Research on Surface Residual Stress of Nano-Composite Ceramics under Multi-Frequency Ultrasonic Grinding and Dressing

2011 ◽  
Vol 487 ◽  
pp. 447-451 ◽  
Author(s):  
Bo Zhao ◽  
Jin Xue Xue ◽  
M.L. Zhao
Keyword(s):  
Residual Stress ◽  
Tensile Stress ◽  
Ultrasonic Vibration ◽  
Residual Tensile Stress ◽  
Ceramic Surface ◽  
Composite Ceramics ◽  
Surface Residual Stress ◽  
Nano Composite ◽  
Ultrasonic Grinding ◽  
Grinding Conditions

The surface residual stress of nano-composite ceramics prepared by mixed coherence system and machined both in ordinary grinding(OG) and ultrasonic vibration grinding(TDUVG) respectively were described. Researches showed that the characteristics of residual stress on ceramic surface is affected by grinding load, ultrasonic vibration frequency and released stress induced by generation of cracks whose magnitude is affected by material removal mechanism. Whether in ordinary grinding or ultrasonic grinding, tangential residual stress (TRS) in X direction is tensile stress, and in Y direction is compressive stress. The surface residual tensile stress in ordinary grinding is larger than that in ultrasonic grinding with the same grinding conditions. The influences of multi-frequency on the residual stress are studied.

Test Research on the Surface Residual Stress of Dimensional Ultrasonic Vibration Grinding for Al2O3/ZrO2(n)

2011 ◽  
Vol 295-297 ◽  
pp. 78-82
Author(s):  
Yan Wu ◽  
Er Geng Zhang ◽  
Wen Zhong Nie
Keyword(s):  
Residual Stress ◽  
Tensile Stress ◽  
Ultrasonic Vibration ◽  
Ground Surface ◽  
Ductile Deformation ◽  
Grinding Wheel ◽  
Ceramic Surface ◽  
Two Dimensional ◽  
Surface Residual Stress ◽  
Xrd Diffraction

Based on the research for the structure of the ceramic nanocomposites’ intragranular for Al2O3/ZrO2(n)，we did the test by the workpiece two-dimensional vibration grinding(WTDUVG), and focus on analyzing the characteristic and the effect element of the two-dimensional ultrasonic vibration grinding ceramic surface residual stress by the XRD diffraction. The result show that ceramic dimensional ultrasonic vibration grinding surface tensile stress is less than the same conventional grinding (CG) surface under tensile stress; two-dimensional ultrasonic vibration grinding surface residual compressive stress than conventional ground surface residual stress under the same grinding. Material removal mechanism of the grinding nature of the surface residual stress, when the material removaled by ductile deformation, grinding surface equal residual stress; when the material removaled by brittle- ductile mixed mode, the grinding surface tensile stress reduced, because the fracture of the ground surface, tensile stress released. As a results, the grit size of grinding wheel, Grinding depth and workpiece mechanical properties are the main technology factors affected the nature and size of the residual stress of ground surface.

Research on Micro Characteristics of Surface and Subsurface Layer in Two-Dimensional Ultrasonic Grinding Nano-Composite Ceramics

2008 ◽  
Vol 375-376 ◽  
pp. 395-400 ◽  
Author(s):  
Bo Zhao ◽  
Guo Fu Gao ◽  
Yan Wu ◽  
Feng Jiao
Keyword(s):  
Ultrasonic Vibration ◽  
Fracture Behavior ◽  
Lattice Distortion ◽  
Ground Surface ◽  
Nano Materials ◽  
Two Dimensional ◽  
Composite Ceramics ◽  
Nano Composite ◽  
Ultrasonic Grinding ◽  
Deformation Layer

This work mainly studied the deterioration layer structure, crystal grain size, crystal lattice distortion of ground surface in two-dimensional ultrasonic vibration grinding nano-composite ceramics. The research indicated that under a certain grinding condition the ductile deformation layer on the ground surface of nano-composite ceramics in two-dimensional ultrasonic vibration grinding is formed by the ways of material powdering, crystal grain fragmentation, materials extrusion, the crystal grain pull-off and so on. The transition layer between the surface layer and the base body is plastic deformation layer by the primarily ways of crystal lattice distortion and the crystal boundary slipping. The removed material in brittleness fracture mode is extremely few. In this work, the structural model of deterioration layer on ground surface in two-dimensional ultrasonic grinding nano-composite ceramics is put forward. The microscopic deformation mechanism of nano materials is inner grain dislocation of inner-grain-structure strengthened phase. Its deformation coordination mechanism is the the grain-boundary sliding of matrix grain and the coordinated deformation of intercrystalline second-phase. The TEM and SEM observation discovers that the nano particles dispersed in grain boundary stops crack from expanding in nano materials, which causes the materials to appear in transcrystalline fracture behavior. And this fracture behavior gives materials favorable finished surface. The plastic deformation is the dominant removal mechanism of the nano materials in two-dimensional ultrasonic vibration grinding.

The Machined Surface Residual Stress of Nano-Ceramics with Two-Dimensional Ultrasonic Vibration Assisted Grinding

2010 ◽  
Vol 455 ◽  
pp. 637-642 ◽  
Author(s):  
X.Q. Zhang ◽  
Chong Yang Zhao ◽  
Bao Yu Du
Keyword(s):  
Residual Stress ◽  
Ultrasonic Vibration ◽  
Wear Particle ◽  
Surface Plastic Deformation ◽  
Work Piece ◽  
Surface Plastic ◽  
Two Dimensional ◽  
Surface Residual Stress ◽  
Machined Surface ◽  
Ultrasonic Grinding

Surface plastic deformation form and residual stress distribution of nano-ceramics machined by ordinary grinding and two-dimensional ultrasonic grinding respectively were investigated. The obtained results show that machined surface residual stress in the two grinding modes is extrusion stress, and it decreased with the increasing of grinding depth. But the decrease of residual stress under two-dimensional ultrasonic grinding is less than that under normal grinding. In addition, under the same grinding parameters, the surface residual stress on two-dimensional ultrasonic vibration grinding is larger than that on ordinary grinding, and if other parameters unchanged, it is increased with the increase of wear particle granularity in the two grinding modes. It is produced by the reason that ductile regime of ceramic grinding become larger under ultrasonic grinding, so that material is still removed by plastic form at great depth. Plastic removal mode will produce greater surface extrusion stress, so with the increasing of grinding depth, the decreasing of residual stress under two-dimensional ultrasonic vibration grinding is less than that under the normal grinding. At the same time, the regular separating between wear particle and work piece improves the heat emission condition, which is also one of the reasons that the surface residual stress under two-dimensional ultrasonic grinding is larger than that under ordinary grinding.

Research on Surface Roughness of Nano-Composite Ceramics under Multi-Frequency Ultrasonic Grinding and Dressing

2011 ◽  
Vol 487 ◽  
pp. 443-446 ◽  
Author(s):  
Jin Xue Xue ◽  
Bo Zhao
Keyword(s):  
Surface Roughness ◽  
Ultrasonic Vibration ◽  
Vibration Frequency ◽  
Grinding Wheel ◽  
Composite Ceramics ◽  
Nano Composite ◽  
Diamond Grinding Wheel ◽  
Elliptical Vibration ◽  
Ultrasonic Grinding ◽  
Feeding Speed

The surface roughness of nano-composite ceramics machined by means of multi-frequency ultrasonic vibration grinding was investigated with the diamond grinding wheel dressed by elliptical vibration. The results indicate that the surface roughness is influenced by ultrasonic vibration frequency, feeding speed, grinding depth. The ultrasonic vibration frequency and the grinding depth are not the higher the better and there are suitable values. The surface roughness gets worse with the increase of feeding speed.

Experimental Study on Damage Mechanism of Nano-Ceramic Surface/Subsurface under Ultrasonic Vibration Aided Grinding

2011 ◽  
Vol 175 ◽  
pp. 107-111 ◽  
Author(s):  
Bo Zhao ◽  
Chong Yang Zhao ◽  
Bao Yu Du
Keyword(s):  
Ultrasonic Vibration ◽  
Damage Mechanism ◽  
Subsurface Damage ◽  
Ceramic Surface ◽  
Processing Efficiency ◽  
Ultrasonic Grinding ◽  
Force Direction ◽  
Grinding Conditions ◽  
Loading And Unloading ◽  
Ultrasonic Vibration Assisted Grinding

In this paper, surface/subsurface damage mechanism of engineering ceramics under ultrasonic vibration assisted grinding was studied by experiment based on its theoretical study. The study shows: under the same grinding conditions, ultrasonic grinding can realize plastic grinding and low crack damage surface grinding in a larger range of cutting depth than that under common grinding, that can improve processing efficiency and reduce workpiece grinding damage. Meanwhile, ultrasonic vibration grinding process can be seen as periodical loading and unloading process of abrasive on the workpiece. Crack is formed and extends initially on loading, the speed of crack expansion slows down, and its direction offsets to workpiece free surface on unloading as the change of ultrasonic force direction. So cracks can not expand to material deep and shallow sub-surface cracks are left in workpiece sub-surface layer. This phenomenon may be one of the main reasons that subsurface damage is reduced on ultrasonic grinding.

Research on the Effects of Ultrasonic Frequencies on the Grinding Surface Quality of Nano-Composite Ceramics

2010 ◽  
Vol 154-155 ◽  
pp. 1680-1683
Author(s):  
Hui Ma ◽  
Bo Zhao
Keyword(s):  
Phase Transition ◽  
Surface Quality ◽  
Ultrasonic Vibration ◽  
Abrasive Particle ◽  
Ultrasonic Frequency ◽  
Particle Removal ◽  
Composite Ceramics ◽  
Nano Composite ◽  
Ultrasonic Grinding

The effects of multiple ultrasonic frequencies on grinding surface quality of Al2O3-ZrO2 nano-composite ceramics are researched to provide optimization laws for ultrasonic grinding parameters. Some SEM photographs of ultrasonic grinding surface with different frequencies are provided to research the surface quality. The enhanced surface quality of ceramics with ultrasonic grinding is explained as the transition of single abrasive particle removal mode from brittle to ductile, which is resulted from the reduction of equivalent rigidity on surface under ultrasonic vibration. And this phenomenon becomes more evident as frequency increases. Through the XRD experiment, the phase transition from tetragonal phase t-ZrO2 to monoclinic phase m-ZrO2 becomes increasingly obvious by the action of ultrasonic vibration. The compressive stress generated during this phase transition can suppress the initiation and expansion of microcracks on the processing surface. The research shows that, the grinding surface quality with ultrasonic vibration is superior to that without ultrasonic vibration, and increasing ultrasonic frequency can contribute to the improvement of the surface quality.

A New Strengthening-Polishing Bearings Equipment Based on the Anti-Fatigue Manufacturing Technology

2011 ◽  
Vol 328-330 ◽  
pp. 2211-2214
Author(s):  
Hao Wang ◽  
Xiao Chu Liu ◽  
Chuan Jian Liu ◽  
Wen Xiong Li
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Tensile Stress ◽  
Field Testing ◽  
Manufacturing Technology ◽  
Residual Tensile Stress ◽  
Surface Residual Stress ◽  
Bearing Ring ◽  
Theoretical Design

Aimed to eliminate the harmful residual tensile stress produced on the surface of bearing ring in the conventional bearing processing and join the automatically strengthen and polished technology together, the paper provide a set of new strengthening-polishing bearings equipment, designed to effectively improve the bearing surface’s quality and produce the surface residual stress which can extend the bearing’s fatigue life. The prototype, based on the pre-theoretical design, has been successfully developed, and now is in field testing.

Coupled Thermal-Mechanical Analysis of CO2 Laser Irradiation on Fused Silica

2016 ◽  
Vol 1136 ◽  
pp. 531-536
Author(s):  
Run Qiang Li ◽  
Peng Yao ◽  
Hao Meng ◽  
Jun Wang ◽  
Ke Zhang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Tensile Stress ◽  
Laser Irradiation ◽  
Laser Energy ◽  
Viscoelastic Behavior ◽  
Mechanical Analysis ◽  
Fused Silica ◽  
Depth Of Cut ◽  
Residual Tensile Stress ◽  
Thermally Induced

To grind fused silica in ductile mode, it was proposed to repair surface and subsurface micro cracks of fused silica by CO2 laser irradiation. However, excessive residual stress remains on the surface because the melt fused silica on the surface quenches in air. It causes the critical depth of cut for ductile grinding fused silica to be smaller than 0.2μm. To investigate the distribution of the residual stress and look for an optimal manner of irradiation to control residual tensile stress, a numerical model of was built for simulating the dynamic behavior of fused silica when irradiated by CO2 laser. Laser energy absorption, heat transmission, viscoelastic behavior of fused silica and thermally induced stress were considered in the numerical simulation. The results show how the residual stress is formed and distributed. We found that an appropriate control of the temperature field as a function of time and position in the laser process is the key to reduce the residual stress. Therefore, three kinds of processes were proposed to reduce residual tensile stress on the surface of fused silica introduced by laser irradiation. The residual stress distributions of these three processes were compared by numerical analysis to decide a better method of laser irradiation.

Residual Stress Distribution in Pure Bending Beam Subjected to Tensile Failure on One Side

2006 ◽  
Vol 524-525 ◽  
pp. 253-258
Author(s):  
X.B. Wang
Keyword(s):  
Residual Stress ◽  
Tensile Strength ◽  
Stress Distribution ◽  
Tensile Stress ◽  
Strain Localization ◽  
Tensile Strain ◽  
Residual Stress Distribution ◽  
Neutral Axis ◽  
Residual Tensile Stress ◽  
Pure Bending

The stress distribution on the midsection of a pure bending beam where tensile strain localization band initiates on the tensile side of the beam and propagates within the beam is analyzed. Using the static equilibrium condition on the section of the midspan of the beam and the assumption of plane section as well as the linear softening constitutive relation beyond the tensile strength, the expressions for the length of tensile strain localization band and the distance from the tip of the band to the neutral axis are derived. After superimposing a linear unloading stress distribution over the initial stress distribution, the residual stress distribution on the midsection of the beam is investigated. In the process of strain localization band’s propagation, strain-softening behavior of the band occurs and neutral axis will shift. When the unloading moment is lower, the length of tensile strain localization band remains a constant since the stress on the base side of the beam is tensile stress. While, for larger unloading moment, with an increase of unloading moment, the length of tensile strain localization band decreases and the distance from the initial neutral axis to the unloading neutral axis increases. The neutral axis of midsection of the beam will shift in the unloading process. The present analysis is applicable to some metal materials and many quasi-brittle geomaterials (rocks and concrete, etc) in which tensile strength is lower than compressive strength. The present investigation is limited to the case of no real crack. Moreover, the present investigation is limited to the case that the length of strain localization band before unloading is less than half of depth of the beam. Otherwise, the residual tensile stress above the elastic neutral axis will be greater than the tensile strength, leading to the further development of tensile strain localization band in the unloading process.

Ultrasonic Vibration Grinding Test of Composite Ceramics Based on the Nonlocal Theory

2010 ◽  
Vol 126-128 ◽  
pp. 139-142
Author(s):  
Bo Zhao ◽  
Ping Xie ◽  
Chong Yang Zhao
Keyword(s):  
Surface Quality ◽  
Ultrasonic Vibration ◽  
Nonlocal Theory ◽  
Grinding Force ◽  
Ultrasonic Frequency ◽  
Composite Ceramics ◽  
Nano Composite ◽  
Better Than

The effects of ultrasonic frequency on the grinding force and surface quality were analyzed from the grinding experiment on ZTA nano-composite ceramics. The results indicate that, in the same parameters, ultrasonic normal grinding force is about 65 to 85 percents of the ordinary grinding condition, and the surface quality is better than that of ordinary grinding condition, as the frequency increasing, this trend will be more evident. The reasons for it were also discussed from microscopic and the nonlocal theory in this paper.

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