Shock Absorbing System Research Articles

Patients of idiopathic normal-pressure hydrocephalus have small dural sac in cervical and upper thoracic levels: A supposed causal association.

Idiopathic normal pressure hydrocephalus (iNPH) is a neurological disorder presenting a triad including dementia and ventricular enlargement. The mechanism causing excessive cerebrospinal fluid (CSF) accumulation in the ventricles in iNPH is poorly understood. We hypothesized that the age-related degradation of the spinal shock-absorbing system composed of a spinal dural sac (SDS) and surrounding soft tissue, preventing ventricular enlargement caused by wide CSF pulsation driven by heartbeats, may be involved in the ventricular enlargement observed in iNPH. Sixty-four patients with iNPH in their seventies who underwent a lumboperitoneal shunt and a control group of 79 people in the same age group who underwent brain check-ups were included in the study. We compared the sizes of the cervical and upper parts of the thoracic SDS using magnetic resonance imaging between the two groups. The anterior-posterior distances of the dural sac at C5 were shorter in patients with iNPH of both sexes than those in the control group (P = 0.0008 in men and P = 0.0047 in women). The number of disc levels with disappeared CSF space surrounding the cervical cord was more in iNPH (P = 0.0176 and P = 0.0003). The midsagittal area of the upper part of the spinal sac, C2-Th4, was smaller in iNPH (P = 0.0057 and P = 0.0290). Narrowing of the cervical dural sac and midsagittal area in the upper part of the SDS in patients with iNPH may reflect the degradation of the shock-absorbing mechanism for CSF pressure pulsations, which may cause iNPH or at least aggravate iNPH by other unknown causes.

Woodpeckers minimize cranial absorption of shocks

The skull of a woodpecker is hypothesized to serve as a shock absorber that minimizes the harmful deceleration of its brain upon impact into trees1-11 and has inspired the engineering of shock-absorbing materials12-15 and tools, such as helmets.16 However, this hypothesis remains paradoxical since any absorption or dissipation of the head's kinetic energy by the skull would likely impair the bird's hammering performance4 and is therefore unlikely to have evolved by natural selection. Invivo quantification of impact decelerations during pecking in three woodpecker species and biomechanical models now show that their cranial skeleton is used as a stiff hammer to enhance pecking performance, and not as a shock-absorbing system to protect the brain. Numerical simulations of the effect of braincase size and shape on intracranial pressure indicate that the woodpeckers' brains are still safe below the threshold of concussions known for primate brains. These results contradict the currently prevailing conception of the adaptive evolution of cranial function in one of nature's most spectacular behaviors. VIDEO ABSTRACT.

What is walking? (orthopedist and biomechanic dialogue)

Orthopedist (referring to the biomechanist). We receive the results of our patients' walking studies from your laboratory. There are indicators that characterize this process. But I can't read your numbers. Your terminology is unfamiliar to me. It is clear to me that the most important thing for an orthopedist and trauma surgeon is to restore such an important process for a person as walking. But when I thought about this seemingly obvious position, I realized that I do not know the essence of this process. And then there are the results of your research that I don't understand. Tell me what walking is.Biomechanic. Okay. I propose the following plan for our conversation:- the temporal structure of the stride;- the kinematics of the legs, pelvis and spine;- external forces, leg support reactions, muscle work;- the foot as a shock absorbing system;- movement of body parts when walking in the frontal plane.

Fabrication and Mechanical Testing of the Uniaxial Graded Auxetic Damper.

Auxetic structures can be used as protective sacrificial solutions for impact protection with lightweight and excellent energy-dissipation characteristics. A recently published and patented shock-absorbing system, namely, Uniaxial Graded Auxetic Damper (UGAD), proved its efficiency through comprehensive analytical and computational analyses. However, the authors highlighted the necessity for experimental testing of this new damper. Hence, this paper aimed to fabricate the UGAD using a cost-effective method and determine its load–deformation properties and energy-absorption potential experimentally and computationally. The geometry of the UGAD, fabrication technique, experimental setup, and computational model are presented. A series of dog-bone samples were tested to determine the exact properties of aluminium alloy (AW-5754, T-111). A simplified (elastic, plastic with strain hardening) material model was proposed and validated for use in future computational simulations. Results showed that deformation pattern, progressive collapse, and force–displacement relationships of the manufactured UGAD are in excellent agreement with the computational predictions, thus validating the proposed computational and material models.

Анализ работы арочного эластомерного амортизатора при сложном нагружении

Elastomeric shock absorbers are used in various technical fields to protect equipment from impacts. Elastomers made in an arched shape have complex nonlinear force characteristics due to large deformations, loss of stability of working elements and closing of surfaces. In this regard, obtaining the power characteristics of arched elastomeric shock absorbers is a complex computational problem. It is noteworthy that, in the literature, these characteristics are given only for the case of normal compression. However, when assessing the possibility of using a shock-absorbing system based on arched elastomeric shock absorbers, it is necessary to take into account their lateral force. The study proposes to solve the problem of determining the elastic force characteristics of a shock absorber while operating in the normal and lateral directions in the system of finite element analysis in a flat formulation. Analytical expressions are obtained for the normal and transverse static reactions of the shock absorber under simultaneous loading in the normal and transverse directions. Analytic expressions can be used to simulate complex shock-absorbing systems with a large number of such shock absorbers.

Analysis of the space debris objects nozzle capture dynamic processed by a telescopic robotic arm

The paper considers a new layout of a two-stage spacecraft designed to remove a group of large space debris objects such as the upper stages of ‘Zenit’ launch vehicles from low-earth orbit. The aim of the work is to preliminarily quantify the parameters of the shock-absorbing system of the robotic arm designed for capturing a redundant upper stage by the main rocket engine nozzle. The estimation will be conducted by means of numerical simulation of the motion dynamics of the "spacecraft - space debris object" system. The paper presents the results of calculating the transient mode of oscillations of objects connected by the manipulator using simplified and detailed dynamic models of parameters, the analysis of the placement options for the manipulator shock-absorbing system, the analysis of the load reduction possibility through the use of attitude control thrusters, the analysis of two dynamic design variants of the mechanism for grabbing the critical section of the nozzle, and analysis of the capture dynamics at different initial angular velocities of rotation of a space debris object. The most rational shock-absorbing solution for a robotic arm with two translational and two rotary dampers is found. It is shown that the dynamic design of the nozzle capture mechanism has the greatest effect on the robotic arm loading. The kinematic design of the gripper selected as a result of the simulation almost completely eliminates shock loads in the process of damping the system vibrations. It is shown that the robotic arm shock-absorbing design has a significant margin for the initial angular velocity of the space debris object.

Kinematic Analysis of the Coupling Between Calcaneal Eversion and Ankle Dorsiflexion in a Contemporary Dancer's Demi-Plié.

Dancing requires a high range of motion in the foot as well as a good shock-absorbing system formed by the foot and ankle joints. Although there is a broad consensus in dance that excessive calcaneal eversion can cause injury and should be avoided, calcaneal eversion is discussed controversially in the dance literature. An increased research focus on the biomechanics of dance, particularly research pertaining to the foot and ankle joints, might help to resolve this controversy. The study's main purpose was to generate hitherto lacking kinematic data of calcaneal eversion in a dancer's demi-plié. Thirty-two contemporary dancers performed three trials in two different conditions: demi-plié in parallel and in turned-out positions. The motion capture system FASTRAK was used to measure calcaneal eversion and foot and lower leg alignment during demi-plié. Maximal calcaneal eversion in turned-out demi-pliés was 3.36°±4° and total range of motion (i.e., maximal minus minimal angle) of calcaneal eversion was 3.73°±1.42°, where the large standard deviations indicate substantial variability across participants. Calcaneal eversion was significantly different between turned-out (3.36°±4°) and parallel (1.17°±4.06°) demi-pliés, as was the alignment of the lower leg and foot, where the lower leg tracked more medially relative to the foot during turned-out pliés. Crucially, both the magnitude of calcaneal eversion and its temporal coupling with ankle dorsiflexion were highly variable across participants. Average calcaneal eversion is a poor indicator of the role calcaneal eversion plays in the demi-plié of contemporary dancers. Rather, the temporal coupling between calcaneal eversion and ankle dorsiflexion needs to be considered.

Increasing the accuracy of lidar measurements by using stacked bars in a shock-absorbing system

This paper proposes the fabrication of a spring of quasi-zero stiffness in the form of stacked bars made up of bundles of parallel spring wires connected at the ends. The optical device to be protected from vibrations is installed on a platform with such a spring. Such a design improves the vibration protection of the device by as much as 15% by reducing the natural frequency of the vibrational system and increasing the energy dissipation in the spring by as much as 20%.

User Assessment of a Novel Suspension for a Wheelchair—A Prospective, Randomized, Double Blind Trial

Background:Many Wheelchair users experience adverse effects specific to their situation, some of which might be avoided if suspension systems are integrated into the wheelchair.Objectives:Our study aimed to compare the user experience using a novel wheelchair suspension system with normal wheels. We tried to quantify the user feelings and impressions while using the different wheels.Study Design:Double blinded comparative randomized study.Methods:The patients were randomized into 2 groups. One used shock absorbing wheels, and the other group had a set of standard wheels with the same exact wheelchairs. The patients were taken to a daily trip by the caregivers and given questionnaires in the second and fourth days. On the morning of the third day the wheels were interchanged, creating a cross over between the groups. We collected general and medical information from the participants. The main outcome measures were the questionnaires filled by the patients and the caregivers aiming to quantify the user experience with the suspension equipped wheels.Results:Statistical significance was reached in 2 questions referred to the patients: “In general—During the ride I didn’t feel the bumps” and “I feel very confident when riding the chair” and in one question referred to the caregiver—“It was easy to push the chair in suboptimal ground.”Conclusions:We conclude that the shock absorbing system provided a better user experience in the immediate term than standard wheels. Further study is needed to assess the long-term implications.

Calculation of Parameters and Design of the Movable Transfer Station with Vibrating Screen Feeder for the Conveyor System of Deep Queries

The paper considers a new design of the movable vibrating screen feeder KVG-1PS designed for the reception and transfer of rocks and ores in conveyor complexes of cyclic-and-continuous technology in open-cast mining. It contains the results of design analysis of the new mining machine. The paper represents the technique of establishing the main parameters and the calculation of the movable vibrating feeder on the basis of a cascade shock-absorbing system at the representation of the machine within a three-mass oscillatory system.

Numerical Simulation of Helmeted Headform Drop Test Based on the EN1078 Standard

The shock absorption test of the EN1078 standard is the focal point of this study. These performances are to setup a shock absorbing system for commercially available helmet, to measure the key parameters when an instrumented helmeted headform drops onto anvils. In this test, the helmet quality is assessed by measuring the acceleration time history of a headform during a helmeted headform impact. Helmet quality is expressed in terms of the injury parameters: maximum resultant linear headform acceleration of the headform's center of gravity and Head Injury Criterion (HIC). Besides, the present study performs to develop and validates a finite element of helmeted headform impact test. The FE model obtains by the scanned shapes of a bicycle helmet. The headform and anvil design in accordance with EN 960: 2006 and the EN1078 specification, respectively. This study performs finite element analyses of helmet impact tests using LS-DYNA software. The results of the present method fit the experimental results well, implying that the numerical method is a practical approach to helmet design problems. Furthermore, the helmet test model proposed here has potential for guiding the future development of helmet technologies.

Design of Shock-Absorbing System for Disaster Rescue Robot

Disaster Rescue Robot is a small caterpillar robot used for carrying first aid articles, reasonable shock-absorbing system is an indispensable part to reduce the rush of the ground because it has to plummet from a certain level to the ground when it works. We use the method of modular design in this article and design the landing gear based on the performance of conical spring in order to absorb some of the forces during a fall. Then the three-dimensional modeling software is used to establish the parametric model of the robot shock-absorbing system to provide an effective way for the design of the Disaster Rescue Robot.

A mechanical analysis of woodpecker drumming and its application to shock-absorbing systems

A woodpecker is known to drum the hard woody surface of a tree at a rate of 18 to 22 times per second with a deceleration of 1200 g, yet with no sign of blackout or brain damage. As a model in nature, a woodpecker is studied to find clues to develop a shock-absorbing system for micromachined devices. Its advanced shock-absorbing mechanism, which cannot be explained merely by allometric scaling, is analyzed in terms of endoskeletal structures. In this analysis, the head structures (beak, hyoid, spongy bone, and skull bone with cerebrospinal fluid) of the golden-fronted woodpecker, Melanerpes aurifrons, are explored with x-ray computed tomography images, and their shock-absorbing mechanism is analyzed with a mechanical vibration model and an empirical method. Based on these analyses, a new shock-absorbing system is designed to protect commercial micromachined devices from unwanted high-g and high-frequency mechanical excitations. The new shock-absorbing system consists of close-packed microglasses within two metal enclosures and a viscoelastic layer fastened by steel bolts, which are biologically inspired from a spongy bone contained within a skull bone encompassed with the hyoid of a woodpecker. In the experimental characterizations using a 60 mm smoothbore air-gun, this bio-inspired shock-absorbing system shows a failure rate of 0.7% for the commercial micromachined devices at 60 000 g, whereas a conventional hard-resin method yields a failure rate of 26.4%, thus verifying remarkable improvement in the g-force tolerance of the commercial micromachined devices.

The blood vessel system in the periodontal ligament of the equine cheek teeth – Part I: The spatial arrangement in layers

Corrosion casts of blood vessels in the periodontium of cheek teeth from eight horses were observed three-dimensionally with a dissection microscope. Selected specimens were examined in a scanning electron microscope. Periodontal blood vessels communicated with those from the gingiva, the alveolar bone, and the apical region. In the upper jaw, there were anastomoses with the blood vessels of the mucosa of the maxillary sinus. The periodontal vascular system was organized in two or three layers. The peripheral layer was mainly composed of large venules, the inner one consisted of capillaries. In the intermediate layer, blood vessels were post-capillary venules. This layer was developed only in horses under 10 years of age. In all layers the vascular orientation was mainly occluso-apical, this was defined as the standard pattern. There were many variations displayed in different courses of certain blood vessels. The vascular organization is discussed with regard to the specialized functions of the periodontal ligament (PDL). The wide vessels of the outer layer are thought to play a mechanical role as part of a shock absorbing system. The capillaries of the inner layer meet nutritional requirements. The disappearance of the intermediate layer in horses older than 10 years is taken as an adaptation to the remodelling of the PDL. Modifications in the standard pattern of vascular arrangements are also interpreted as adaptations to life-long changes in the periodontal space. Anastomoses between the periodontal vasculature and the blood vessels of the maxillary sinus indicate that periodontal disease may be transferred into the sinus.

Mechanical Evaluation of the Skeletal Structure and Tissue of the Woodpecker and Its Shock Absorbing System

A woodpecker strikes its beak toward a tree repeatedly. But, the damage of brain or the brain concussion doesn’t occur by this action. Human cannot strike strongly the head without the damage of a brain. Therefore, it is predicted that the brain of a woodpecker is protected from the shock by some methods and that the woodpecker has the original mechanism to absorb a shock. In this study, the endoskeltal structure, especially head part structure of woodpecker is dissected and the impact-proof system is analyzed by FEM and model experiment. From the results, it is obvious that the woodpecker has the original impact-proof system as the unique states of hyoid bone, skull, tissue and brain. Moreover it is considered that woodpecker has the advanced impact-proof system relating with not only the head part but also with the whole body.

The Blood‐Vessel System of the Equine Periodontal Ligament: a Mesoscopic Study on Corrosion Casts

Several investigators have suggested that the blood-vessel system in the equine periodontal ligament does not only serve nutritional needs, but also specific functional needs, e.g. in terms of a shock absorbing system. In order to supplement the previous data, corrosion casts of the periodontal blood vessels were studied with special attention to the spatial arrangement and connections of the vessels. The heads of eight warm-blooded horses (age 2.5–23 years, seven female, one male), which had been killed for medical reasons, were dissected. The arteria alveolaris inferior and the a. infraorbitalis were perfused with 100 ml Heparin (20 000 IU) followed by 100 ml tap water. After storage at 4°C for 24–96 h, 10–200 ml methacrylate resin (BiodurTM E20) were injected by use of a cartridge pistol for approx. 1 h. After polymerization for 24 h at 60°C, the jaws were frozen and cut with a steel band saw in a horizontal, sagittal or transversal plane to obtain segments that exposed the periodontal space. The specimens were macerated in detergent at 60°C until the soft tissues had vanished. Care was taken to keep the periodontal vessels complete and in topographical integrity. The vascular casts were mesoscopically examined by use of a dissection microscope (magnification 5.8×–40×). The blood vessels in the periodontal space connected with vessels in three other sites: 1 occlusal – with the blood vessels of the gingiva; 2 apical – with blood vessels next to the apical foramen; 3 at the sides – with blood vessels that penetrated the lamina cribriformis. The blood-vessel system in the periodontal space consisted of main vessels in a parallel alignment with interconnecting branches with smaller diameter. There were indications in some of the specimens that these blood vessels were arranged in layers: one layer next to the cementum, the other next to the alveolar bone.

Design of elastomeric bearing system and analysis of it mechanical properties

This paper proposes a new type of bearing system. In this study, a method for design of on elastomeric bearing system and its mechanical property analysis are carried. Experimental and theoretical studies of the elastomeric bearings with fiber reinforcement were proved effective new lightweight bearing system. The fibers in the bearings for isolation are assumed to be flexible in extension, in contrast to the steel plates in the conventional bearing system. Several kinds of bearing systems in the form of long strips are designed, fabricated and tested. The results suggest that it is possible to produce the economical and effective fiber-reinforced elastomeric bearing that matches the behavior of a steel-reinforced bearing. Feasibility and advantages of the proposed bearings are illustrated by the application of the analytic procedure to the structure system. Results obtained here are reported to be an efficient approach with respect to bearing system and design of bearing against shock absorbing system when compared with other conventional one.

A Concept for Containing Inertial Fusion Energy Pulses in a Z-Pinch-Driven Power Plant

The Z-Pinch Power Plant (ZP-3) is the first concept to use the results at Sandia National Laboratories’ Z accelerator in a power plant application. Assuming high-yield fusion pulses (of 1 to 20 GJ per shot at a rate of 0.1 Hz), we consider a unique shock and energy absorbing system to contain the energy. One concept answers the need for system standoff from the fusion reaction with a replaceable mechanical cartridge manufactured on-site. System studies suggest integrated blanket designs for absorbing the fusion energy, cartridge manufacture of recycled materials, and cartridge installation/replacement to maintain a reasonable duty cycle. An effective system design for ZP-3 requires an integrated blanket to shield the permanent structures from the high-energy neutron flux and strong shock wave, breed tritium, and simultaneously absorb the released fusion energy. We investigate the feasibility of this integrated blanket concept and explore the principles of a containment chamber—a crucible—and the containment mechanisms. An operational cycle is proposed to physically load hardware in 10-s intervals while maintaining operational conditions. Preliminary pressure and shock calculations demonstrate that high-yield inertial fusion energy pulses can be contained if the appropriate energy-absorbing materials are used.

ネット式入港支援ガイドの波浪下における機能確認実験

The guide is a proposed facility which makes fishing boat entry into harbours safer under strong wind and wave conditions. Waves interrupt ship navigation in many harbours where an entry problem exists, therefore experiments on the effectiveness of the net type guide under high wave conditions were carried out. In the broaching-to condition, vessels collided with the guide. The collision speed against the guide is approximately the sum of the vessel's sea speed and the instantaneous surface water particle velocity. The energy of such a collision is a problem for the long-term structural integrity of the guide, therefore the shock absorbing system should be designed against the collision speed and surface water particle velocity.

入港支援ガイド接触時の船体運動について

Ship navigation is interrupted at the time of entering harbors under strong wind and waves. Then Guide Way is proposed as a new harbor facility to solve the problems. The characteristics of ship motions running into Guide Way must be estimated to determine its structure and strength. Therefore, numerical simulations and experiments of ship motions are carried out to confirm the fundamental properties of ship motions. The agreements between the numerical simulations and experimental results of ship motions are fairly well. So it is possible to design the structural form and the shock absorbing system by means of the simulations.