scholarly journals Falling weight impact test of a new-type flexible rock-shed

2018 ◽  
Vol 38 (2) ◽  
pp. 242-252
Author(s):  
Jianrong Yang ◽  
Zhiyu Zhang
Keyword(s):  
Experimental Studies ◽  
Steel Tube ◽  
Time Interval ◽  
Explicit Finite Element ◽  
Numerical Studies ◽  
Structural Details ◽  
Tensile Forces ◽  
New Type ◽  
Falling Weight ◽  
The Impact

A new concept of a flexible rock-shed is presented for protection of the railway from falling rocks. The flexible rock-shed is made of flexible nets connected by specific spring spacer bars to an array of reinforced concrete portable frames which are linked by a longitudinal steel tube truss. To evaluate the performance of the flexible rock-shed, experimental and numerical studies are carried out in the present study. Impact tests are conducted on a full-scale partial model of the prototype structure when it is subjected to a falling block of 340 kg. The impact time interval, maximum deflection of the flexible net, tensile forces in the supporting ropes, and axial strains of spring spacer bars are recorded. To further examine the dynamic behavior of the flexible rock-shed, numerical simulations are also carried out by using the explicit finite element code ANSYS/LS-DYNA. It is found that the numerical results coincide well with the experimental data and both the numerical and experimental studies reveal that the structure can withstand impact energy of 50 kJ with all the materials working in the elastic range. The structural details are improved and the basis for the design and construction of similar structures in the future is provided.<br>

EXPERIMENTAL STUDIES OF DETERMINING THE FORCE INFLUENCE OF THE SEPARATING SURFACE OF THE MODULE FOR POST-HARVESTING PROCESSING ROOT CROPS AND ONIONS

2020 ◽  
Keyword(s):  
Experimental Studies ◽  
Time Interval ◽  
Data Logger ◽  
Negative Effects ◽  
Post Harvest ◽  
Root Crops ◽  
Force Impact ◽  
Post Harvesting ◽  
Working Bodies ◽  
The Impact

Despite the availability of extensive research on the mechanized post-harvest processing of root crops and onions, which continues today, there are unresolved problems in this area, which in most cases are associated with the imperfection of the design of separating bodies of post-harvest processing machines. Existing machines cause damage to commercial products as a result of the interaction of root crops and onions with each other, with working bodies and soil lumps. However, the largest percentage of damage is formed as a result of their interaction with the working bodies of the separating machines. The article presents a structural and technological scheme of a module for separation of a pile of root crops and bulbs developed at the VIM Federal Agroengineering Center. In order to determine the place of the greatest force impact and to carry out subsequent measures to eliminate these negative effects in the design of the module under consideration, industrial studies were conducted. A methodology has been developed for conducting industrial studies to as sess the impact of working bodies on the amount of damage to root crops and onions during operation using the «Tuber Log» electronic tuber. The results of studies of module working bodies force impact that affect the damage to marketable products are obtained, processed and graphically presented. The greatest force impact (до 10 Н) on tuber falls on the time interval of values from 4 to 6 s, while the standard deviation and coefficient of variation are σ = 5,52 and ν = 26,9 %, respectively. The most «sparing» force impacts of the working bodies of the machine for separating the data logger at the translational speed of rubberized rollers V0B =0,8 m/s were determined, where the minimum power impact in the range from 2 H to 4 H is created throughout the entire process.

scholarly journals Experimental and Numerical Studies of Air Curtains for Falling Particle Receivers

2014 ◽  
Author(s):  
Clifford K. Ho ◽  
Joshua M. Christian ◽  
Adam C. Moya ◽  
Josh Taylor ◽  
Daniel Ray ◽  
...  
Keyword(s):  
Convective Heat ◽  
Flow Rate ◽  
Experimental Studies ◽  
Flow Characteristics ◽  
Heat Losses ◽  
Air Curtain ◽  
Hot Air ◽  
Numerical Studies ◽  
Release Location ◽  
The Impact

The use of an air curtain blowing across the aperture of a falling-particle receiver has been proposed to mitigate convective heat losses and to protect the flow of particles from external winds. This paper presents experimental and numerical studies that evaluate the impact of an air curtain on the performance of a falling particle receiver. Unheated experimental studies were performed to evaluate the impact of various factors (particle size, particle mass flow rate, particle release location, air-curtain flow rate, and external wind) on particle flow, stability, and loss through the aperture. Numerical simulations were performed to evaluate the impact of an air curtain on the thermal efficiency of a falling particle receiver at different operating temperatures. Results showed that the air curtain reduced particle loss when particles were released near the aperture in the presence of external wind, but the presence of the air curtain did not generally improve the flow characteristics and loss of the particles for other scenarios. Numerical results showed that the presence of an air curtain could reduce the convective heat losses, but only at higher temperatures (>600°C) when buoyant hot air leaving the aperture was significant.

scholarly journals Explicit Simulation of Circular CFST Stub Columns with External Steel Confinement under Axial Compression

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 23 ◽  
Author(s):  
Faesal Alatshan ◽  
Siti Aminah Osman ◽  
Fidelis Mashiri ◽  
Roszilah Hamid
Keyword(s):  
Failure Modes ◽  
Axial Loading ◽  
Steel Tube ◽  
Fe Model ◽  
Explicit Finite Element ◽  
Steel Ratio ◽  
Short Columns ◽  
Early Loading ◽  
Experimental Findings ◽  
The Impact

Concrete-filled steel tube (CFST) structural members have been widely used in engineering projects for their superior strength and ductility. However, the different lateral dilation characteristics between concrete infill and steel tube have caused imperfect composite interaction during the early loading stage. To overcome this issue, external steel confinements in the form of rings and spiral were previously suggested to minimise the lateral expansion of the steel tube and enhance the concrete confinement effects. This study presented the analytical behaviour of circular CFST short columns with an external ring or spiral confinements which are subjected to axial loading. An explicit finite element (FE) model was developed and verified based on previous experimental findings. Besides that, this study analysed the failure modes, axial load–strain relationship, stress distributions, and bond strength of the composite column components. Parametric analysis was also undertaken to evaluate the impact of material strengths, total steel ratio, and diameter-to-thickness ratio. The results suggest that the use of external steel confinement can enhance the compressive behaviour of CFSTs better than increasing the thickness of the steel tube when using the same steel ratio. Finally, simplified design formulations were developed to accurately calculate the ultimate capacity of CFST columns with and without external steel confinement.

Investigation of Engine Distortion Interaction

2016 ◽  
Author(s):  
Fabian Wartzek ◽  
Heinz-Peter Schiffer ◽  
Jakob P. Haug ◽  
Reinhard Niehuis ◽  
Martin Bitter ◽  
...  
Keyword(s):  
Numerical Models ◽  
Experimental Studies ◽  
Stability Limit ◽  
Analytical Models ◽  
Test Case ◽  
Transonic Compressor ◽  
Numerical Studies ◽  
Small Distortion ◽  
The Stability ◽  
The Impact

Inflow distortions in the compression system of a jet engine are becoming increasingly important for research focus. The investigation of the emergence of a distortion, its interaction with the rotor and the resulting impact on the rotor flow is challenging. In this work a separation in the inflow of a transonic compressor was created and the impact on stage aerodynamics investigated. The separation resulted in a total pressure distortion close to the casing within a sector of 120°. Effects were studied both numerically and experimentally in a joint collaboration project. The numerical model consisted of the full rotor-stator compressor stage, the inlet duct and the distortion generator upstream of the stage. This enables both an accurate validation of the numerical results and contributes to a deeper understanding of the flow. The results of both the numerical and experimental studies were in good agreement. The rotor is locally throttled by the inlet separation, resulting in the formation of an additional loss core at the stability limit due to a local aerodynamic overload. Considering classic distortion descriptors like the DC60, it is shown that they are not able to adequately assess the impact of a strong, but small distortion close to the tip of the rotor. The data can be considered as test case for future numerical models as well as for the validation of new analytical models. Furthermore, the results of this study reveal effects in both experimental and numerical studies that would not be realized if only a model of the separation was analyzed.

Experimental Studies of the Parameters of the Contact Problem in the Design of Plastic Tube Concrete Structures

2019 ◽  
Vol 974 ◽  
pp. 542-550
Author(s):  
Alexander V. Dolzhenko ◽  
Andrey E. Naumov ◽  
Andrey V. Shevchenko ◽  
N. Stoykovich
Keyword(s):  
Rational Design ◽  
Strain State ◽  
Experimental Studies ◽  
Steel Tube ◽  
Plastic Shell ◽  
Stress Strain ◽  
Plastic Tube ◽  
Concrete Core ◽  
Stress Strain State ◽  
Numerical Studies

The article presents numerical studies of the stress-strain state of the centrally compressed short plastic-concrete-tubal vertical constructions (PCT). The authors experimentally obtained and analyzed the effect of friction on the boundary between the layers of the concrete core and the plastic tube on the stress-strain state of the PCT vertical constructions. The need to carry out these studies is associated with a deficiency of theoretical and numerical studies of this phenomenon, including for the traditional pipe concrete in a steel tube. In this regard, mathematical modeling and the creation of engineering methods for calculating the PCT based on the study of the factual joint operation of the concrete core and the cylindrical plastic shell has significant scientific potential. The calculations and experimental analysis demonstrated the validity with engineering accuracy of using the mathematical model of a short PCT column for engineering calculations and structural analysis. It has been established that the use of an analytical model makes it possible to investigate the influence of the variation of the physical and mechanical characteristics properties of the materials of the core and tube of the PCT on the parameters of the stress-strain state design and to carry out a rational design of the PCT elements in the structures of civil and industrial buildings with reference to the materials actually used widely represented in the market.

The Impact Of Composite Mesh On The Strength Of Masonry Under The Action Of Loads That Simulate Temperature Effects

2020 ◽  
pp. 25-30
Keyword(s):  
Temperature Effects ◽  
Experimental Studies ◽  
Basalt Fiber ◽  
Effect Of Temperature ◽  
Composite Mesh ◽  
Stone Materials ◽  
Tensile Forces ◽  
Concrete Blocks ◽  
The Impact ◽  
Cellular Concrete

The results of experimental studies of the tensile strength of the bandaged seam of walls masonry made of autoclave-hardened cellular concrete blocks are presented. A description of the installation for testing wall fragments for loads that simulate temperature effects that occur in buildings made of stone materials is given. There is no research in the effect of temperature impacts on the masonry of the walls made of cellular concrete blocks reinforced with composite grids based on basalt fiber. The results of tests for normal adhesion of cellular concrete blocks in the case of using an "AeroStone" adhesive mixture are presented. According to the results of tests of wall fragments on the load that simulates temperature effects, the effect of using a composite mesh based on basalt fiber of the "NOVAGRID" brand during axial stretching of the masonry along the bandaged seam was noted. Schemes of destruction of samples of masonry with composite mesh reinforcement and without reinforcement are presented, as well as values of destructive loads for each of the structural schemes are given. On the example of the analysis of the results of experimental studies of fragments of walls made of cellular concrete blocks, the effectiveness of using the NOVAGRID composite mesh when it is used as a reinforcement for the perception of horizontal tensile forces arising in the masonry is shown.

Evaluation of Load-Time Functions Due to Impact of Soft Missiles

2009 ◽  
Author(s):  
Daniela Ruch ◽  
Nico Herrmann ◽  
Harald S. Mu¨ller
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Video Camera ◽  
Commercial Aircraft ◽  
Explicit Finite Element ◽  
High Speed Video Camera ◽  
Measurement Results ◽  
Impact Phenomena ◽  
Simplified Calculation ◽  
The Impact

The threat spectrum of safety related structures has severely changed since September 11, 2001. The deterioration capability of large aircrafts impacting on structures has become aware in a dramatic manner. Simplified calculation models for aircraft impact are available but have not been verified for large commercial aircrafts. Based on this background, experimental studies are performed at the Materials and Testing Research Institute (MPA) Karlsruhe of the Universita¨t Karlsruhe (TH) to examine the shape and the peak loads of load-time functions induced by an impacting soft missile with a mass and stiffness distribution along the missile’s axis similar to a commercial aircraft onto a rigid target. Different levels of water filling for simulating the kerosene tanks can be realised to investigate their influence on the load-time function. The characterisation of the major impact phenomena and their variation due to changing test parameters is the foremost goal of these experiments. The missiles are accelerated up to the impact velocity using an air-pressure gun. Impact forces are measured with a piezoelectric measuring platform as well as with accelerometers positioned on the target. The impact is filmed using a high-speed video camera. The experimental setup, measurement results and their evaluation will be presented in detail. The experimental study forms the reference for accompanied numerical calculations using the explicit finite element code LS-DYNA. Thus, a numerical model validated on the experiments shall be generated in order to provide an enhanced confidence level for the future calculation of real impact scenarios. First simulation results will be shown and briefly compared to the solution using the Riera method. A possible enhancement of this analytical method based on the experiments is beyond the scope of the project.

Воздействиеультразвуковогополянадинамическуювязкостьводы

2019 ◽  
pp. 27-29
Author(s):  
P. Vikulin ◽  
K. Khlopov ◽  
M. Cherkashin
Keyword(s):  
Dynamic Viscosity ◽  
Experimental Studies ◽  
Ultrasonic Field ◽  
Maximum Effect ◽  
Ultrasonic Frequency ◽  
Ultrasonic Vibrations ◽  
Wastewater Disposal ◽  
Laboratory Setup ◽  
Sonic Treatment ◽  
The Impact

Enhancing water purification processes is provided by various methods including physical ones, in particular, exposure to ultrasonic vibrations. The change in the dynamic viscosity of water affects the rate of deposition of particles in the aquatic environment which can be used in natural and wastewater treatment. At the Department Water Supply and Wastewater Disposal of the National Research Moscow State University of Civil Engineering experimental studies were conducted under laboratory conditions to study the effect of ultrasound on the change in the dynamic viscosity of water. A laboratory setup has been designed consisting of an ultrasonic frequency generator of the relative intensity, a transducer (concentrator) that transmits ultrasonic vibrations to the source water, and sonic treatment tanks. Experimental studies on the impact of the ultrasonic field in the cavitation mode on the dynamic viscosity of the aqueous medium were carried out the exposure time was obtained to achieve the maximum effect.Интенсификация процессов очистки воды осуществляется с помощью различных методов, в том числе и физических, в частности воздействием ультразвуковых колебаний. Изменение динамической вязкости воды влияет на скорость осаждения частиц в водной среде, что может быть использовано в процессах очистки природных и сточных вод. На кафедре Водоснабжение и водоотведение Национального исследовательского Московского государственного строительного университета в лабораторных условиях проведены экспериментальные исследования по изучению влияния ультразвука на изменение динамической вязкости воды. Разработана схема лабораторной установки, состоящая из генератора ультразвуковых частот с соответствующей интенсивностью, преобразователя (концентратора), передающего ультразвуковые колебания в исходную воду, и емкости для озвучивания. Выполнены экспериментальные исследования по влиянию ультразвукового поля в режиме кавитации на динамическую вязкость водной среды, получено время экспозиции для достижения максимального эффекта.

Family Influences on Youth Offending

2018 ◽  
pp. 377-403
Author(s):  
Abigail A. Fagan ◽  
Kristen M. Benedini
Keyword(s):  
Life Course ◽  
Family Environment ◽  
Parenting Practices ◽  
Experimental Studies ◽  
The United States ◽  
Parental Violence ◽  
Youth Delinquency ◽  
The Impact ◽  
Children’S Exposure

This chapter reviews the degree to which empirical evidence demonstrates that families influence youth delinquency. Because they are most likely to be emphasized in life-course theories, this chapter focuses on parenting practices such as parental warmth and involvement, supervision and discipline of children, and child maltreatment. It also summarizes literature examining the role of children's exposure to parental violence, family criminality, and young (teenage) parents in affecting delinquency. Because life-course theories are ideally tested using longitudinal data, which allow examination of, in this case, the impact of parenting practices on children's subsequent behaviors, this chapter focuses on evidence generated from prospective studies conducted in the United States and other countries. It also discusses findings from experimental studies designed to reduce youth substance use and delinquency by improving the family environment.

scholarly journals Evaluation of the impact of compliance of precast discs of overlapping on the work of the frame of a multi-storey building

2019 ◽  
Vol 97 ◽  
pp. 04022
Author(s):  
Nikolay Trekin ◽  
Emil Kodysh ◽  
Alexander Bybka ◽  
Alexander Yamalov ◽  
Nikita Konkov
Keyword(s):  
Economic Performance ◽  
Computational Models ◽  
Precast Concrete ◽  
Building Frames ◽  
Frame Building ◽  
Numerical Studies ◽  
Frame Buildings ◽  
The Impact ◽  
Structural Solutions ◽  
Storey Building

The article provides an analysis and justification of the need to take into account the compliance of discs of overlapping and coatings when calculating frames from precast concrete structures. Previously conducted full-scale experiments showed that the rigidity of the precast overlapping with full filling of the seams, in comparison with the monolithic overlapping, decreases by 3-15 times due to the ductility of the joints. The use of refined computational models of structural solutions for frames, which take into account the compliance of the conjugations of elements, makes it possible to trace possible redistribution of efforts. Such an approach when reconstructing, it is possible to optimally select and calculate the enforcement of structure, and on new designing, to increase reliability and / or improve the economic performance of frame buildings. According to the results of analytical studies, formulas were adopted for the parameters that allow one to take into account the overall compliance of overlapping disks and coatings in computational models of building frames. Numerical studies on the computational model of a frame building made it possible to evaluate the effect of accounting for compliance on the stress-strain state of a multi-storey frame.

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