Dynamic Elastic-Plastic Buckling of Structural Elements: A Review

2008 ◽  
Vol 61 (4) ◽  
Author(s):  
D. Karagiozova ◽  
Marcílio Alves
Keyword(s):  
Cross Sections ◽  
High Efficiency ◽  
Transportation Systems ◽  
Review Article ◽  
Experimental Investigations ◽  
Structural Elements ◽  
Postbuckling Behavior ◽  
Elastic Plastic ◽  
Material Characteristics ◽  
Energy Absorbing

Structural elements, which deform inelastically, are often used in energy-absorbing devices due to their simple design and the high efficiency achieved by several buckling deformation mechanisms. The application of light ductile materials in transportation systems and increased loading intensity requires studies on the influence of the rate of loading and material characteristics on dynamic buckling behavior. The present review article is focused on summarizing the state of the art related to the inelastic dynamic stability and postbuckling behavior of various basic structural members. In particular, studies on the dynamic response of axially loaded idealized elastic-plastic models, rods, shells with circular and square cross sections, and long tubes are discussed with consideration given to the influence of the geometric and material characteristics as well as the loading conditions on the buckling phenomena observed in these structural elements. The findings from the theoretical and experimental investigations on the phenomenon of dynamic inelastic buckling reported in this review article are based on 118 references.

Theoretical Aspects of Construction of Turning up and Loading Machine with Disinfection Option for Agricultural Waste by Carbon Nanostructures Modified Sodium Acetate

2017 ◽  
Vol 13 ◽  
pp. 130-134 ◽  
Author(s):  
Alexandr V. Shchegolkov ◽  
Boris S. Trufanov ◽  
Victor D. Hmyrov ◽  
Vyacheslav B. Kudenko ◽  
Yulia V. Guryanova ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanostructures ◽  
Sodium Acetate ◽  
High Efficiency ◽  
New Technology ◽  
Agricultural Waste ◽  
Experimental Investigations ◽  
Structural Elements ◽  
Theoretical Substantiation ◽  
Processed Waste

The present paper describes the results of the use of new technology of disinfection and processing of agricultural waste by carbon nanostructures modified sodium acetate. Improving the efficiency of processing of agricultural waste was obtained via sodium acetate in the presence of carbon nanotubes. In order to distribute the sodium acetate in the processed waste and subsequent processing of waste effectively special machines/devices were developed. The theoretical substantiation of the basic structural elements was presented for mechanical processing of agricultural waste devices. The experimental investigations showed a high efficiency of technology which led to a reduction of pathogens at the pre-processing of manure by 60%. The consumption of sodium acetate with carbon nanotubes was 50 liters per 1 ton of manure.

scholarly journals THE CRASH ENERGY ABSORPTION OF THE VEHICLES FRONT STRUCTURES

Transport ◽  
2003 ◽  
Vol 18 (2) ◽  
pp. 97-101 ◽  
Author(s):  
Paulius Griškevičius ◽  
Antanas Žiliukas
Keyword(s):  
Mechanical Characteristics ◽  
Axial Loading ◽  
Computer Code ◽  
Experimental Investigations ◽  
Fe Model ◽  
Structural Elements ◽  
Crash Analysis ◽  
Absorbed Energy ◽  
Frontal Crash ◽  
Energy Absorbing

During the frontal crash the longerons absorb most energy of all vehicles construction elements. In order to analyse the energy absorbing capabilities of longerons under axial compression loading and to evaluate the influence of longerons geometrical characteristics and materials degradation on the vehicles safety experimental investigations and numerical calculations were performed. To assess the crashworthiness of longerons the main objective was to study the behaviour of thin-walled structural elements under axial loading conditions using the Finite Element (FE) model. The numerical FE models were created using the computer code LS-DYNA. Two models of longerons were investigated with different sections shape and for each of them materials with the four different mechanical characteristics were applied. Validation of created FE model was performed according to the experimental investigation and the results were obtained of validated FE models of vehicles crash analysis [1]. The results of analyses show that the value of absorbed energy by the longerons of new vehides exceeds the value of the oldest cars. The degradation of structures in the old cars has the significant influence on the absorbed energy.

scholarly journals FINITE ELEMENT MODELING OF CRASHING BEHAVIOR CONCERNING RECTANGULAR MULTI-LAYERED THIN-WALLED STRUCTURES

2017 ◽  
Vol 20 (1) ◽  
Author(s):  
VLAD ANDREI CIUBOTARIU
Keyword(s):  
Finite Element ◽  
Cross Sections ◽  
Peak Load ◽  
Numerical Data ◽  
Transportation Systems ◽  
Steel Sheets ◽  
Thin Walled Structures ◽  
Different Shapes ◽  
Thin Walled ◽  
Energy Absorbing

<p>Tubular thin-walled structures with different shapes of the cross-sections are widely used in various transportation systems as energy absorbing components to dissipate the kinetic energy during violent collisions and crashes. The aims of this paper are to obtain numerical data on the crashing of thin-walled structures made by multiple layers of steel sheets. A series of finite element calculations was carried out on four different models crashed axially in dynamic conditions by using LS_Dyna V971. The effect of the generated fold depth on the peak load and the mean crashing load of these types of structures were also examined. </p>

scholarly journals Low Power Cusped Field Thruster Developed for the Space-Borne Gravitational Wave Detection Mission in China

2021 ◽  
Vol 11 (14) ◽  
pp. 6549
Author(s):  
Hui Liu ◽  
Ming Zeng ◽  
Xiang Niu ◽  
Hongyan Huang ◽  
Daren Yu
Keyword(s):  
Low Power ◽  
Gravitational Wave ◽  
Attitude Control ◽  
High Efficiency ◽  
Experimental Investigations ◽  
Attitude Control System ◽  
Gravitational Wave Detection ◽  
Wave Detection ◽  
Wide Range ◽  
Institute Of Technology

The microthruster is the crucial device of the drag-free attitude control system, essential for the space-borne gravitational wave detection mission. The cusped field thruster (also called the High Efficiency Multistage Plasma Thruster) becomes one of the candidate thrusters for the mission due to its low complexity and potential long life over a wide range of thrust. However, the prescribed minimum of thrust and thrust noise are considerable obstacles to downscaling works on cusped field thrusters. This article reviews the development of the low power cusped field thruster at the Harbin Institute of Technology since 2012, including the design of prototypes, experimental investigations and simulation studies. Progress has been made on the downscaling of cusped field thrusters, and a new concept of microwave discharge cusped field thruster has been introduced.

scholarly journals A Multi-Loop Vehicle-Counting Method under Gray Mode and RGB Mode

2021 ◽  
Vol 11 (15) ◽  
pp. 6831
Author(s):  
Yue Chen ◽  
Jian Lu
Keyword(s):  
Intelligent Transportation Systems ◽  
High Efficiency ◽  
Road Traffic ◽  
Low Cost ◽  
Rapid Development ◽  
Intelligent Transportation ◽  
Transportation Systems ◽  
Counting Method ◽  
Moving Vehicle ◽  
Available Information

With the rapid development of road traffic, real-time vehicle counting is very important in the construction of intelligent transportation systems (ITSs). Compared with traditional technologies, the video-based method for vehicle counting shows great importance and huge advantages in its low cost, high efficiency, and flexibility. However, many methods find difficulty in balancing the accuracy and complexity of the algorithm. For example, compared with traditional and simple methods, deep learning methods may achieve higher precision, but they also greatly increase the complexity of the algorithm. In addition to that, most of the methods only work under one mode of color, which is a waste of available information. Considering the above, a multi-loop vehicle-counting method under gray mode and RGB mode was proposed in this paper. Under gray and RGB modes, the moving vehicle can be detected more completely; with the help of multiple loops, vehicle counting could better deal with different influencing factors, such as driving behavior, traffic environment, shooting angle, etc. The experimental results show that the proposed method is able to count vehicles with more than 98.5% accuracy while dealing with different road scenes.

scholarly journals Recent Developments on Five-Component Reactions

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1986
Author(s):  
Xiaoming Ma ◽  
Sanjun Zhi ◽  
Wei Zhang
Keyword(s):  
Multicomponent Reactions ◽  
High Efficiency ◽  
Review Article ◽  
Reaction Centers ◽  
Synthetic Approach ◽  
Recent Developments

Multicomponent reactions (MCRs) have inherent advantages in pot, atom, and step economy (PASE). This important green synthetic approach has gained increasing attention due to high efficiency, minimal waste, saving resources, and straightforward procedures. Presented in this review article are the recent development on 5-compoment reactions (5CRs) of the following six types: (I) five different molecules A + B + C + D + E; pseudo-5CRs including (II) 2A + B + C + D, (III) 2A + 2B + C, (IV) 3A + B + C, (V) 3A + 2B, and (VI) 4A + B. 5CRs with more than five-reaction centers are also included.

scholarly journals Roll Bonding of Al-Based Composite Reinforced with C10 Steel Expanded Mesh Inlay

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1044
Author(s):  
Yaroslav Frolov ◽  
Maxim Nosko ◽  
Andrii Samsonenko ◽  
Oleksandr Bobukh ◽  
Oleg Remez
Keyword(s):  
Impact Energy ◽  
High Efficiency ◽  
Shape Change ◽  
Experimental Investigations ◽  
Aluminum Composite ◽  
Rolling Mills ◽  
Roll Bonding ◽  
Finite Element Software ◽  
Steel Mesh ◽  
Bonded Composite

The most complex issue related to the design of high efficiency composite materials is the behavior of the reinforcing component during the bonding process. This study presents numerical and experimental investigations of the shape change in the reinforcing inlay in an aluminum-steel mesh-aluminum composite during roll-bonding. A flat composite material consisting of two outer strips of an EN AW 1050 alloy and an inlay of expanded C10 steel mesh was obtained via hot roll bonding with nominal rolling reductions of 20%, 30%, 40% and 50% at a temperature of 500 °C. The experimental procedure was carried out using two separate rolling mills with diameters equal to 135 and 200 mm, respectively. A computer simulation of the roll bonding was performed using the finite element software QForm 9.0.10 by Micas Simulations Limited, Oxford, UK. The distortion of the mesh evaluated via the change in angle between its strands was described using computer tomography scanning. The dependence of the absorbed impact energy of the roll bonded composite on the parameters of the deformation zone was found. The results of the numerical simulation of the steel mesh shape change during roll bonding concur with the data from micro-CT scans of the composites. The diameter of rolls applied during the roll bonding, along with rolling reduction and temperature, have an influence on the resulting mechanical properties, i.e., the absorbed bending energy. Generally, the composites with reinforcement exhibit up to 20% higher impact energy in comparison with the non-reinforced composites.

scholarly journals Experimental Evaluation of Airlift Performance for Vertical Pumping of Water in Underground Mines

2021 ◽  
Author(s):  
Parviz Enany ◽  
Oleksandr Shevchenko ◽  
Carsten Drebenstedt
Keyword(s):  
Water Flow ◽  
High Efficiency ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Injection System ◽  
Experimental Investigations ◽  
Flow Mode ◽  
New Device ◽  
Riser Pipe ◽  
Airlift Pump

AbstractThis paper presents experimental studies on the optimization of air–water flow in an airlift pump. Airlift pumps use compressed gas to verticall transport liquids and slurries. Due to the lack of theoretical equations for designing and predicting flow regimes, experimental investigations must be carried out to find the best condition to operate an airlift pump at high efficiency. We used a new air injection system and different submergence ratios to evaluate the output of a simple pump for vertical displacement of water in an underground mine. The tests were carried out in a new device with 5.64 m height and 10.2 cm circular riser pipe. Three air-jacket pipes, at different gas flows in the range of 0.002–0.09 m3/s were investigated with eight submergence ratios. It was found that with the same air flow rate, the most efficient flow of water was achieved when an air jacket with 3 mm diameter holes was used with a submergence ratio between 0.6 and 0.75. In addition, a comparison of practical results with two theoretical models proposed by other investigators showed that neither was able to accurately predict airlift performance in air–water flow mode.

Deformation distortions of geometric form tube blanks in the process of drilling holes

2021 ◽  
pp. 104-110
Author(s):  
A.N. Isaev ◽  
S.V. Vlaskin ◽  
V.A. Lebedev ◽  
M.D. Gavrilenko
Keyword(s):  
Stress State ◽  
Wall Thickness ◽  
Cross Sections ◽  
Theoretical Studies ◽  
Geometric Form ◽  
Axisymmetric Stress ◽  
Axisymmetric Stress State ◽  
Elastic Plastic ◽  
The Cross

The influence of deviations of the shape of the cross-sections of pipes from roundness on the axisymmetric stress state and taking this factor into account in theoretical studies and methods for solving problems of mandrel drilling in the elastic-plastic mode are considered. The features of the choice of tubular blanks, which help to reduce the unevenness of deformation and increase the accuracy of processing in the process of mandrel drilling, are revealed. Recommendations are given for eliminating the variance in wall thickness of blanks at the stage of their preparation for the mandrel operation.

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