Shock Absorption Function Research Articles

A Biomechanical and Evolutionary Perspective of the Menisci Indicate They Are Not Shock Absorbers

Human bipedalism entails high‐magnitude, short‐duration impact transient forces that occur every heel strike. These transient forces, or ‘shock’, are attenuated as they propagate up the body, and many structures have been proposed as ‘shock absorbers’ within the body. The medial and lateral menisci of the knee are a pair of fibrocartilaginous structures that have often been cited as shock absorbers. However, despite the frequency with which this claim is made in scientific literature, medical education and clinical practice, there is little primary data that supports the notion that the menisci function as shock absorbers.Here we compile evolutionary and biomechanical data to critique this oft‐cited notion. First, we show that the origin of this idea draws on a limited number of studies, each with caveats that make that evidence for a shock absorptive function dubious. We then review evolutionary and comparative evidence to show that human menisci are unremarkable in morphology compared with most other tetrapods. Humans possess two, crescentic‐shaped menisci that are similar in morphology to most mammals and many tetrapods. This suggests that the null hypothesis of meniscal function is one of similarity among tetrapods. Furthermore, we show that among tetrapods, shock during locomotion is uncommon; humans stand out as one of the only tetrapods that regularly experience high levels of shock during locomotion. Thus, a shock‐absorption function does not explain the origin of menisci, nor are human menisci specialized in any way that would explain this unique function during human gait. We further assess the mechanical material properties of menisci and show that the menisci overwhelmingly behave like springs and are poorly suited for energy absorption. We compiled data on phase angle and loss tangent, two properties used to assess energy absorption or release. Loss tangents of the menisci are typically between 0.1–0.2, close to an ideal spring (0.0) as opposed to an energy absorbing damper (>1.0). Similarly, phase angles were generally <10°, more similar to an idealized spring value of 0°, as opposed to a pure damper at 90°. Thus, when deformed menisci release most of this energy as opposed to shock absorbers, which dissipate energy.Finally, we integrated data on material properties of the meniscus and loading data from previous studies to estimate actual meniscal energy absorption in comparison to other known energy‐absorbing structures in the body. The heel pad, a well‐known contributor to absorbing energy from heel strike, absorbed 50–69% (0.70 +/‐ 0.11 J) of impact loading when using realistic loading conditions in vitro. All knee structures combined absorbed 0.12 +/‐ 0.01 J of impact energy, only 6–17% of the energy absorbed by the heel pad alone. Available loading data suggest that energy absorption of the menisci alone likely account for only ~4% of all energy absorption at the knee. Thus, our estimates of the total shock absorption capacity of the menisci is essentially negligible.These findings indicate that the menisci did not originally develop for shock‐absorption in tetrapods and did not develop a specialized shock absorbing function in humans.

Vertical Breast Displacement in Asian Women During Exercise: influence of Bra Type, Size and Different Parts of the Breast

Abstract Asian women have smaller breast sizes and greater breast density, which suggests specific research on their breast kinematics and biomechanics. To investigate vertical breast displacement of Asian women among exercise modalities (rope skipping, walking, jogging, running) in different support conditions (wearing everyday bra or sports bra), and assess the motion between different parts of the breast, seven participants were selected to participate in this study. Five infrared markers were placed on each of their left breasts, and a three-dimensional motion capture system (NDI Optotrak Investigator) was used to collect the data on vertical breast displacement during walking (5 km/h), jogging (7.5 km/h), running (10 km/h) and rope skipping (2 Hz). No significant difference was found in the vertical displacement of different parts of the breast in the two bra conditions. Also, there was significant difference in vertical breast displacement among rope skipping, jogging and running. Breast size did not significantly affect its vertical displacement. The smaller, denser breast appears to reach a threshold of vertical displacement that is similar at high severities of dynamic exercises (jogging, running and rope skipping). The results might be useful for designing special sports bras for Asian women with small breasts or rope skipping participants to improve the shock absorption function.

The menisci are not shock absorbers: A biomechanical and comparative perspective.

The lateral and medial menisci are fibrocartilaginous structures in the knee that play a crucial role in normal knee biomechanics. However, one commonly cited role of the menisci is that they function as "shock absorbers." Here we provide a critique of this notion, drawing upon a review of comparative anatomical and biomechanical data from humans and other tetrapods. We first review those commonly, and often exclusively, cited studies in support of a shock absorption function and show that evidence for a shock absorptive function is dubious. We then review the evolutionary and comparative evidence to show that (1) the human menisci are unremarkable in morphology compared with most other tetrapods, and (2) "shock" during locomotion is uncommon, with humans standing out as one of the only tetrapods that regularly experiences high levels of shock during locomotion. A shock-absorption function does not explain the origin of menisci, nor are human menisci specialized in any way that would explain a unique shock-absorbing function during human gait. Finally, we show that (3) the material properties of menisci are distinctly poorly suited for energy dissipation and that (4) estimations of meniscal energy absorption based on published data are negligible, both in their absolute amount and in comparison to other well-accepted structures which mitigate shock during locomotion. The menisci are evolutionarily ancient structures crucial for joint congruity, load distribution, and stress reduction, among a number of other functions. However, the menisci are not meaningful shock absorbers, neither in tetrapods broadly, nor in humans.

Self-Capacitance Proximity and Tactile Skin Sensor With Shock-Absorbing Structure for a Collaborative Robot

Human collaborative robots (HCRs) work in close cooperation with humans. The proximity and tactile sensors placed on the HCR surface ensure the safety of humans working with the robots. However, many of these sensors do not have a collision absorption function. In this paper, we propose a self-capacitance proximity and tactile skin sensor with a shock-absorbing structure for HCRs. We evaluated the shock absorption performance and the proximity and tactile measurements of the prototype sensors using different thicknesses of the soft layer, which acted as a shock absorber. Results confirmed that when the thickness of the soft layer increased, the shock absorption function also increased, but the contact detection sensitivity decreased. In addition, we evaluated the collision between the robot with the sensor and an object when the robot moved. The sensor could absorb the impact of the collision between the robot and the object. Furthermore, multiple sensors placed on the robotic arm could detect an object before and after making contact in real time. We proved that the proposed sensor system with the shock absorber is reliable and can be used as a proximity and tactile skin sensor for HCRs.

Structural design on reactor coupled with the spallation target for a lead-based ADS

In the Accelerator Driven Sub-critical System (ADS), the spallation neutron target is a core component connecting accelerator and the reactor, which makes the structure of different from the conventional fission reactor such as PWR and FBR. In the project of the China Initiative Accelerator Driven System (CiADS), the granular flow of the gravity driven Dense Granular flow Target (DGT) is adopted, which is an original spallation target scheme different from the existing international spallation target type. As a new form of target structure, DGT faces new technical challenges in the process of coupling with the reactor, i.e. special attention must be paid for the structure design of the reactor coupled with spallation target so that it can bear both of seismic and thermal loadings. In this paper, the coupling schemes of DGT and reactor are analyzed from engineering feasibility and safety, and the proposal of reactor-target coupling scheme is given. The supporting design and seismic analysis of the “hot pot type” design scheme and “bellows type” design scheme of reactor-target coupling systems for CiADS are carried out. A new damper-based support method is designed: roll-damper support. The calculation results show that the new support method effectively reduces the thermal stress of the container and the target, and realizes the shock absorption function even taking the effect of fluid–structure interaction (FSI) into account. Combining the advantages of the two schemes, a “hybrid type” optimization design scheme is proposed. The seismic calculation of the optimization scheme was completed by the time history analysis method, and then the stress evaluation was carried out. The results show that the “hybrid type” design scheme meets nuclear safety regulations and specifications. The research results can provide guidance for the selection of lead-based ADS reactor- target coupling systems, and propose optimization suggestions and ideas for reactor-target coupling problems.

Aging impairs smooth muscle-mediated regulation of aortic stiffness: a defect in shock absorption function?

Increased aortic stiffness is an early and independent biomarker of cardiovascular disease. Here we tested the hypothesis that vascular smooth muscle cells (VSMCs) contribute significantly to aortic stiffness and investigated the mechanisms involved. The relative contributions of VSMCs, focal adhesions (FAs), and matrix to stiffness in mouse aorta preparations at optimal length and with confirmed VSMC viability were separated by the use of small-molecule inhibitors and activators. Using biomechanical methods designed for minimal perturbation of cellular function, we directly quantified changes with aging in aortic material stiffness. An alpha adrenoceptor agonist, in the presence of N(G)-nitro-l-arginine methyl ester (l-NAME) to remove interference of endothelial nitric oxide, increases stiffness by 90-200% from baseline in both young and old mice. Interestingly, increases are robustly suppressed by the Src kinase inhibitor PP2 in young but not old mice. Phosphotyrosine screening revealed, with aging, a biochemical signature of markedly impaired agonist-induced FA remodeling previously associated with Src signaling. Protein expression measurement confirmed a decrease in Src expression with aging. Thus we report here an additive model for the in vitro biomechanical components of the mouse aortic wall in which 1) VSMCs are a surprisingly large component of aortic stiffness at physiological lengths and 2) regulation of the VSMC component through FA signaling and hence plasticity is impaired with aging, diminishing the aorta's normal shock absorption function in response to stressors.

Design and Functional Evaluation of a Quasi-Passive Compliant Stance Control Knee–Ankle–Foot Orthosis

In this paper, we present the mechanical design, control algorithm, and functional evaluation of a quasi-passive compliant stance control knee-ankle-foot orthosis. The orthosis implements a spring in parallel with the knee joint during the stance phase of the gait and allows free rotation during the swing phase. The design is inspired by the moment-angle analysis of the knee joint revealing that the knee function approximates that of a linear torsional spring in the stance phase of the gait. Our orthosis aims to restore the natural function of a knee that is impaired by injury, stroke, post-polio, multiple sclerosis, spinal cord injury, patellofemoral pain syndrome, osteoarthritis, and others. Compared with state-of-the-art stance control orthoses, which rigidly lock the knee during the stance phase, the described orthosis intends to provide the natural shock absorption function of the knee in order to reduce compensatory movements both in the affected and unaffected limbs. Preliminary testing on three unimpaired subjects showed that compliant support of the knee provided by the orthosis explained here results in higher gait speed as well as more natural kinematic profiles for the lower extremities when compared with rigid support of the knee provided by an advanced commercial stance control orthosis.

Method to Aid Product Innovation by TRIZ, DSM and Patent Knowledge

For effectively use patents as information resource for aiding product innovation and avoid patent infringement, a method using patent knowledge based on Design Structure Matrix (DSM) and Theory of Innovative Problem Solving (TRIZ) is proposed. First the couple relationship between different components in objective patent of product is analyzed by DSM. Next deep knowledge of component which has least couple relationship with other components and lower restriction of creation is acquired from patent. Last the component is redesigned by TRIZ according to the design requirements. The method is illustrated by the innovation design of an ATV with shock-absorption function.

Friction Analysis of the Sneakers Insole

INTRODUCTION To enable athletes in a sport more comfortable, better performance, more emphasis sports shoes design technology and demand for the athletes, the coverage of sports shoes to protect feet it is not a simple function, it also has the following functions : 1. Foot protection and support. 2.The role of comfort and health. 3.Shock absorption functions and aesthetic and decorative (Zhao, zhi xiong. 1997). Generally, the basic structure of sports shoes are four parts : upper, outside end, and end with the end of upper surface of the shoes is part of foreign soles touch the ground and what is the end, the end is the sole internal material. also known as end within pad inside, we called soles. Most of the bones have come into contact with (Richard C.. Wilson, D.P.M. 2003). The main demand is pleasing uppers, soles part of the performance is related to the main characters, Design is the essence of sports shoes, from the outside non-slip function to the end of the inner end of the shock absorber function, and so far, insole studies have focused on the distribution of pressure in the shock absorber function or circumstances, mostly to do with the nature of the material soles study at the expense of human contact with the soles comfort, as well as contact friction arising impact on the campaign. When we engage in an activity at the same time several external forces in our bodies and friction is one of them.

614 新ウォーターインソールの開発(J04-3 歩行支援・車いす,J04 ライフサポート)

A new water insole including water in the insole was developed. The positions, sizes, number and shape of some dams and some orifices in the insole control a flow of water in this insole. This insole have two functions, one is the shock absorption function when the heel lands, and the other is the press function to the arch of a foot part. For the water insoles designed and manufactured, some experiments were made as the capacity of compression pressure, the freezing characteristics and the static and the dynamic pressure distribution of a foot part.

THE EVOLUTIONARY SIGNIFICANCE OF MOUNTAIN SHEEP HORNS.

In proportion to body size, North American wild sheep (Ovis canadensis and Ovis dalli) carry the largest horns among ruminants. Their horns have been recorded as exceeding 51 inches (130 cm.) in length, and 16 inches (40.6 cm.) in circumference at the base (Anonymous, 1964). Old males may bear eight to twelve per cent of their body weight as horns. The horns of rams grow substantially in length and mass each year. This increase is greatest in the early years of life and smallest in later years. The horns of females remain quite small throughout life and rarely exceed nine inches (23 cm.) in length. The huge horns of rams invite enquiry as to what selection processes brought about and retain such disproportionate organs. Several functions can be proposed for ram horns. Horns act as weapons.-This implies that horns can inflict damage on opponents when used in fighting. This I have found. The tiny horns of mountain goat (Oreamnos), however, also serve as weapons (Geist, 1964). Hence this proposed function alone explains little about the evolution of sheep horns. Horns act as a shield.-During fighting rams attempt to catch the opponents' head blows with their horns (Fig. 1). There is little doubt that sheep horns function in this manner. Other bovids, however, also attempt to catch an opponent's attack with their horns, i.e., Bos and Bison. These cattle carry only small, curved horns. Again, this function explains by itself little about the evolution of mountain sheep horns. Horns act as shock absorbers.-During their frequent social interactions, rams collide head on. They may run on their hindlegs at each other and then jump into the clash. Since the rams may weigh about 220--250 pounds each, the collisions must be frightful. It appears quite reasonable hence, that the heavy horns function in absorbing the heavy impact. This appearance is deceptive. A number of Artiodactyla clash head on during fighting, or deal out blows with their heads. None carry horns to match those of sheep males. Though female sheep fight very similar to rams, they carry only tiny horns. The wart hogs (Phacochoerus) and giant forest hogs (Hylockoerus) in fighting clash head on after a run at each other (Mohr, 1960; Fradrich, 1965). They possess no horns at all. Bison bulls may clash head on with considerable force (McHugh, 1958). They have only tiny horns. Giraffes (Giraffa) deal out severe blows with their heads, but carry only little ossicones on the skull. All these species (including sheep of both sexes) possess however one feature in common. They have a pneumated skull with a double roof of bone over the brain. Since there is no correlation between horn size and the mode of fighting: I reject the shock-absorption function. Horns act as display organs.-This is an old, but unverified concept of obscure origin. Beninde (1937) stated it clearly. He proposed that large-antlered deer could intimidate small-antlered opponents with their horn size, and hence gain social advantages without fighting. This hypothesis was never carried through to its various logical conclusions and hence never verified or rejected. If the horns of mountain sheep have been selected for as display or intimidation organs, then the following predictions must be inherent: