Chip Segmentation in Machining: A Study of Deformation Localization Characteristics in Ti6Al4V

2013 ◽  
Author(s):  
Abhijit Chandra ◽  
Pavan Karra ◽  
Adam Bragg ◽  
Jie Wang ◽  
Gap Yong Kim
Keyword(s):  
Shear Band ◽  
Shear Bands ◽  
Shear Plane ◽  
Time Varying ◽  
State Variables ◽  
Dynamics Model ◽  
Deformation Localization ◽  
Additional State ◽  
Nonlinear Dynamics Model ◽  
Band Spacing

Chip segmentation by deformation localization is an important process in a certain range of velocities and might be desirable in reducing cutting forces and by improving chips’ evacuation, whereas few studies of practical criteria to calculate shear band spacing are available in literature. This paper extends nonlinear dynamics model for chip segmentation by allowing time varying orientation of the shear plane that are pronounced in strain hardening materials. The model extends the non-linear dynamics approach with additional state variables to the Burns and Davies approach. The model is simulated numerically to predict the shear bands of the chip. The numerical simulation of the model is compared with experimental observations and is in agreement with experimental observations in Ti6Al4V. This offers guidance to predict shear band spacing of other materials.

scholarly journals Effect of Cold Rolling on the Evolution of Shear Bands and Nanoindentation Hardness in Zr41.2Ti13.8Cu12.5Ni10Be22.5 Bulk Metallic Glass

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1670
Author(s):  
Abhilash Gunti ◽  
Parijat Pallab Jana ◽  
Min-Ha Lee ◽  
Jayanta Das
Keyword(s):  
Shear Band ◽  
Metallic Glass ◽  
Cold Rolling ◽  
Bulk Metallic Glass ◽  
Shear Bands ◽  
Three Dimensional ◽  
Peak Loads ◽  
Nanoindentation Hardness ◽  
Band Spacing ◽  
Calorimetric Studies

The effect of cold rolling on the evolution of hardness (H) and Young’s modulus (E) on the rolling-width (RW), normal-rolling (NR), and normal-width (NW) planes in Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vitreloy 1) bulk metallic glass (BMG) was investigated systematically using nanoindentation at peak loads in the range of 50 mN–500 mN. The hardness at specimen surface varied with cold rolling percentage (%) and the variation is similar on RW and NR planes at all the different peak loads, whereas the same is insignificant for the core region of the specimen on the NW plane. Three-dimensional (3D) optical surface profilometry studies on the NR plane suggest that the shear band spacing decreases and shear band offset height increases with the increase of cold rolling extent. Meanwhile, the number of the pop-in events during loading for all the planes reduces with the increase of cold rolling extent pointing to more homogeneous deformation upon rolling. Calorimetric studies were performed to correlate the net free volume content and hardness in the differently cold rolled specimens.

scholarly journals CHARACTERIZATION OF SHEAR BANDS IN TWO BULK METALLIC GLASSES WITH DIFFERENT INHERENT PLASTICITY

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1217-1222 ◽  
Author(s):  
JIANSHENG GU ◽  
LEI LI ◽  
TAIHUA ZHANG ◽  
PENG JIANG ◽  
BINGCHEN WEI ◽  
...  
Keyword(s):  
Shear Band ◽  
Metallic Glasses ◽  
Shear Banding ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Similar Chemical ◽  
Significant Difference ◽  
Band Spacing ◽  
Plastic Deformation Region

Shear banding characterization of Zr 64.13 Cu 15.75 Ni 10.12 Al 10 and Zr 65 Cu 15 Ni 10 Al 10 bulk metallic glasses (BMGs) with significant difference in inherent plasticity and quite similar chemical composition was studied by depth sensitive macroindentaion tests with conical indenter. Well-developed shear band pattern can be found for both BMGs after indentation. Distinct difference in the shear band spacing, scale of plastic deformation region and the shear band branching in the two BMGs account for the different plasticity.

Influence of Preheating on Chip Segmentation and Microstructure in Orthogonal Machining of Ti6Al4V

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Shashikant Joshi ◽  
Asim Tewari ◽  
Suhas Joshi
Keyword(s):  
Shear Band ◽  
Cutting Forces ◽  
Conceptual Models ◽  
Shear Bands ◽  
Shear Plane ◽  
Band Formation ◽  
Orthogonal Machining ◽  
On Chip ◽  
Compressive Residual Stresses ◽  
Machined Surfaces

Chip segmentation due to shear localization during machining of titanium alloys affects cutting forces and their machinability. Despite several studies on modeling and understanding influence of chip segmentation, little is known about the effect of preheating on it. This work therefore, involves orthogonal machining of Ti6Al4V alloy under preheating between 100 °C and 350 °C to investigate chip segmentation, shear band configuration, and microstructure of machined surfaces, through optical and scanning electron microscopy of chips and chip roots. Conceptual models of chip segment formation have been evolved. Shear band formation appears to be the dominant mechanism of chip segmentation up to 260 °C preheating, however at 350 °C, extent of fracture along the shear plane increases. The preheating increases spacing between shear bands in chips, reduces shear band thickness from 21 μm at 100 °C to 8 μm at 350 °C, and ultimately reduces cutting forces fluctuation, and compressive residual stresses in the machined surfaces.

scholarly journals An Insight into Amorphous Shear Band in Magnetorheological Solid by Atomic Force Microscope

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4384
Author(s):  
Mohd Aidy Faizal Johari ◽  
Asmawan Mohd Sarman ◽  
Saiful Amri Mazlan ◽  
Ubaidillah U ◽  
Nur Azmah Nordin ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Shear Band ◽  
Shear Bands ◽  
Test Duration ◽  
Phase Imaging ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Matrix ◽  
Relaxation Stress ◽  
Band Deformation

Micro mechanism consideration is critical for gaining a thorough understanding of amorphous shear band behavior in magnetorheological (MR) solids, particularly those with viscoelastic matrices. Heretofore, the characteristics of shear bands in terms of formation, physical evolution, and response to stress distribution at the localized region have gone largely unnoticed and unexplored. Notwithstanding these limitations, atomic force microscopy (AFM) has been used to explore the nature of shear band deformation in MR materials during stress relaxation. Stress relaxation at a constant low strain of 0.01% and an oscillatory shear of defined test duration played a major role in the creation of the shear band. In this analysis, the localized area of the study defined shear bands as varying in size and dominantly deformed in the matrix with no evidence of inhibition by embedded carbonyl iron particles (CIPs). The association between the shear band and the adjacent zone was further studied using in-phase imaging of AFM tapping mode and demonstrated the presence of localized affected zone around the shear band. Taken together, the results provide important insights into the proposed shear band deformation zone (SBDZ). This study sheds a contemporary light on the contentious issue of amorphous shear band deformation behavior and makes several contributions to the current literature.

A novel robust finite-time tracking control of uncertain robotic manipulators with disturbances

2020 ◽  
pp. 107754632098244
Author(s):  
Hamid Razmjooei ◽  
Mohammad Hossein Shafiei ◽  
Elahe Abdi ◽  
Chenguang Yang
Keyword(s):  
Finite Time ◽  
Control Method ◽  
Sliding Mode ◽  
Robotic Manipulators ◽  
Sliding Mode Controller ◽  
Time Varying ◽  
State Variables ◽  
Terminal Sliding Mode ◽  
Control Laws ◽  
Finite Time Boundedness

In this article, an innovative technique to design a robust finite-time state feedback controller for a class of uncertain robotic manipulators is proposed. This controller aims to converge the state variables of the system to a small bound around the origin in a finite time. The main innovation of this article is transforming the model of an uncertain robotic manipulator into a new time-varying form to achieve the finite-time boundedness criteria using asymptotic stability methods. First, based on prior knowledge about the upper bound of uncertainties and disturbances, an innovative finite-time sliding mode controller is designed. Then, the innovative finite-time sliding mode controller is developed for finite-time tracking of time-varying reference signals by the outputs of the system. Finally, the efficiency of the proposed control laws is illustrated for serial robotic manipulators with any number of links through numerical simulations, and it is compared with the nonsingular terminal sliding mode control method as one of the most powerful finite-time techniques.

The Investigation of the Influence of Structure Parameters on the Friction-Induced Self-Excited Vibration

2011 ◽  
Vol 66-68 ◽  
pp. 933-936
Author(s):  
Xian Jie Meng
Keyword(s):  
Nonlinear Dynamics ◽  
Numerical Method ◽  
Calculation Result ◽  
Dry Friction ◽  
Vibration Amplitude ◽  
The Self ◽  
Structure Parameters ◽  
Dynamics Model ◽  
Excited Vibration ◽  
Nonlinear Dynamics Model

A one degree of freedom nonlinear dynamics model of self-excited vibration induced by dry-friction was built firstly, the numerical method was taken to study the impacts of structure parameters on self-excited vibration. The calculation result shows that the variation of stiffness can change the vibration amplitude and frequency of the self-excited vibration, but can not eliminate it, Along with the increase of system damping the self-excite vibration has the weakened trend and there a ritical damping, when damping is greater than it the self-excite vibration will be disappeared.

Using a sensitivity analysis of a weed dynamics model to develop sustainable cropping systems. I. Annual interactions between crop management techniques and biophysical field state variables

2012 ◽  
Vol 151 (2) ◽  
pp. 229-245 ◽  
Author(s):  
N. COLBACH ◽  
D. MÉZIÈRE
Keyword(s):  
Weed Management ◽  
Cropping Systems ◽  
Crop Management ◽  
State Variables ◽  
Long Term Effects ◽  
Dynamics Model ◽  
Previous Crop ◽  
Field State ◽  
Management Techniques ◽  
Weed Dynamics

SUMMARYEnvironmental problems mean that herbicide applications must be drastically reduced and optimized. Models that quantify the effects of crop management techniques on weed dynamics are valuable tools for designing weed management strategies. Indeed, the techniques to be optimized are numerous and diverse, and their effects vary considerably with environmental conditions and the state of the weed flora. In the present study, a mechanistic weed dynamics model,AlomySys, was used to carry outin silicoexperiments in order to: (1) rank crop management components according to the resulting decrease in weed infestation, and (2) study the sensitivity of the major component effects to biophysical field state variables in order to identify indicators and thresholds that could serve for future decision-rules for farmers. The various results were compiled into rules for optimizing timing and other options (tillage tools, herbicide types) for the different crop management techniques. The rules were based on a series of biophysical field state variables, i.e. cumulated rainfall, thermal time, soil moisture and weed densities prior to the operation, in the previous and pre-previous crops. For instance, the first tillage should be delayed until the cumulated rainfall since harvest exceeds 50 mm and be carried out in moist conditions. Mouldboard ploughing is advised if the infestation of the previous crop exceeds 20 weeds/m2and particularly if this exceeds 0·3 times that of the pre-previous crop. Ploughing should occur when the cumulated rainfall since harvest reaches 100–200 mm. The effects of crop succession and long-term effects of management techniques have been studied in a companion paper (Colbachet al. 2012).

Plastic Deformation-Induced Nanocrystalline Aluminum in Al-Based Amorphous Alloys

1993 ◽  
Vol 321 ◽  
Author(s):  
H. Chen ◽  
Y. He ◽  
G. J. Shiflet ◽  
S. J. Poon
Keyword(s):  
Plastic Deformation ◽  
Amorphous Alloy ◽  
Shear Band ◽  
Thin Layer ◽  
Ball Milling ◽  
Direct Observation ◽  
Amorphous Alloys ◽  
Shear Bands ◽  
Amorphous Ribbons ◽  
Nanocrystalline Aluminum

ABSTRACTWe report the first direct observation of crystallization induced in the slipped planes of aluminum based amorphous alloys by bending the amorphous ribbons. Nanometer-sized crystalline precipitates are found exclusively within a thin layer (shear band) in the slipped planes extending across the deformed amorphous alloy ribbons. It is also found that the nanocrystalline aluminum can be produced by ball-Milling. It is likely that local atomic rearrangements within the shear bands create the nanocrystals which appear after plastic deformation.

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