of them experimentally, laboratory tests on the granite and cement mortar continuum and blocks models were conducted on the self-independently developed multipurpose testing system, respectively. The ALF phenomenon was realized under two loading schemes, the blocks model and working block were acted upon by the joint action of vertical impact and horizontal static force as well as the joint action of both vertical and horizontal impacts with different time intervals. It revealed that the discrete time delays corresponding to the local maximums and minimums of the horizontal displacement amplitudes and residual horizontal displacements of the working block satisfied the canonical sequences with the multiple of 2 , most of which satisfied the quantitative expression 2 i Δ / V p . Besides, the one-dimensional impact experiments were carried out on the blocks granite model, continuum, and blocks cement mortar models, respectively. Based on the comparison and analysis of the propagation properties (amplitudes and the Fourier spectrums of acceleration time histories of blocks) of the 1D stress wave in the above models, it is indicated that the fractures in rock mass have tremendous effect on the attenuation of acceleration amplitudes and high-frequency waves. By comparison of the model test data with the in situ measurement conclusions, the existence of the μ wave was confirmed experimentally in the cement mortar blocks model with larger dimensions, and the frequencies corresponding to the local maximums of spectral density curves of three-directional acceleration time histories of sub-blocks also satisfied several canonical sequences with the multiple of 2 .

Force platform for rats measures fore and hind forces concurrently

Animal models are commonly used to test the efficacy of impact loading regimens on bone strength. We designed an inexpensive force platform to concurrently measure the separate peak vertical impact forces produced by the fore and hindfeet of immature F-344 rats when dropped onto the platform. The force platform consisted of three load cells placed in a triangular pattern under a flat plate. Rats were dropped from heights of 30, 45 and 60 cm onto the platform so that they landed on all four feet concurrently. The peak vertical impact forces produced by the feet of the rats were measured using a sampling frequency of 100 kHz. The location of each foot at landing relative to the load cells, and the force received by each load cell were combined in a series of static equations to solve for the vertical impact forces produced by the fore and hindfeet. The forces produced by feet when rats stood on the single platform were similarly determined. The forces exerted separately by the fore and hindfeet of young rats when landing on the plate as a ratio to standing forces were then calculated. Rats when standing bore more weight on their hindfeet but landed with more weight on their forefeet, which provides rationale for the greater response to landing forces of bones in the forelimbs than those in the hindlimbs. This system provided a useful method to simultaneously measure peak vertical impact forces in fore and hindfeet in rats.

Feedback linearization and sliding mode control for active hydropneumatic suspension of a special-purpose vehicle

Based on modelling and experimental validation of the hydropneumatic spring, a non-linear dynamic model is developed for active hydropneumatic suspensions of a special-purpose vehicle. In order to improve the system response to off-road terrain unevenness and vertical impact force, the non-linear system is transformed into a linear one by means of feedback linearization. Furthermore, a sliding mode control strategy is introduced for the purpose of raising the robustness of the system. The simulation results indicate that the present non-linear controller combining the feedback linearization with the linear control algorithm possesses high control accuracy and strong robustness, and the unique requirements for the special-purpose vehicle are therefore fairly well satisfied.

The Use of External Transducers for Estimating Bone Strain at the Distal Tibia During Impact Activity

Noninvasive methods for monitoring the in vivo loading environment of human bone are needed to determine osteogenic loading patterns that reduce the potential for bone injury. The purpose of this study was to determine whether the vertical ground reaction impact force (impact force) and leg acceleration could be used to estimate internal bone strain at the distal tibia during impact activity. Impact loading was delivered to the heels of human-cadaveric lower extremities. The effects of impact mass and contact velocity on peak bone strain, impact force, leg acceleration, and computed impact force (leg acceleration *impact mass) were investigated. Regression analysis was used to predict bone strain from six different models. Apart from leg acceleration, all variables responded to impact loading similarly. Increasing impact mass resulted in increased bone strain, impact force, and computed impact force, but decreased leg acceleration. The best models for bone strain prediction included impact force and tibial cross-sectional area (R(2)=0.94), computed impact force and tibial cross-sectional area (R(2)=0.84), and leg acceleration and tibial cross-sectional area (R(2)=0.73). Results demonstrate that when attempting to estimate bone strain from external transducers some measure of bone strength must be considered. Although it is not recommended that the prediction equations developed in this study be used to predict bone strain in vivo, the strong relationship between bone strain, impact force, and computed impact force suggested that force platforms and leg accelerometers can be used for a surrogate measure of bone strain.

The effect of increasing inertia upon vertical ground reaction forces and temporal kinematics during locomotion

The addition of inertia to exercising astronauts could increase ground reaction forces and potentially provide a greater health benefit. However, conflicting results have been reported regarding the adaptations to additional mass (inertia) without additional net weight (gravitational force) during locomotion. We examined the effect of increasing inertia while maintaining net gravitational force on vertical ground reaction forces and temporal kinematics during walking and running. Vertical ground reaction force was measured for 10 healthy adults (five male/five female) during walking (1.34 m s(-1)) and running (3.13 m s(-1)) using a force-measuring treadmill. Subjects completed locomotion at normal weight and mass and at 10, 20, 30 and 40% of added inertial force. The added gravitational force was relieved with overhead suspension, so that the net force between the subject and treadmill at rest remained equal to 100% body weight. Ground reaction forces were affected by the added inertial force, but not to the magnitude predicted by the increase in mass, suggesting that adaptations in motion occurred. Vertical ground reaction force production and adaptations in gait temporal kinematics were different between walking and running. Peak vertical impact forces and loading rates increased with increased inertia during walking, and decreased during running. As inertia increased, peak vertical propulsive forces decreased during walking and did not change during running. Stride time increased during walking and running, and contact time increased during running. The increased inertial forces were utilized independently from gravitational forces by the motor control system when determining coordination strategies.

Probabilistic analysis of train–track vertical impact forces

As part of a project developing a new limit states design method for prestressed concrete railway sleepers, extensive measurements were conducted of vertical impact forces exerted by trains on track. The vertical impact forces due to defects in the train wheels were found to occur randomly and followed an exponential distribution with time. This distribution is used to predict return periods for various levels of impact forces, needed for limit states design of sleepers. The effect of train speed was studied and showed that doubling the speed of a train would increase impact forces by about 140% for a wide range of return periods, but increasing the return period from 25 years to 200 years increased the impact force by only 10 to 15%. Applying a proposed cumulative damage model to the Monte Carlo method, it was found that the return period used for potential design of sleepers had little effect on the rate of sleeper failure in the period up to 20 years sleeper age, but that the return period had a large effect after that time.

Effect of Cushioned Insoles on Impact Forces During Running

The use of cushioned or shock-absorbing insoles has been suggested as a mechanism to reduce the impact forces associated with running, thereby protecting against overuse injuries. The purpose of this study was to determine whether the use of cushioned insoles reduced impact forces during running in healthy subjects. Sixteen recreational runners (9 females and 7 males) ran at a self-selected pace for five trials with and without the use of cushioned insoles. During each trial, ground reaction forces, tibial accelerations, lower-extremity kinematics, and subject-perceived comfort were recorded. All variables were tested with the level of statistical significance set at alpha = .05. The use of cushioned insoles resulted in significant reductions in mean vertical ground reaction force peak impact (6.8%) and ground reaction force loading rate (8.3%), as well as peak tibial acceleration (15.8%). Spectral analysis of the tibial acceleration data in the frequency range associated with impact accelerations (12-25 Hz) revealed no change in the predominant frequency or the power of the predominant frequency. The knee flexion angle at initial contact and perceived comfort were similar for the two conditions. This study demonstrates the effectiveness of one type of cushioned insole in reducing peak impact force and tibial acceleration at initial foot-ground contact during running. The impact reduction observed was independent of knee kinematic adjustments or changes in perceived comfort. Further study is required to determine whether the reduction in loading that accompanied the use of the cushioned insoles can affect the incidence of running-related injuries.

Biomechanics of aggressive inline skating: Landing and balancing on a grind rail

Currently, only epidemiological injury data have been reported for the new extreme sport of aggressive inline skating, or trick skating. No studies have examined the biomechanics of this sport, which involves repetitive jumping and landing from railings, ramps, and ledges, often over 1 m in height. We present results of a pilot study that examined the effect of skater experience and lower extremity biomechanics on energy absorption ability, and observed balance strategies used during two basic tricks. In these tricks, the skater jumps onto an elevated rail and maintains balance while standing in a single position (stall) or sliding along the rail (grind). Lower extremity joint kinematics, impact force characteristics, and general movement behaviours were examined during landing and balance phases. Ten male skaters performed ten stalls and ten frontside grinds on an instrumented grind rail, capable of measuring vertical force. Vertical impact force was found to decrease with increasing skater experience in stalls (r = −0.84, P = 0.002) and grinds (r = −0.84, P = 0.009). This might imply that less-experienced skaters are (subconsciously) more concerned about maintaining balance than refining technique to minimize impact force. Similar to drop landing experiments, peak impact force decreased with increasing knee flexion during stalls (r = −0.65, P = 0.04). During stalls, skaters demonstrated classic balance maintenance strategies (ankle, hip, or multi-joint) depending on trick length. During grinds, skater centre of mass never passed over the rail base of support, suggesting the use of momentum produced from obliquely approaching the rail.

런닝화의 일반인솔과 기능성인솔의 운동역학적 비교 분석

These studies show that I applied to functional insole (a specific S company) for minimizing shocks and sprain people's ankle arising from running. How to an effect on human body which studied a kinematics and kinetics from 10 college students during experiments. This study imposes several conditions by barefoot, normal running shoes and put functional insole shoes ran under average <TEX>$2.0{\pm}0.24$</TEX> meter per second by motion analysis, ground reaction force and electromyography that used to specific A company. First of all, Motion analysis was caused by Achilles tendon angle, Angle of the lower leg, Angle of the knee, Initial sole angle and Barefoot angle. Second, Contact time, Vertical impact force peak timing, Vertical active force and Active force timing, and Maximum loading rate under impulse of first 20 percent and Value of total impulse caused Ground reaction force. Third. The tendon fo Quadriceps femoris, Biceps femoris, Tibialis anterior and gastronemius medials caused. electromyography. 1. Ground reaction force also showed that statically approximates other results from impact peak timing (p.001), Maximum loading rate(p<.001), Maximum loading rate timing (p<.001) and impulse of first 20 percent (p<.001). 2 Electromyography showed that averagely was distinguished from other factors, and did not show about that. Above experiment values known that there was statically difference between Motion analysis and Ground reaction force under absorbing of the functional insole shoes which was not have an effect on our body for kinetics and kinematics.

Kinetic asymmetry in female runners with and without retrospective tibial stress fractures

Gait asymmetry may be linked to the tendency for runners to sustain chronic overuse injuries. This paper compares gait asymmetry in female runners who have never sustained a running-related injury to those who have sustained unilateral tibial stress fractures. The symmetry index was used to characterize asymmetry in the kinetics of both subject groups. There were three aims to this study: (1) to report natural levels of asymmetry for healthy, never-injured female runners, (2) to compare asymmetry levels between never-injured runners and those who have sustained stress fractures, and (3) to examine the kinetics between the involved and uninvolved limbs of runners who have sustained stress fractures. In all three aims, peak medial, lateral, braking, vertical impact, and vertical ground reaction forces, average and peak instantaneous vertical loading rates, and peak shock were examined. In the never-injured runner group, natural levels of asymmetry ranged from 3.1% for peak vertical ground reaction force up to 49.8% for peak lateral ground reaction force. Symmetry indices were not significantly different in the runners who had previously sustained stress fractures. The involved limb of the previously injured runners demonstrated higher values for braking and vertical impact ground reaction force and peak shock. Interestingly, these runners appeared to have bilaterally-elevated lateral ground reaction forces and loading rates as compared to the never-injured group, although this was not statistically tested. This suggests that previously injured runners may be closer to the injury threshold and, thus, more susceptible. Asymmetry may simply influence the side on which they become injured.

The Effect Of Socks On Running Biomechanics

Previous studies have shown that sensory feedback on the sole of the foot could be altered by disease or anesthesia. It has also been shown that specially designed socks with sand of differing degrees of “coarseness” altered the pressure distribution on the mid-and forefoot area during walking and running with shoes. PURPOSE The aim of this study was to investigate the effect of wearing commercially available cotton running socks and running shoes, compared with no socks and running shoes, on kinetics and lower limb kinematics during running. METHODS Twelve injury free runners performed 10 running trials using their own shoes, with (S) and without (NS) standard commercially available cotton running socks at a self selected running speed in a randomized fashion. During each running trial temporal distance parameters, kinetic and lower limb kinematic data were collected using a strain gauge force plate and six infrared cameras respectively. A modified Helen Hayes marker set, was used to collect kinematic data. RESULTS Self-selected running speed (m/s) (S: 3.05±0.38; NS: 3.04±0.38), vertical impact force (BW) (S: 1.50±0.34;NS: 1.43±0.23); horizontal breaking force (BW) (S: 025±0.09;NS:0.24±0.05); knee angle (degrees) at terminal swing phase (KswE, S:10.94±6.91; NS:11.32±6.48), heel strike (Khs, S:14.81±6.5 7;NS: 16.31±6.31) and midstance (Kst, S:40.97±6.19;NS:42.17±4.82), and ankle angle (degrees) at terminal swing phase (Asw, S:−8.67±4.91;NS:−7.17±6.68), heel strike (Ahs, S:−9.33±4.68; NS:−8.47±4.57) and midstance (Ast, S:−19.67±8. 8;NS:−19.18±8.5) were similar between S and NS conditions. CONCLUSIONS Wearing a commercially available cotton running sock does not alter vertical impact force, horizontal breaking force, knee flexion and extension angle, and ankle plantar dorsi-flexion angle during running.