Subsurface damage evaluation in the single abrasive scratching of BK7 glass by considering coupling effect of strain rate and temperature

et al. 2022

Materials

Self Cite

A novel grain-based DEM (Discrete Element Method) model is developed and calibrated to simulate RB-SiC (Reaction-Bonded Silicon Carbide) ceramic and associated scratching process by considering the bonded SiC and Si grains and cementitious materials. It is shown that the grain-based DEM model can accurately identify transgranular and intergranular cracks, and ductile and brittle material removal modes. It also shows that by increasing the scratching speed or decreasing the depth of cut, the maximum depth of subsurface damage decreases, because the scratching force is relatively large under the low scratching speed or large depth of cut that facilitates the occurrence of transgranular cracks, large grain spalling from the target surface and the propagation of median cracks into the target subsurface. It has further been found that increasing the cutting-edge radius can enhance the target ductile machinability and reduce the target subsurface damage.

Section: Introductionmentioning

confidence: 99%

A Novel Grain-Based DEM Model for Evaluating Surface Integrity in Scratching of RB-SiC Ceramics

et al. 2022

Materials

Self Cite

“…The principle is to use viscoelastic material with non-Newtonian fluid properties to prepare a specific shear pad in order to enhance the control of abrasive particles and improve the stress evenness and contact pressure on the workpiece surface based on the shear dilatancy and solidification effects under high-pressure and high-speed conditions to finally achieve high-efficiency and high-quality polishing. The scratching effect of abrasives on the workpiece is the key to achieving material removal [ 20 , 21 ]. Compared with conventional polishing pads, the dilatancy pad can hold more abrasives.…”

Section: Introductionmentioning

confidence: 99%

Effects of pH Values and H2O2 Concentrations on the Chemical Enhanced Shear Dilatancy Polishing of Tungsten

Chen

et al. 2022

Micromachines

In order to obtain tungsten with great surface qualities and high polishing efficiency, a novel method of chemical enhanced shear dilatancy polishing (C-SDP) was proposed. The effects of pH values and H2O2 concentrations on the polishing performance of tungsten C-SDP were studied. In addition, the corrosion behaviors of tungsten in solutions with different pH values and H2O2 concentrations were analyzed by electrochemical experiments, and the valence states of elements on the tungsten surface were analyzed by XPS. The results showed that both pH values and H2O2 concentrations had significant effects on tungsten C-SDP. With the pH values increasing from 7 to 12, the MRR increased from 6.69 µm/h to 13.67 µm/h. The optimal surface quality was obtained at pH = 9, the surface roughness (Ra) reached 2.35 nm, and the corresponding MRR was 9.71 µm/h. The MRR increased from 9.71 µm/h to 34.95 µm/h with the H2O2 concentrations increasing from 0 to 2 vol.%. When the concentration of H2O2 was 1 vol.%, the Ra of tungsten reached the lowest value, which was 1.87 nm, and the MRR was 26.46 µm/h. This reveals that C-SDP technology is a novel ultra-precision machining method that can achieve great surface qualities and polishing efficiency of tungsten.

“…The distribution of residual stress in shot peening of 12Cr2Ni4A steel was investigated by Zhao et al [ 11 ] in order to optimize the processing parameters, and a numerical stimulation using the Computational Fluid Dynamics and Finite Element Model was also conducted in order to study the influence of processing parameters on the induced compressive residual stress and its strengthening mechanism [ 14 ]. Residual stress is one of the most important factors affecting machining performance in the advanced manufacturing process [ 15 , 16 ], and should be considered in the shot peening process as well.…”

Section: Introductionmentioning

confidence: 99%

Strengthening Performance Optimization of Single Ball Impact Treatment by Evaluating Residual Stress

Yang

2022

Materials

Self Cite

Residual stress plays an essential role in affecting the strengthening performance by a surface treatment. Studying the impact of a single ball on a target surface is the basis of shot peening technology in order to obtain the distribution of the residual stress, and to optimize the processing parameters. In this paper, a numerical model has been developed to represent single ball impacts on high manganese steel by considering different processing parameters. It was found that by increasing the ball diameter and impact velocity, the depth of maximum residual compressive stress and the depth of the residual compressive stress layer became significantly enlarged due to increasing kinetic energy of the impacting ball. It was also found from simulation that with an increase in ball impact angle, the maximum residual compressive stress, the depth of maximum residual compressive stress and the depth of the residual compressive stress layer were significantly improved; an exception was the surface residual compressive stress, which showed a decreasing trend. Moreover, by employing quantitative analysis with the entropy method, it was found that within the range of processing parameters considered in the simulation, it is recommended to use a ball with a diameter of 0.6 mm to impact the target, with a velocity of 80 m/s and an angle of 90° for the best strengthening performance.