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Surface texturing was widely applied in improving the tribological properties of mechanical components, but study of measurement of this technology was still insufficient. This study proposed the multi-layers fitting (MLF) method to characterise the dimples array texture surface. Based on the synergistic effect among the dimples, the 3D morphology...
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We have selected two different apertures one in the
form of concentric unequal ratio of annuli and the second has
longitudinal successive black and white strips made inside a
circular aperture. We compute the Point Spread Function
(PSF) in the two cases for the sake of resolution improvement.
In addition, the Resultant PSF is obtained in case of co...
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... As shown in Figure 1a,b, VLT is a composite morphology containing convex and concave regions; the outer diameter of the ring-shaped bump was regarded as its diameter, d v . The characterization adopted the parameter systems in [27]. The width and depth of MGT referenced the previous research in [28,29], as shown in Figure 1c,d. ...
In recent years, surface texturing in micro-scale has been attempted on the surface of cutting tools for multiple purposes, e.g., cutting force reduction, prolonging life-span, anti-adhesion, etc. With respect to machinability and performance, micro-groove texture (MGT) has dominated in this field compared to other textured patterns. In this study, a novel volcano-like texture (VLT) was fabricated on the rake face of cemented carbide inserts (WC-Co, YG6) by fiber laser. The following cutting experiment tested the flat, MGT and VLT tools in turning aluminum alloy 6061. The effects of coolant and cutting conditions were investigated. In addition, a validated FEM model was employed to explore the distribution of stress and temperature fields in the tool-chip interface. The initial forming process of adhesion layer on rake face was investigated as well. The results indicated that lower cutting force and less adhesion can be achieved by small scale VLT. This study not only introduced VLT on cutting tools but also revealed its comprehensive performance.
... The previous studies showed that dimple depth, area density, and movement speed are crucial for lubrication [8,14], therefore a three-factor experiment, each factor has five levels (see Table 2), was established. The area density of micro-dimple array was controlled by the same equal space in row and [20]. Every specimen experienced the continuous increasing of rotation speed from 80 to 400 r/min. ...
The camshaft is a crucial component of an engine’s valve train. This paper devotes to the experimental studies of the performance of laser surface textured (LST) camshaft. The first part experiment was carried out on the block-on-ring tester to investigate the tribological behaviors of textured surface in line contact. The area density of the textured dimples was in the range 3–40% with depths 5–24 μm and diameter 70 μm. The friction coefficient and wear tracks were analyzed to confirm the optimum textured patterns. After that, the local LST cams (textured on the lifting region) were further tested in a single-cylinder diesel. It was found that after 300 h durability test at the rated speed and load, the total lifting loss of cams decreased nearly 34.4% in maximum. In addition, the performance of the engine was not affected evidently. The enhanced lubricity and local hardening were two mechanisms for highly promoting the anti-wear property of the LST cams.
Current machine vision methods for surface measurement rely excessively on feature design to quantify surface morphology and build predictive models, but metric design suffers from human intervention, and data acquisition is heavily dependent on light source environment and shooting angle. This paper uses the Swin-Transformer model to evaluate and classify roughness directly on colour images of milled samples acquired in a convertible image environment. The images used in the experiment are taken in a completely dark environment and in an environment disturbed by light sources, such as LED energy-saving lamps during the day. By using two kinds of lenses and combining custom light sources and ordinary light sources, respectively, and for different angles, it deeply simulates the environment of online inspection of industrial production. The roughness classification results prove that the method has very good robustness to light source environment and shooting angle, avoiding the artificial design and extraction of image features. The accuracy of the validation set of samples can reach 98.94%, while the accuracy of the test set can reach 97.54%. To wrap it up, the method provides an optimised strategy for visual roughness measurement in industrial production.
The optimization of cylinder surface topography draws immense amounts of researches, since it has far-reaching effects on engines’ overall performances. In order to promote the lubricity of ring/bore interface, the present study developed the multidimensional laser surface texturing (MLST) process, which fabricates controllable arrays of micro dimples on cylinder surface. The MLST process was achieved by a series of innovations, including its hardware and software systems, and optimization of process parameters and efficiency. A post-process was developed based on the finishing honing process to remove the recast bulges (RCB) induced by laser ablation. Additionally, the cylinder liners with different surface texturing schemes were bench tested on a single cylinder diesel engine. The experimental results indicated that near TDC (top dead center) region and piston skirt contacting region (SKIRT) were two high-impact regions for the technical efficiency of the MLST process. Benefiting from the reasonable optimization of oil distribution and enhanced hydrodynamic lubrication, the MLST process was able to reduce engine oil and fuel consumptions simultaneously. This paper provides a comprehensive introduction of equipment, pre- and post-process, and capacities of the newly developed surface modification technology.
Tool-chip adhesion impacts on cutting performance significantly, especially in finish cutting process. To promote cutting tools’ anti-adhesion property, the concave micro-grooves texture (MGT) and convex volcano-like texture (VLT) were fabricated separately on lathe tools’ rake faces by laser surface texturing (LST). Various orientations of MGT and different area densities (9% and 48%) and regions (partial and full) of VLT were considered in textured patterns designing. The following orthogonal cutting experiments, machining of aluminum alloy 5038, analyzed tools’ performances including cutting force, cutting stability, chip shape, rake face adhesion and abrasion. It indicated that under dry finish cutting conditions, MGT contributed to cutting stability and low cutting forces, meanwhile friction and normal force reduced by around 15% and 10%, respectively with a weak correlation to the grooves’ orientation. High density VLT tools, on the other hand, presented an obvious anti-adhesion property. A 5 μm reduction of crater wear’s depth can be observed on textured rake faces after long length cutting and textured rake faces presented half size of BUE regions comparing to the flat tool, however, once the texture morphologies were filled or worn, the anti-adhesion effect could be invalid. The bearing ratio curve was employed to analysis tool-chip contact and durability of textured surfaces contributing to a better understanding of anti-adhesion and enhanced durability of the textured tools.
Strain-controlled cyclic simple-shear tests were performed on silica sand with radial strain measurements. The specimens were tested under a constant K0 condition and subjected to cyclic loading and postcyclic monotonic loading. Threshold cyclic shear strain, volumetric strain, secant shear modulus, and damping ratio are investigated. Generally, the volumetric strain behavior in this study agreed well with literature findings that were investigated using the conventional cyclic direct simple shear test (without radial constraints). Radial strain during monotonic simple shear (postcyclic loading) was found to be a good parameter in monitoring the onset of flow slide in cohesionless soil. The concept of threshold cyclic shear strain, γt, was adequately applied in assessing the specimen volume change. Dynamic engineering properties, including equivalent shear modulus and damping ratio, were also studied. The damping ratio was found to decrease when the cyclic shear strain amplitude was greater than 2%. Possible reasons for the decrease in damping were explored.
