Development of a Novel Oil Cavitation Jet Peening System and Cavitation Jet Erosion in Aluminum Alloy, AA 6063-T6

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
A. Sahaya Grinspan ◽  
R. Gnanamoorthy
Keyword(s):  
Aluminum Alloy ◽  
Residual Stresses ◽  
High Speed ◽  
Surface Deformation ◽  
Pressure Ratio ◽  
High Speed Photography ◽  
Electron Microscopies ◽  
Jet Impact ◽  
The Impact ◽  
Compressive Residual Stresses

Compressive residual stresses that improve fatigue strength of material are obtained by peening the surface. Unlike traditional processes, a novel process of oil cavitation jet peening was developed. The process is based on implosion generated by the oil cavitation jet that plastically deforms the surface, imparting compressive residual stresses. The process developed involves injection of a high-speed oil jet (∼230 m/s) through a suitably designed nozzle, into an oil-filled chamber containing the specimen to be peened. The region of cavitation generation, growth, and collapse, at the various cavitation numbers, was recorded using high-speed photography. To optimize the process parameters, a simple erosion test was performed in aluminum alloy, AA 6063-T6, specimens. The impact pressure generated during the implosion of cavitation bubbles causes plastic deformation and erosion of the surface. The surface deformation and cavitation jet erosion in the exposed specimens were characterized using optical and scanning electron microscopies. The standoff distance, which measures jet impact zone of the specimen from nozzle, was optimized at 15 mm in a cavitation number (which is a measure of pressure ratio across the nozzle) of 0.0017. The surface deformation produced by collapse of the oil bubble was similar to impact of oil droplet on the surface. The material removal mechanism during implosion of the bubble is predominately by ductile shear deformation.

Effect of Nozzle-Traveling Velocity on Oil Cavitation Jet Peening of Aluminum Alloy, AA 6063-T6

2007 ◽  
Vol 129 (4) ◽  
pp. 609-613 ◽  
Author(s):  
A. Sahaya Grinspan ◽  
R. Gnanamoorthy
Keyword(s):  
Aluminum Alloy ◽  
Residual Stresses ◽  
Cavitation Number ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compressive Stresses ◽  
Modification Process ◽  
Oil Jet ◽  
The Impact ◽  
Compressive Residual Stresses

A new surface modification process was developed to introduce compressive residual stresses at the surface of components. In this process, instead of oil droplets a high-velocity cavitation jet (cloud of oil bubbles) impinges on the surface of the component to be peened. The impact pressure generated during implosion of cavitation bubbles causes severe plastic deformation at the surface. Consequently, beneficial compressive stresses are developed at the surface. In order to find the potential of this process, aluminum alloy AA6063-T6 specimens were peened at a constant cavitation number with various nozzle-traveling velocities. Residual stress induced by oil jet cavitation peening was measured using X-ray diffraction. Oil cavitation jet peening results in a smooth and hard surface. The developed compressive residual stresses at the peened surface are about 52%, 42%, and 35% of yield strength in samples for peened at nozzle traveling velocities of 0.05mm∕s, 0.10mm∕s, and 0.15mm∕s, respectively.

scholarly journals X-ray Determination of Compressive Residual Stresses in Spring Steel Generated by High-Speed Water Quenching

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1154
Author(s):  
Diego E. Lozano ◽  
George E. Totten ◽  
Yaneth Bedolla-Gil ◽  
Martha Guerrero-Mata ◽  
Marcel Carpio ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
High Speed ◽  
Spring Steel ◽  
X Ray Diffraction ◽  
Laboratory Equipment ◽  
X Ray ◽  
Water Chamber ◽  
Hardened Case ◽  
Compressive Residual Stresses

Automotive components manufacturers use the 5160 steel in leaf and coil springs. The industrial heat treatment process consists in austenitizing followed by the oil quenching and tempering process. Typically, compressive residual stresses are induced by shot peening on the surface of automotive springs to bestow compressive residual stresses that improve the fatigue resistance and increase the service life of the parts after heat treatment. In this work, a high-speed quenching was used to achieve compressive residual stresses on the surface of AISI/SAE 5160 steel samples by producing high thermal gradients and interrupting the cooling in order to generate a case-core microstructure. A special laboratory equipment was designed and built, which uses water as the quenching media in a high-speed water chamber. The severity of the cooling was characterized with embedded thermocouples to obtain the cooling curves at different depths from the surface. Samples were cooled for various times to produce different hardened case depths. The microstructure of specimens was observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) was used to estimate the magnitude of residual stresses on the surface of the specimens. Compressive residual stresses at the surface and sub-surface of about −700 MPa were obtained.

Influence of Milling Parameters on Surface Residual Stresses of 7050-T7451 Aluminum Alloy

2012 ◽  
Vol 723 ◽  
pp. 208-213 ◽  
Author(s):  
Yi Wan ◽  
Chen Li ◽  
Zhan Qiang Liu ◽  
Shu Feng Sun
Keyword(s):  
Aluminum Alloy ◽  
Residual Stresses ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Milling Process ◽  
X Ray Diffraction ◽  
Orthogonal Direction ◽  
Mechanical Coupling ◽  
Surface Residual Stresses ◽  
Compressive Residual Stresses

Residual stresses generated in milling process affect the performance of machined components. Milling residual stresses correlate closely with the cutting parameters. In this paper, the generation and distribution of surface residual stresses in milling of aluminum alloy 7050-T7451 was investigated. The cutting speed changes from 300m/min to 3000m/min. In the experiments, the residual stresses on the surface of specimen are detected by X-ray diffraction technique. The result shows that compressive residual stresses are generated when cutting speed is under 500 m/min. In feed and its orthogonal direction, the effect of cutting speed and feed rate on residual stresses is similar. The formation of the residual stresses can be explained by thermo-mechanical coupling effects.

Hydraulic Performance and Jet Breakup Characteristics of the Impact Sprinkler with Circular and Non-circular Nozzles

2019 ◽  
Vol 35 (6) ◽  
pp. 911-924 ◽  
Author(s):  
Yue Jiang ◽  
Hong Li ◽  
Chao Chen ◽  
Lin Hua ◽  
Daming Zhang
Keyword(s):  
High Speed ◽  
Cone Angle ◽  
Hydraulic Performance ◽  
High Speed Photography ◽  
Breakup Process ◽  
Breakup Length ◽  
Jet Breakup ◽  
Circular Jets ◽  
Square Jets ◽  
The Impact

HighlightsThe hydraulic performance of the impact sprinkler with circular and non-circular nozzles were measured.A High-Speed Photography (HSP) technique was employed to extract the jet breakup process of the impact sprinkler.Two index equations of jet characteristic lengths and equivalent diameters of non-circular nozzles were fitted. Abstract. An experiment was carried out to investigate the hydraulic performance of an impact sprinkler by using circular and non-circular nozzles. A High-Speed Photography (HSP) technique was employed to extract the breakup process and flow behavior of low-intermediate pressure water jets issued from the different types of orifices. These orifices were selected by the principle of equal flowrate with the same pressure. Moreover, two characteristic lengths: the jet breakup length and the initial amplitude of surface wave were measured. It was found that the sprinkler with circular nozzles produced the largest radius of throw followed by square nozzles and regular triangular nozzles when the cone angle of nozzle and pressure were unchanged, while the sprinkler with regular triangular nozzle had the best variation trend of water distribution and combination uniformity coefficient. Regular triangular jets exhibited a higher degree in breakup and the shortest breakup length compared with the square jets and the circular jets. The initial amplitudes of surface waves of regular triangular jets were larger than the square jets and the circular jets with the same cone angle. Two index equations of jet characteristic lengths and equivalent diameters of both circular and non-circular orifices were fitted with a relative error of less than 10%, which means the fitting formulas were accurate. Keywords: Breakup length, Fitting formula, Hydraulic performance, Initial amplitude, Non-circular jets.

scholarly journals Selected Properties of the Surface Layer of C45 Steel Parts Subjected to Laser Cutting and Ball Burnishing

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3429 ◽  
Author(s):  
Agnieszka Skoczylas ◽  
Kazimierz Zaleski
Keyword(s):  
Surface Layer ◽  
Residual Stresses ◽  
Laser Cutting ◽  
Experimental Studies ◽  
Hardened Layer ◽  
Ball Burnishing ◽  
Absolute Value ◽  
The Impact ◽  
Compressive Residual Stresses

In this article, we report the results of experimental studies on the impact of ball burnishing parameters on the roughness, microstructure and microhardness of the surface layer of laser-cut C45 steel parts. We also analysed the distribution of residual stresses generated in the surface layer of these parts. Laser-cut parts often require finishing to improve the quality of their surface. The tests performed in this study were aimed at assessing whether ball burnishing could be used as a finishing operation for parts of this type. Ball burnishing tests were performed on an FV-580a vertical machining centre using a mechanically controlled burnishing tool. The following parameters were varied during the ball burnishing tests: burnishing force Fn, path interval fw and the diameter of the burnishing ball dn. Ball burnishing of laser-cut C45 steel parts reduced the surface roughness parameters Sa and Sz by up to 60% in relation to the values obtained after laser cutting. Finish machining also led to the reorganization of the geometric structure of the surface, resulting in an increase in the absolute value of skewness Ssk. This was accompanied by an increment in microhardness (maximum microhardness increment was ΔHV = 95 HV0.05, and the thickness of the hardened layer was gh = 40 µm) and formation of compressive residual stresses in the surface layer.

scholarly journals Dynamic damage in carbon-fibre composites

2016 ◽  
Vol 374 (2071) ◽  
pp. 20160018 ◽  
Author(s):  
N. K. Bourne ◽  
S. Parry ◽  
D. Townsend ◽  
P. J. Withers ◽  
C. Soutis ◽  
...  
Keyword(s):  
Carbon Fibre ◽  
High Speed ◽  
Failure Modes ◽  
Structural Integrity ◽  
High Speed Photography ◽  
Compression Phase ◽  
Impact Surface ◽  
Fibre Composites ◽  
The Impact ◽  
Carbon Fibre Composites

The Taylor test is used to determine damage evolution in carbon-fibre composites across a range of strain rates. The hierarchy of damage across the scales is key in determining the suite of operating mechanisms and high-speed diagnostics are used to determine states during dynamic loading. Experiments record the test response as a function of the orientation of the cylinder cut from the engineered multi-ply composite with high-speed photography and post-mortem target examination. The ensuing damage occurs during the shock compression phase but three other tensile loading modes operate during the test and these are explored. Experiment has shown that ply orientations respond to two components of release; longitudinal and radial as well as the hoop stresses generated in inelastic flow at the impact surface. The test is a discriminant not only of damage thresholds but of local failure modes and their kinetics. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.

The brittle fracture of solids by liquid impact, by solid impact, and by shock

1964 ◽  
Vol 282 (1390) ◽  
pp. 331-352 ◽  
Keyword(s):  
Surface Wave ◽  
High Velocity ◽  
High Speed ◽  
Turbine Blades ◽  
Explosive Loading ◽  
Back Surface ◽  
High Speed Photography ◽  
Liquid Mass ◽  
Liquid Impact ◽  
The Impact

The type of stress pulse produced when a liquid mass strikes a solid at high velocity is first examined. Compressible behaviour, giving rise to a sharp peak of pressure, is found to occur in the initial stages of the impact. The duration of this peak depends on the dimensions and impact velocity of the liquid mass, and also on the compressible wave velocity for the liquid. A comparison is made with pulses produced by solid/solid impact and by the detonation of small quantities of explosive. Both the high-speed liquid impact and the explosive loading give intense pulses of duration only a few microseconds. A solid/solid impact has, by comparison, a much longer impact time of the order of hundreds of microseconds. The fracture of glasses and hard polymers using these three types of loading is described. The development of fracture is followed by high-speed photography. Differences in the modes of fracture are attributed to variations in the shape and duration of the applied stress pulses. Short circumferential fractures produced around the loaded area in liquid impact and explosive loading are shown to be initiated by the Rayleigh surface wave at points where flaws existed. More complex fracture patterns on the front surfaces of plates are due to the reinforcement of the surface wave with components of stress waves reflected from the back surface. A combination of impact loading and etching makes it possible to investigate the distribution and depths of flaws, their role in the fracture process, and the effect which etching has upon them. The observation on the deformation produced in solids by liquid impact has practical significance in the problem of supersonic aircraft flying through rain and in the erosion of turbine blades moving at high velocity through wet steam.

A New Concept of Needle-Free Jet Injector by the Impact Driven Method

2017 ◽  
Vol 11 (1) ◽  
Author(s):  
Prachya Mukda ◽  
Kulachate Pianthong ◽  
Wirapan Seehanam
Keyword(s):  
High Speed ◽  
Liquid Jet ◽  
High Speed Photography ◽  
Free Jet ◽  
Impact Peak ◽  
Lower Pain ◽  
Jet Velocity ◽  
Commercial Device ◽  
Jet Injectors ◽  
The Impact

Currently, most of commercial needle-free jet injectors generate the liquid jet by a method called “driving object method” (DOM); however, the reliability and efficiency are still questioned. This paper proposes a new concept of jet generation method, known as “impact driven method” (IDM). A prototype of an IDM jet injector is designed, built, tested, and compared to a commercial device (Cool.click, Tigard, OR). Fundamental characteristics, i.e., the exit jet velocity and impact pressure, are measured. Jet injection processes are visualized both in air and in 20% polyacrylamide by high speed photography. In this study, from the prototype of the IDM jet injector, a maximum jet velocity of 400 m/s and impact peak pressure of 68 MPa can be obtained. It is clear that the IDM jet injector provides a double pulsed liquid jet, which is a major advantage over the commercial jet injector. Because, the first pulse gives a shorter erosion stage, and then, immediately the second pulse follows and provides a better penetration, wider lateral dispersion, and considerably less back splash. Hence, lower pain level and higher delivery efficiency should be achieved. It can be concluded that the IDM concept is highly feasible for implementation in real applications, either for human or animal injection. However, the control and accuracy of IDM still needs to be carefully investigated.

Behavior of Soft Spheres During Impact by High-Speed Photography

1983 ◽  
Vol 105 (1) ◽  
pp. 67-73 ◽  
Author(s):  
Yoichi Tatara
Keyword(s):  
Deformation Process ◽  
High Speed ◽  
High Impact ◽  
High Speed Photography ◽  
Tennis Ball ◽  
Hertz Model ◽  
Hertz Theory ◽  
Soft Spheres ◽  
Almost All ◽  
The Impact

Previously, it has been verified experimentally for durations of impact that the Hertz theory (the quasi-statical theory) holds during impact of spheres without any exception. However, no measurement of duration of impact has been presented for spheres of materials other than metal. This study presents exceptional cases of impacts of spheres during which the Hertz model does not directly hold. By the use of a high-speed camera running at a speed of 5000 frames/s, durations of impact are measured directly for impacts of two solid rubber spheres of the same size and content and impacts of a soft ball (Japanese type-soft tennis ball) on a rigid foundation. As a result, the measured durations of impact in the two impacting cases are found to be decreased as the impact velocity is increased, similar in tendency to durations of impact of elastic metal spheres during which the Hertz theory holds. However, the measured durations of impact are found to be clearly shorter than results calculated according to the Hertz theory, approximately half in the former impacts at high impact velocities, and about 70 percent of the Hertzian results in the latter impacts at almost all impact velocities. Deformation process of the ball impacting on the foundation is also presented to indicate both durations in the compressive process and the restitution one to be shorter than those expected by the Hertz theory. The other results observed on the films are noted to investigate the origin of the great discrepancies between the measured and Hertzian durations (that is, the impacting mechanism of the rubber spheres or the rubber ball packed with air treated here).

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