scholarly journals Plastic response of conical shells with stiffeners to blast loading

2020 ◽  
Vol 24 (1) ◽  
pp. 5-18
Author(s):  
Jaan Lellep ◽  
Ella Puman
Keyword(s):  
Time Moment ◽  
Yield Condition ◽  
Blast Loading ◽  
Theoretical Method ◽  
Initial Time ◽  
Conical Shells ◽  
Initial Time Moment ◽  
Circular Conical Shells ◽  
Load Intensity ◽  
The Impact

The inelastic response of circular conical shells to the blast loading is studied. The impact loading is applied at the initial time moment and it is removed at a certain instant of time. The load intensity depends of the coordinate of the shell. The material of the shell is a perfect plastic one obeying the Johansen yield condition and the associated flow law. It is assumed that the frustum of the cone is furnished with ring stiffeners made of the same material. A theoretical method for the evaluation of the stress strain state of the shell and for determination of maximal residual deflections is developed.

scholarly journals Estimation of the parameters of barbell’ lifting law of motion

2016 ◽  
Author(s):  
Mečislovas Mariūnas ◽  
Julius Griškevičius ◽  
Gintaras Jonaitis
Keyword(s):  
Experimental Study ◽  
Time Moment ◽  
Initial Time ◽  
Maximal Velocity ◽  
Lifting Force ◽  
Initial Time Moment ◽  
Characteristic Points ◽  
The Law

Characteristic points of the law of motion were determined based on the results of experimental study on the velocities and accelerations of the lifted barbell. Relationship between the height of the athlete, lifted weight, maximal velocity and acceleration was estimated analytically. It was shown, that at the initial time moment the athlete must apply approximately 1,5 times larger force than lifted weight. The values of the parameters of the barbell’ law of motion and lifting force approximate law of change were estimated.

scholarly journals Microchannel cleaning by the external laminar flow

2020 ◽  
pp. 5-13
Author(s):  
L. S. Klimenko ◽  
◽  
B. S. Maryshev ◽  
◽  
◽  
...  
Keyword(s):  
Flow Rate ◽  
Constant Pressure ◽  
Van Der Waals ◽  
Time Moment ◽  
Van Der Waals Interactions ◽  
Initial Time ◽  
Channel Cross Section ◽  
Viscous Stress ◽  
Interacting Particles ◽  
Initial Time Moment

The paper is devoted to study of the cleaning a microchannel contaminated by solute particles deposited on channel walls. The main and the most common cause of microchannel clogging is sorption of solute particles on channel walls or “physical sorption”. In this paper, we study the problem of the drift of solid non-interacting particles into a microchannel, which can stick to its walls due to Van der Waals interactions and break away from the wall due to viscous stress. A constant pressure drop is fixed between the inlet and the outlet of the channel. At the initial time moment, the channel walls are contaminated with adhering particles, i.e. the form of walls affects the formation of the flow structure through the channel. Over time, under the action of viscous stress the particles detach from the channel walls, thus cleaning occurs. The interaction of the detached particles with the flow is taken into account within the Stokes approximation. In addition, the model takes into account random walks caused by diffusion. The problem is solved numerically in the framework of the random walk model. The evolution of the fluid flow in the channel during its cleaning is obtained. The dependences of the concentration of settled particles on the flow rate and the strength of the Van der Waals interaction between particle and wall are determined. The dependence of the flow rate through the channel cross section on the concentration of settled particles was investigated. The channel cleaning time was estimated.

scholarly journals Boundary Value Problems for Fourth-Order Sobolev Type Equations

2001 ◽  
Vol 14 (4) ◽  
pp. 425-432
Author(s):  
Alexander I. Kozhanov ◽  
Keyword(s):  
Boundary Value Problems ◽  
Fourth Order ◽  
Boundary Value ◽  
Linear Equations ◽  
Time Moment ◽  
Initial Boundary ◽  
Initial Time ◽  
Sobolev Type ◽  
Initial Time Moment ◽  
Initial Boundary Value

The goal of the article is the study of solvability in the Sobolev spaces of boundary value problems for some classes of Sobolev-type fourth-order linear equations. We will prove that an initial boundary value problems well problems with data both at the initial time moment and the final time moments can be well-posed for the equations under study

scholarly journals PREPARATION AND LYOPHILIC PROPERTIES OF CHITOSAN AEROGELS MODIFIED WITH GLYCYDYL METHACRYLATE COPOLYMERS

2020 ◽  
pp. 82-89
Author(s):  
V. M. Yartseva ◽  
E. B. Bryuzgina ◽  
V. V. Klimov ◽  
E. V. Bryuzgin ◽  
A. V. Navrotskii
Keyword(s):  
Water Absorption ◽  
Glycidyl Methacrylate ◽  
Time Moment ◽  
Contact Angles ◽  
Initial Time ◽  
Oil Absorption ◽  
Methacrylate Copolymers ◽  
Initial Time Moment ◽  
Highly Hydrophobic ◽  
Surface Modified

The article presents the results of a study of the properties of chitosan spongy materials (aerogels) surface modified with copolymers of glycidyl methacrylate. The surface of the obtained materials is characterized by a highly hydrophobic state with contact angles at the initial time moment more than 140 degrees, while a decrease in water absorption of aerogels and a slight decrease in oil absorption are also observed as a result of the modification.

scholarly journals Analysis of Reinforced Concrete Structures for Accidental Blast during Launching of a Rocket

2021 ◽  
Vol 13 (3) ◽  
pp. 195-204
Author(s):  
Lovepreet SINGH ◽  
Nirmal Rakeshbhai RAVALIYA ◽  
M. Abdul AKBAR
Keyword(s):  
Blast Loading ◽  
Element Model ◽  
Civil Infrastructure ◽  
Parametric Studies ◽  
Convergence Study ◽  
Load Intensity ◽  
Mesh Convergence ◽  
The Impact ◽  
The Finite Element Model ◽  
Launching Site

Despite the greatest efforts, accidents continue to happen during the process of rocket launching, either in the form of generated blast wave or the debris that flies and hits random objects. In this paper, the impact of blast loading created by a rocket launch on the tie connection and the three-hinged arch is studied using the finite element model in ABAQUS. The impact of rocket launching was modelled using the physical characteristics/geometry of the launch pad, and a blast load intensity equivalent to 20,000lbs of TNT is applied using the CONWEP module. The tie connection and three-hinged arch after validation and mesh convergence study are applied with service loads in concurrence with the blast loading. The additional impact of blast loads on the static and dynamic response of the structure is studied. The distance of the structures from the point of blast (rocket launching site) is varied, and parametric studies are carried out to arrive at detailed guidelines on the minimum safety distance that stand-alone civil infrastructure should follow in order to minimize the rocket launching impact.

Analysis of Plastic Shallow Conical Shells

1963 ◽  
Vol 30 (2) ◽  
pp. 199-209 ◽  
Author(s):  
R. H. Lance ◽  
E. T. Onat
Keyword(s):  
Yield Surface ◽  
Digital Computer ◽  
Yield Condition ◽  
Shell Material ◽  
Rigid Plastic ◽  
Conical Shells ◽  
Simply Supported ◽  
State Of Stress ◽  
Load Intensity ◽  
Yield Conditions

The paper is concerned with simply supported shallow conical shells loaded through a central boss. The shell material is rigid-plastic and the relevant stress resultants are subject to a nonlinear yield condition. The critical load intensity at which the shell will begin to deform and the associated fields of stress resultants and plastic flow are to be determined. For this purpose, a problem concerned exclusively with stress resultants is formulated by using the equation of stress compatibility. The resulting nonlinear problem is solved, with the help of a digital computer, in cases where the yield-point state of stress is controlled, over the pertinent intervals covering the entire shell, by three distinct yield conditions, each corresponding to a given face of the appropriate four-dimensional nonlinear yield surface.

Sign in / Sign up

Export Citation Format

Share Document