Effect of Surface Relaxation on Characteristics of Nanomachined Surface

2011 ◽  
Vol 211-212 ◽  
pp. 742-746
Author(s):  
Yu Lan Tang ◽  
Ya Ting He ◽  
Guo Zhi Liu ◽  
Jing Xiang Fu ◽  
Hong Sun ◽  
...  
Keyword(s):  
Residual Stress ◽  
Surface Energy ◽  
Mechanical Systems ◽  
Surface Hardness ◽  
Surface Relaxation ◽  
Surface Residual Stress ◽  
Machined Surface ◽  
Micro Electro Mechanical Systems ◽  
Machined Parts ◽  
Effect Of Surface

With the development of Micro-electro-mechanical systems (MEMS) and Nano-electro-mechanical systems (NEMS), dimension of their parts is required to nanometer scale, and the characteristics of machined-surface of nano-scale parts affect strongly its application. Surface relaxation plays an important role to the characteristics of the machined-surface. In this paper, machined-surface of monocrystal copper used as the specimen of surface relaxation, and its surface relaxation process is simulated. The influences of surface relaxation on surface energy, atom array, surface roughness, surfaces hardness and surface residual stress of the monocrystal copper are analyzed. Results show that surface energy and surface hardness decrease due to relaxation; work-hardening can’t be completely eliminated by the relaxation; compression residual stress of the machined surface is changed gradually to tensile stress during the relaxation. These research results are very helpful to the application of nano-machined parts.

A Hybrid Neural Network for Prediction of Surface Residual Stress in MQL Face Turning

2014 ◽  
Vol 633-634 ◽  
pp. 574-578 ◽  
Author(s):  
Xia Ji ◽  
Alexander H. Shih ◽  
Manik Rajora ◽  
Ya Min Shao ◽  
Steven Y. Liang
Keyword(s):  
Neural Network ◽  
Residual Stress ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Tool Geometry ◽  
Surface Residual Stress ◽  
Machined Surface ◽  
Hybrid Neural Network ◽  
Marquardt Algorithm ◽  
Machined Parts

Surface integrity, such as surface roughness and residual stress, is an aspect of surface quality on machined parts. Residual stress in the machined surface and subsurface is affected by materials, machining conditions, and tool geometry. These residual stresses could affect the service qualify and component life significantly. Residual stress can be determined by empirical or numerical experiments for selected configurations, even if both are expensive procedures. This paper presents a hybrid neural network that is trained using Simulated Annealing (SA) and Levenberg-Marquardt Algorithm (LM) in order to predict the values of residual stresses in cutting and radial direction after the MQL face turning process accurately. To verify the performance of the proposed approach, the predicted results are compared with the results obtained by training an ANN using SA and LM separately. The results have shown that the hybrid neural network outperforms SA and LM in predicting machining induced surface integrity that is critical to determine the fatigue life of the components.

Effect of Milling Speed and Feed on Surface Residual Stress of 7050-T7451 Aluminum Alloy

2012 ◽  
Vol 499 ◽  
pp. 217-222 ◽  
Author(s):  
C. Li ◽  
Yi Wan ◽  
R.R. Zhang ◽  
Zhan Qiang Liu
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Cutting Speed ◽  
Diffraction Method ◽  
Cutting Condition ◽  
Feed Speed ◽  
X Ray Diffraction ◽  
Surface Residual Stress ◽  
Orthogonal Direction ◽  
Machined Surface

The residual stress in the milling of 7050-T7451 aluminum alloy was measured using X-ray diffraction method in which Psi-oscillation, Phi-oscillation and peak fit were adopted. Cutting speed and feed are main variables which were considered in this study. The results show that compressive residual stresses are generated in surface for the down milling generally, which is mainly due to burnishing effect between the tools flank face and the machined surface. In feed and its orthogonal direction, the effect of cutting speed and feed speed on residual stress is similar. Therefore, required residual stress can be achieved by controlling the cutting condition such as cutting speed, feed speed etc.

Pull-In Instability of Functionally Graded Cantilever Nanoactuators Incorporating Effects of Microstructure, Surface Energy and Intermolecular Forces

2018 ◽  
Vol 10 (08) ◽  
pp. 1850091 ◽  
Author(s):  
Mohamed A. Attia ◽  
Salwa A. Mohamed
Keyword(s):  
Residual Stress ◽  
Surface Energy ◽  
Boundary Conditions ◽  
Van Der Waals ◽  
Surface Elasticity ◽  
Van Der Waals Forces ◽  
Functionally Graded ◽  
Surface Residual Stress ◽  
Electrically Actuated ◽  
Classical Boundary

In this paper, an integrated non-classical continuum model is developed to investigate the pull-in instability of electrostatically actuated functionally graded nanocantilevers. The model accounts for the simultaneous effects of local-microstructure, surface elasticity and surface residual in the presence of fringing field as well as Casimir and van der Waals forces. The modified couple stress and Gurtin–Murdoch surface elasticity theories are employed to conduct the scaling effects of microstructure and surface energy, respectively, in the context of Euler–Bernoulli beam hypothesis. Bulk and surface material properties are varied according to the power-law distribution through the beam thickness. The physical neutral axis position for mentioned FG nanobeams is considered. Hamilton principle is employed to derive the nonlinear size-dependent governing equations and the non-classical boundary conditions. The resulting nonlinear differential equations are solved utilizing the generalized differential quadrature method (GDQM). In addition, the non-classical boundary conditions of nanocantilever beams due to surface residual stress are exactly implemented. After validation of the obtained results by previously available data in the literature, the influences of different geometrical and material parameters on the pull-in instability of the FG nanocantilevers are examined in detail. It is concluded that the pull-in behavior of electrically actuated FG micro/nanocantilevers is significantly influenced by the material distribution, material length scale parameter, surface elasticity constant, surface residual stress, initial gap, slenderness ratio, Casimir, and van der Waals forces. The obtained results can be considered for modeling and analysis of electrically actuated FG nanocantilevers.

Investigation into Influence of Cutting Fluid and Liquid Nitrogen on Machined Surface Residual Stress

2012 ◽  
Vol 566 ◽  
pp. 7-10 ◽  
Author(s):  
Meng Yang Qin ◽  
Bang Yan Ye ◽  
Bo Wu
Keyword(s):  
Residual Stress ◽  
Liquid Nitrogen ◽  
Cutting Fluid ◽  
Rough Machining ◽  
Surface Residual Stress ◽  
Dry Cutting ◽  
Machined Surface ◽  
Residual Stress State ◽  
Aisi 1045 Steel ◽  
1045 Steel

This paper gives the details of turning experiments on AISI 1045 steel by using various cutting fluid and liquid nitrogen condition. Residual stress on machined surface is generated in rough machining and fine machining with different rounded cutting edge radius. The effects of cutting fluid and liquid nitrogen on residual stress state are obtained by compared with dry cutting. Experimental results show that cutting fluid and liquid nitrogen have influence on machined residual stressl and liquid nitrogen generates residual compressive stress in all specimens.

Effects of Residual Stresses on the High Cycle Fatigue Behavior of Ti-6Al-4V

2010 ◽  
Author(s):  
Yu-Jia Li ◽  
Fu-Zhen Xuan ◽  
Zheng-Dong Wang ◽  
Shan-Tung Tu
Keyword(s):  
Residual Stress ◽  
Fatigue Limit ◽  
Stress Ratio ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
X Ray Diffraction ◽  
Surface Residual Stress ◽  
Manufacturing Techniques ◽  
Stress Ratios ◽  
Effect Of Surface

Axial force-controlled fatigue tests are conducted at various stress ratios (R) on Ti-6Al-4V specimens prepared by two different manufacturing techniques (hard turning plus polishing with and without vacuum stress relieve anneal carried out after polishing). Residual stress is measured by using X-ray diffraction. Results indicate that the surface compressive residual stress lead to an increase of fatigue limit at a given life and stress ratio. This effect decreases with increasing stress ratio R. At R = 0.6, the effect of surface residual stress on fatigue limit fades away. In addition, the location of crack initiation shifts from surface to interior when the stress ratio changes from −1 to 0.6.

The Influence of Surface Residual Stress on Fatigue Limit of Titanium

1960 ◽  
Vol 82 (1) ◽  
pp. 76-78 ◽  
Author(s):  
E. C. Reed ◽  
J. A. Viens
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Fatigue Limit ◽  
Experimental Error ◽  
Endurance Limit ◽  
Simple Equation ◽  
Surface Residual Stress ◽  
A Value ◽  
Effect Of Surface

Investigation of the effect of surface residual stress on the endurance limit of 6Al 4V titanium alloy shows that this effect is equal within experimental error to the residual stress divided by a constant. Results can be expressed by a simple equation. A value for the constant has been derived.

Investigation on surface residual stress distribution and evaluation of engineering ceramics in rotary ultrasonic grinding machining

2016 ◽  
Vol 231 (15) ◽  
pp. 2773-2782 ◽  
Author(s):  
SL Wei ◽  
H Zhao ◽  
JT Jing ◽  
FH Yun ◽  
XL Li
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Stress Tolerance ◽  
Surface Integrity ◽  
Residual Stress Distribution ◽  
Distribution Model ◽  
Surface Residual Stress ◽  
Machined Surface ◽  
Engineering Ceramics ◽  
Ultrasonic Grinding

Residual stress of engineering ceramics is one of surface integrity evaluation indexes affecting the parts’ strength properties. Rotary ultrasonic grinding machining is the most powerful machining method for engineering ceramics with better surface integrity. The residual stress field distribution is changed due to micro cracks which are inevitable in the process. A residual stress distribution model of machined surface micro crack tip has been established in the paper. And the experimental results enable us to obtain surface residual stress distribution of engineering ceramics in rotary ultrasonic grinding machining. Then, we propose an evaluation parameter called confidence stress tolerance to evaluate surface residual stress characteristic. Preliminary results indicate that surface residual stress distribution is in line with the normal distribution. Confidence stress tolerance is an effective parameter to improve the evaluation reliability. Furthermore, precision and affecting factors of confidence stress tolerance evaluation have also been investigated.

Local Residual Stress Distribution at the Tooth Root Surface of a Broached Steel Component

2012 ◽  
Vol 706-709 ◽  
pp. 1731-1736 ◽  
Author(s):  
Tobias Strauss ◽  
Harald Meier ◽  
Jens Gibmeier ◽  
Volker Schulze ◽  
Alexander Wanner
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Cutting Forces ◽  
Cutting Speed ◽  
Surface Hardness ◽  
Case Hardening ◽  
Dry Cutting ◽  
Machined Surface ◽  
Near Surface ◽  
Case Hardening Steel

Broaching is an important technique for creating tooth structures in mechanical components. In the present work, the effects of the broaching process on the material state in the near surface region at the root of the tooth was analyzed. The studies were carried out on broached plates made from case hardening steel SAE 5120. The cutting speed and machining condition (cooling lubricant, dry machining) were varied. During broaching with a TiAlN coated tool the cutting forces were monitored. Subsequently, the local residual stresses at the root of the tooth were determined using X-ray diffraction. Further, surface roughness and micro hardness measurements as well as microstructure analysis complement the results. The results indicate that cutting forces have a high influence on the development of the residual stress state at the machined surface whereas no significant effect on changes in surface hardness and microstructure could be observed. Dry cutting with relatively high cutting speeds (≥ 30m/min) result in low cutting forces and hence in high tensile residual stresses in broaching direction.

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