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The foundation of offshore wind turbines is an important factor that determines their bearing capacity and service life. A theoretical analysis and model test of the bucket foundation with and without bulkheads at a scale of 1:150 are conducted in this study. The frequency-domain impedances of the two models were obtained and compared via cyclic loading tests at different frequencies. When the loading frequency was low, the absolute values of the real and imaginary impedances of the foundation model without a bulkhead in the frequency domain were higher than those of the foundation model with a bulkhead. Based on the analysis of the variation in soil pressure at the top of the bucket, it was found that the variation in soil pressure almost alternated with the cyclic load. The adsorption force is beneficial for the bearing capacity of a composite bucket foundation, making the structure safer. The impedance matrix of the foundation is determined by the size and shape of the foundation, mechanical parameters of the foundation medium, and frequency of the forced vibration. Wolf's lumped-parameter model was evaluated for applicability to analyse the bucket foundations with bulkheads. • A theoretical analysis and model test of the bucket foundation with and without bulkheads are conducted. • The frequency-domain impedances of the two models are obtained and compared via cyclic loading tests at different frequencies. • The adsorption force is beneficial for the bearing capacity of a composite bucket foundation, making the structure safer. [ABSTRACT FROM AUTHOR]

This paper aims to use machine learning (ML) based on a regression algorithm to predict the damage degree of a concrete-filled double-skin steel tubular column (CFDST) after explosion. Three classical single learning algorithms and five excellent ensemble learning algorithms were used to train 2476 sets of data. Five regression indicators were used to evaluate and compare the effectiveness and accuracy of the ML model. The results show that the integrated CatBoost model is superior to the other models, and the model performances are ranked as CatBoost > LightGBM > XGBoost > GBDT > MLP > RF > SVR > DT. Shapley Additive exPlanations (SHAP) is used to explain the contribution of each feature parameter to CatBoost prediction results. Finally, the CatBoost model is used to predict the collected test data, and R2 = 0.989, MSE = 2.98 × 10−6, RMSE = 0.00172, MAE = 0.00151, and MAPE = 7.4% are obtained. This shows that the model has high prediction accuracy and can accurately predict the damage degree after CFDST explosion. • An extensive database of CFDST columns subjected to the close-in explosion is established. • Three classical single learning algorithms and five excellent integrated learning algorithms are used to predict the damage degree of concrete-filled double-skin steel tubular column (CFDST) columns under close-in explosion loads. • After model training and evaluation, the CatBoost model has the best accuracy among the eight models. • The global and local interpretation of the CatBoost model is carried out through the Shapley Additive exPlanations(SHAP), and the influence of different input parameters on the model is visualized. • In the actual damage assessment, compared with the problem that the traditional P-I curve regression formula can only obtain the damage degree of the CFDST column, the CatBoost model can obtain accurate damage conditions. [ABSTRACT FROM AUTHOR]

As an appropriate type of foundation for offshore wind turbines (OWTs), wide-shallow composite bucket foundation (WSCBF) is cost-competitive, and it has a unique and special substructure that comprises seven internal rooms arranged in a honeycomb-like structure. In this study, the cyclic behavior of WSCBF for OWTs embedded in saturated clay was investigated using a large-scale model subjected to lateral cyclic loading. The responses of foundation under constant- and various-amplitude cyclic loadings were recorded in terms of displacements, rotations, and bending moments. The variations in stiffness and damping were obtained, and a collaborative bearing mechanical model between the bucket and soil was considered, which was beneficial for improving the stiffness of the whole structure. Accumulative deformation was found to have little effect on the bearing capacity of the foundation. Dynamic analysis in frequency domain was further performed on both moment and rotation data, and the complex, frequency-dependent impedance was also studied. [ABSTRACT FROM AUTHOR]

Generally speaking, in the melting process of alumina ceramics, all the metastable transitional phase will be gradually transformed into the stable α phase with rising temperature due to an irreversible lattice reconstruction. However, under the action of pulsed laser cutting, the lattice structure of α-alumina needs to withstand the great stress from instantaneous high energy impact. Thus, a slip dislocation of 1/4 at. diameter is generated on the atomic plane of each second basal layer to produce γ-alumina. In this work, a ceramic plate comprised of α-alumina is taken as the object of study. The α-to-γ reverse phase transformation of the molten removal is verified by the observed microstructure from scanning electron microscope (SEM) and transmission electron microscope (TEM). Simultaneously, the X-ray diffraction (XRD) investigation shows that the basis of molten removal after laser cutting is still α-alumina. The micrographs of octahedral corners or hexagons are shown in different observation directions. There is no γ-alumina phase transformation product in the spherical granular removal at each vapor-to-melt ratio (r vmr ). In contrast, γ-alumina is detected in the adhering slag with a micro-morphology of cubic phase. The mass fraction is increased with the rising of vapor-to-melt ratio. At the same time, θ-alumina also exists in some spattering removal as intermediate product between α and γ phase. It is indicated that the generation of α-to-γ reverse phase transformation occurs mainly in the melting process of temperature rise, and the maintenance of phase transformation results mainly occurs during cooling process of condensation. [ABSTRACT FROM AUTHOR]

An investigation of particle morphology based on vapor-to-melt ratio is carried out to reflect the relationship between the forms of material removal and effects of cutting process. The influences of vapor-to-melt ratio on morphology of removal particles (average diameter, diameter distribution, sphericity, spheroidization rate and density distribution) is investigated by the experimental observation and analysis. It is shown that, a steady processing state with maximum average diameter, concentrated distribution, better sphericity, lager spheroidization rate and higher hollow proportion of removal particles is obtained at a relatively large value of vapor-to-melt ratio. However, at a too high value of vapor-to-melt ratio, a small quantity of material breaks and strips in a substrate form by the hot tearing effect of material. These irregular residues are mixed in the total removal collection, thereby reducing the average sphericity of the overall removal. When the particle diameter is greater than 100 μm, a complete cavity is formed close to the center, and the diameter is about 1/2 that of the whole particle. [ABSTRACT FROM AUTHOR]

Because of the multiple selections on different crystalline faces in nucleation process of α-alumina, it is necessary to confirm the nucleation mode and growth mechanism of molten removal particles produced by alumina ceramics laser cutting. A model based on driving force of Helmholtz and Gibbs free energies is built to compare different critical nucleation sizes and corresponding nucleation barriers among several crystal planes. The calculation shows that when alumina ceramic is cooled and solidified from a molten state, the material is preferably nucleated in the parallelepiped model with extension and stack along the ( 11 2 ¯ 0 ) plane. X-ray diffraction and scanning electron microscopy detections are taken to verify the nucleation mode that the morphologies thereof are shown as corners of an octahedron or edges of hexagons in different section directions. A pyramid stacking growth mode of spherical particles is proposed to coincide with the hollow micro morphology. The analysis concludes this model is feasible and it makes contribution to the potential application of removal particles for the field of ceramic powder metallurgy during laser processing. [ABSTRACT FROM AUTHOR]

In order to predict the particle size of molten removal in laser cutting Al 2 O 3 ceramic plate, an atomization model based on vapor-to-melt ratio is developed to reveal the relationship between material remove forms and results during the process of vaporization-melt. Model correction of vapor-to-melt ratio with different parameters is obtained by laser cutting of 96.4% Al 2 O 3 ceramic plate to get the slit width. The experimental verification is carried out on a JK701H Nd:YAG pulse laser cutting system by simulating under the regression correction of melt flow diameter. Micro-observation on the molten particles with different plate thickness (1.5 mm, 2.0 mm, 3.0 mm varied with increasing of vapor-to-melt ratio) and the calculations show that the particle diameter decreases rapidly (70 μm, 60 μm, 35 μm) with vapor-to-melt ratio after increasing to an extreme value (80 ∼ 85 μm). It is proved that there is an antagonistic relationship between kinetic and thermodynamic effect in the impact of vapor-to-melt ratio (with critical value of 0.1) on the morphology of cutting removal. The results show good agreement between atomization model and experiments with average error below 8%. The analysis verifies this model is feasible and it makes contribution to determine the reasonable processing parameters (such as the control of vapor-to-melt ratio) in laser precision cutting. [ABSTRACT FROM AUTHOR]

[Display omitted] • Secondary oxidation was foremost stage for unique flavor formation in salted egg yolk. • Primary oxidation directly inhibited the accumulation of aldehydes and ketones. • Primary oxidation indirectly produced beneficial volatiles by changing metabolites. • Secondary oxidation induced the synthesis of flavor precursors in salted egg yolk. • Amino acid metabolism etc. induced by secondary oxidation formed salted egg yolk flavor. To explore the contribution of different lipid oxidation stages to flavor formation in salted egg yolk, potential pathways of flavor formation were characterized by multi-omics strategy and partial least squares structural equation model (PLS-SEM). 72 lipids, 135 metabolites and 5 volatiles related to lipid oxidation were screened out. The degradation of aldehydes and ketones, and the generation of tryptamine and elaidic acid, etc. were promoted by triglycerides (TG) (10:0 16:0 18:1), triglycerides (TG) (18:0 20:1 22:0), etc. at primary and secondary oxidation stage, respectively. The generation of acetophenone, thianaphthene, etc. through the pathway of 2-phenylacetamide, hexanoylcarnitine, etc. was facilitated by these triglycerides (TG) at primary oxidation stage. Furthermore, amino acid metabolisms, pentose phosphate pathway and linoleic acid metabolism occurred at secondary oxidation stage were key pathways to form distinctive flavor. In conclusion, secondary oxidation stage may be more important for the formation of unique flavor (taste) in salted egg yolk. [ABSTRACT FROM AUTHOR]

To study the regular pattern of vapor-to-melt ratio in laser cutting sheet metal, a physical model of vapor-to-melt ratio is developed to demonstrate the material remove forms of vaporization-melt in cutting area and the state of energy and mass flow in the molten layer. Variation of vapor-to-melt ratio with laser power and cutting velocity is obtained by laser cutting of 6063 aluminum alloy sheet. The 0.5-mm sheet thickness is carried out on a JK701H Nd:YAG pulse laser cutting system by simulating under the regression correction of cut radius. Observation on the cut samples with different parameters (65 W, 85 W, 105 W varied with laser power increasing, and 2.2 mm/s, 2.0 mm/s, 1.8 mm/s with decreasing of beam cutting speed) and the calculations show that vapor-to-melt ratio increases (0.595–1.995, 0.672–2.631, 0.787–4.171) with laser power (65 W–110 W) and decreases with cutting velocity (1.8 mm/s–2.4 mm/s). At the same time, the laser cutting quality increases with vapor-to-melt ratio and the decrease with thickness of residual molten layer. The results show good agreement between vapor-to-melt ratio model and experiments. The analysis verifies that this model is feasible and it makes contribution to laser precision cutting. [ABSTRACT FROM PUBLISHER]

High cleaning quality for silicon wafers without damage is a challenge in laser cleaning technologies. Laser cleaning of Al2O3 micro-particles, which are the main contaminants of silicon wafer lapping and polishing solutions used in industry, from silicon wafers was studied for determining laser energy for high efficient particle removal while not causing damage to the wafers. As the cleaning force is generated from laser-energy absorption and conduction of the wafer, heat-conduction model on silicon wafer was developed during laser irradiation using a finer finite element method, from which cleaning force exerting on the particles greater than the adhesion force between the particle and the substrate, but less than the wafer damage energy of laser input was determined. Calculations of the laser energy threshold values for both particle cleaning and wafer damage were conducted for silicon wafers of 200 mm in diameter and 0.2 mm in thickness, and they were found to be about 60 mJ/cm2 and 320 mJ/cm2, respectively. The laser energy threshold model was finally verified experimentally using a KrF Excimer laser and found to be in good agreement with the experimental data. With the cleaning parameters from the model, the cleaning efficiency of as high as 98% has been achieved. [ABSTRACT FROM PUBLISHER]

Abstract: The deformation and failure behaviors of brittle or quasi-brittle solids are closely related to interaction and propagation of stochastically distributed microcracks. The influence of microcrack interaction and evolution on the mechanical properties of materials presents a problem of considerable interest, which has been extensively argued but has not been resolved as yet. In the present paper, a novel numerical method is used to calculate the effective elastic moduli and the tensile strength, and to simulate the failure process of brittle specimens containing numerous microcracks. The influences of some crack distribution parameters reflecting the non-uniform spatial concentration, size and orientation distributions are examined. The effective elastic moduli and the tensile strength of brittle materials exhibit different dependences on microcrack interaction. For example, two microcrack distributions that lead to the identical effective elastic moduli may cause a pronounced difference in the tensile strengths and failure behaviors of materials. By introducing two criteria for microcrack growth and coalescence in terms of Griffith’s energy release rate, the above numerical method is extended to simulate the coalescence process of microcracks that results in a fatal crack and the final rupture of a specimen. [Copyright &y& Elsevier]

The problem of an interface crack between dissimilar piezoelectric layers under mechanical and electrical impacts is formulated by using integral transform and Cauchy singular integral equation methods. The dynamic stress intensity factor and dynamic energy release rate (DERR) are determined through use of the obtained solutions and the effects of the loading ratio, the geometry of crack configuration and the combination of material parameters on the above two quantities are discussed. The numerical calculations indicate that the electrical load can promote or retard the crack growth depending on its magnitude, direction and the existence of the mechanical load and that with the increase of the value of ratio of two material parameters, some material parameters will inhibit the crack growth. On the other hand, some material parameters play the contrary roles. In addition, the geometry of the crack configuration has the significant effects on the DERR. Finally the results are compared with those obtained in a previous investigation. [Copyright &y& Elsevier]

[Display omitted] Physicochemical, texture indexes, microstructure and volatiles were used to characterize the changes in quality, structure and flavor of cooked salted egg yolks (SEYs) with or without ultrasonic treatment. Experimental results indicated that ultrasonic significantly increased cooking (water) loss, oil exudation, lipids oxidation (TBARS), accelerated the doneness of cooked SEYs and then promoted the generation of volatiles. These results were further confirmed by the improvement of thermal stability, the changes in color, secondary structure of proteins, water distribution and mobility. Meanwhile, more "fragments" and "cracks" were observed in scanning electron microscope (SEM) and the decrease in gumminess and chewiness were detected using texture profile analysis (TPA), inducing that the migration of lipids and collapse of gel network were intensified. Moreover, ultrasonic treatment decreased the content of sodium chloride in SEYs. Therefore, it was concluded that the doneness, quality and flavor of cooked SEYs were improved by ultrasonic treatment, which could be used as an effective and alternative method for the production of SEYs with good flavor, sandy and oily texture. [ABSTRACT FROM AUTHOR]

According to ANSYS software and an electron probe experiment, a multi-layer finite element model (FEM) of pulsed laser bending of stainless steel-carbon steel laminated plate (SCLP) including interfaces has been established. Compared with a single-layer stainless steel plate (SLSP), based on a temperature gradient mechanism considering the depth of the plastic zone, the influence of the interfaces and carbon steel layer in the model of the SCLP on the bending angle has been studied by analyzing the distributions of the temperature field, stress field and strain field in the thickness direction. The simulation results show that the temperature of the SCLP in the thickness direction is lower than that of the SLSP due to interfacial thermal resistance of the interface and fast heat conduction of the carbon steel layer, resulting in a smaller depth of the plastic zone of the SCLP defined by the recrystallization temperature. Affected by the temperature distribution, the plastic stress and strain of the SCLP in the plastic zone are smaller than those of the SLSP, leading to a smaller bending angle of the SCLP. When the laser power is 140 W, the scanning speed is 400 mm/min, the defocus distance is 10 mm, and the scanning time is 1, the bending angle of the SCLP is 1.336°, which is smaller than the bending angle 1.760° of the SLSP. The experimental verifications show that the maximum error of the bending angle is 3.74%, which verifies that the model of laser bending is usable and contributes to refining the laser bending mechanism of the SCLP. [ABSTRACT FROM AUTHOR]

Compared with the single-component metal plate, there is a special transition layer on the joint interface between two kinds of materials in the stainless steel-carbon steel laminated plate (SCLP). In order to describe the finite element model of laser bending accurately, it is of great significance to determine material properties of the transition layer. Based on the element distribution, an equivalent method is adopted to calculate thermal conductivity, thermal expansion coefficient, elastic modulus, density, Poisson's ratio, and specific heat capacity of transition layer. The electron probe experiments show that the transition layer is formed by interfacial element diffusion with thickness of 7 μm. Besides, the volume fraction of stainless steel (46.63%) and carbon steel (53.37%) in the transition layer is tested by energy dispersive spectrometer, respectively. Through the equivalent method, a laser bending model of SCLP is simulated by ANSYS software to predict the bending angle under different parameters. The experimental verification shows that the maximum of bending angle errors is 3.74%, which is lower than the maximum 4.93% of errors calculated by the mean value method. The analysis verifies that the laser bending model is feasible and contributes to improving the accuracy of modeling SCLP in the laser bending process. [ABSTRACT FROM AUTHOR]

• Novelly developed shear-thickening guar gum hydrogel based media for AFM is proposed in this paper. • A new model for the calculation of shear rate under shear-thickening condition is established and validated. • Surface roughness in terms of Ra using this media reduces from 120.12 nm to 6.48 nm, with a mirror surface obtained. • The conclusions show that shear thickening in AFM is an efficient way to develop the polishing efficiency and quality. Abrasive flow machining (AFM) is a non-traditional finishing method by extruding abrasive media through workpieces' surfaces. In AFM process, the machining capacity of traditional shear-thinning media will be reduced with the decline of viscosity at high shear rate condition. Additionally, the environmental-friendly property of traditional oil-soluble media is poor as the recycling of the media is difficult. In this paper, with an attempt to apply shear thickening to AFM, a novel type of guar gum hydrogel based media with shear-thickening property is proposed. To investigate its shear-thickening and finishing performance, a model of identifying the shear-thickening behavior in AFM is established. Results of the validation experiment show that the model can identify and predict the experimental conditions accurately, and the simulation results are approximately some with the model results. Results of AFM experiments show that finely polished surface can be obtained in the AFM process utilizing this new media. Compared with styrene-butadiene rubber based media (traditional shear-thinning media for AFM), guar gum hydrogel based media can obtain a better finished surface under shear-thickening condition. With shear rate increasing from shear-thinning phase to shear-thickening phase, material removal rate for AISI316 stainless steel in the experiment utilizing this new media increases from 69 mg/h to 351 mg/h, and surface roughness in terms of Ra under shear-thickening condition reduces from 120.12 nm to 6.48 nm. [ABSTRACT FROM AUTHOR]

Reducing the contact time while water droplets impact on solid surface has become a vital object concerned by many researchers in recent years. However, previous methods of preparing superhydrophobic surfaces for shortening the contact time, with low efficiency and high expense, are not suitable for large-area fabrication and some obtained surfaces cannot work unless droplets just impact on the specific textures which limits their application in the field of anti-icing from freezing rain. Moreover, the contact time reduction has been mostly observed on metals, but rarely on nonmetals. Here, a facile method of fabricating superhydrophobic cotton was first conducted to largely reduce the contact time between droplet and substrate surface, which obviously eliminated the previous weakness. The treated cotton showed an excellent self-cleaning property and water droplet could also easily roll off the surface. The subsequent impact experiments show that the contact time was shortened by ~ 36% compared with that on the regular hard superhydrophobic surface. Moreover, the influence of the impact velocity and droplet radius on the overall contact time or spreading time and recoiling time had been also observed. And the elasticity of soft elastic superhydrophobic material plays a significant role in making the droplet early bounce off the surface causing a large contact time reduction, which leads to a new way to understand the dynamics of bouncing droplets. [ABSTRACT FROM AUTHOR]

[Display omitted] The vacuum method is a widely adopted technique for eliminating bubbles from polymers containing particles. To investigate the influence of bubbles on the behavior of particles and the concentration distribution in high-viscosity liquids under negative pressure, experimental and numerical methods have been employed. The experimental findings demonstrated a positive correlation between the diameter and rising velocity of bubbles and the negative pressure. As the negative pressure increased from − 10 kPa to − 50 kPa, the position of the region where the particles were concentrated in the vertical direction was elevated. Furthermore, when the negative pressure exceeded − 50 kPa, the particle distribution became sparse and layered locally. The Lattice Boltzmann method (LBM) integrated with the discrete phase model (DPM) was utilized to investigate the phenomenon, and the outcomes revealed that rising bubbles have an inhibitory effect on particle sedimentation, and the extent of inhibition was determined by the negative pressure. In addition, vortexes generated by differences in the rising velocity between bubbles resulted in a particle distribution that was sparse and layered locally. This research provides a reference for achieving desired particle distributions using a vacuum defoaming approach and should be further studied to extend its applicability to suspensions containing particles with different viscosities. [ABSTRACT FROM AUTHOR]

Gears with a complex curve tooth, such as spiral bevel and hypoid gears, lack an ideal technique for the final finishing process. Pulse electrochemical finishing (PECF) is considered a promising method for surface finishing due to its micro-removal characteristics. A PECF system for spiral bevel gear (SBG) is established according to the generation of SBG tooth surfaces. An SBG (module, 12 mm; number of teeth, 38) is selected as the processing test piece, and mathematical models are developed for analyzing the characteristics of PECF. The influence of the experimental variables, including applied voltage, interelectrode gap, and finishing time, on the total removal thickness and surface roughness is discussed. The calculated values are found to be approximately consistent with the experimental values. The other parameters, including the concentration of electrolyte, tool rotational speed, flow rate of electrolyte, and pulse period, are also studied. Results show that the roughness of the SBG tooth surface is reduced from Rz 7.13 to 4.32 μm. The precision of the SBG is also improved. [ABSTRACT FROM AUTHOR]

Abstract: Surface quality of the workpiece has great influence on its service performance and lifespan. Pulse electrochemical finishing (PECF) provides an effective method for improving surface quality of the workpiece. In PECF, surface irregularities are removed by electrochemical dissolution rather than by cutting force. Due to non-contact nature of the process, there is no residual stress and thermal effect on the workpiece surface. For successful utilization of PECF, in present manufacturing, it still demands for more intensive research, including the mechanism of anodic smoothing. The anodic smoothing characteristics of PECF are analyzed through a developed mathematical model. The main influencing factors such as the finishing time, the interelectrode gap, the applied voltage and the rotational speed of electrode have been examined. The predictive values based on the developed mathematical model are found to be in reasonable agreement with the experimental values. The surface roughness Rz ranges from 3μm to 1.22μm. The research achievement through various parametric studies can be used as a guideline for the operation of a PECF system. [Copyright &y& Elsevier]

Extreme wettability materials, which can enable high-efficiency oil/water separation, has become a widely discussed topic due to increasingly severe oil pollutions including frequent offshore oil-spills accidents and industrial oily wastewater emission. However, most of existing methods to prepare these materials involved complicated machining processes or dangerous operations, especially the use of corrosive or toxic chemicals. Herein, a novel and environment friendly method including mark electrochemical machining (MECM) and subsequent chemical immersion, was proposed to acquire micropore arrays on Al foil for efficient oil collection from oil/water mixtures. Micro-dimple arrays were generally fabricated by MECM process followed by CuCl2 immersion to make it through. Both simulation and experimental verification were conducted to elucidate how dimple structures varied with machining parameters. The micro-scale rectangular-shaped step-like structures on micropore arrays endowed as-prepared samples with excellent superhydrophibic and underwater superoleophobic properties. Moreover, oils with kinematic viscosities ranging from 0.41 to 74.4 cSt could be separated from water with separation efficiencies above 95%. The superhydrophilic Al foil still showed good durability through repeated oil/water separation tests, and retained its superhydrophilicity even after the storage in water for 120 hours. Therefore, this novel and green method gives researchers new insights into functional materials preparation for practical oil/water separation. [ABSTRACT FROM AUTHOR]

Superhydrophobic surfaces with tunable water adhesion and adjustable wettability have the capacity to manipulate water droplets under complicated conditions and, therefore, have great prospects in various domains. Hence, developing a facile method to prepare highly stable superhydrophobic surfaces with tunable water adhesion and adjustable wettability is of great importance. Herein, we prepare the superhydrophobic aluminum surface by combining laser etching and stearic acid modification. The variations of water contact angle, water sliding angle and water adhesive force with temperature of the prepared surface are characterized during the adhesion tuning process to investigate its temperature-responsive characteristics. A low/high adhesion switching of water on the prepared surface is subsequently achieved under alternating temperature. In addition, a facile approach is designed to achieve the superwettability switching process (from superhydrophobic state to superhydrophilic state) on the prepared surface. The prepared superhydrophobic surface displays excellent recoverability, stability and repeatability in the adhesion switching process and the superwettability switching process, even after being cycled for 10 times. Unlabelled Image • The superhydrophobic surface shows excellent temperature-responsive characteristic in adhesion tuning process. • A reversible low/high adhesion switching of water is readily achieved under alternating temperature. • A facile approach is designed to achieve the reversible switching from superhydrophobicity to superhydrophilicity. [ABSTRACT FROM AUTHOR]

Abstract Abrasive flow machining (AFM) is a non-traditional surface finishing method by extruding abrasive media through workpieces' surfaces. It is difficult to implement uniformity and controllability for material removal in AFM, which makes predictions of material removal and its distribution along media flow direction significantly imperative. In this paper, a new predictive model for material removal in AFM is proposed based-on combination of material removal model for single abrasive and statistics model of active abrasives. To validate its applicability, two experiments are conducted to calibrate the material removal model, and another two experiments are carried out to validate the calibrated material removal model. Results show that this model can predict material removal in terms of profile height variation Δ H and variation trend of mass variation Δ M precisely, with predictive error (δ error) of 6.4% and 6.9% achieved in the validation experiments. In the case that the workpiece and flow channel are given, the variation of profile height Δ H on the workpiece surface shows consistent distribution trend with the distribution of the pressure and media flow velocity on the workpiece surface. Highlights • A material removal model is proposed to predict distribution of material removal along flow direction in AFM process. • A repositioning method is proposed to gauge material removal by measuring profiles before and after AFM process. • Predictions of material removal distribution in terms of profile height variation Δ H are justified by validation experiments. • Relationship between distribution of material removal and pressure field of abrasive media flow is established. [ABSTRACT FROM AUTHOR]

Liquid marbles which can be created by encapsulating water droplets using superhydrophobic powders have attracted extensive attention for their various promising application prospects. Cupric stearate coated liquid marbles was created by encapsulating water droplet using cupric stearate powders in a droplet rolling process. Hierarchies of robustness have been constructed which showed that the cupric stearate coated liquid marbles survived on surfaces with different wettabilities and could keep intact after impact, manipulation, transportation and mechanical compression. To evaluate robustness of the liquid marbles in manipulation processes, the mass of superhydrophobic powders per unit area on the surface of liquid marbles (powder surface density) was investigated. Powder surface density was decreased with the increase of water volume in the liquid marble. Moreover, water volume of the liquid marble was adjusted in situ, and the critical powder surface density was obtained via increasing or decreasing water volume of the liquid marble. By analyzing the critical surface density upon rupture or collapse of the liquid marble, the dependence of the critical surface density on the water volume of the liquid marble was predicted, which agrees well with experimental results. [ABSTRACT FROM AUTHOR]

[Display omitted] • The sedimentation velocity decreases first with particle volume fraction but then increases. • The inelastic collisions are the main interactions between particles. • The velocity equation is corrected by the effective diameter coefficient of aggregation. • The particle dynamic behavior and sedimentation in high-viscosity fluids were observed in micro-scale. To further understand the characteristics of particle–fluid flow, the particle sedimentation process in a high-viscosity fluid is conducted with both experimental and numerical methods. In this work, inelastic collisions between particles during the sedimentation process are observed. Different from the sedimentation in a low-viscosity fluid, the increase of particle sedimentation velocity can be found due to the inelastic collisions in a high-viscosity fluid. This phenomenon is more obvious with the increase of the particle volume fractions and the viscosity of the fluid. The necessary conditions for the inelastic collision phenomenon are determined based on the viscous dissipative dynamics of particle collisions. According to the experimental and numerical results, the interactions between particles in high-viscosity liquids are mainly the inelastic collisions which caused the particle aggregation. The correction coefficient of particle sedimentation velocity equation is obtained, and the applicability of the equation for the sedimentation in a high-viscosity fluid is improved. [ABSTRACT FROM AUTHOR]

• Elastic superhydrophobic film was easily prepared to reduce the contact time. • The as-prepared film was stretchable and durable. • There was a step-like reduction of the contact time with Weber number We. • Drop pancake and saucer bouncing phenomenon were both observed on the film. • Pancake and saucer bouncing just corresponded to the intermediate and high We. Realizing a short contact between water drops and surfaces has become a research focus owing to its promising application prospect in anti-icing. Here, we developed an elastic superhydrophobic film with a water contact angle of 166.6°±1.6° and roll-off angle of 2.0°±0.8° to largely reduce the contact time of an impinging drop. The thin films with different strains and after different cycles with a 50% strain could still maintain its low-adhesion superhydrophobicity, demonstrating its excellent adaptability and durability to deal with deformation. It was also found that there was a step-like reduction of the contact time with Weber number We , showing the pancake and saucer bouncing at intermediate and high We , respectively. In comparison with the conventional symmetric bouncing (at low We), the higher elasticity of the film caused by the drop impact contributed to the large contact time reduction for the pancake and saucer bouncing phenomenon. [ABSTRACT FROM AUTHOR]