Some Results in the Erosion of Prestressed Materials due to Water-Jet Impact

1973 ◽  
Vol 15 (4) ◽  
pp. 295-301 ◽  
Author(s):  
G. W. Vickers ◽  
W. Johnson
Keyword(s):  
Brittle Material ◽  
Stress Ratio ◽  
Water Jet ◽  
Ductile Material ◽  
Fracture Modes ◽  
Impact Stress ◽  
Water Jets ◽  
Compressive Stresses ◽  
Jet Impact ◽  
Prestressed Materials

Two methods are described of applying uniaxial and biaxial tensile and compressive stresses to specimens subject to the erosive action of repetitive water jets which have speeds in the range 30–220 m/s. The influence which prestress has on erosion is examined in a ductile material, α-brass, and in a brittle material, Perspex. The behaviour of these materials contrasts sharply due to their different fracture modes. Also the values of prestress to impact stress ratio and the type of stress applied, are shown to have a bearing on results.

Non-Traditional Machining Using Pulsed Water Drops

2004 ◽  
Author(s):  
M. J. Jackson
Keyword(s):  
Experimental Data ◽  
Plane Surface ◽  
Water Jet ◽  
Surface Cracks ◽  
Response Characteristics ◽  
Water Jets ◽  
Jet Impact ◽  
Water Drops ◽  
Pulsed Water Jet ◽  
Traditional Manner

This paper discusses water jet machining of selected materials using a non-traditional way of delivering water jets in the form of a series of discrete pulses. The theory of water jet impact has been used to demonstrate the principle of removing material by exploiting the existence of a Rayleigh wave that excites the formation of surface cracks and the lateral outflow of water that extends the cracks and removes material. A mathematical model has been developed that predicts changes in the response characteristics of materials owing to an idealised representation of a finite jet of water impacting a plane surface. The analytical approach used is applicable to the first stages of impact where the compressibility of water in the droplet is significant. The predicted response characteristics are compared with experimental data generated using controlled water jet impacts produced by a specially constructed pulsed water jet machining centre. The predicted response of selected materials compare well with experimental data. The results presented in this paper illustrate the importance of using pulsed water jets as a way of machining materials in a non-traditional manner.

Ice breaking by a high-speed water jet impact

2022 ◽  
Vol 934 ◽  
Author(s):  
G.-Y. Yuan ◽  
B.-Y. Ni ◽  
Q.-G. Wu ◽  
Y.-Z. Xue ◽  
D.-F. Han
Keyword(s):  
High Speed ◽  
Water Jet ◽  
Crack Development ◽  
Water Tank ◽  
Water Jets ◽  
Cold Room ◽  
Water Region ◽  
Jet Impact ◽  
Plate Size ◽  
Series Of Experiments

Ice breaking has become one of the main problems faced by ships and other equipment operating in an ice-covered water region. New methods are always being pursued and studied to improve ice-breaking capabilities and efficiencies. Based on the strong damage capability, a high-speed water jet impact is proposed to be used to break an ice plate in contact with water. A series of experiments of water jet impacting ice were performed in a transparent water tank, where the water jets at tens of metres per second were generated by a home-made device and circular ice plates of various thicknesses and scales were produced in a cold room. The entire evolution of the water jet and ice was recorded by two high-speed cameras from the top and front views simultaneously. The focus was the responses of the ice plate, such as crack development and breakup, under the high-speed water jet loads, which involved compressible pressure ${P_1}$ and incompressible pressure ${P_2}$ . According to the main cause and crack development sequence, it was found that the damage of the ice could be roughly divided into five patterns. On this basis, the effects of water jet strength, ice thickness, ice plate size and boundary conditions were also investigated. Experiments validated the ice-breaking capability of the high-speed water jet, which could be a new auxiliary ice-breaking method in the future.

Investigation of rain erosion on a brittle material by means of numerical simulation

2011 ◽  
Vol 9 (4) ◽  
pp. 327-334
Author(s):  
H Anıl Salman ◽  
R Orhan Yıldırım
Keyword(s):  
Brittle Material ◽  
Plate Thickness ◽  
Material Model ◽  
Float Glass ◽  
Water Jet ◽  
Arbitrary Lagrangian Eulerian ◽  
Arbitrary Lagrangian Eulerian Method ◽  
Maximum Water ◽  
Water Speed ◽  
Rain Erosion

In this work, the resistance and deformation characteristics of a brittle material against rain erosion are examined by using the non-linear, explicit software LS-DYNA. The water jet with varying speeds impinges at 90° on silica float glass plates with different thicknesses. In the simulations, the Arbitrary Lagrangian Eulerian method is used for modelling of the water. In order to analyse the deformations on the brittle material Johnson–Holmquist–Ceramics (JH-2) is used as the material model. Minimum plate thickness (for constant water jet speed) and maximum water speed (for constant plate thickness), which do not cause any damage to the target, are determined depending on the geometry, boundary conditions and assumed failure strain value for erosion. The results are compared with the water-hammer pressure.

scholarly journals Simulation of the ductile machining mode of silicon

2021 ◽  
Author(s):  
Hagen Klippel ◽  
Stefan Süssmaier ◽  
Matthias Röthlin ◽  
Mohamadreza Afrasiabi ◽  
Uygar Pala ◽  
...  
Keyword(s):  
Brittle Material ◽  
Material Removal ◽  
Machining Process ◽  
Ductile Material ◽  
Diamond Wire ◽  
Ductile Machining ◽  
Mesh Free ◽  
Diamond Wire Sawing ◽  
Material Removal Mode ◽  
Brittle Material Removal

AbstractDiamond wire sawing has been developed to reduce the cutting loss when cutting silicon wafers from ingots. The surface of silicon solar cells must be flawless in order to achieve the highest possible efficiency. However, the surface is damaged during sawing. The extent of the damage depends primarily on the material removal mode. Under certain conditions, the generally brittle material can be machined in ductile mode, whereby considerably fewer cracks occur in the surface than with brittle material removal. In the presented paper, a numerical model is developed in order to support the optimisation of the machining process regarding the transition between ductile and brittle material removal. The simulations are performed with an GPU-accelerated in-house developed code using mesh-free methods which easily handle large deformations while classic methods like FEM would require intensive remeshing. The Johnson-Cook flow stress model is implemented and used to evaluate the applicability of a model for ductile material behaviour in the transition zone between ductile and brittle removal mode. The simulation results are compared with results obtained from single grain scratch experiments using a real, non-idealised grain geometry as present in the diamond wire sawing process.

Schleifen von WC-Co-Hartmetallen*/Grinding of Cemented Carbides (WC-Co)

2016 ◽  
Vol 106 (06) ◽  
pp. 374-379
Author(s):  
C. Wirtz ◽  
F. Vits ◽  
P. Mattfeld ◽  
F. Prof. Klocke
Keyword(s):  
Brittle Material ◽  
Brittle Materials ◽  
Material Behavior ◽  
Ductile Material ◽  
Cemented Carbides ◽  
Multi Phase

Beim Schleifen mehrphasiger Werkstoffe mit sprödhartem Charakter, beispielsweise Hartmetall, wurde ein Übergang von sprödhartem zu duktilem Werkstoffverhalten nachgewiesen. Der Fachartikel stellt eine neu entwickelte Methodik zur systematischen Analyse des Zerspanverhaltens – im Speziellen den Übergang von vorwiegend duktilem zu überwiegend sprödhartem Zerspanverhalten – für Hartmetalle vor.   In grinding of multi-phase, brittle materials, e. g. cemented carbides, a transition from predominantly brittle to predominantly ductile material behavior has been proven scientifically. This paper presents a newly developed methodology to analyze the material behavior of cemented carbides, in particular the transition from ductile to brittle material behavior.

scholarly journals Archerfish coordinate fin-maneuvers with their shots

2021 ◽  
pp. jeb.233718
Author(s):  
Peggy Gerullis ◽  
Caroline P. Reinel ◽  
Stefan Schuster
Keyword(s):  
Water Jet ◽  
Characteristic Sequence ◽  
Target Height ◽  
Pectoral Fins ◽  
Water Jets ◽  
Low Amplitude

Archerfish down a variety of aerial prey from a range of distances using water jets that they adjust to size and distance of their prey. We describe here that characteristic rapid fin maneuvers, most notably of the pectoral and pelvic fins, are precisely coordinated with the release of the jet. We discovered these maneuvers in two fish that had been trained to shoot from fixed positions at targets in different height, whose jets had been characterized in detail and who remained stable during their shots. Based on the findings in these individuals we examined shooting-associated fin-movement in 28 further archerfish of two species that could shoot from freely chosen positions at targets of different height. Slightly before onset of the water jet, at a time when the shooter remains stable, the pectoral fins of all shooters switched from asynchronous low-amplitude beating to a synchronized rapid forward flap. Onset and duration of the forward and subsequent backward flap were robust across all individuals and shooting angles but depended on target height. The pelvic fins are slowly adducted at the start of the jet and stop after its release. All other fins also showed a characteristic sequence of activation, some starting about 0.5 s before the shot. Our findings suggest that shooting-related fin-maneuvers are needed to stabilize the shooter and that they are an important component in the precise and powerful far-distance shooting in archerfish.

The Effect of Nozzle Type on Air Entrainment by Plunging Water Jets

2002 ◽  
Vol 37 (3) ◽  
pp. 599-612 ◽  
Author(s):  
Tamer Bagatur ◽  
Ahmet Baylar ◽  
Nusret Sekerdag
Keyword(s):  
Penetration Depth ◽  
Oxygen Transfer ◽  
Free Water ◽  
Air Entrainment ◽  
Water Jet ◽  
Transfer Efficiency ◽  
Entrainment Rate ◽  
Water Jets ◽  
Air Entrainment Rate ◽  
Oxygen Transfer Efficiency

Abstract In this study, for the plunging water jet aeration system using various inclined nozzle types, bubble penetration depth, air entrainment rate, water jet expansion, effect of water jet circumference at impact point, oxygen transfer coefficient and oxygen transfer efficiency which changed depending on the water jet velocity, were researched in an air-water system. Numerous studies were conducted with circular nozzles. The present study describes new experiments performed with different nozzle types. Three types of nozzles were examined, i.e., those with circular, ellipse and rectangle duct with rounded ends. Experimental results showed that water jets produced with ellipse and rectangle duct with rounded ends nozzles have very different flow characteristics, entrainment patterns on free water jet surface, and submerged water jet region within the receiving tank. Higher air entrainment rate and oxygen transfer efficiency was observed in the rectangle duct with rounded ends nozzle due to water jet expansion. Bubble penetration depth, however, is lower for the rectangle duct with rounded ends nozzle than for the other nozzles. The ellipse nozzle provided the highest bubble penetration depth. These results showed that it is appropriate to use ellipse nozzle in aeration of deep pool and rectangle duct with rounded ends nozzle in the applications where high bubble concentration is desirable.

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 and simulation study of the flow pattern characteristics of water jet impingements in boreholes

2021 ◽  
pp. 014459872110520
Author(s):  
Yabin Gao ◽  
Xin Xiang ◽  
Ziwen Li ◽  
Xiaoya Guo ◽  
Peizhuang Han
Keyword(s):  
High Speed ◽  
Impact Force ◽  
Jet Impingement ◽  
Flow Patterns ◽  
Water Jet ◽  
Solid Boundary ◽  
Force Model ◽  
Water Jets ◽  
Contact Surfaces ◽  
The Impact

Hydraulic slotting has become one of the most common technologies adopted to increase permeability in low permeability in coal field seams. There are many factors affecting the rock breaking effects of water jets, among which the impact force cannot be ignored. To study the influencing effects of contact surface shapes on jet flow patterns and impact force, this study carried out experiments involving water jet impingement planes and boreholes under different pressure conditions. The investigations included numerical simulations under solid boundary based on gas–liquid coupling models and indoor experiments under high-speed camera observations. The results indicated that when the water jets impinged on different contact surfaces, obvious reflection flow occurred, and the axial velocity had changed through three stages during the development process. Moreover, the shapes of the contact surfaces, along with the outlet pressure, were found to have impacts on the angles and velocities of the reflected flow. The relevant empirical formulas were summarized according to this study's simulation results. In addition, the flow patterns and shapes of the contact surfaces were observed to have influencing effects on the impact force. An impact force model was established in this study based on the empirical formula, and the model was verified using both the simulation and experimental results. It was confirmed that the proposed model could provide important references for the optimization of the technical parameters water jet systems, which could provide theoretical support for the further intelligent and efficient transformation of coal mine drilling water jet technology.

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