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The study of bone cement disintegration is important for advancing orthopedic and trauma surgery outcomes. Bone cement, commonly used in joint replacement procedures, plays a vital role in fixation implants. However, the long-term stability and integrity of bone cement are critical for the success of these procedures. This study focuses on the use of ultrasonic pulsating water jet technology for the selective removal of bone cement, aiming to provide a precise and efficient method for revision surgeries. The disintegration efficiency is measured in terms of depth, width and volume of the disintegrated bone cement as a result of variations in the nozzle geometry, supply pressure and traverse speed. Two different nozzle types, the standard nozzle insert and nozzle with an extension tube of 100 mm having a diameter of 0.3 mm, are used. Two supply pressure levels were taken as 10 and 20 MPa with five levels of traverse speeds as 0.5, 1, 1.5, 2 and 2.5 mm/s. The results showed an increased disintegration efficiency for all experimental conditions using an extension tube nozzle as compared to a standard nozzle (20 - 25% in terms of disintegration volume). Also, the disintegration efficiency increased with higher pressure level values (8.2 mm3 and 4.85 mm3 for p = 20 and 10 MPa, respectively) and lower traverse speed values. The results showed a promising direction in terms of the utilization of an ultrasonic pulsating jet with a modified nozzle type for higher bone cement disintegration efficiency. [ABSTRACT FROM AUTHOR]

Pulsating water jet technology for rock erosion application has been emphasized in this study. The erosion phenomena are explored as an eroded depth, eroded width and volume eroded of the sandstone at frequency f = 20,000–40,000 Hz by using pulsed water jet. The surface was eroded at pressure 20–40 MPa; standoff distance 20 mm; nozzle diameter 1.6 mm; and feed rate of the jet 125–200 mm/s. The eroded depth, eroded width, and volume of the eroded sections were evaluated through non-contact-type optical profilometer. The result shows the relationship between feed rate of the jet, pressure, and standoff distance, which affects the erosion depth and width and volume removal. At f = 40,000 Hz, the maximum value of erosion depth, width, and volume removal was obtained. The microstructural analysis Field Emission Scanning Electron Microscopy (FESEM) examined the erosion topography, plastic deformation, and failure analysis at a frequency f = 20,000–40,000 Hz. The results reveal that the frequency change affects the erosion, and failure was observed at 40,000 Hz. This is the result of the deeper and narrow eroded surface caused by the enhanced number of impacts (200–320 impact per mm) and concentrated stream of a jet at 40,000 Hz. [ABSTRACT FROM AUTHOR]

• Pulsating water jet (PWJ) induces local deformation on AISI 304 surface. • PWJ at 20 kHz induces stresses ranging between 287 MPa – 540 MPa. • Inhomogeneous plastic deformation is responsible for enhancing the surface integrity. Enhancement of the life of the engineering components is essential from the perspective of its performance, therefore, it is necessary to eliminate the negative effects that attenuates the life of these components. Numerous surface treatment methods are used at present out of which water jet peening process have been stated to overcome the shortcoming reported in other surface treatment methods like surface defects caused by the embedment of particles during shot peening, thermal effects caused by laser shock peening. It has been reported in studies that the technological modification of water jet technology, ultrasonically generated pulsed water jet (PWJ) can be used for the peening application but still the detailed study of parametric variations for the peening process is not clearly explained. The present work aims at reporting the effect of variation of parameters: jet pressure (40 MPa to 100 MPa), traverse speed of the nozzle (5 mm/s to 25 mm/s) and standoff distance (15 mm to 31 mm) during the ultrasonically generated PWJ peening process. The peened surface was quantified in terms of surface residual stress measurements, micro hardness and surface roughness measurements. The results indicate that the variations in the parameters shows significant changes in the surface residual stress enhancement and strengthening process. The lower pressure (40 MPa), lower traverse speed (5 mm/s) and higher standoff distance (31 mm) showed the maximum improvement in the surface residual stress (up to 540 MPa) and micro-hardness (up to 570 HV). The impact of the repeated pulses causes plastic deformation on the surface and sub-surface layers which results into the change in the microstructures of the affected area. The microstructural examination through field emission scanning electron microscopy showed variations in these deformations under different parametric conditions. This study can give better understanding for the proper selection of the peening parameters for practical applications using ultrasonically generated pulsed water jet technology. [ABSTRACT FROM AUTHOR]

This study addresses the erosion transition of an aluminium surface arising from the periodic impact of a tangentially acting pulsating water jet (PWJ) with a spatial frequency of f = 20 kHz. The erosion effect was observed as a function of the standoff distance z (mm) along an incline (from 5 mm to 90 mm) and constant trajectory (at standoff distances of z = 25 mm, 75 mm and 125 mm) at a jet pressure of 100 MPa and traverse speed v = 10 mm/s. The aim of this study is to assess the manner in which the erosion along the PWJ pathway changes the measured dynamic signal (by means of acoustic emission measurements). The effects of hydrodynamic erosion, such as elastic and plastic deformation, were observed with the aid of a scanning electron microscope and compared with time records in terms of acoustic emission (AE) recorded during impact. Moving the PWJ head and gradually changing the standoff distance along the inclined trajectory resulted in different erosion regimes. With a gradual increase in the standoff distance (from 5 mm–90 mm), the observed erosion regimes were observed in terms of micro-pitting action, crack and crater formation and material folding/upheaving. The erosion effects of a PWJ compared with those of a continuous water jet were investigated at constant standoff distances of z = 25 mm, z = 75 mm and z = 125 mm. The differences in the erosion phenomenon under different conditions were observed in terms of the material damage, crater dimensions and surface and sub-surface features. The AE recorded during the impact of the PWJ demonstrates a correlation between the ongoing erosion phenomenon and the AE signals. This relation for the encoded complex waveform (PWJ) confirms the significant information about the ongoing process in terms of material deformation and dislocation movement. • Standoff distance generates different erosion regions. • Isolated sub-surface voids were observed. • The time records clearly exhibit an increase in amplitudes whenever material disintegration-separation-tearing occurs (load above the strength limit). • The correlation between the depth profile and AW reveals the effective interaction between the dynamic signal. [ABSTRACT FROM AUTHOR]

This article deals with the manifestations of erosion of statically acting concentrated multiple droplet impingements on materials over different lengths of time in order to assess the erosion evolution when the materials are submerged, as compared with the action of droplets on the materials under atmospheric conditions. The study aims to determine the extent of the erosive effects of droplets in underwater conditions. Experiments were conducted in a plastic pool in which the water level was varied from h = 80 to h = 120 mm to identify the effect of hydrostatic pressure at p 120 = 0.1025 MPa and p 80 = 0.1021 MPa. The results were compared with that of a control group of samples obtained under atmospheric air conditions. To observe the erosive damage evolution, 15 (n = 5) sites on the ductile materials EN AW-Al 99.5 and CW004A were exposed to high-intensity droplet impingement at defined exposure times. The exposure time varied from 0.125 s to 1.875 s, with increments of 0.125 s. As a droplet generator, an ultrasonic pulsating water jet with a frequency f = 20 kHz, a pressure p = 30 MPa and a nozzle diameter d = 0.4 mm was used to achieve the theoretical subsonic speed of the droplets. The results exceeded the assumptions regarding the possible attenuation of water pulses. It was found that under the theoretical speed of the jet v w = 225 m/s, the submerged condition causes attenuation in its erosive action. The incident area in the case of submerged treatment was more symmetrical. The erosion shift in term of prolonging incubation erosion stage was found to be a result of the increasing hydrostatic pressure. The results suggest that this method can also be used under submerged conditions for treatment or material drilling. • A low-pressure pulsating water jet under submerged conditions causes erosion. • Hydrostatic pressure influences the erosion shift. • The incident area is symmetrical under submerged conditions. [ABSTRACT FROM AUTHOR]

The residual stress and subsurface hardness of welded joints treated by peening using an ultrasonic pulsed water jet at pressures of 20–60 MPa with various traverse speeds and standoff distances were measured. The effect of the treatment was quantified by measuring the residual stress using X-ray diffraction in three regions (the welded zone, heat-affected zone, and base metal). To analyse the depth of the plastic deformation induced by the pulsating water jet, microstructural analyses and micro-hardness measurements were conducted. The surface topography of the treated samples was examined by measuring the surface roughness using a contact surface roughness profilometer. After pulsating water jet treatment, the samples showed both increased residual stress and surface roughness at pressures of 20–60 MPa. Increased subsurface hardness of the treated region was observed up to a depth of 200–250 µm at pressures of 40 and 60 MPa, deeper than that of the sample prepared at 20 MPa. The microstructural analysis identified the involved plastic deformation phenomenon occurred during the treatment process. This method of surface treatment, where the efficiency of the jet is enhanced by the generation of pulses using an acoustic generator, showed promising results for its practical application as a post-weld treatment method. [ABSTRACT FROM AUTHOR]

The erosion of 25CrMo4 (EA4T) steel was studied to determine the surface and subsurface damage due to the high-frequency impingement of water droplets using an ultrasonic droplet generator. The material under investigation is railway axle steel, where the pulsating water jet can be used as a surface treatment method to increase the fatigue resistance. The surface processing is related mainly to standoff-distance which was changed to explore the effect of pulsating water jet while the other parameters were kept constant. Surface and subsurface conditions of the material were analyzed by means of light microscopy, scanning electron microscopy and transmission electron microscopy. By altering the standoff distance, it is possible to investigate droplet impingement from the point of view of the pulsating water jet process for different purposes, such as for maximal erosion or for an increase of fatigue resistance by introduction of severe plastic deformation to the surface. The maximum erosion state was reached for a standoff distance of 35 mm when a crater depth of 750 μm and a width of 1500 μm was observed. The mild conditions, when only plastic deformation is reached occurred at a standoff distance of 21 mm. The occurrence of subsurface cavities in materials with higher hardness indicates a significant penetration ability of the periodic high-density action of water droplets at subsonic speeds. • Surface and subsurface erosion manifestations on EA4T steel were analyzed. • Microchannels due to penetration ability under the visible groove were observed. • The subsurface hardening on the sides of the groove is stochastic. [ABSTRACT FROM AUTHOR]

Presented article is focused on surface integrity evaluation of brass CW614N form the sight of surface topography, structural changes in surface layers and strengthening character in subsurface layers after impact of acoustically excited pulsating water jet (PWJ). Surface topography was evaluated using optical profilometry. Structural changes in subsurface layer were observed based on mass material removal Δm [mg/s] and maximal depth of penetrance of PWJ h max [mm]. Nano indentation measurement according to Berkovich were used to examination of strengthening character in subsurface layer. Disintegration of experimental samples was performed under constant technological conditions: hydraulic power of plunger pump P h = 19 kW; round nozzle diameter d = 1.6 mm; feed speed rate v = 0.75 mm/s; pressure of plunger pump p = 38 MPa, stand-off distance of nozzle from target material z = 45 mm; ultrasound frequency f = 20.29 kHz and as variable factor was set power of ultrasound P on values 340, 360 and 380 W. In terms of surface topography experimental investigation proved that PWJ under selected conditions is not suitable for precision machining. Evaluation of the surface characteristics indicates that the chemical composition has a significant effect on material weight loss Δm [mg/s] and a maximum depth of penetration of PWJ h max [mm]. Evaluation of characteristics of subsurface layer was observed strengthened area with lower elasticity. [ABSTRACT FROM AUTHOR]

This article deals with the analysis of the subsurface deformation effects of materials due to the periodic action of liquid droplets, each with a constant volume of approximately 36 mm3 distributed with a spatial frequency of 20,000 i/mm. Sample grooves were analyzed within standoff distances where the prevailing mechanism is acceleration culmination depletion using the stair trajectory to avoid a possible Doppler effect. Using X-ray μ-CT, a network of cavities corresponding to a fractal shape was identified below the surface. It is apparent that the ability to erode does not end with the formation of a groove but continues into the core of the material in the form of microjetting, tunneling, or piercing. From that perspective, two types of these cavities have been identified, blind and transient, with diameters of a few micrometers. The topological changes in the subsurface region of the sample were analyzed using X-ray μ-CT progressive sectioning. The anticipated subsurface deformation was further explored and analyzed using SEM analysis. The integrity of the material around the cavities was assessed according to microhardness to explain the microjetting, tunneling, and piercing propagation. The results suggest that the effect of the lateral jetting after droplet collapsing causes extensive hydrodynamic tunneling in the material that is much higher during the intense periodic action of water droplets, even at subsonic speeds. [Display omitted] • The origin of subsurface voids is clarified. • Subsurface network microcavities are identified. • Blind and transient subsurface cavities are observed. • Relative and real erosion depths are identified. • Residual water microjetting is observed to be multidirectional. [ABSTRACT FROM AUTHOR]

This study compared the effect of the interaction time of periodic water clusters on the surface integrity of AISI 304 tungsten inert gas (TIG) welded joints at different excitation frequencies, as the effect of the technological parameters of pulsating water jet (PWJ) on the mechanical properties of TIG welded joints are under-researched. The TIG welded joints were subjected to different frequencies (20 and 40 kHz) and traverse speeds (1–4 mm/s) at a water pressure of 40 MPa and a standoff distance of 70 mm. The effect of the interaction of the pulsating jet on the material and the enhancement in its mechanical properties were compared through residual stress measurements, surface roughness, and sub-surface microhardness. A maximum enhancement in the residual stress values of up to 480 MPa was observed in the heat-affected zone, along with a maximum roughness of 6.03 µm and a maximum hardness of 551 HV using a frequency of 40 kHz. The improvement in the surface characteristics of the welded joints shows the potential of utilizing pulsed water jet technology with an appropriate selection of process parameters in the treatment of welded structures. [ABSTRACT FROM AUTHOR]

The water hammer effect is the basis of technologies which is artificially responsible for the decay of continuous jets. A recently developed technique enhances the pressure fluctuations using an acoustic chamber, leading to enhanced erosion effects for various water volume flow rates. The optimum standoff distance for an ultrasonic enhanced water jet is not appropriately estimated using an inclined trajectory. The objective of this study is to comprehend the true nature of the interaction of the standoff distance following the stair trajectory and traverse speed of the nozzle on the erosion depth. Additionally, it also critically compares the new method (staircase trajectory) that obeys the variation in frequency of the impingements for defined volume flow rates with the inclined trajectory. In this study, at constant pressure (p = 70 MPa), the role of impingement distribution with the variation of traverse speed (v = 5–35 mm/s) along the centerline of the footprint was investigated. The maximum erosion depth corresponding to each traverse speed is observed at approximately same standoff distance (65 ± 5 mm) and decreases with the increment in traverse speed (h = 1042 and 47 µm at v = 5 and 35 mm/s, respectively). The results are attributed to the variation in the number of impingements per unit length. The surface and morphology analysis of the cross-section using SEM manifested the presence of erosion characteristics (micro-cracks, cavities, voids, and upheaved surface). By varying the water cluster, different impingement densities can be achieved that are suitable for technological operations such as surface peening, material disintegration, or surface roughening. [ABSTRACT FROM AUTHOR]

This research article aims at comparing the erosion performance of continuous and ultrasonically generated pulsating water jet technologies on granite samples at three pressure levels of 20 MPa, 40 MPa and 60 MPa. The granite surface was eroded using the circular nozzle of diameter d = 1.9 mm with the variation of traverse speed at each pressure levels. The depth, width and volume erosion of the grooves generated by both the technologies were evaluated using surface profilometer. It was evident from the results, that the variations in the process parameters show the influential behaviour on the erosion performance of granite by pulsating water jet in comparison to the continuous water jet. The optical microscopy and scanning electron microscopy (SEM) of the generated grooves were analysed to observe the surface morphology and plastic deformation phenomenon during the erosion of the granite samples. The above study shows that the pulsating water jet technology is the preferable approach over continuous water jet that can be utilised for different manufacturing applications. Also, the technology is economically more beneficial than the presently used cleaner technologies (non-abrasive and abrasive) as it reduces the extra cost invested in high-pressure pumps. [ABSTRACT FROM AUTHOR]

This study focuses on the analysis of the surface material integrity of the polished, rigid, solid surface of an aluminium alloy after periodical impingement of liquid droplets with variable volume and impact frequency distributions normal to the solid surface. The volume of water droplets was determined for the pressures of 20 and 40 MPa. By increasing the traverse speed of the ultrasonic pulsating water jet head with respect to the stationary tested specimen, the number of water droplet impacts on one area was controlled in order to reach the early erosion stages. Also, for the comparative study, aluminum alloy was exposed to continuous water jet for both supply pressure 20 and 40 MPa with traverse speed of 1 mm/s over the material surface. Systematic testing focused on material integrity in the early erosion stages in the interval between the elastically deformed surface and material disintegration was conducted with the aid of microhardness measurements, X-ray analysis of stress state, and microstructural analysis by SEM. The motivation for carrying out this experiment was to verify the effects of periodic drops on the integrity of the material and to identify the parameters leading to surface strengthening without erosion as compared to continuous jet. Such surface treatments can improve fatigue life, similarly to shot peening. • Material integrity investigation of early erosion stages with variable numbers of impingements. • Compressive stress and residual stress built up during each erosion stage. • Relationship between impingement distribution vs. hardness and surface roughness. • High intensity impingement of rigid surfaces does not increase compressive stresses. [ABSTRACT FROM AUTHOR]