The problem that the not clear influence mechanism of micro-morphology characteristics on macro lubrication performance under water-lubricated bearings in service is studied. A two-dimensional fluid ...dynamics model of typical texture is constructed. The internal flow field characteristics and evolution law of micro-texture are investigated. The generation mechanisms of hydrodynamic effects of micro-texture are revealed. The water film model with 3D features is proposed. The functional mapping relationship between micro features and macro lubrication behavior is clarified, and the change characteristics of macro lubrication behavior are studied. Experimental data coincides with theoretical research. Fruits establish substantial base towards the optimization of load-increase and drag-reduction under water-lubricated bearing.
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•A novel two-dimensional fluid dynamics model of typical texture is constructed.•The lubrication model with 3D features is established.•The mapping function between micro features and macro lubrication behavior is clarified.•The rationality and correctness of the model and the algorithm have been verified.
Both texturing and residual stress have a positive effect on tribological properties of surface. According to the effect, a synergistic processing method by laser and abrasive belt is proposed. The ...results show that the texture of co-processed surface is more regular and flatter with stronger grooves retention. With none stress and initial stress as the benchmark, the co-processed surfaces are all in compressive stress. The co-processed surfaces exhibit some advantages under dry friction and boundary lubrication. When residual compressive stress is greater than the initial, the surfaces show better wear resistance where wear depth can be reduced by 56.88 % from 2.69 mm to 1.16 mm and wear area width can be reduced by 44.90 % from 689.41 mm to 379.84 mm.
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•Texture on the synergistic surfaces exhibit stronger retention.•Synergistic surfaces are compressive stress as the basis of none or initial stress.•Texture surface with compressive stress beyond the initial is more wear resistant.•Laser and belt grinding lead texture and residual stress respectively in synergy.
Formation of the {100} cube texture component has been reported extensively in many heavily deformed face-centered cubic (FCC) metals and alloys after annealing. The present study shows how to avoid ...the formation of strong cube texture on the surface of high-temperature annealed Ni foils subjected to large rolling reductions and also retain the high intensity of twin boundaries. The evolution of the surface texture of rolled and annealed foils are discussed in comparison to conventional rolling, shear, and recrystallization texture components. The stability of the cube and ND-rotated cube components in rolled foils are elaborated. In spite of discontinuous recrystallization mechanisms, a high fraction of rolling texture components is retained after annealing. Suppression of the cube component after annealing has been attributed to the constricted-annealing process and possible activation of low-energy twin boundaries. Annealing twins were found to form during the recrystallization process via a growth fault mechanism.
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•Surface shear and friction retain cube and rotated cube components.•Cube orientations from rolling did not lead to a strong cube texture after annealing.•Constricted annealing leads to the retaining of deformation texture components.•Twin boundaries resist mobility even during high-temperature annealing.
•A novel parameter called matching phase difference is proposed to quantitatively characterize the matching relationship between the vibration and grinding parameters in ultrasonic assisted ...grinding.•An improved model for predicting the surface texture and surface roughness in ultrasonic assisted grinding is developed.•The surface micro-topography (surface texture and surface roughness) is predicted accurately by comparing experimental results.•The influence of matching phase difference on surface micro-topography (surface texture and surface roughness) is studied.
In comparison with ordinary grinding (OG), ultrasonic assisted grinding (UAG) yields unique texture structure and better surface quality. Considerable research effort has been devoted to the investigation of the relationship between UAG parameters and surface roughness. However, the quantitative description of the matching relationship of UAG parameters and its effect on surface micro-topography (surface texture structure and roughness) is still a subject little investigated by the scientific community. In this paper, a novel parameter called matching phase difference (MPD) was proposed to quantitatively characterize the matching relationship between the ultrasonic and grinding parameters based on the interaction effect of multiple wheel rotation cycles. A comprehensive analytical model of MPD and surface micro-topography (surface texture and surface roughness) was developed. The experimental results and theoretical analysis both showed that the MPD could well characterize the matching relationship between the ultrasonic and grinding parameters. Then, the optimal UAG parameters for surface roughness and texture patterns was further studied based on the analytical model. The novel model proposed in this paper sheds new light on surface micro-topography in UAG, which is conducive to get a better insight into the material removal mechanism and the development of industrial applications of UAG.
Automated defect inspection has long been a challenging task especially in industrial applications, where collecting and labeling large amounts of defective samples are usually harsh and ...impracticable. In this paper, we propose an approach to detect and localize defects with only defect-free samples for model training. This approach is carried out by reconstructing image patches with convolutional denoising autoencoder networks at different Gaussian pyramid levels, and synthesizing detection results from these different resolution channels. Reconstruction residuals of the training patches are used as the indicator for direct pixelwise defect prediction, and the reconstruction residual map generated in each channel is combined to generate the final inspection result. This novel method has two prominent characteristics, which benefit the implementation of automatic defect inspection in practice. First, it is absolutely unsupervised that no human intervention is needed throughout the inspection process. Second, multimodal strategy is utilized in this method to synthesize results from multiple pyramid levels. This strategy is capable of improving the robustness and accuracy of the method. To evaluate this approach, experiments on convergence, noise immunity, and defect inspection accuracy are conducted. Furthermore, comparative tests with some excellent algorithms on actual and simulated data sets are performed. Experimental results demonstrated the effectiveness and superiority of the proposed method on homogeneous and nonregular textured surfaces.
•Expanding Gaussian heat flux and variable plasma flushing efficiency incorporated.•Stochastic multi-spark distribution in location, energy and chronological order.•User-defined subroutines used for ...dynamic simulation of spark erosions in ABAQUS.•Evolution of surface texture in EDT simulation with increasing crater overlaps.•Simulated topographies validated using error function and distribution methods.
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The prediction of surface topography obtained with electrical discharge texturing (EDT) process is very challenging, due to stochastic nature and complex physics in occurrence of sparks. Though there are a few models for surface texture prediction in the literature, there are still ample opportunities to improve upon by adopting more realistic assumptions and formulations for simulation. This paper presents a numerical simulation of progressive development of surface topography due to sequential application of spark discharges on an instantaneous textured surface formed by all previous spark discharges. The model incorporates major single-spark features such as, Gaussian distribution of heat flux, temperature-dependent work material properties, latent heat of melting, and operating parameter dependent variation of factors such as, cathode energy fraction, spark radius, and plasma flushing efficiency; besides the multi-spark features such as, stochastic distribution of sparks with respect to: i) location, ii) energy level, and iii) chronological order. Finite element simulation of EDT is performed in ABAQUS with the help of user-defined subroutines for the dynamic simulation of spark discharges, flagging of elements attaining evaporation temperature from further heat flux application and storage of the highest temperatures attained by each element. An evolution of surface texture through the progress of spark erosions has been studied. As EDT continues, the number of craters overlapping generally tend to increase, whereas the center-to-center distance between a crater with its nearest neighbour tends to decrease. The simulated surface textures are validated with the experimental ones using two methods: error function method and Ra distribution method, and were found to be in good agreement.
The demand for cone-beam computed tomography (CBCT) imaging in clinics, particularly in dentistry, is rapidly increasing. Preoperative surgical planning is crucial to achieving desired treatment ...outcomes for imaging-guided surgical navigation. However, the lack of surface texture hinders effective communication between clinicians and patients, and the accuracy of superimposing a textured surface onto CBCT volume is limited by dissimilarity and registration based on facial features. To address these issues, this study presents a CBCT imaging system integrated with a monocular camera for reconstructing the texture surface by mapping it onto a 3D surface model created from CBCT images. The proposed method utilizes a geometric calibration tool for accurate mapping of the camera-visible surface with the mosaic texture. Additionally, a novel approach using 3D-2D feature mapping and surface parameterization technology is proposed for texture surface reconstruction. Experimental results, obtained from both real and simulation data, validate the effectiveness of the proposed approach with an error reduction to 0.32 mm and automated generation of integrated images. These findings demonstrate the robustness and high accuracy of our approach, improving the performance of texture mapping in CBCT imaging.
The tribological behavior of tungsten carbide-textured samples with different particle types (silica, alumina and diamond) and sizes (5 and 25 µm) are investigated. Pin-on-disk experiments are ...conducted. Surface texture can effectively reduce the friction coefficient and wear rate of the sample with different particle types and sizes. When the lubricant has silica particles, the friction reduction efficiency of texture is the lowest. Softer particles are more likely to be crushed, making it easier to enter the friction interface and fill into the texture. The wear resistance increases with decreasing particle hardness. The particles will cause three-body and two-body abrasion. Small particles (5 µm) are more likely to enter the friction interface and roll more easily than larger particles (25 µm), causing more three-body abrasion. As the hardness of the particles increases, they are more likely to press against the surface of the specimen as they roll, leading to more three-body abrasion. Compared with untextured samples, textured samples can store particles and lubricant and thus have less three-body abrasion and two-body abrasion. This study provides new ideas for reducing the friction and wear of samples in water containing different particle types and sizes.
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•Under water containing different types particles with different sizes, surface texturing can reduce wear.•Small particles cause more wear than large particles.•Particles with different types have different wear mechanisms.
Computer vision based methods have been widely used in surface defect inspection. However, most of these approaches are task specific, and it is hard to transfer them to similar detection scenarios. ...This paper proposes an entity sparsity pursuit (ESP) method to identify surface defects. Based on the observation that surface image textures usually form a low-rank structure and the structure can be violated by the presence of rare defects, we formulate the detection task as a low-rank and ESP problem. To alleviate the feature shortage issue existed in industrial gray-scale images, we customize a kind of intuitive features for surface defect inspection. Different from previous work utilizing complicated regularization terms, we resort to mine intrinsic priors of defect images, which can be neatly incorporated into the designed architecture. The proposed model is compact and able to detect surface defects in an unsupervised manner. To fully evaluate the presented method, we conduct a series of experiments using three real-world and one synthetic defect datasets. Experimental results demonstrate that ESP outperforms state-of-the-art methods.
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