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.

scholarly journals Impact Force Evaluation of the Derailment Containment Wall for High-Speed Train through a Collision Simulation

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Hyun-Ung Bae ◽  
Kyung-Min Yun ◽  
Jiho Moon ◽  
Nam-Hyoung Lim
Keyword(s):  
High Speed ◽  
Impact Force ◽  
Numerical Models ◽  
Force Analysis ◽  
Train Derailment ◽  
Software Application ◽  
Impact Forces ◽  
The Masses ◽  
The Impact ◽  
Economical Alternative

Fatal train accidents usually involve derailments or collisions. These derailment/collision accidents are infrequent. However, the damage due to derailment can be catastrophic. Derailment containment walls are usually used in Korea to minimize such damages. However, the impact forces that are needed to design the derailment containment walls were not well defined, and only limited studies were conducted for the behavior of the derailment containment walls. In this study, the focus was made on the impact force analysis of the containment wall through a series of 3D collision simulation after train derailment. Finite element modeling was conducted to analyze the dynamic behavior of the derailed train that collides with a structure such as containment wall using the LS-DYNA analysis software application. The FE models of car bodies, bogie frames, and wheel sets were created such that full conformity was achieved between their numerical models and actual vehicles with respect to the masses and principal mass moments of inertia. In addition, various installation situations of the containment wall were considered for the collision simulation. Finally, the economical alternative method to reduce the impact force was proposed.

Influence of Attached Masses on Impact Forces and Running Style in Heel-Toe Running

1987 ◽  
Vol 3 (3) ◽  
pp. 264-275 ◽  
Author(s):  
Alexander Bahlsen ◽  
Benno M. Nigg
Keyword(s):  
Body Mass ◽  
High Speed ◽  
Impact Force ◽  
Force Plate ◽  
The Body ◽  
Additional Mass ◽  
Impact Forces ◽  
Running Shoes ◽  
High Speed Film ◽  
Vertical Impact

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.

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

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 m<sup>3</sup> and 6 m<sup>3</sup> 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.

Resolving the Unique Invariant Slip-Direction in Rigid Three-Dimensional Multi-Point Impacts at Stick-Slip Transitions

2018 ◽  
Author(s):  
Abhishek Chatterjee ◽  
Alan Bowling
Keyword(s):  
Single Point ◽  
Three Dimensional ◽  
Impact Behavior ◽  
Slip Direction ◽  
Stick Slip ◽  
Impact Forces ◽  
Post Impact ◽  
Impact Problems ◽  
Slip Transition ◽  
The Impact

This work presents a new approach for resolving the unique invariant slip direction at Stick-Slip Transition during impact. The solution method presented in this work is applicable to both single-point and multi-point impact problems. The proposed method utilizes rigid body constraints to resolve the impact forces at all collision points in terms of a single independent impact forces parameter. This work also uses an energetic coefficient of restitution to terminate impact events, thereby yielding energetically consistent post-impact behavior.

scholarly journals Evolution of mantis shrimp telson armour and its role in ritualized fighting

2019 ◽  
Vol 16 (157) ◽  
pp. 20190203 ◽  
Author(s):  
Jennifer R. A. Taylor ◽  
Nina I. Scott ◽  
Greg W. Rouse
Keyword(s):  
Comparative Analysis ◽  
Impact Resistance ◽  
High Impact ◽  
Mantis Shrimp ◽  
Impact Forces ◽  
Drop Tests ◽  
Impact Parameters ◽  
Ritualized Combat ◽  
Stiff Spring ◽  
The Impact

Mantis shrimp possess both formidable weapons and impact-resistant armour that clash during ritualized combat. The telson is one of few biological structures known to withstand the repeated high impact forces of smashing mantis shrimp strikes, and it is hypothesized that this pairing of armour and weapon is associated with the evolution of telson sparring. We carried out a comparative analysis of telson impact mechanics across 15 mantis shrimp species to assess if the telsons of sparring species (i) are consistently specialized for impact-resistance, (ii) are more impact-resistant than those of non-sparring species, and (iii) have impact parameters that correlate with body size, and thereby useful for assessment. Our data from ball drop tests show that the telsons of all species function like a stiff spring that dissipates most of the impact energy, but none of the measured impact parameters are correlated with the occurrence of sparring behaviour. Impact parameters were correlated with body mass for only some species, suggesting that it is not broadly useful for size assessment during ritualized fighting. Contrary to expectation, sparring mantis shrimp do not appear to have coevolved telson armour that is more robust to impact than non-sparring species. Rather, telson structure is inherently impact-resistant.

scholarly journals Comparison of branded rugby headguards on their effectiveness in reducing impact on the head

2018 ◽  
Vol 4 (1) ◽  
pp. e000361 ◽  
Author(s):  
Erin R A Frizzell ◽  
Graham P Arnold ◽  
Weijie Wang ◽  
Rami J Abboud ◽  
Tim S Drew
Keyword(s):  
Impact Force ◽  
Linear Acceleration ◽  
Baseline Measurement ◽  
Peak Acceleration ◽  
Impact Forces ◽  
Impact Attenuation ◽  
The Mean ◽  
Force Reduction ◽  
The Right ◽  
The Impact

AimTo compare the available brands of rugby headguards and evaluate their impact attenuation properties at various locations on the cranium, with regard to concussion prevention.MethodsSeven different branded headguards were fitted onto a rigid headform and drop-tested in three different positions. An accelerometer measured the linear acceleration the headform experienced on impact with the ground. Each test involved dropping the headform from a height that generated 103.8 g on average when bare, which is the closest acceleration to the upper limit of the concussion threshold of 100 g. A mean peak acceleration for each drop position was calculated and compared with the bare baseline measurement.ResultsEach headguard demonstrated a significant decrease in the mean peak acceleration from the baseline value (all p≤0.01). Overall the Canterbury Ventilator was the most effective headguard, decreasing the impact force on average by 47%. The least effective was the XBlades Elite headguard, averaging a force reduction of 27%. In five of the seven headguards, the right side of the headwear was the most effective at reducing impact force.ConclusionOverall, the results indicate that it would be beneficial to wear a headguard during rugby in order to reduce the impact forces involved in head collisions. There was also a clear difference in performance between the tested brands, establishing the Canterbury headguard as the most effective. However, only one model of headguard from each brand was tested, so further research evaluating all other models should be considered.

scholarly journals STUDY ON IMPACT FORCES OF THE UNDERWATER CAVITY PROJECTILE

2016 ◽  
Vol 54 (6) ◽  
pp. 797
Author(s):  
Nguyen Thai Dung ◽  
Nguyen Duc Thuyen
Keyword(s):  
Drag Force ◽  
Impact Force ◽  
Center Of Mass ◽  
Forward Direction ◽  
Cavity Wall ◽  
Impact Point ◽  
Impact Forces ◽  
Underwater Projectile ◽  
The Impact ◽  
Cavity Effect

The motion of the underwater projectile with cavity effect including two motions: the projectile moves in the forward direction, center of mass of the projectile rotation around its nose makes tail of the projectile impacts on the cavity wall. According to, the impact forces occur, they include the drag force at its none, the impact force at impact point. The paper studies the forces occur on during motion of the underwater cavity projectile. Added, this paper considers the effect of the length and distributive projectile to the magnitude of impact force and the drag force of the underwater cavity projectile.

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.

A system for simulating the kinematics and measuring the impact force from riding whips used in Thoroughbred horseracing

2020 ◽  
pp. 175433712098062
Author(s):  
John W Bridge ◽  
Kaleb M Dempsey ◽  
Kayla M Danicki ◽  
Robin L Angotti ◽  
Alan K Kwiatkowski ◽  
...  
Keyword(s):  
Impact Force ◽  
Dynamic Force ◽  
Horse Racing ◽  
Testing Device ◽  
Shaft Length ◽  
Impact Forces ◽  
The Face ◽  
Flap Design ◽  
Arm Motion ◽  
The Impact

Thirty horse racing whips of four different designs were tested to measure dynamic impact force and compared using a specially designed mechanical testing device to simulate the whipping action of a jockey during racing. The whips tested included designs used in Thoroughbred horse racing in North America, which meet the design criteria established by the Association of Racing Commissioners International (ARCI) model rules, as well as the most common whip used in British horse racing. The objective of the device was to allow comparisons to be made between peak impact loads resulting from different whip designs. A high peak dynamic force on a horse’s shoulder or hind quarter may result in injuries, such as welts. The testing device contains a planar three-bar, open mechanical linkage loaded by torsion springs to model the arm motion of a jockey. The whip strikes a flat plate covered by an elastomeric pad. The energy input is replicated during the simulated impact. A single axis dynamic load cell under the loading plate and three single-turn precision potentiometers located at each joint of the three-arm mechanical system measure impact forces and relative angular positions, respectively. Force measurements are compared from the face of each whip and the edge or seam where applicable. In addition to the flap design, other physical differences between whip designs included mass, shaft length, shaft stiffness, flap cushion thickness/compression factor, flap surface area, and flap seam area. Statistically significant impact force differences were found between flap face and flap seam impact orientations, with higher impact forces delivered by the flap face. Significant differences were also found in impact forces between the three whip styles with seams.

The effect analysis of an engine jet on an aircraft blast deflector

2018 ◽  
Vol 41 (4) ◽  
pp. 990-1001
Author(s):  
Song Ma ◽  
Jianguo Tan ◽  
Xiankai Li ◽  
Jiang Hao
Keyword(s):  
High Temperature ◽  
Flow Field ◽  
High Speed ◽  
Deflection Angle ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Aircraft Engine ◽  
Experimental Results ◽  
Exhaust Gases ◽  
The Impact

This paper establishes a novel mathematical model for computing the plume flow field of a carrier-based aircraft engine. Its objective is to study the impact of jet exhaust gases with high temperature, high speed and high pressure on the jet blast deflector. The working condition of the nozzle of a fully powered on engine is first determined. The flow field of the exhaust jet is then numerically simulated at different deflection angle using the three-dimensional Reynolds averaged Navier–Stokes equations and the standard [Formula: see text]-[Formula: see text] turbulence method. Moreover, infra-red temperature tests are further carried out to test the temperature field when the jet blast deflector is at the [Formula: see text] deflection angle. The comparison between the simulation results and the experimental results show that the proposed computation model can perfectly describe the system. There is only 8–10% variation between them. A good verification is achieved. Moreover, the experimental results show that the jet blast deflector plays an outstanding role in driving the high-temperature exhaust gases. It is found that [Formula: see text] may be the best deflection angle to protect the deck and the surrounding equipment effectively. These data results provide a valuable basis for the design and layout optimization of the jet blast deflector and deck.

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