scholarly journals Fragmentation Pattern and Removal Mechanism of Concrete Subjected to Abrasive Water Jet Impact

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jialiang Liu ◽  
Yujie Zhu ◽  
Yongzhi Xue ◽  
Hao Sun
Keyword(s):  
Transition Zone ◽  
Pure Water ◽  
Ct Scanning ◽  
Water Jet ◽  
Fragmentation Pattern ◽  
Abrasive Water Jet ◽  
Removal Mechanism ◽  
Jet Impact ◽  
Propagation Law ◽  
The Impact

Abrasive water jet (AWJ) breaking technology is suitable for the maintenance and repair of concrete structures, generating minimal dust, low tool wear, and no vibrations or selective destruction. The failure features and mechanisms of concrete subjected to AWJ impact are fundamental issues of AWJ breaking technology, which are also related to the safety and quality of engineering construction. Based on computed tomography (CT), scanning electron microscopy (SEM), and image processing technology, this paper studied the fragmentation pattern and removal mechanism of concrete under AWJ impact. The general failure characteristics and crack propagation law of concrete subjected to AWJ impact were described through AWJ impact concrete tests. The spatial distribution of damage in concrete subjected to AWJ impact can be divided into the intensive action zone, the transition zone, and the weak action zone. The removal mechanism of AWJ was discussed by comparing the impact performance of a pure water jet (PWJ) system. The results indicate that abrasive particles can cause cliff-shaped fracture and lip-shaped distortion in the aggregate part and flat fracture surface in the matrix part. There is no obvious crack in the interfacial transition zone (ITZ) due to the weakening of the water wedge effect.

scholarly journals Influence of Local Temperature Changes on the Material Microstructure in Abrasive Water Jet Machining (AWJM)

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5399
Author(s):  
Sławomir Spadło ◽  
Damian Bańkowski ◽  
Piotr Młynarczyk ◽  
Irena M. Hlaváčová
Keyword(s):  
Local Heat Transfer ◽  
Water Jet ◽  
Local Temperature ◽  
Adjacent Area ◽  
Abrasive Water Jet ◽  
Material Microstructure ◽  
Temperature Changes ◽  
Abrasive Water Jet Machining ◽  
Jet Impact ◽  
The Impact

This article considers effects of local heat transfer taking place insteel cutting by abrasive water jet machining (AWJM). The influence of temperature changes during AWJM has not been investigated thoroughly. Most studies on AWJM suggest that thermal energy has little or no effect on the material cut. This study focused on the analysis of the material microstructure and indentation microhardness in the jet impact zone and the adjacent area. The structure features revealed through optical metallography and scanning microscopy suggest local temperature changes caused by the impact of the abrasive water jet against the workpiece surface. From the microscopic examinationand hardness tests, it is clear that, during the process, large amounts of energy were transferred locally. The mechanical stress produced by the water jet led to plastic deformation at and near the surface. This was accompanied by the generation and transfer of large amounts of heat resulting in a local rise in temperature to 450 °C or higher.

scholarly journals Analysis and modeling of the effects of process parameters on specific cutting energy in abrasive water jet cutting

2018 ◽  
Vol 22 (Suppl. 5) ◽  
pp. 1459-1470 ◽  
Author(s):  
Predrag Jankovic ◽  
Milos Madic ◽  
Dusan Petkovic ◽  
Miroslav Radovanovic
Keyword(s):  
Mathematical Model ◽  
Process Parameters ◽  
Water Jet ◽  
Abrasive Water Jet ◽  
Specific Cutting Energy ◽  
Important Indicator ◽  
Cutting Energy ◽  
Water Jet Cutting ◽  
Abrasive Water Jet Cutting ◽  
The Impact

The problem of cutting difficult-to-machine materials used in the aerospace industry, aircraft industry, and automobile industry, led to the development and application one of today?s most attractive technology for contour cutting - abrasive water jet cutting. For the efficient use of abrasive water jet cutting, it is of great importance to analyze the impact of process parameters on performance indicators, such as cutting quality, productivity, and costs. But also, from the energy utilization point of view, it is very important to analyze the impact of these parameters on the specific cutting energy which represents the amount of energy spent on the removal of material in the unit time. Having this in mind, this study presents the experimental results of abrasive water jet cutting of aluminum alloy with the aim of creating a mathematical model for estimating specific cutting energy as an important indicator of the degree of utilization of the available energy in the cutting process. The mathematical model of the specific cutting energy is explicitly represented as a non-linear function of the process parameters, obtained by the artificial neural network.

scholarly journals A Short Note about the Impact Action of a Water Jet Stabilized by a Coaxial Air Stream in the Air and Underwater

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5015
Author(s):  
Josef Poláček ◽  
Irena Marie Hlaváčová ◽  
Martin Tyč
Keyword(s):  
Near Field ◽  
Pure Water ◽  
Air Flow ◽  
Relevant Literature ◽  
Short Note ◽  
Original Method ◽  
Water Jet ◽  
Impact Action ◽  
Dual Action ◽  
The Impact

A new original method, applying a coaxial protective airflow, was tested aiming to improve the pure water jet efficiency in surface layer removal or medium hard materials cutting or blasting. The dual action of the air flow is expected: the air co-flowing the water jet with approximately the same velocity should prevent the central jet from breaking up into tiny droplets in the near field, and simultaneously, it should support jet decomposition into big parts with enough destructive potential in the far-field. A brief survey of the relevant literature dealing with the water jet instability is presented, introducing four recognized breakup regimes. An original cutting head designed to generate a waterjet surrounded by protective coaxial air flow is introduced. The submitted device is supposed to operate within the first wind-induced regime. Two types of experiments, consisting of blasting limestone bricks placed either in the air or underwater, were realized. The depths of kerfs produced with different water pressures and air overpressures were evaluated. While no substantial positive effect was recognized in the air performance, the submerged blasting of the same material under similar conditions appeared to be promising.

scholarly journals Design and Simulation of Nozzle for Pure Water Jet Portable Cutting Tool

2019 ◽  
Vol 8 (12S2) ◽  
pp. 703-706
Keyword(s):  
Pressure Drop ◽  
Cross Sections ◽  
Pure Water ◽  
Water Jet ◽  
Element Analysis ◽  
Cutting Machine ◽  
Water Jet Cutting ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
The Impact

A pure water jet at subsonic speed provides an opportunity for application in cutting soft material with the advantage of not contaminating the workpiece. Inside the nozzle, water is flowing through various cross sections, which lead to pressure drop and loss of energy. This requires a nozzle with a design that causes minimum pressure drop. In this work, Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) were used to analyse the flow through five different nozzles. For each nozzle, the pressures of 10 MPa, 20 MPa and 30 MPa were applies at the inlet. For the inlet pressure of 10 MPa, the highest outlet velocity us 136.12 m/s at the pressure of 9.261 MPa. The impact pressure at stand distance of 0.5 mm and 1.0 mm were 8.26 MPa and 8.02 MPa, respectively. For this nozzle, the Factor of Safety for 10 MPa, 20 MPa and 30 MPa were 6.4, 3.2 and 2.961, respectively. The findings are relevant to the development of pure water jet cutting machine

scholarly journals Modelling of water jet impact on molten metal

2021 ◽  
Vol 2119 (1) ◽  
pp. 012073
Author(s):  
S E Yakush ◽  
N S Sivakov ◽  
V I Melikhov ◽  
O I Melikhov
Keyword(s):  
Steam Explosion ◽  
Water Jet ◽  
Point Of View ◽  
Change Model ◽  
Water Pool ◽  
Jet Impact ◽  
Melt Water ◽  
Height Dependence ◽  
The Impact ◽  
Primary Melt

Abstract Splashes of high-temperature melt spreading over a water pool bottom can be a reason for the formation of a zone where melt, water and steam are mixed, providing conditions for powerful steam explosions. The paper considers the formation of melt splashes arising from the impact of a water jet on the surface of the melt. Numerical simulations are performed in 3D formulation, using the VOF method and an improved phase change model. The evolution of melt surface following the water jet impact is demonstrated, including the formation of a cavern, a primary melt splash known as the crown, as well as a secondary splash following the collapse of the cavern, known as the cumulative jet. Parametric study for the melt splash height dependence on the water jet geometry and velocity is carried out. The results of numerical analysis are discussed from the point of view of the similarity with respect to the momentum and kinetic energy of water jet. The significance of the results for the steam explosion problem is discussed.

An Experimental Study of the Abrasive Water Jet Micro-Machining Process for Quartz Crystals

2012 ◽  
Vol 565 ◽  
pp. 339-344 ◽  
Author(s):  
H. Qi ◽  
J.M. Fan ◽  
Jun Wang
Keyword(s):  
Experimental Study ◽  
Removal Rate ◽  
Water Jet ◽  
Machining Process ◽  
Bottom Surface ◽  
Micro Machining ◽  
Abrasive Water Jet ◽  
Process Variables ◽  
Jet Impact ◽  
Micro Channels

An experimental study of the machining process for micro-channels on a brittle quartz crystal material by an abrasive slurry jet (ASJ) is presented. A statistical experiment design considering the major process variables is conducted, and the machined surface morphology and channelling performance are analysed to understand the micro-machining process. It is found that a good channel top edge appearance and bottom surface quality without wavy patterns can be achieved by employing relatively small particles at shallow jet impact angles. The major channel performance measures, i.e. material removal rate (MRR) and channel depth, are then discussed with respect to the process parameters. It shows that with a proper control of the process variables, the abrasive water jet (AWJ) technology can be used for the micro-machining of brittle materials with high quality and productivity.

scholarly journals Effect of Abrasive Concentration on Impact Performance of Abrasive Water Jet Crushing Concrete

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Xiaohui Liu ◽  
Ping Tang ◽  
Qi Geng ◽  
Xuebin Wang
Keyword(s):  
Internal Energy ◽  
Impact Force ◽  
Abrasive Particle ◽  
Water Jet ◽  
Abrasive Water Jet ◽  
Sph Method ◽  
Impact Performance ◽  
Water Jets ◽  
The Impact ◽  
Peak Impact Force

It has been found that the impact performance of water jets can be changed by its properties, which include pressure, additive, and mode of jet. Thus, an abrasive water jet (AWJ) has been developed as a new method. However, there is little research on the effect of abrasive concentration on the impact performance of abrasive jets. Thus, the SPH method is used to establish an abrasive water jet crushing concrete model to study the effect of abrasive concentration on the impact force, concrete internal energy, abrasive particle distribution, crushing depth, and damage and crushing efficiencies under different concrete compressive strengths and abrasive densities. The results indicate that there is little effect of the abrasive concentration on the peak impact force under different compressive strengths and abrasive densities, while the mean impact force tends to increase linearly with the abrasive concentration. The internal energy of the concrete increases stepwise with the abrasive concentration under different compressive strengths and abrasive densities. The concentration of 10%∼20% is the rapid increasing stage. The crushing depth and damage efficiencies are all maximum at a concentration of 20% under different compressive strengths and abrasive densities. After the concrete was impacted by the water from the water jet, it is divided into rebounding particles and intrusive particles. The more the intrusive particles, the easier the concrete to be crushed and damaged.

A Study on Erosion of Alumina Wafer in Abrasive Water Jet Machining

2014 ◽  
Vol 1017 ◽  
pp. 228-233 ◽  
Author(s):  
Yong Wang ◽  
Hong Tao Zhu ◽  
Chuan Zhen Huang ◽  
Jun Wang ◽  
Peng Yao ◽  
...  
Keyword(s):  
Process Parameters ◽  
Water Pressure ◽  
Abrasive Particle ◽  
Particle Diameter ◽  
Water Jet ◽  
Abrasive Waterjet ◽  
Abrasive Water Jet ◽  
Alumina Ceramics ◽  
Abrasive Water Jet Machining ◽  
Jet Impact

Abrasive water jet machining is considered as a promising technique in hard and brittle material processing. This paper studies the erosion performance of the alumina ceramics in the different process parameters. In the erosion experiments, alumina ceramics wafers were eroded by the abrasive waterjet machining. The single factor experiments were carried out to understand the effect of different process parameters (jet impact angle, standoff distance, water pressure, abrasive particle diameter) on the material removal rate (MRR), the removal depth and surface roughness (Ra). The experimental results can provide guidance for alumina ceramics abrasive water jet cutting and polishing.

Vibration and Experimental Comparison of Machining Process

2015 ◽  
Vol 669 ◽  
pp. 179-186 ◽  
Author(s):  
Anton Panda ◽  
Marek Prislupčák ◽  
Jozef Jurko ◽  
Iveta Pandová ◽  
Peter Orendáč
Keyword(s):  
Water Jet ◽  
Machining Process ◽  
Experimental Comparison ◽  
Abrasive Water Jet ◽  
Technological Parameters ◽  
Microsoft Excel ◽  
Frequency Spectra ◽  
Acceleration Amplitude ◽  
The Impact ◽  
The Given

Abrasive water jet technology is among the unconventional ways of machining. In today's modern and progressive era is often used for cutting and machining of various types of materials because of lower costs and environmental impact, as the cutting tool is water, in our case, with the addition of abrasives. Objective of the measurements was to evaluate the impact of vibration on the technological head in abrasive water jet technology in changing the selected technological parameters and the flow rate of technological head. In the given experiment, the used material - steel Hardox 500 with a thickness of 10 mm. The effort was to investigate the effects of changes in the speed rate of technological head (by speeds - 40, 200, 400 mm / min) on the size of the vibration acceleration amplitude and its frequency. Based on the measured values ​​of vibration to the technological head create the database and from it is evaluated the data in selected softwares (LabVIEW, SignalExpress and Microsoft Excel). Findings and conclusions are formulated on the basis of graphical dependencies, envelopes frequency spectra and comparison chart of envelopes.

Diagnostic and Experimental Valuation on Progressive Machining Unit

2014 ◽  
Vol 616 ◽  
pp. 191-199 ◽  
Author(s):  
Marek Prislupčák ◽  
Anton Panda ◽  
Marek Jančík ◽  
Iveta Pandová ◽  
Peter Orendáč ◽  
...  
Keyword(s):  
Feed Rate ◽  
Water Jet ◽  
Abrasive Water Jet ◽  
Technological Parameters ◽  
Microsoft Excel ◽  
Frequency Spectra ◽  
New Findings ◽  
Acceleration Amplitude ◽  
Vibration Impact ◽  
The Impact

The main effort of each technological process is not only to reduce the costs, but also to reduce the impact on the environment. The technology of abrasive water jet is one of the methods of division and cutting materials with the lowest impact on the environment, since water is the cutting tool, in our case with the addition of an abrasive. The aim of the measurement was the observation (examination) and evaluation of the vibration impact on the technological head in the technology of abrasive water jet when changing the selected technological parameters, namely the feed rate of the technological head. The experiments were carried out on one kind of material - steel HARDOX 500 with a thickness of 10 mm. The impact of the change of the technological head’s feed rate (100, 50, mm/min) on the size of the vibration acceleration amplitude and its frequency were examined. A database was created from the measured vibration values on the technological head and from that database the data was evaluated in selected softwares (LabVIEW, SignalExpress a Microsoft Excel). Graphical dependencies, frequency spectra covers and covers comparison graph were created from which new findings and conclusions were formulated.

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