Mechanics of Modulation Assisted Machining

2013 ◽  
Author(s):  
Ho Yeung ◽  
Yang Guo ◽  
Narayan K. Sundaram ◽  
James B. Mann ◽  
W. Dale Compton ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Specific Energy ◽  
Frequency Modulation ◽  
Chip Formation ◽  
Low Frequency ◽  
Contact Condition ◽  
Force Measurements

The controlled application of low-frequency modulation to machining — Modulation Assisted Machining (MAM) — effects discrete chip formation and disrupts the severe contact condition at the tool-chip interface. The role of modulation in reducing the specific energy of machining with ductile alloys is demonstrated using direct force measurements. The observed changes in energy dissipation are analyzed and explained, based on the mechanics of chip formation.

Effect of Low-Frequency Modulation on Deformation and Material Flow in Cutting of Metals

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Ho Yeung ◽  
Yang Guo ◽  
James B. Mann ◽  
W. Dale Compton ◽  
Srinivasan Chandrasekar
Keyword(s):  
Frequency Modulation ◽  
Chip Formation ◽  
Material Flow ◽  
High Speed ◽  
Surface Deformation ◽  
Low Frequency ◽  
High Speed Imaging ◽  
Machining Processes ◽  
Asperity Contacts ◽  
2D System

The deformation field, material flow, and mechanics of chip separation in cutting of metals with superimposed low-frequency modulation (<1000 Hz) are characterized at the mesoscale using high-speed imaging and particle image velocimetry (PIV). The two-dimensional (2D) system studied involves a sharp-wedge sliding against the workpiece to remove material, also reminiscent of asperity contacts in sliding. A unique feature of the study is in situ mapping of material flow at high resolution using strain fields and streaklines and simultaneous measurements of tool motions and forces, such that instantaneous forces and kinematics can be overlaid onto the chip formation process. The significant reductions in specific energy obtained when cutting with modulation are shown to be a consequence of discrete chip formation with reduced strain levels. This strain reduction is established by direct measurements of deformation fields. The results have implications for enhancing sustainability of machining processes and understanding surface deformation and material removal in wear processes.

Modulation-Assisted Machining: A New Paradigm in Material Removal Processes

2011 ◽  
Vol 223 ◽  
pp. 514-522 ◽  
Author(s):  
James B. Mann ◽  
Yang Guo ◽  
Christopher Saldana ◽  
Ho Yeung ◽  
W. Dale Compton ◽  
...  
Keyword(s):  
Tool Wear ◽  
Chip Formation ◽  
Material Removal ◽  
Surface Texturing ◽  
Low Frequency ◽  
Contact Condition ◽  
New Paradigm ◽  
Machining Performance ◽  
Removal Processes ◽  
Conventional Machining

Modulation Assisted Machining (MAM), based on controlled superimposition of low-frequency modulation to conventional machining, effects discrete chip formation and disrupts the severe contact condition at the tool-chip interface. The underlying theory of discrete chip formation and its implications are briefly described and illustrated. Benefits such as improved chip management and lubrication, reduction of tool wear, enhanced material removal, particulate manufacturing and surface texturing are highlighted using case studies. MAM represents a new paradigm for machining in that it deliberately employs ‘good vibrations’ to enhance machining performance and capability.

Calculation-and-experimental estimation of the role of the frequency ratio in changing the endurance at two-frequency deformation modes

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 64-71 ◽  
Author(s):  
M. M. Gadenin
Keyword(s):  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Reduction Factor ◽  
Single Frequency ◽  
Cyclic Loads ◽  
Small Ratio ◽  
Harmonic Components ◽  
Deformation Modes

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.

Effect of cluster-gradient architecture of nanostructured topocomposites on features of tribointeraction with heterophased material

2020 ◽  
pp. 130-135
Author(s):  
D.N. Korotaev ◽  
K.N. Poleshchenko ◽  
E.N. Eremin ◽  
E.E. Tarasov
Keyword(s):  
Wear Resistance ◽  
Titanium Alloy ◽  
Energy Dissipation ◽  
Phase Structure ◽  
Diffusion Processes ◽  
Structural Phase ◽  
High Wear Resistance ◽  
Wear Characteristics ◽  
And Diffusion

The wear resistance and wear characteristics of cluster-gradient architecture (CGA) nanostructured topocomposites are studied. The specifics of tribocontact interaction under microcutting conditions is considered. The reasons for retention of high wear resistance of this class of nanostructured topocomposites are studied. The mechanisms of energy dissipation from the tribocontact zone, due to the nanogeometry and the structural-phase structure of CGA topocomposites are analyzed. The role of triboactivated deformation and diffusion processes in providing increased wear resistance of carbide-based topocomposites is shown. They are tested under the conditions of blade processing of heat-resistant titanium alloy.

scholarly journals High Ripple-Density Resolution for Discriminating Between Rippled and Nonrippled Signals: Effect of Temporal Processing or Combination Products?

2021 ◽  
Vol 25 ◽  
pp. 233121652110101
Author(s):  
Dmitry I. Nechaev ◽  
Olga N. Milekhina ◽  
Marina S. Tomozova ◽  
Alexander Y. Supin
Keyword(s):  
Low Frequency ◽  
Noise Signal ◽  
Density Variation ◽  
Choice Procedure ◽  
Masker Level ◽  
Reference Signals ◽  
Forced Choice Procedure ◽  
The Mean ◽  
Density Resolution

The goal of the study was to investigate the role of combination products in the higher ripple-density resolution estimates obtained by discrimination between a spectrally rippled and a nonrippled noise signal than that obtained by discrimination between two rippled signals. To attain this goal, a noise band was used to mask the frequency band of expected low-frequency combination products. A three-alternative forced-choice procedure with adaptive ripple-density variation was used. The mean background (unmasked) ripple-density resolution was 9.8 ripples/oct for rippled reference signals and 21.8 ripples/oct for nonrippled reference signals. Low-frequency maskers reduced the ripple-density resolution. For masker levels from −10 to 10 dB re. signal, the ripple-density resolution for nonrippled reference signals was approximately twice as high as that for rippled reference signals. At a masker level as high as 20 dB re. signal, the ripple-density resolution decreased in both discrimination tasks. This result leads to the conclusion that low-frequency combination products are not responsible for the task-dependent difference in ripple-density resolution estimates.

scholarly journals NMDA Receptor-Dependent Synaptic Activity in Dorsal Motor Nucleus of Vagus Mediates the Enhancement of Gastric Motility by Stimulating ST36

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Xinyan Gao ◽  
Yongfa Qiao ◽  
Baohui Jia ◽  
Xianghong Jing ◽  
Bin Cheng ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Gastric Motility ◽  
Low Frequency ◽  
Synaptic Activity ◽  
Motor Nucleus ◽  
Dorsal Motor Nucleus ◽  
Vagal Reflex ◽  
Precise Molecular Mechanism ◽  
Lines Of Evidence

Previous studies have demonstrated the efficacy of electroacupuncture at ST36 for patients with gastrointestinal motility disorders. While several lines of evidence suggest that the effect may involve vagal reflex, the precise molecular mechanism underlying this process still remains unclear. Here we report that the intragastric pressure increase induced by low frequency electric stimulation at ST36 was blocked by AP-5, an antagonist of N-methyl-D-aspartate receptors (NMDARs). Indeed, stimulating ST36 enhanced NMDAR-mediated, but not 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propanoic-acid-(AMPA-) receptor-(AMPAR-) mediated synaptic transmission in gastric-projecting neurons of the dorsal motor nucleus of the vagus (DMV). We also identified that suppression of presynapticμ-opioid receptors may contribute to upregulation of NMDAR-mediated synaptic transmission induced by electroacupuncture at ST36. Furthermore, we determined that the glutamate-receptor-2a-(NR2A-) containing NMDARs are essential for NMDAR-mediated enhancement of gastric motility caused by stimulating ST36. Taken together, our results reveal an important role of NMDA receptors in mediating enhancement of gastric motility induced by stimulating ST36.

Heating and low-frequency modulation of electrons observed during electron beam operations on TSS 1

1997 ◽  
Vol 102 (A8) ◽  
pp. 17335-17357 ◽  
Author(s):  
M. P. Gough ◽  
D. A. Hardy ◽  
W. J. Burke ◽  
M. R. Oberhardt ◽  
L. C. Gentile ◽  
...  
Keyword(s):  
Electron Beam ◽  
Frequency Modulation ◽  
Low Frequency

scholarly journals The Influence ofNrf2on Cardiac Responses to Environmental Stressors

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Reuben Howden ◽  
Eva Gougian ◽  
Marcus Lawrence ◽  
Samantha Cividanes ◽  
Wesley Gladwell ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Low Frequency ◽  
Therapeutic Strategies ◽  
Environmental Stressors ◽  
Total Power ◽  
Airborne Pollutants ◽  
Cardiac Responses

Nrf2protects the lung from adverse responses to oxidants, including 100% oxygen (hyperoxia) and airborne pollutants like particulate matter (PM) exposure, but the role ofNrf2on heart rate (HR) and heart rate variability (HRV) responses is not known. We hypothesized that genetic disruption ofNrf2would exacerbate murine HR and HRV responses to severe hyperoxia or moderate PM exposures.Nrf2-/-andNrf2+/+mice were instrumented for continuous ECG recording to calculate HR and HRV (low frequency (LF), high frequency (HF), and total power (TP)). Mice were then either exposed to hyperoxia for up to 72 hrs or aspirated with ultrafine PM (UF-PM). Compared to respective controls, UF-PM induced significantly greater effects on HR (P<0.001) and HF HRV (P<0.001) inNrf2-/-mice compared toNrf2+/+mice.Nrf2-/-mice tolerated hyperoxia significantly less thanNrf2+/+mice (~22 hrs;P<0.001). Reductions in HR, LF, HF, and TP HRV were also significantly greater inNrf2-/-compared toNrf2+/+mice (P<0.01). Results demonstrate thatNrf2deletion increases susceptibility to change in HR and HRV responses to environmental stressors and suggest potential therapeutic strategies to prevent cardiovascular alterations.

Effects of Local Nicotinic Activation of the Superior Colliculus on Saccades in Monkeys

2005 ◽  
Vol 93 (1) ◽  
pp. 519-534 ◽  
Author(s):  
Masayuki Watanabe ◽  
Yasushi Kobayashi ◽  
Yuka Inoue ◽  
Tadashi Isa
Keyword(s):  
Superior Colliculus ◽  
Reaction Times ◽  
Low Frequency ◽  
Visually Guided ◽  
Population Activity ◽  
Affected Area ◽  
Movement Field ◽  
Neural Interactions ◽  
Restricted Region

To examine the role of competitive and cooperative neural interactions within the intermediate layer of superior colliculus (SC), we elevated the basal SC neuronal activity by locally injecting a cholinergic agonist nicotine and analyzed its effects on saccade performance. After microinjection, spontaneous saccades were directed toward the movement field of neurons at the injection site (affected area). For visually guided saccades, reaction times were decreased when targets were presented close to the affected area. However, when visual targets were presented remote from the affected area, reaction times were not increased regardless of the rostrocaudal level of the injection sites. The endpoints of visually guided saccades were biased toward the affected area when targets were presented close to the affected area. After this endpoint effect diminished, the trajectories of visually guided saccades remained modestly curved toward the affected area. Compared with the effects on endpoints, the effects on reaction times were more localized to the targets close to the affected area. These results are consistent with a model that saccades are triggered by the activities of neurons within a restricted region, and the endpoints and trajectories of the saccades are determined by the widespread population activity in the SC. However, because increased reaction times were not observed for saccades toward targets remote from the affected area, inhibitory interactions in the SC may not be strong enough to shape the spatial distribution of the low-frequency preparatory activities in the SC.

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