Experimental Research on the Relationship between Surface Polishing and Fracture Strength for Ground Ceramics

2013 ◽  
Vol 770 ◽  
pp. 433-436
Author(s):  
Xin Li Tian ◽  
Jian Quan Wang ◽  
Bao Guo Zhang ◽  
Peng Xiao Wang
Keyword(s):  
Residual Stress ◽  
Fracture Strength ◽  
Ground Surface ◽  
Residual Tensile Stress ◽  
Residual Stress Field ◽  
Polishing Process ◽  
Machined Surface ◽  
X Ray ◽  
Surface Polishing ◽  
The Relationship

Fracture strength is one of the key mechanics performances for engineering ceramics products, greatly influenced by the microscopic topography and residual stress field of ground surface. In this work, several testing equipments, such as the metallurgical microscope, surface profiler and X ray residual stress tester were introduced to investigate the relationships between microscopic topography, surface roughness, residual stress and fracture strength of ground ceramics, after the surface grinding and mechanical polishing. The experimental results show that a smoother machined surface with low roughness and residual stress is obtained through polishing with absolute alcohol for 20 minutes; the fracture strength of Si3N4SiC and Al2O3 are increased by 6.64%8.18% and 6.58% respectively, comparing to the ceramics without polishing; the surface stress concentration and residual tensile stress of polished ceramics are both reduced after an appropriate time of polishing process, which causes a certain improvement of ground fracture strength.

X-ray diffraction at constant penetration depth – a viable approach for characterizing steep residual stress gradients

2008 ◽  
Vol 41 (2) ◽  
pp. 377-385 ◽  
Author(s):  
Thomas Erbacher ◽  
Alexander Wanner ◽  
Tilmann Beck ◽  
Otmar Vöhringer
Keyword(s):  
Residual Stress ◽  
Penetration Depth ◽  
Ground Surface ◽  
Shear Stresses ◽  
X Rays ◽  
X Ray Diffraction ◽  
Machined Surface ◽  
Near Surface ◽  
X Ray ◽  
Surface Residual Stresses

The experimental analysis of near-surface residual stresses by X-ray diffraction methods is based on measuring the spacings of lattice planes while the inclination ψ with respect to the surface plane is changed stepwise. A characteristic feature of conventional techniques is that the penetration depth of the X-rays is altered as inclination is varied. By simultaneously varying three different goniometer angles in a particular fashion, both the penetration depth and the measuring direction can be held constant while ψ is varied. Thus the normal and shear stresses can be derived from the sin2ψ plots by means of standard evaluation procedures developed for gradient-free stress states. The depth profile of residual stress is then obtainedviaLaplace transformation of the results from several stress measurements carried out at different penetration depths. In the present paper, the feasibility of this experimental approach for characterizing the strongly graded, non-equiaxed stress state existing at a machined surface is demonstrated. The results from constant-penetration-depth measurements on the ground surface of an engineering ceramic are compared with those from conventional sin2ψ measurements.

Simulation and Experiment on the Residual Stress in Super-High Speed Grinding

2010 ◽  
Vol 135 ◽  
pp. 238-242
Author(s):  
Yue Ming Liu ◽  
Ya Dong Gong ◽  
Wei Ding ◽  
Ting Chao Han
Keyword(s):  
Residual Stress ◽  
High Speed ◽  
Element Model ◽  
Residual Stress Distribution ◽  
X Ray Diffraction ◽  
Machined Surface ◽  
X Ray ◽  
High Speed Grinding ◽  
Simulation And Experiment ◽  
Cylindrical Workpiece

In this paper, effective finite element model have been developed to simulation the plastic deformation cutting in the process for a single particle via the software of ABAQUS, observing the residual stress distribution in the machined surface, the experiment of grinding cylindrical workpiece has been brought in the test of super-high speed grinding, researching the residual stress under the machined surface by the method of X-ray diffraction, which can explore the different stresses from different super-high speed in actual, and help to analyze the means of reducing the residual stresses in theory.

Measurement of Residual Stress Distribution of Ground Silicon Nitride by Glancing Incidence X-ray Diffraction Technique

1995 ◽  
Vol 39 ◽  
pp. 331-338
Author(s):  
Yoshihisa Sakaida ◽  
Keisuke Tanaka ◽  
Shintaro Harada
Keyword(s):  
Residual Stress ◽  
Surface Layer ◽  
Stress Distribution ◽  
Stress Measurement ◽  
Scintillation Counter ◽  
Ground Surface ◽  
Residual Stress Distribution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Very High

A new method of X-ray stress measurement was proposed to estimate non-destructively the steep residual stress distribution in the surface layer of ground Si3N4. We assumed an exponential decrement of the residual stress near the ground surface, and derived a formula for the lattice strain as a function of sin2Ψ. In the experiments, the diffraction angles were measured on the ground surface for a widest possible range of sin2ѱ using an Ω-goniometer. In order to measure the diffraction angle at very high sin η values, a scintillation counter was located on the -η side and an incident X-ray beam impinged on the ground surface with a very low angle from the +η side using the glancing incidence X-ray diffraction technique. A strong non-linearity was found in the 20-sin2ѱ diagrams especially at very high ѱ -angles. From the analysis of non-linearity, the stress distribution in the surface layer was determined. Tine residual stress took the maximum compression of 2 GPa at a depth of about 0.5 μm from the surface, and then diminished to zero at about 25 μm in depth. In the close vicinity of the ground surface, the compressive residual stress was relieved because of both the surface roughness and microcracking induced during the grinding process.

Comparison of the hole-drilling and X-ray diffraction methods for measuring the residual stresses in shot-peened aluminium alloys

2005 ◽  
Vol 40 (2) ◽  
pp. 199-209 ◽  
Author(s):  
V Fontanari ◽  
F Frendo ◽  
Th Bortolamedi ◽  
P Scardi
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Surface Layer ◽  
Hole Drilling ◽  
X Ray Diffraction ◽  
Residual Stress Field ◽  
X Ray ◽  
Sources Of Uncertainty ◽  
Stress Profiles ◽  
Good Agreement

The incremental blind hole-drilling and the X-ray diffraction methods were used to measure the residual stress field introduced by shot peening in aluminium alloy 6082-T5 plates. Two peening treatments were selected to produce different depth extensions and peak values arising from different extents of plastic deformation in the surface layer. The results are discussed considering the various sources of uncertainty; in addition to the measuring technique, the effects of the surface treatment that usually induces a strong plastic deformation in the surface layer resulting in material work hardening and worsening of the surface morphology were considered. The residual stress profiles determined by the two methods showed quite good agreement for the two conditions, as regards the values both of the compressive peak and of the penetration depth. The present results provide mutual confirmation of the effectiveness of the two methods for the study of this class of materials.

Study on Pre-Stress Cutting of Bearing Race and Its Machined Surface State

2006 ◽  
Vol 532-533 ◽  
pp. 528-531 ◽  
Author(s):  
Bang Yan Ye ◽  
Bo Wu ◽  
Jian Ping Liu ◽  
Xiao Chu Liu ◽  
Xue Zhi Zhao
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Compressive Stress ◽  
Contact Fatigue ◽  
Residual Compressive Stress ◽  
Residual Tensile Stress ◽  
Machined Surface ◽  
Residual Stress State ◽  
Bearing Race ◽  
Hard Cutting

Theoretical analysis and experiments on bearing race show that a suitable residual compressive stress on roll path of bearing race can prolong its contact fatigue life. However, residual tensile stress is often found on workpiece surface of bearing race. To actively control the residual stress state and improve fatigue life of bearing part, a new method of pre-stress hard cutting is applied. In this paper, the principle of pre-stress hard cutting for bearing race is introduced as well as the experiments on it. In the experiments, residual stress, hardness and roughness of machined surface are measured and analyzed. Moreover, micro-topography and texture characteristics of machined surface are investigated and experimental results are compared with that by grinding. It is found that we can get residual compressive stress and fine quality on machined surface of bearing race by pre-stress hard cutting and increase its productivity as well.

Study on Residual Stress for High-Speed Cutting Titanium Alloy Based on Finite Element Method

2011 ◽  
Vol 188 ◽  
pp. 216-219 ◽  
Author(s):  
M.H. Wang ◽  
Zhong Hai Liu ◽  
Hu Jun Wang
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Titanium Alloy ◽  
High Speed ◽  
Cutting Speed ◽  
Simulation Method ◽  
Residual Tensile Stress ◽  
Cutting Depth ◽  
Machined Surface ◽  
High Speed Cutting

In order to improve machined surface quality and reduce the deformation, the residual stress involved in cutting titanium alloy was studied under different cutting speed and cutting depth by finite element simulation method. The results indicate that the increase of cutting speed and cutting depth are helpful to the surface residual compressive stress generating. However the increase of cutting speed also leads to the increase of surface residual tensile stress, the effect degree is relatively small. It is required to select higher cutting speed and smaller cutting depth to improve the surface stress state and reduce the unexpected distortion.

Measurement of Residual Hoop Stresses in Cylinders Using the Compliance Method

1986 ◽  
Vol 108 (2) ◽  
pp. 87-92 ◽  
Author(s):  
Weili Cheng ◽  
Iain Finnie
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Hoop Stress ◽  
Axial Stress ◽  
Hole Drilling ◽  
Residual Stress Field ◽  
Axial Coordinate ◽  
X Ray ◽  
Axial Crack ◽  
Hoop Stresses

A method is proposed for measurement of the hoop stress in an axisymmetric residual stress field in cylinders in which the axial stress is independent of the axial coordinate. The method involves measuring strains at the outside surface while an axial crack is cut progressively from the outside. Experimental results are presented for two short cylindrical rings cut from a long quenched cylinder. Good general agreement is obtained with X-ray and hole drilling measurements of residual stresses.

Further Research Into Wheel Rim Axial Residual Stress and Vertical Split Rim Failures

2012 ◽  
Author(s):  
Cameron Lonsdale ◽  
John Oliver
Keyword(s):  
Residual Stress ◽  
Tensile Stress ◽  
Stress Profile ◽  
Residual Tensile Stress ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wheel Rim ◽  
Axial Tensile ◽  
Axial Residual Stress ◽  
Class C

Recent work using x-ray diffraction techniques has shown that the axial residual stress pattern within the railroad wheel rim is significantly different for as-manufactured AAR Class C wheels vs. AAR Class C wheels that have failed due to a vertical split rim (VSR), and non-failed AAR Class C wheels that have been operating in service. VSRs almost always begin at areas of tread damage, resulting from shelling or spalling, and cracking propagates into the rim section under load. At the locations tested, the as-manufactured wheels have a relatively “flat” axial residual stress profile, compressive but near neutral, caused by the rim quenching operation, while wheels that have been in service have a layer of high axial compressive stress at the tread surface, and a balancing zone of axial tensile stress underneath. The magnitude and direction of this tensile stress is consistent with the crack propagation of a VSR failure. When cracks from the tread surface propagate into this sub-surface axial tensile zone, a VSR can occur under sufficient additional service loading, such as loads caused by in-service wheel/rail impacts from tread damage. Further, softer Class U wheels, removed from service and tested, were found to have a balancing axial tensile stress layer that is deeper below the tread surface than that found in used Class C wheels. This paper describes further efforts to characterize the axial residual stress present in failed VSR and used Class C wheels. Axial residual stress results are obtained near the initiation point of several VSR wheels using x-ray diffraction. Sub-surface axial residual stress patterns are also determined at points of high out-of-roundness for a group of wheels that were tested for TIR (total indicated runout) on the tread surface. Residual stress data and a photo are presented for a wheel rim slice containing a second VSR crack. Additionally, wheel rim ultrasonic testing data, collected by the wheel manufacturer when the wheels were new, are discussed for wheels that have failed due to VSRs and these data are compared to ultrasonic data for non-VSR wheels. Chemistry data are also compared. These data show that the driving force for VSRs is axial residual tensile stress, not a material cleanliness issue.

Investigation on Machined Surface Quality During Cutting of GH4169 Under High-Pressure Cooling

2020 ◽  
Vol 12 (7) ◽  
pp. 994-1003
Author(s):  
Ming-Yang Wu ◽  
Wei-Xu Chu ◽  
Ke-Ke Liu ◽  
Shu-Jie Wu ◽  
Yao-Nan Cheng
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
High Pressure ◽  
Tensile Stress ◽  
Surface Quality ◽  
Work Hardening ◽  
Surface Plastic ◽  
Residual Tensile Stress ◽  
Machined Surface ◽  
Machined Surface Quality

The aerospace component material GH4169 has low thermal conductivity and poor machinability, resulting in difficulty to guarantee good surface quality after conventional cutting. High-pressure cooling assisted machining technology can effectively improve the problem. In order to study the effect of high-pressure cooling assisted processing technology on the machined surface quality of GH4169, in this paper, Deform-3D was first used to construct a thermo-mechanical coupling finite element model for turning GH4169 under high-pressure cooling conditions, to analyze the turning temperature and surface residual stress. Then, analysis was carried out on the residual stress, work hardening behavior, and metamorphic layer of the GH4169 machined surface, in combination with the turning experiment. The results show that, under the conditions of little feeding and highspeed cutting, the GH4169 turning surface generates residual tensile stress along with both the feeding and turning directions. Moreover, the residual tensile stress gradually turns into the residual compressive stress along the depth direction. The application of high-pressure coolant can reduce the residual tensile stress of the machined surface. As the cooling pressure increases, the residual tensile stress of the machined surface decreases. The coupling effect between thermal deformation and plastic deformation when turning GH4169 can cause the work hardening of the surface, and the hardening degree decreases with the increase of cooling pressure. The high-pressure cooling assisted machining technology can effectively reduce surface plastic deformation, and promote the lessening of grain refinement degree of the material surface, thereby reducing the thickness of the metamorphic layer.

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