Numerical Simulation of Localized Bulging in an Inflated Hyperelastic Tube with Fixed Ends

2020 ◽  
pp. 2050118
Author(s):  
Zehui Lin ◽  
Linan Li ◽  
Yang Ye
Keyword(s):  
Axial Stress ◽  
Necessary Condition ◽  
Theoretical Studies ◽  
Inflation Pressure ◽  
Material Models ◽  
Rubber Material ◽  
Bifurcation Phenomenon ◽  
A Value ◽  
Pressure Maximum ◽  
Almost All

When a hyperelastic tube is inflated, the inflation pressure has a maximum for almost all rubber material models, but has no maximum for commonly used arterial models. It is generally believed that the pressure having a maximum is a necessary condition for localized bulging to occur, and therefore aneurysms cannot be modeled as a mechanical bifurcation phenomenon. However, recent theoretical studies have shown that if the axial stretch is fixed during inflation, localized bulging may still occur even if a pressure maximum does not exist in uniform inflation. In this paper, numerical simulations are conducted to confirm this theoretical prediction. It is also demonstrated that if the axial pre-stretch is not sufficiently large, unloading near the two ends can reduce the axial stress to a value close to zero and Euler-type buckling then occurs.

Performance study of RTV-2 Silicone Rubber Material For Soft Actuator by Experimental and Numerical methods: The Effect of Inflation Pressure and Wall Thickness

2020 ◽  
Vol 17 (1) ◽  
pp. 7524-7532 ◽  
Author(s):  
Deepak D. ◽  
Nitesh Kumar ◽  
Shreyas P. Shetty ◽  
Saurabh Jain ◽  
Manoj Bhat
Keyword(s):  
Numerical Methods ◽  
Wall Thickness ◽  
Silicone Rubber ◽  
Inflation Pressure ◽  
Performance Study ◽  
Rubber Material ◽  
Soft Actuator ◽  
Alternative Materials ◽  
Load Carrying ◽  
Influential Parameters

The expensive nature of currently used materials in the soft robotic industry demands the consideration of alternative materials for fabrication. This work investigates the performance of RTV-2 grade silicone rubber for fabrication of a soft actuator. Initially, a cylindrical actuator is fabricated using this material and its performance is experimentally assessed for different pressures. Further, parametric variations of the effect of wall thickness and inflation pressure are studied by numerical methods. Results show that, both wall thickness and inflation pressure are influential parameters which affect the elongation behaviour of the actuator. Thin (1.5 mm) sectioned actuators produced 76.97% more elongation compared to thick sectioned, but the stress induced is 89.61 % higher. Whereas, the thick sectioned actuator (6 mm) showed a higher load transmitting capability. With change in wall thickness from 1.5 mm to 6 mm, the elongation is reduced by 76.97 %, 38.35 %, 21.05 % and 11.43 % at pressure 100 kPa, 75 kPa, 50 kPa and 25 kPa respectively. The induced stress is also found reduced by 89.61 %, 86.66 %, 84.46 % and 68.68 % at these pressures. The average load carrying capacity of the actuator is found to be directly proportional to its wall thickness and inflation pressure.

scholarly journals Launch Velocities in Successful Golf Putting: An Analytical Analysis

2017 ◽  
Vol 5 (2) ◽  
pp. 24
Author(s):  
John F. Mahoney ◽  
Daniel P. Connaughton
Keyword(s):  
Critical Value ◽  
Theoretical Studies ◽  
Newtonian Mechanics ◽  
Ambient Conditions ◽  
Analytical Analysis ◽  
Bouncing Ball ◽  
Golf Putting ◽  
A Value ◽  
Special Case

Background: This study is concerned with the special case of a putted ball intersecting a standard golf hole at its diameter. The velocity of the ball at the initial rim of the hole is termed the launch velocity and depending upon its value the ball may either be captured or it may escape capture by jumping over the hole. The critical value of the launch velocity (V) is such that lesser values result in capture while greater values produce escape. Purpose: Since the value of the V entered prominently in some theoretical studies of putting, the aim of the current study is to provide an original re-evaluation of V and to contrast our results with existing results. Method: This analytical analysis relies on trigonometry in conjunction with Newtonian mechanics and the mathematics of projectiles. The results of a recent study into the mathematics of a bouncing ball which included the notions of restitution and friction were also employed in the analysis. Results: If bouncing and slipping do not occur when the ball hits the far rim of the hole our analysis produces a value of V of 1.356 m/s. When bouncing and slipping are present we find that V is at least 1.609 m/s but increases beyond this value as slipping and friction become greater. Useful relations which relate the dynamics and geometry of the ball to V are provided. Conclusion: Since ambient conditions may influence the extent of bounce and slippage we conjecture that the value of V is not unique.

SPIRITUAL DEVELOPMENT AS A NECESSARY CONDITION OF WAY OUT OF THE CRISIS FOR SOCIETY

2021 ◽  
pp. 7-14
Author(s):  
Svitlana Repetii
Keyword(s):  
Spiritual Development ◽  
Value Orientations ◽  
Mental Illnesses ◽  
Necessary Condition ◽  
Human Being ◽  
Emotional Instability ◽  
Life Activity ◽  
Almost All

The crisis of the present day, which covered almost all types of life activities, contributes to the development of impoverishment, degradation, leads to an increase of criminality, generates fear, emotional instability in the society. Forced isolation, threat of loss of work and value orientations contribute to the emergence of mental illnesses. Each person is responsible for his actions, thoughts and feelings – for themselves and society. Spiritual development is interpreted as a conscious life activity, transformation of negative qualities, which is considered as a daily inner action. This kind of life activity contributes to the development of unconditioned love, which we interpret as perception of a human being in its entirety without condemnation and pretensions.

scholarly journals How much does turbulence change the pebble isolation mass for planet formation?

2018 ◽  
Vol 615 ◽  
pp. A110 ◽  
Author(s):  
S. Ataiee ◽  
C. Baruteau ◽  
Y. Alibert ◽  
W. Benz
Keyword(s):  
Aspect Ratio ◽  
Planet Formation ◽  
Turbulent Viscosity ◽  
Analytical Calculation ◽  
Radial Pressure ◽  
Stokes Number ◽  
High Viscosity ◽  
Necessary Condition ◽  
Pressure Maximum ◽  
Hydrodynamical Simulations

Context. When a planet becomes massive enough, it gradually carves a partial gap around its orbit in the protoplanetary disk. A pressure maximum can be formed outside the gap where solids that are loosely coupled to the gas, typically in the pebble size range, can be trapped. The minimum planet mass for building such a trap, which is called the pebble isolation mass (PIM), is important for two reasons: it marks the end of planetary growth by pebble accretion, and the trapped dust forms a ring that may be observed with millimetre observations. Aims. We study the effect of disk turbulence on the PIM and find its dependence on the gas turbulent viscosity, aspect ratio, and particles Stokes number. Methods. By means of 2D gas hydrodynamical simulations, we found the minimum planet mass to form a radial pressure maximum beyond the orbit of the planet, which is the necessary condition to trap pebbles. We then carried out 2D gas plus dust hydrodynamical simulations to examine how dust turbulent diffusion impacts particles trapping at the pressure maximum. We finally provide a semi-analytical calculation of the PIM based on comparing the radial drift velocity of solids and the root mean square turbulent velocity fluctuations around the pressure maximum. Results. From our results of gas simulations, we provide an expression for the PIM vs. disk aspect ratio and turbulent viscosity. Our gas plus dust simulations show that the effective PIM can be nearly an order of magnitude larger in high-viscosity disks because turbulence diffuse particles out of the pressure maximum. This is quantified by our semi-analytical calculation, which gives an explicit dependence of the PIM with Stokes number of particles. Conclusions. Disk turbulence can significantly alter the PIM, depending on the level of turbulence in regions of planet formation.

Growth rate of perivascular cuffs in liquid-inflated dog lung lobes

1986 ◽  
Vol 61 (2) ◽  
pp. 647-653 ◽  
Author(s):  
R. L. Conhaim
Keyword(s):  
Cross Sections ◽  
Time Course ◽  
Inflation Pressure ◽  
Cuff Volume ◽  
Edema Formation ◽  
Lung Capacity ◽  
A Value ◽  
Liquid Storage ◽  
Additional Lobes ◽  
Lung Lobes

In the early stages of pulmonary edema, excess liquid leaving the pulmonary exchange vessels accumulates in the peribronchovascular interstitium where it forms large peribronchovascular cuffs. The peribronchovascular interstitium therefore acts as a reservoir to protect the air spaces from alveolar flooding. The rate of liquid accumulation and the liquid storage capacity of the cuffs determine how quickly alveolar flooding is likely to follow once edema formation has begun. To measure the rate and capacity of interstitial filling we inflated 11 isolated degassed dog lung lobes with liquid to an inflation pressure of 14 cmH2O (total lung capacity) for 1–300 min, then froze the lobes in liquid N2. We made photographs of 20 randomly selected 12 X 8-mm cross sections from each lobe and measured cuff volume from the photographs by point-counting. We found that cuff volume increased from 2.2% of air-space volume after 1 min of inflation to 9.3% after 300 min. To measure the driving pressure responsible for cuff formation we used micropipettes to measure subpleural interstitial liquid pressure at the hilum of three additional lobes. With liquid inflation pressure set to 14 cmH2O interstitial pressure rose exponentially to 11.5 cmH2O. Interstitial compliance calculated from our volume and pressure measurements equaled 0.09 ml X cmH2O–1 X g wet wt-1, a value similar to that measured in air-inflated lungs. Goldberg [Am. J. Physiol. 239 (Heart Circ. Physiol. 8): H189-H198, 1980] has likened interstitial filling to the charging of a capacitor, a process that follows a monoexponential time course.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Measurement of the Permeability of Biological Membranes Application to the glomerular wall

1973 ◽  
Vol 62 (4) ◽  
pp. 489-507 ◽  
Author(s):  
A. Verniory ◽  
R. Du Bois ◽  
P. Decoodt ◽  
J. P. Gassee ◽  
P. P. Lambert
Keyword(s):  
Poiseuille Flow ◽  
Path Length ◽  
Pore Radius ◽  
Frictional Resistance ◽  
Theoretical Studies ◽  
Equivalent Radius ◽  
A Value ◽  
Anesthetized Dogs ◽  
The Mean ◽  
Diffusion And Convection

The transport equation describing the flow of solute across a membrane has been modified on the basis of theoretical studies calculating the drag of a sphere moving in a viscous liquid undergoing Poiseuille flow inside a cylinder. It is shown that different frictional resistance terms should be introduced to calculate the contributions of diffusion and convection. New sieving equations are derived to calculate r and Ap/Δx (respectively, the pore radius and the total area of the pores per unit of path length). These equations provide a better agreement than the older formulas between the calculated and the experimental glomerular sieving coefficients for [125I]polyvinylpyrrolidone (PVP) fractions with a mean equivalent radius between 19 and 37 Å. From r and Ap/Δx, the mean effective glomerular filtration pressure has been calculated, applying Poiseuille's law. A value of 15.4 mm Hg has been derived from the mean sieving curve obtained from 23 experiments performed on normal anesthetized dogs.

Miejsce pracy w Marksowskim humanizmie

Etyka ◽  
1970 ◽  
Vol 6 ◽  
pp. 113-131
Author(s):  
Zbigniew Kuderowicz
Keyword(s):  
Human Life ◽  
Social Systems ◽  
Division Of Labour ◽  
Necessary Condition ◽  
A Value ◽  
Individual Personality ◽  
Free Development ◽  
Spontaneous Expression ◽  
Material Conditions ◽  
The Individual

The article deals with the attitude of Marx and Engels towards the appraisal of labour as a value, and the relation between labour and the implementation of the principle of universal development of the individual personality. First, the changes in their views on the appraisal of labour are discussed. In his Economic and Philosophical Manuscripts Marx understood labour as a spontaneous expression of human thought and the formation of a new environment in which man recognizes his own qualities. In that period Marx considered value to be an affirmation of human life and a requirement put to the individual and to society. In his later, mature works Marks refused to consider an act of labour as value and defined it as conquering nature. The act of labour was to Marx no longer a value but a process which is giving value to human products and, therefore, is a necessary condition of human existence in all social systems. Marx did not regard the act of labour as a postulate or an ideal. In his opinion, the act of labour acquired value depending on its effects for the universal development of all individuals. The Marxian ideal of a perfect man implied a series of postulates relating to the organization of labour. The author criticizes Raymond Aron’s interpretation of Marxian humanism. In the works of Marx, Aron perceives a contradiction between the postulate of universal labour and the postulate of leisure in the meaning of condition in which the idea of the perfect man is realized. According to the author, from the ideal of a perfect man results the postulate of obligatory labour for all members of the society, i.e., that everybody should contribute to the development of the productive forces in order to secure the material conditions for the development of their personality. The realization of Marxian humanism requires also the maintenance of definite proportions between labour determined by the social division of labour (necessary in this sense), and leisure which should imply not only resting but also activity towards a free development of various individual abilities. In the works of Marx there is no contradiction but a complementary relation between labour and leisure. Pobierz

Plastic flow and fracture of glass

1964 ◽  
Vol 282 (1388) ◽  
pp. 33-43 ◽  
Keyword(s):  
Plastic Flow ◽  
Energy Balance Equation ◽  
Static Fatigue ◽  
Secondary Effects ◽  
New Approach ◽  
Theoretical Support ◽  
A Value ◽  
Fracture Theory ◽  
As Stress ◽  
Almost All

It is usual to regard glass as a purely brittle solid and this has been taken for granted in almost all past papers on the mechanical strength, static fatigue, and ageing properties of glasses. However, in the present note this approach is rejected as being incompatible with experimental evidence of plastic flow in glass, and incapable of explaining the strengths observed. Instead a completely new approach is attempted in which glass is treated as an elastic-plastic solid and a complete theory of glass flow and strength is developed. The note summarizes the contents of three papers soon to be published which develop these ideas in more detail, and readers are referred to these three papers (Marsh 1964 a , b , c ) for full experimental and theoretical support of the ideas presented here. In brittle fracture theory glass is expected to exhibit its theoretical cohesive strength if it is flaw-free (e. g. untouched glass fibre), but if handled surface cracks are introduced and the strength should fall to a value predicted either by the Griffith (1920) energy balance equation or by the known stress concentration factor at the crack tip. Secondary effects such as static fatigue and ageing can then be explained as stress corrosion phenomena.

scholarly journals A Design of Bamboo Plywood Pressing Machine

2020 ◽  
Vol 3 (SI1) ◽  
pp. First
Author(s):  
Le Khanh Dien ◽  
Tran Van Hung ◽  
Hoang Duc Lien ◽  
Svetlin Antonov
Keyword(s):  
Flat Plate ◽  
Environmental Benefits ◽  
Customer Requirements ◽  
Official Statistic ◽  
Technical Requirements ◽  
A Value ◽  
Hardwood Trees ◽  
Wood Flooring ◽  
Almost All ◽  
Collaboration Project

Bamboo is very popular in the countryside of almost all Southeast countries, particularly in Vietnam. Its ability can replace some kinds of wood in decoration and household goods. Bamboo grows up rapidly and can be harvested within 3 to 5 years of planting; in the meanwhile, the harvesting time of other hardwood trees must be from 8 to 10 years or longer. The inherent characteristics of bamboo are lighter than other wood materials and have a value in social and environmental benefits. Its advances in manufacturing technology have created high-value products such as bamboo flooring and bamboo furniture that can substitute for wood flooring and wood furniture. Bamboo plywood presses play an important role in the production of bamboo plywood in the industry. The machine has the function of pressing bamboo powder, and binder has been mixed from the front to the bamboo plank to meet the technical requirements. This article presents a design of bamboo plywood pressing machine that combines the heating function for the blocking board and keeps that temperature during the pressing process to create a suitable size bamboo plywood according to customer requirements. The simulation results show that the complete bamboo plywood-pressing machine is appropriate and authentic to the initial design. The result of the design was applied to manufacture the machine in DCSELAB workshop via a collaboration project between Langtre PhuAn company and the DCSELAB. The system is installed a resistance flat plate capacity of 1KW, and 2 resistors flat plate with the capacity of 0.8KW. The first manufactured machine is now in the initial working session in Langtre Villige, Binh Duong province. The initial experimental products were accepted by the partner company, and we have recommended some measures to ameliorate time by time the quality as well as the productivity of the machine. There is really not yet an official statistic on the comparison with the products of a similar machine, and we are attending the response of the customers.

scholarly journals Revisiting Metallicity of Long Gamma-Ray Burst Host Galaxies: The Role of Chemical Inhomogeneities in Galaxies

2011 ◽  
Vol 7 (S279) ◽  
pp. 369-370
Author(s):  
Yuu Niino
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Necessary Condition ◽  
Theoretical Studies ◽  
Host Galaxies ◽  
Cast Doubt ◽  
Low Metallicity ◽  
High Metallicity ◽  
Metallicity Distribution

AbstractSome theoretical studies on the origin of long gamma-ray bursts (GRBs) using stellar evolution models suggest that a low metallicity environment may be a necessary condition for a GRB to occur. However, recent discoveries of high-metallicity host galaxies of some GRBs cast doubt on the requirement of low-metallicity in GRB occurrence. In this study, we predict the metallicity distribution of GRB host galaxies, assuming empirical formulations of galaxy properties. We take internal dispersion of metallicity within each galaxy into account. Assuming GRBs trace low-metallicity star formation 12+log(O/H) < 8.2, we find that ≳ 10% of GRB host galaxies may have Z > Z⊙, depending on the internal dispersion of metallicity within galaxies.

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