scholarly journals Forces prediction in micro-grinding single-crystal copper considering the crystallographic orientation

2018 ◽  
Vol 5 ◽  
pp. 15
Author(s):  
Man Zhao ◽  
Xia Ji ◽  
Beizhi Li ◽  
Steven Y. Liang
Keyword(s):  
Flow Stress ◽  
Single Crystal ◽  
Crystallographic Orientation ◽  
Factor Model ◽  
Taylor Factor ◽  
Force Model ◽  
Stress Model ◽  
Single Crystal Copper ◽  
Accuracy Of Prediction ◽  
Flow Stress Model

In the micro-grinding of single-crystal copper, the effect of crystallography becomes significant as the wheel works intra-crystalline. To quantify the effect of crystallographic orientation (CO) related to the cutting direction on the micro-grinding process, this article presents a Taylor factor model by examining the number and style of activated slip systems. Then, the flow stress model of monocrystalline material is developed considering the variation of the Taylor factor. Furthermore, the models of chip formation and rubbing forces are derived from the flow stress model, while the plowing force is predicted by the Vickers hardness. Then, the overall grinding force model of the whole wheel is developed by incorporating the process parameters and the wheel properties. Finally, micro-grinding experiments are conducted to verify the model, using only the Taylor factor as the variable. The proposed analysis is also compared with the previously reported model, which considers the Taylor factor as a constant of 3.06. The comparison between the two predictions and experimental data shows that the consideration of Taylor factor variability improves the accuracy of prediction.

Influence of AA7075 crystallographic orientation on micro-grinding force

2018 ◽  
Vol 233 (8) ◽  
pp. 1831-1843 ◽  
Author(s):  
Man Zhao ◽  
Xia Ji ◽  
Steven Y Liang
Keyword(s):  
Flow Stress ◽  
Crystallographic Orientation ◽  
Factor Model ◽  
Grinding Force ◽  
Taylor Factor ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Force Model ◽  
Workpiece Material ◽  
Flow Stress Model

In micro-grinding, the depth of cut is smaller than the grain size of workpiece material. Since the micro-grinding wheel cuts through the grain boundaries, the crystallographic effects become more significant in the micro-grinding than that in macro-machining. To quantify the effect of crystallographic orientation on the flow stress of polycrystalline material, the Taylor factor model is developed by examining the number and type of the activated slip systems. Then, the shear force model is developed based on the flow stress model considering the effect of crystallographic orientation. Moreover, the plowing force is predicted based on the Vickers hardness of workpiece material and the plowing friction coefficient. A comprehensive model is then proposed to predict micro-grinding force by consolidating the mechanical, thermal, crystallographic, and size effect. Micro-grinding experiments adopting Taguchi’s method were conducted to verify the model, and the results indicated that the predictions agree well with the experimental data. Besides, single-factorial experiments were conducted with the only variable being Taylor factor and the results suggest that the Taylor factor model is capable of capturing the effect of crystallographic orientation on grinding force.

Effect of crystallographic orientation on the hardness of polycrystalline materials AA7075

2018 ◽  
Vol 233 (9) ◽  
pp. 3182-3192
Author(s):  
Man Zhao ◽  
Xia Ji ◽  
Beizhi Li ◽  
Steven Y Liang
Keyword(s):  
Experimental Data ◽  
Flow Stress ◽  
Vickers Hardness ◽  
Crystallographic Orientation ◽  
Factor Model ◽  
Taylor Factor ◽  
Polycrystalline Materials ◽  
Compression Tests ◽  
Micro Hardness ◽  
Model Compression

As one of the most important properties of materials, micro-hardness is influenced by material microstructure significantly. The reported data show that the micro-hardness of materials varies with the variation of crystallographic orientation. This paper presents an analytical model to quantify the effect of crystallographic orientation on micro-hardness by analyzing the mechanical behavior in the test of Vickers hardness. The plastic deformation occurs under the micro-indentation with the flow stress affected significantly by crystallographic orientation of material. This paper develops a Taylor factor model to quantify the effect of crystallographic orientation on the flow stress of polycrystalline materials, by examining the number and the style of activated slip systems. Considering the linear relationship between the flow stress and Vickers hardness, the effect of crystallographic orientation on the Vickers hardness is established. To verify the Taylor factor model, compression tests and Vickers hardness tests were conducted. The result shows that the predictions coincided with the experimental data, which suggests that the model considering the variation of crystallographic orientation is accurate and the Taylor factor model is reasonable. To analyze the sensitivity of flow stress and Vickers hardness to CO, this paper also predicted flow stress and hardness using models without considering the variability of Taylor factor and the athernal stress. The three predictions were compared with the experimental data, and the results proved that the model considering the variability Taylor factor improves flow stress and accuracy of hardness models.

Hot Forming Flow Stress Model of Steel 50A1300

2012 ◽  
Vol 446-449 ◽  
pp. 3591-3595
Author(s):  
Xu Dong Zhou ◽  
Xiang Ru Liu ◽  
Xu Yi Shan
Keyword(s):  
Flow Stress ◽  
Hot Forming ◽  
Stress Model ◽  
Flow Stress Model

Study on High Temperature Flow Stress Model of As-cast SA508-3 Low Alloy Steel

2020 ◽  
Vol 831 ◽  
pp. 25-31
Author(s):  
Pan Fei Fan ◽  
Jian Sheng Liu ◽  
Hong Ping An ◽  
Li Li Liu
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Strain Rate ◽  
Alloy Steel ◽  
Flow Behavior ◽  
Peak Stress ◽  
Stress Model ◽  
Low Alloy Steel ◽  
Two Stage ◽  
Flow Stress Model

In order to obtain the high temperature flow behavior of as-cast SA508-3 low alloy steel, the stress-strain curves of steel are obtained by Gleeble thermal simulation compression test at deformation temperature 800°C-1200°C and strain rate 0.001s-1-1s-1. Based on Laasraoui two-stage flow stress model, a high temperature flow stress model is established by multiple linear regression method. The results show that the peak stress characteristics are not obvious at low temperature and high strain rate, which is a typical dynamic recovery characteristic. Meanwhile, the peak stress characteristics are obvious at high temperature and low strain rate, which is a typical dynamic recrystallization characteristic. By means of the comparisons between experiments and calculations, the Laasraoui two-stage flow stress model can truly reflect flow behavior of steel at high temperature, which provides theoretical guidance for the hot deformation of the steel.

scholarly journals Johnson Cook Material and Failure Model Parameters Estimation of AISI-1045 Medium Carbon Steel for Metal Forming Applications

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 609 ◽  
Author(s):  
Mohanraj Murugesan ◽  
Dong Jung
Keyword(s):  
Flow Stress ◽  
Metal Forming ◽  
Flow Behavior ◽  
Medium Carbon Steel ◽  
Material Behavior ◽  
Model Parameters ◽  
Stress Model ◽  
Medium Carbon ◽  
Aisi 1045 ◽  
Flow Stress Model

Consistent and reasonable characterization of the material behavior under the coupled effects of strain, strain rate and temperature on the material flow stress is remarkably crucial in order to design as well as optimize the process parameters in the metal forming industrial practice. The objective of this work was to formulate an appropriate flow stress model to characterize the flow behavior of AISI-1045 medium carbon steel over a practical range of deformation temperatures (650–950 ∘ C) and strain rates (0.05–1.0 s − 1 ). Subsequently, the Johnson-Cook flow stress model was adopted for modeling and predicting the material flow behavior at elevated temperatures. Furthermore, surrogate models were developed based on the constitutive relations, and the model constants were estimated using the experimental results. As a result, the constitutive flow stress model was formed and the constructed model was examined systematically against experimental data by both numerical and graphical validations. In addition, to predict the material damage behavior, the failure model proposed by Johnson and Cook was used, and to determine the model parameters, seven different specimens, including flat, smooth round bars and pre-notched specimens, were tested at room temperature under quasi strain rate conditions. From the results, it can be seen that the developed model over predicts the material behavior at a low temperature for all strain rates. However, overall, the developed model can produce a fairly accurate and precise estimation of flow behavior with good correlation to the experimental data under high temperature conditions. Furthermore, the damage model parameters estimated in this research can be used to model the metal forming simulations, and valuable prediction results for the work material can be achieved.

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