Journal articles: 'Lobe diagramy'

1

Harrison, A. J. L., and T. R. A. Pearce. "Prediction of lobe growth and decay in centreless grinding based on geometric considerations." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 216, no. 9 (September 1, 2002): 1201–16. http://dx.doi.org/10.1243/095440502760291763.

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The growth and decay of lobes during centreless grinding have been studied by previous researchers using physical tests, time-domain simulation and identification of the roots of the Laplace transform of the characteristic equation. In this paper, the authors have extended these latter two methods to generate complete stability diagrams encompassing the entire practical range of machine set-up angles. These diagrams indicate that by varying the set-up angles in a prescribed manner during grinding, rapid rounding of arbitrarily lobed components can be achieved. This is verified via time-domain simulation. Secondly, a novel and arguably more intuitive method of predicting the lobe growth and decay during centreless grinding is presented. The method considers the locations of the three points of contact between a lobed workpiece and the regulating wheel, the support plate and the grinding wheel. Axial symmetry is assumed. A unique circle can be drawn through these three points. The centre and radius of this circle vary continually as the workpiece rotates, in a manner dependent upon the workpiece's profile and the set-up angles. An above-average instantaneous radius leads, via machine stiffness, to a correspondingly larger grinding force and so to an increased instantaneous depth of cut. If this occurs when the trough of a lobe is being ground, the trough will become deeper and lobe growth will result. By contrast, if the instantaneous radius is below average when the trough is being ground, the lobe will decay. From this simple geometric consideration, the authors have calculated the rates of decay and growth of a range of numbers of lobes, across a wide range of set-up angles. The results are shown to agree well with those given using the previous methods.

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Hayati, Sajad, Mohammad Hajaliakbari, Yalda Rajabi, and Sajad Rasaee. "Chatter reduction in slender boring bar via a tunable holder with variable mass and stiffness." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 232, no. 12 (March 1, 2017): 2098–108. http://dx.doi.org/10.1177/0954405417690554.

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In this study, a new strategy is presented to increase the machining stability due to chatter suppression for boring and turning machining processes. The proposed approach is based on varying the position of stability lobes via changing mechanical properties of the tool body such as the mass and stiffness. Because of the shape of stability lobe diagrams, having a tool with a tunable stability lobe diagram can be useful to alter an unstable condition to a stable condition. For this purpose, a structure for the tool body is designed that is consisted of a hollow body with a core as a tunable screw inside it. As the core gets in or out, it changes the mass and stiffness of the tool body that leads to change the position of stability lobe diagram. In order to study the effect of designed structure on stability, the structure is simulated using a validated finite element time domain model. The time domain simulation shows a considerable improvement in stability of process. The strategy is experimentally applied to the process via modulation of the tool structure in the machining process to validate the simulation results. The experimental results have a high coincidence with theory and show a good improvement in stability.

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Dhupia, Jaspreet S., Bartosz Powalka, A. Galip Ulsoy, and Reuven Katz. "Effect of a Nonlinear Joint on the Dynamic Performance of a Machine Tool." Journal of Manufacturing Science and Engineering 129, no. 5 (April 17, 2007): 943–50. http://dx.doi.org/10.1115/1.2752830.

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This paper presents the effect of experimentally evaluated nonlinearities in a machine joint on the overall machine tool dynamic performance using frequency response functions and stability lobe diagrams. Typical machine joints are very stiff and have weak nonlinearities. The experimental evaluation of the nonlinear joint parameters of a commercial translational guide has been discussed in Dhupia et al., 2007, J. Vibr. Control, accepted. Those results are used in the current paper to represent the connection between the column and the spindle of an idealized column-spindle machine structure. The goal is to isolate and understand the effects of such joints on the machine tool dynamic performance. The nonlinear receptance coupling approach is used to evaluate the frequency response function, which is then used to evaluate the stability lobe diagrams for an idealized machine structure. Despite the weak nonlinearities in the joint, significant shifts in the natural frequency and amplitudes at resonance can be observed at different forcing amplitudes. These changes in the structural dynamics, in turn, can lead to significant changes in the location of chatter stability lobes with respect to spindle speed. These variations in frequency response function and stability lobe diagram of machine tools due to nonlinearities in the structure are qualitatively verified by conducting impact hammer tests at different force amplitudes on a machine tool.

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WIGG, CRISTINA MARIA DUARTE, and LUIZ ANTONIO ALVES DURO. "Evaluation of two infants with myotonic dystrophy by the McFie's diagram from the results of WISC." Arquivos de Neuro-Psiquiatria 56, no. 3B (September 1998): 633–38. http://dx.doi.org/10.1590/s0004-282x1998000400018.

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In this paper the authors disclose the result of a research carried out on two brothers whose parents were first cousins, being the gene transmitted by the father. The psychological test Wechsler Intelligence Scale of Children (WISC) was used in two occasions in order to assess the verbal and non-verbal skills. FRM and IRM were nine and eleven-year-old respectively, in the first examination, being the former thirteen and the latter fifteen-year-old on the second one. A comparison between the McFie's diagram and the WISC scores was made: the McFie's diagram showed the impairment severity in each cortical lobe when the left hemisphere was compared with the right one. The McFie's diagram was made from WISC's scores: the McFie's diagram showed the impairment severity in each cortical lobe when the left hemisphere was compared with the right one. On the second examination the performance was worse than in the first, mainly in the non-verbal aspects. The IRM's diagram showed a reduction in the right frontal and parietal lobes. In the FRM's diagram a reduction in the left frontal, temporal and parietal lobes, and also, in the right parietal lobe was found. The visual-spatial constructive aspects showed greatest impairment in this result.

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Chen, Ming, Xiao Hui Zhang, and Wei Wei Ming. "Fuzzy Chatter Stability Lobes Model in Milling." Key Engineering Materials 443 (June 2010): 308–13. http://dx.doi.org/10.4028/www.scientific.net/kem.443.308.

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Based on the conventional chatter stability model, stability Lobes diagram in die & mould steel milling system is obtained. The derived diagram can be divided into two independent regions by a Lobes curve: absolutely stable and instable region. In fact, it is more reasonable that there should be a transition stage between the stable and instable state. That is to say, grade of stability (GOS) should be in a closed interval [0, 1], rather than Boolean logic. Due to the different stability sensibilities for different order Lobe curve in milling system, there should be different widths of transition belts for different order curve. Thus, with the help of Sigmoid transfer function widths of each order Lobe curve are studied. Finally, the fuzzy chatter stability is implemented by an adjustable slope coefficient.

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KĘCIK, KRZYSZTOF, RAFAŁ RUSINEK, and JERZY WARMIŃSKI. "STABILITY LOBES ANALYSIS OF NICKEL SUPERALLOYS MILLING." International Journal of Bifurcation and Chaos 21, no. 10 (October 2011): 2943–54. http://dx.doi.org/10.1142/s0218127411030258.

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In this paper, we study the stability of a high speed milling process of nickel superalloys Inconel 713C by methods used in nonlinear dynamics. Stability Lobe Diagram was a result of modal analysis and next verified by recurrence plots, recurrence quantification analysis and classical nonlinear methods. A stability lobes diagram shows the indistinct boundary between chatter-free stable machining and unstable processes. Nevertheless, some recurrence quantification analysis measures give interesting results.

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Li, Hong Kun, and Peng Shi Zhao. "Milling Stability Lobe Diagram Construction on FV520B Stainless Steel and Experimental Testing Investigation." Applied Mechanics and Materials 437 (October 2013): 586–89. http://dx.doi.org/10.4028/www.scientific.net/amm.437.586.

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This paper investigates the zero-order analytical method to construct milling stability lobe diagram to improve the impeller milling efficiency. It is used to determine FV520B material milling parameters optimization. This method can select the appropriate number of revolutions and the cutting depth processing avoiding chatter occurrence. It can keep the required accuracy and surface quality for the workpiece. At the same time, it improves the safety of the tool and machine reliability. Through experiments data analysis, parameters constructing lobe diagram can be obtained. Different testing points in the constructed lobes are used to verify the correctness of the method. The results show that this method has great significance in the actual impellers manufacturing process.

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Zhao, D., and Q. Zhang. "Regenerative Chatter Stability and Hopf Bifurcation Analysis in Milling System." Advanced Materials Research 739 (August 2013): 400–407. http://dx.doi.org/10.4028/www.scientific.net/amr.739.400.

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The shifted Chebyshev polynomials and Floquet theory are both adopted for the prediction regenerative chatter stability and Hopf bifurcation in milling. The influences of the system parameter on the stability of the milling system have been analyzed. The stability lobe diagrams are obtained. The result shows that the shifted Chebyshev polynomials method is more accurate than the semi-discretion scheme for spindle speed lower than 3500 round per minutes. The stability in milling can well be predicted by the cutting depth and feed rate lobes diagrams. Only Hopf bifurcations are detected by the Eigen-value analysis. The stable solution transform from the stable equilibrium point to the quasi-periodic oscillation after Hopf bifurcation.

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Sun, Shan Shan, Wei Xiao Tang, and Xi Qing Xu. "Chatter Stability Prediction in High Speed Milling Considering Multi-Degree of Freedom." Key Engineering Materials 431-432 (March 2010): 373–76. http://dx.doi.org/10.4028/www.scientific.net/kem.431-432.373.

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Chatter problems occurring during high speed milling affect the quality of the finished workpiece and, to a lesser extent, the tool life and the spindle life. Therefore, the prediction of stable milling regions is a critical requirement for high speed milling operations. In this paper, a dynamic model of a high speed spindle system considering the multi-mode dynamics is elaborated for the purposed of stability prediction. A stability lobes diagram (SLD) shows the boundary between chatter-free machining operations and unstable processes, in terms of axial depth of cut as a function of spindle speed. These diagrams are used to select chatter-free combinations of machining parameters. The proposed method enables a new stability lobes diagram to be established that takes into account the effect of spindle speed on multi-mode dynamic behavior.

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10

Abele, E., and U. Fiedler. "Creating Stability Lobe Diagrams during Milling." CIRP Annals 53, no. 1 (2004): 309–12. http://dx.doi.org/10.1016/s0007-8506(07)60704-5.

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Liu, Hong, and Guo Zhu Zhao. "Two Methods to Test Transducer Array Directivity." Advanced Materials Research 912-914 (April 2014): 1485–88. http://dx.doi.org/10.4028/www.scientific.net/amr.912-914.1485.

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An array which possess more array element number and whose frequency of the drive signal can be as large as possible in a range, directivity will be more preferable. On the other hand, when the structure of the sound radiating surface of the transducer or array layout is symmetrical, the corresponding directivity pattern will be symmetrical. In order to test transducer directivity, two methods are designed. The one is to measure the ultrasonic sound pressure level by instruments. The sound pressure level is measured at multiple points to deduce the directivity angle of the acoustic transducer array. The beam width of the 3×3 array is about at 23kHz, and the directivity acute angle is about 10°; higher frequencies will lead to the side lobes, but it can be negligible when compared to the main lobe. The other method is using the frequency analyzer to test transducer directivity in a silencer chamber. The sound pressure level can be read out from frequency response diagrams. The angle between the sound pressure value that decreasing 3db from the max value 111.7db and the max value is about 11°. So the directivity acute angle is about 11°. It should be noticed that, as the directivity diagram can not be directly attributed, there is some deviation in the conclusion.

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12

Zheng, Charles M., Chou-Fu Liang, Hai-Yi Cai, and Shui-Shen Zhang. "Identification of process damping for chatter prediction in milling." MATEC Web of Conferences 175 (2018): 02002. http://dx.doi.org/10.1051/matecconf/201817502002.

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Traditionally, forecasting stability lobe diagram in milling is limited by complex damping identification procedures, so only structural damping from the impact experiment is used for predicting stability lobe diagram in most milling cases. In this study, by using the mathematical expressions among damping ratio, “critical limiting depth of cut” and “worst spindle speed”, it is shown that the predicted “critical limiting depth of cut” based on the structural damping divided by the measured “critical limiting depth of cut” can be approximately equal to the structural damping divided by the total damping. Based on this relationship, it is easy to estimate the total damping or process damping from the experiment within the selected spindle speeds. In practice, this paper presents an easy method for predicting stability lobe diagram using the total damping. At the same time, experiments have confirmed that using the prediction model of total damping can more accurately predict the stability lobe diagram.

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Ibañez, Aratz Iturgaiz, Pedro Jose Arrazola, and Klaus Bonde Ørskov. "Workpiece Material Influence on Stability Lobe Diagram." Procedia Manufacturing 47 (2020): 479–86. http://dx.doi.org/10.1016/j.promfg.2020.04.342.

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14

Friedrich, Jens, Jonas Torzewski, and Alexander Verl. "Online Learning of Stability Lobe Diagrams in Milling." Procedia CIRP 67 (2018): 278–83. http://dx.doi.org/10.1016/j.procir.2017.12.213.

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15

Hsiao, Te Ching, and Shyh Chour Huang. "The Effect of Cutting Process Parameters on the Stability in Milling." Advanced Materials Research 887-888 (February 2014): 1200–1204. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.1200.

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In the milling process, the dynamic system in the cutting process is composed of the tool, workpiece, and machine tools themselves. Therefore the mill geometric parameter, workpiece material behavior, and the modal parameters of the cutting system all will influence the stability in milling. Using FLN method and convolution force model to predict the chatter stability of milling process, and discussing the effect of milling parameter on the stability in this article. According to the result: with the increase of the tool diameter, stiffness, damping ratio or the reducing of tangential cutting force coefficient and radial width of cut, the stability lobe diagram tends to move upward. With the increase of natural frequency, the stability lobe diagram tends to move to right side. With the increase of the number of tooth, the stability lobe diagram tends to move downward.

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Kapylov, E. L., V. V. Neyolov, A. A. Samorodov, and B. A. Samorodov. "Evaluation of systematic error of measuring object scattering diagrams caused by quasimonostatic character of measurement scheme using irradiator’s assembly sets in anechoic chamber of collimator type." Issues of radio electronics 49, no. 5 (July 5, 2020): 17–27. http://dx.doi.org/10.21778/2218-5453-2020-5-17-27.

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The main factors causing the occurrence of systematic errors in measuring the backscatter patterns of targets when using irradiator assemblies in collimator type radar measuring complexes are considered. It is shown that the implementation of a quasimonostatic measurement scheme with a bistatic angle determined by spatial separation of the phase centers of irradiators assembly is the most significant factor in the experimental determination of the backscattering characteristics of reflectors with highlighted directed properties, to which the monostatic-bistatic equivalence theorem is not applicable. To quantify the influence of this factor, it is proposed to use indicators characterizing the decrease of the maximum and average recorded cross-section of trihedral corner reflectors within the main lobe of the backscatter diagram, determined by the half power level. The listed indicators do not take into account the non-flatness of the phase surface of the probe field, however, they can be considered as reasonably justified lower bounds for systematic measurement errors for each irradiators assembly. Using the mathematical modeling, mono- and bistatic cross-section diagrams of trihedral corner reflectors of various wave sizes with different face shapes were calculated, error estimation for their backscattering diagrams were determined using a set of irradiator assemblies. Ratios are obtained for estimating of width of the lobe of the bistatic scattering indicatrix at the level of –3 dB of trihedral corner reflectors with triangular, radial, and square face shapes, and a recommendation on the rational choice of the working frequency of the assembly when implementing large-scale electrodynamic modeling is made.

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Gaber, Omar, and Seyed M. Hashemi. "Effects of Machine Tool Spindle Decay on the Stability Lobe Diagram: An Analytical-Experimental Study." Shock and Vibration 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/4390185.

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An analytical-experimental investigation of machine tool spindle decay and its effects of the system’s stability lobe diagram (SLD) is presented. A dynamic stiffness matrix (DSM) model for the vibration analysis of the OKADA VM500 machine spindle is developed and is validated against Finite Element Analysis (FEA). The model is then refined to incorporate flexibility of the system’s bearings, originally modeled as simply supported boundary conditions, where the bearings are modeled as linear spring elements. The system fundamental frequency obtained from the modal analysis carried on an experimental setup is then used to calibrate the DSM model by tuning the springs’ constants. The resulting natural frequency is also used to determine the 2D stability lobes diagram (SLD) for said spindle. Exploiting the presented approach and calibrated DSM model it is shown that a hypothetical 10% change in the natural frequency would result in a significant shift in the SLD of the spindle system, which should be taken into consideration to ensure chatter-free machining over the spindle’s life cycle.

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Zhang, Nan, Yaoyao Shi, Zhen Chen, Hongxia Chen, Jia Liu, and Pan Zhao. "Chatter reliability prediction of side milling blisk." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 39, no. 1 (February 2021): 111–18. http://dx.doi.org/10.1051/jnwpu/20213910111.

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During the blisk side milling, the blade is thin and the tool suspension length is large, which is easy to occur milling system chatter. The wavy surface left by chatter has great effect on the surface roughness and service performance of the aero-engine blisk. To accurately predict the stability of the blisk side milling, the influence of random variables on the machining stability was considered. In this paper, the chatter reliability model of the blisk side milling system was established using the first-order second-moment method. The model takes structural parameters and spindle speed as random variables and chatter frequency as intermediate variables. The chatter reliability model was used to draw the reliability lobe diagram, which can be used to divide the machining reliability area. The effectiveness of this method was verified by experiments and compared with Monte Carlo method. The validation results showed that the reliability lobe diagram can be used to determine the stability probability prediction of blisk side milling and can replace the traditional stability lobe diagram.

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Wiseman, Richard, and Adrian M. Owen. "Turning the Other Lobe: Directional Biases in Brain Diagrams." i-Perception 8, no. 3 (May 18, 2017): 204166951770776. http://dx.doi.org/10.1177/2041669517707769.

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Past research shows that in drawn or photographic portraits, people are significantly more likely to be posed facing to their right than their left. We examined whether the same type of bias exists among sagittal images of the human brain. An exhaustive search of Google images using the term ‘brain sagittal view’ yielded 425 images of a left or right facing brain. The direction of each image was coded and revealed that 80% of the brains were right-facing. This bias was present in images that did not contain any representation of a human head. It is argued that the effect might be aesthetic in nature, the result of the Western tradition of reading left to right or due to the facial factors that underlie the bias previously found in portraits.

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Et. al., Jeevan Raju B,. "Design and optimized analysis of high speed precise machine tool spindles." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 2 (April 11, 2021): 2965–77. http://dx.doi.org/10.17762/turcomat.v12i2.2336.

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Upcoming machine tools need to be extremely efficient systems to maintain the needed intellectual performance and stability. The spindle tool system is necessary to optimize which enhances the rigidity of the spindle and in turn produces the cutting stability with higher productivity. Prediction of the dynamic behavior at spindle tool tip is therefore an important criterion for assessing the machining stability of a machine tool at design stage. In this work, a realistic dynamic high-speed spindle /milling tool holder/ tool system model is elaborated on the basis of rotor dynamics predictions. The integrated spindle tool system in analyzed with the Timoshenko beam theory by including the effects of shear and rotary deformation effects. Using the frequency response at the tool tip the corresponding stability lobe diagrams are plotted for the vertical end mill system. Furthermore an optimization study is carried out at design stage for the bearing system and the rotor positions for maximizing the chatter vibration free cutting operation at the desired depth of cuts with precise rotational speeds.It is markedly found that the first mode of vibration had a large impact on the dynamic stability of the system. The parametric studies are conducted such as tool overhang and bearing span and the influence of these on the system dynamics are identified and the corresponding stability lobe diagrams are plotted. It is evidently found that the second mode of the frequency response has critically affected the bearing span and competing lobes are identified. These results are assisted to design a spindle bearing system at the desired machining conditions. A neural network based observer is designed based on the simulation resultsto predict optimum design parameter values.

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Montiel, Óscar I., Mario A. Ayala, and Lácides Ripoll S. "Design and simulation of a non-resonant antenna: waveguide slot antenna for 30 GHz." Visión electrónica 10, no. 1 (June 20, 2016): 49–56. http://dx.doi.org/10.14483/22484728.11611.

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The main contribution of this article is the design and simulation of a non-resonant slot antenna based on wave guides to operate in the range of microwaves. The design is done using MATLAB and the Chebyshev synthesis to determine the distribution of current in each element. Based on this information, the size and distribution of the elements are calculated. Different design conditions are simulated, such as: changes in the level from main lobe to secondary and dierent number of slots at one frequency. The slots are interleaved with respect to the axis of the waveguide and separated by a distance (d). To determine its dimensions, it is necessary to deduce the conductances of the array. A particular design case is compared with simulations from the software CST Microwave Studio. It is observed that radiation diagrams are very similar in both number and amplitude of the lobes, validating the tool used.

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Mei, C., J. G. Cherng, and Y. Wang. "Active Control of Regenerative Chatter During Metal Cutting Process." Journal of Manufacturing Science and Engineering 128, no. 1 (June 14, 2005): 346–49. http://dx.doi.org/10.1115/1.2124991.

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Chatter, a violent relative vibration between a workpiece and a cutting tool, is a frequent problem in a machining operation. Among the many factors which contribute to the problem, regenerative chatter is found to be the most detrimental. Optimal control is designed for suppressing regenerative chatter with the critical regenerative effect taken into account. Furthermore, a novel hybrid time and frequency domain approach is developed for generating the stability lobe diagram for the dynamic system after control, since the conventional frequency domain approach is no longer feasible. Numerical results are obtained in both time and frequency domain for verifying the effectiveness of the controller as well as the hybrid approach for generating the stability lobe diagram.

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Mokhtari, Ali, Abbas Mazidi, and Mohammad M. Jalili. "Investigation of rotary inertial dynamic effects on chatter boundary in milling process using three-dimensional Timoshenko tool model." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 233, no. 1 (July 26, 2018): 93–110. http://dx.doi.org/10.1177/1464419318788504.

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Chatter prediction is essential to conduct stable machining. Many of the previous studies made to simulate milling process have not considered gyroscopic and rotary inertial dynamics effects. The aim of this research is to investigate the effects of rotary inertial dynamics on prediction of chatter in the milling operation. For this purpose, a three-dimensional rotating cantilever Timoshenko beam is considered for modeling the cutting tool. In the proposed model, cutting forces are applied at the end of the beam. Imposing spectral finite element model, the governing delay partial differential equations of the system reduce to nondelay ordinary differential equations. The main contributions of the current research are modeling the cutting tool as a continuous model by Timoshenko beam theory, finding and solving nondelay ordinary differential equations of the cutter via spectral finite element model, and studying the effects of gyroscopic and rotary inertial dynamics, completely. For validating, the system stability predictions obtained from the presented model are compared with experimental outcomes from the literature. Besides the common stability lobe diagram which is in terms of depth of cut and the spindle speed, other stability diagrams based on cutter length and diameter are illustrated. Using this model, influences of rotary inertial dynamics on these stability diagrams are investigated. The results show that ignoring the rotary inertial dynamics causes significant errors in prediction of chatter boundaries especially in high angular velocity of the tool. In addition, the effect of number of the cutter teeth on the stability of milling process is studied. The presented stability diagram may help a machinist to choose a better set of parameters, such as tool length and diameter, number of cutter flutes, depth of cut, and spindle velocity, for doing a stable milling process.

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N.S, Belwalkar, Mohite S.S, and Kashyapi G.V. "IDENTIFICATION OF STABILITY LOBE DIAGRAM FOR MILLING USING VIBRATION ANALYSIS." International Journal on Design and Manufacturing Technologies 9, no. 2 (2015): 23–27. http://dx.doi.org/10.18000/ijodam.70155.

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Zare Mehrjardi, M., AD Rahmatabadi, and R. Rashidi Meybodi. "Linear and nonlinear analysis of mount angle effects on the dynamic stability of micropolar lubricated hydrodynamic lobed journal bearings." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 234, no. 1 (July 2, 2019): 104–25. http://dx.doi.org/10.1177/1350650119855904.

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Journal bearings are one of the most widely used types of supporting devices for industrial machinery, especially for high-speed rotary systems. Considering the importance of mechanical systems ability to control vibrations and motion disturbances, the design of noncircular journal bearings has been one of the appropriate techniques used in recent years. In the present work, the effects of mount angle as a noncircularity unique feature on the dynamic stability of lobed journal bearings with micropolar lubricant are studied. For this purpose, modified Reynolds equation based on the linear and nonlinear methods is solved by generalized differential quadrature (GDQ) method. Then the static and dynamic characteristics of two-, three- and four-lobe bearings including load carrying capacity, whirl frequency ratio, critical mass parameter and rotor perturbation in terms of bifurcation diagram and Poincare map are presented for different values of mount angle. Nonlinear analysis results indicate that variation of mount angle can change the rotor response from limit cycle oscillations to convergent perturbation to static equilibrium point. Further, against plain circular journal bearings, choosing an appropriate orientation or mounting angle provides the optimal stability of noncircular lobed journal bearings. Also, the linear analysis results for the range of dynamic stability are more cautious than the nonlinear method in most of investigated cases.

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Prikhodko, V. Yu, and Do Vu Minh Thang. "Diffraction of low-frequency waves on elastic thin-walled shells of rotation." Russian Technological Journal 8, no. 6 (December 18, 2020): 157–66. http://dx.doi.org/10.32362/2500-316x-2020-8-6-157-166.

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Asymptotic and functional relations connecting the characteristics of scattered near and far fields with elastic and spectral characteristics of thin-walled elongated elastic shells described by the Love theory were found. The study was carried out by the method of two-scale expansions. For the near scattered field, recurrent systems of boundary value problems for Laplace and Poisson equations were obtained, the solutions of which were found explicitly. The radiation patterns of the scattered field were obtained using the theory of wave potentials for the Helmholtz equation. Asymptotic formulas for the potential densities of simple and double layers were found. This made it possible to present the asymptotics of the scattered field directivity diagram in the form of parametric integrals that depend on the angles of incidence and observation, frequency, surface shape, and material characteristics of the shell. The asymptotic method was effective for strongly elongated shells when the ratio of the maximum longitudinal diameter to the maximum diameter of rotation is more than ten. For such highly elongated bodies, the use of various difference and iterative schemes is problematic due to the difficulties of triangulating the shell surface. Numerical implementations of calculations of directional diagrams of a spheroidal steel shell in water at different angles of incidence of plane waves in a wide frequency range are given. The numerical calculations performed in this work are not tied to a specific frequency, since the geometric dimensions are given in wavelengths. Calculations have shown that the radiation pattern for elongated bodies begins to differ from the spherically symmetrical one at values kl > 4. When the wave size of the shell increases, the lobes of the directional diagram appear. The lobes direction depends on the above parameters. The number of lobes, their direction and power can be changed by using special distributions of the shell surface impedances.

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Gómez-González, V. M. A., J. A. Toalá, M. A. Guerrero, H. Todt, L. Sabin, G. Ramos-Larios, and Y. D. Mayya. "Planetary nebulae with Wolf–Rayet-type central stars – I. The case of the high-excitation NGC 2371." Monthly Notices of the Royal Astronomical Society 496, no. 1 (June 3, 2020): 959–73. http://dx.doi.org/10.1093/mnras/staa1542.

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ABSTRACT We present the analysis of the planetary nebula (PN) NGC 2371 around the [Wolf–Rayet] (WR) star WD 0722+295. Our Isaac Newton Telescope intermediate dispersion spectrograph spectra, in conjunction with archival optical and ultraviolet images, unveil in unprecedented detail the high ionization of NGC 2371. The nebula has an apparent multipolar morphology, with two pairs of lobes protruding from a barrel-like central cavity, a pair of dense low ionization knots misaligned with the symmetry axis embedded within the central cavity, and a high-excitation halo mainly detected in He ii. The abundances from the barrel-like central cavity and dense knots agree with abundance determinations for other PNe with [WR]-type central stars of PNe. We suggest that the densest knots inside NGC 2371 are the oldest structures, remnant of a dense equatorial structure, while the main nebular shell and outer lobes resulted from a latter ejection that ended the stellar evolution. The analysis of position–velocity diagrams produced from our high-quality spectra suggests that NGC 2371 has a bipolar shape with each lobe presenting a double structure protruding from a barrel-like central region. The analysis of the spectra of WD 0722+295 results in similar stellar parameters as previously reported. We corroborate that the spectral subtype corresponds with a [WO1] type.

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Friedrich, Jens, Christoph Hinze, Anton Renner, Alexander Verl, and Armin Lechler. "Estimation of stability lobe diagrams in milling with continuous learning algorithms." Robotics and Computer-Integrated Manufacturing 43 (February 2017): 124–34. http://dx.doi.org/10.1016/j.rcim.2015.10.003.

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Löser, Michael, and Knut Großmann. "Influence of Parameter Uncertainties on the Computation of Stability Lobe Diagrams." Procedia CIRP 46 (2016): 460–63. http://dx.doi.org/10.1016/j.procir.2016.04.031.

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Tyler, Christopher T., John Troutman, and Tony L. Schmitz. "Radial depth of cut stability lobe diagrams with process damping effects." Precision Engineering 40 (April 2015): 318–24. http://dx.doi.org/10.1016/j.precisioneng.2014.11.004.

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Denkena, Berend, Benjamin Bergmann, and Svenja Reimer. "Analysis of different machine learning algorithms to learn stability lobe diagrams." Procedia CIRP 88 (2020): 282–87. http://dx.doi.org/10.1016/j.procir.2020.05.049.

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32

Quintana, Guillem, Joaquim Ciurana, Inés Ferrer, and Ciro A. Rodríguez. "Sound mapping for identification of stability lobe diagrams in milling processes." International Journal of Machine Tools and Manufacture 49, no. 3-4 (March 2009): 203–11. http://dx.doi.org/10.1016/j.ijmachtools.2008.11.008.

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Habib, Anasri, and Abdul Ghofur. "PENGARUH LSA (LOBE SEPARATION ANGEL) PADA CAMSHAFT TERHADAP UNJUK KERJA MESIN JUPITER Z1." JTAM ROTARY 3, no. 1 (June 10, 2021): 43. http://dx.doi.org/10.20527/jtam_rotary.v3i1.3465.

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Penelitian ini bertujuan untuk mengetahui performa mesin terbaik dari perubahan angel separasi lobe pada camshaft, dan mengetahui diagram timing katup dari setiap modifikasi camshaft. Penelitian dilakukan dengan mengubah profil poros bubungan untuk menghasilkan waktu katup dan sudut preparasi lobus yang berbeda, kemudian dilakukan pengujian menggunakan dynotest untuk mendapatkan performa mesin Jupiter z1. Hasil penelitian menggunakan dynotest untuk mengetahui performa mesin, dari hasil pengujian mendapatkan hasil tertinggi dari setiap profil camshaft yaitu pada tenaga LSA 103.25o (standar) sebesar 9.035 Hp dan torsi 8.093 Nm, pada tenaga LSA 105.5o Dengan tenaga 9.162 Hp dan torsi 9.062 Nm, LSA 102.5o bertenaga 9.036 Hp dan torsinya 8.949 Nm. Pengaruh LSA pada camshaft standar dan modifikasinya yaitu pada camshaft dengan LSA 105.5o tenaga bertambah 1,3% dan torsi bertambah 10.7% sedangkan tenaga LSA 102.5o bertambah 0.01% dan torsi bertambah 9,5 %. Sehingga performa terbaik didapatkan pada camshaft dengan LSA 105.5o.This study aims to determine the best engine performance from changes in the angel separation lobe on the camshaft, and to find out the valve timing diagram of each camshaft modification. The research was carried out by changing the camshaft profile to produce different valve timing and lobes preparation angles, then do a test using dynotest to get Jupiter z1 engine performance. The results of the study used dynotest to determine engine performance, from the results of testing to get the highest results from each camshaft profile, namely the LSA 103.25o (standard) power of 9.035 Hp and torque of 8.093 Nm, on LSA 105.5o power is 9,162 Hp and torque is 9,062 Nm, the LSA 102.5o power is 9.036 Hp and torque is 8.949 Nm. The effect of LSA on the standard camshaft and modification, namely on the camshaft with LSA 105.5o, the power increased by 1.3% and torque increased by 10.7% while the LSA 102.5o the power increased by 0.01% and torque increased by 9,5%. So that the best performance is obtained on the camshaft with LSA 105.5o.

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Jiang, Zhuoda, and Yongyi He. "Research on Stability Prediction of the Crankshaft CNC Tangential Point Tracing Grinding." Mathematical Problems in Engineering 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/106159.

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As the key part of internal combustion engines, crankshaft with high efficiency and accuracy processing has always been the target of the engine manufacturer’s pursuit. Grinding is used to obtain the ultimate dimensional accuracy and surface finish in the crankshaft machining. Grinding of the main journals and the pin journals can be accomplished in a single clamping operation by CNC Tangential Point Tracing grinding technology. However, the chatter in the grinding process is harmful to the precision and surface quality. In this paper, stability lobe diagram is developed to predict the grinding chatter. First the dynamic model of Tangential Point Tracing grinding system is established. Then the limit formula of the critical grinding depth is calculated and the stability lobe diagram of the grinding system is presented. Finally, the validation experiments are carried out on the crankshaft grinding machine and the results are consistent with the calculation.

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Zhao, Zhengcai, Junming Hou, and Yucan Fu. "Measurement-Based Modal Analysis and Stability Prediction on Turn-Milling of Hollow Turbine Blade." Shock and Vibration 2020 (September 24, 2020): 1–9. http://dx.doi.org/10.1155/2020/8861373.

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Hollow blades with honeycomb structures are increasingly used in the turbine engines for reducing weight and saving costs. The hollow blade is a typical thin-walled structural part with low stiffness, the machining system of which is often unstable and likely to chatter. The most effective solution to avoid the machining chatter is to guide the hollow blade to be machined in a stable machining zone. This paper proposes a measurement-based approach for modal analysis and stability prediction of turn-milling hollow blade. The impact test was carried out to achieve the FRF curves on the hollow blade and the milling tool. An extremum method was employed to obtain an equivalent FRF curve, from which the modal parameters involving the natural frequency, damping ratio, and stiffness were computed. Afterwards, the semidiscretization method was used to draw a stability lobe diagram to predict the stability when turn-milling hollow blades. The experimental results confirm the feasibility of the predicted stability lobe diagram.

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Paliwal, Vineet, and N. Ramesh Babu. "Prediction of Stability Lobe Diagrams in High-Speed Milling by Operational Modal Analysis." Procedia Manufacturing 48 (2020): 283–93. http://dx.doi.org/10.1016/j.promfg.2020.05.049.

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Zatarain, Mikel, Jorge Alvarez, Iñigo Bediaga, Jokin Munoa, and Zoltan Dombovari. "Implicit subspace iteration as an efficient method to compute milling stability lobe diagrams." International Journal of Advanced Manufacturing Technology 77, no. 1-4 (October 21, 2014): 597–607. http://dx.doi.org/10.1007/s00170-014-6470-7.

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Kashyapi, Gautam, Suhas Mohite, and Nachiket Belwalkar. "Formation of Stability Lobe Diagram (SLD) for Chatter Free Milling on Aluminium Alloy." Manufacturing Science and Technology 3, no. 2 (May 2015): 32–37. http://dx.doi.org/10.13189/mst.2015.030202.

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Li, Zhongyun, Shanglei Jiang, and Yuwen Sun. "Chatter stability and surface location error predictions in milling with mode coupling and process damping." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 233, no. 3 (May 15, 2017): 686–98. http://dx.doi.org/10.1177/0954405417708225.

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Together with machining chatter, surface location error induced by forced vibration may also inhibit productivity and affect workpiece surface quality in milling process. Addressing these issues needs the combined consideration of stability lobes diagram and surface location error predictions. However, mode coupling and process damping are seldom taken into consideration. In this article, an extended dynamic milling model including mode coupling and process damping is first built based on classical 2-degree-of-freedom dynamic model with regeneration. Then, a second-order semi-discretization method is proposed to simultaneously predict the stability lobes diagram and surface location error by solving this extended dynamic model. The rate of convergence of the proposed method is also investigated. Finally, a series of experiments are conducted to verify the veracity of the extended dynamic model. The modal parameters including direct and cross terms are identified by impact experiments. Via experimental verification, the experimental results show a good correlation with the predicted stability lobes diagram and surface location error based on the extended dynamic model. Also, the effects of mode coupling and process damping are revealed. Mode coupling increases the whole stability region; however, process damping plays a vital role in stability improvement mainly at low spindle speeds.

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Fukumoto, Shinji, Taiju Matsuo, Daisuke Kuroda, and Harushige Tsubakino. "Micro-Resistance Spot Welding of Nickel Free Austenitic Stainless Steel." Materials Science Forum 539-543 (March 2007): 4081–86. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.4081.

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Micro-resistance spot weldability of nickel free stainless steel sheet was studied to fabricate medical implants. Weld lobe was established and the effect of welding parameters on joint strength was investigated. Weld nugget represented a rapidly quenched austenitic cellular structure whose cell size is several μm with a little ferrite. The amount of δ-ferrite in weld nugget is smaller than that predicted by some Schaefller diagrams due to rapid solidification during micro-resistance spot welding.

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41

Kundra, Emil, Ladislav Hric, and Rudolf Gális. "Accretion and pulsation of IU Per based on INTEGRAL and ground base photometry." Proceedings of the International Astronomical Union 8, S290 (August 2012): 377–78. http://dx.doi.org/10.1017/s1743921312020480.

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AbstractIU Persei (IU Per) is an eclipsing semi detached (SD) binary with pulsating component (oscillating eclipsing Algol - oEA). Using our ground base photometry in Johnson's B and V filters and INTEGRAL/OMC (Optical Monitoring Camera) data in V filter we introduce the model of this system. We determined the (O - C) diagram behavior. Moreover, the short term variations of the light curve were detected. Whats more, we obtained residua, by comparison of observational and synthetic light curves (LC), of which the detailed period analysis enabled to characterize and localize their source, that can be explained as the pulsation activity of the primary component. The secondary, less massive component, is beyond the instability belt on H-R diagram and fulfills its Roche lobe. The accreting primary component pulsates in modes typical for the δ Scuti stars.

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42

Molnár, Tamás G., and Tamás Insperger. "On the Effect of Distributed Regenerative Delay on the Stability Lobe Diagrams of Milling Processes." Periodica Polytechnica Mechanical Engineering 59, no. 3 (2015): 126–36. http://dx.doi.org/10.3311/ppme.7995.

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43

DAI, Yuebang. "Research on Prediction Method of Stability Lobe Diagram for Ball-end Mill Based on Engagement." Journal of Mechanical Engineering 55, no. 1 (2019): 52. http://dx.doi.org/10.3901/jme.2019.01.052.

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Terada, Yoshihiro, Kenji Ohkubo, Tetsuo Mohri, and Tomoo Suzuki. "Site preference determination in intermetallic compounds by thermal conductivity measurement." Journal of Materials Research 16, no. 8 (August 2001): 2314–20. http://dx.doi.org/10.1557/jmr.2001.0318.

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A method for the determination of site preference of substitutional elements in intermetallic compounds is proposed. It is demonstrated in Ni3Al–X alloys that the ridge direction in thermal conductivity contours in the ternary γ′ phase agrees with that of the solubility lobe of the γ′ phase in ternary phase diagrams. The ridge direction is a reliable indication of site preference of substitutional elements in intermetallic compounds. The present method is conveniently applied to a normal polycrystalline specimen with small size, and therefore, a versatile class of brittle compounds can be studied.

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Han, Zhanwen, Philipp Podsiadlowski, Pierre F. L. Maxted, Tom R. Marsh, and Natasha Ivanova. "The Formation of Subdwarf B Stars." International Astronomical Union Colloquium 187 (2002): 285–90. http://dx.doi.org/10.1017/s0252921100001500.

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AbstractWe performed full binary evolution calculations and carried out binary population synthesis studies in order to investigate the formation of subdwarf B (sdB) stars via the channels of stable Roche lobe overflow (RLOF), common envelope ejection and helium white dwarf mergers. Our model is successful in the explanation of observational properties of sdB stars, e.g. we explained the orbital period – minimum companion mass (log P – Mcomp) diagram, the effective temperature – surface gravity (Teff – log g) diagram, the orbital period distribution, the log(gθ4) (θ = 5040/Teff) distribution, the mass function distribution, the binary fraction of sdB stars, the fraction of sdB binaries with WD companions, the birth rates, the space number densities, etc. We conclude that (a) the first RLOF needs to be more stabilized than commonly assumed, (b) the first stable RLOF is not conservative, (c) common envelope ejection is very efficient.

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Wang, Ming, and Ming Zhou. "Study on Processing Optimization in Ultrasonic-Assisted Grinding of SiCp/Al Thin-Walled Workpiece." Applied Mechanics and Materials 313-314 (March 2013): 673–76. http://dx.doi.org/10.4028/www.scientific.net/amm.313-314.673.

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Thin-walled workpieces have the characteristics to withstand a greater load with less material and they are used in aerospace field widely. SiCp/Al composite has high strength and stiffness, which meets the requirements of the aerospace workpieces well. The optimization method is studied with grinding stability and material removal rate as constraint conditions in this paper. The processing parameters optimization of a SiCp/Al thin-walled cylinder is analyzed according to stability lobe diagram. The grinding parameters optimization could be achieved by this method and the chatter could be prevented effectively.

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Brecher, Christian, Prateek Chavan, and Alexander Epple. "Efficient determination of stability lobe diagrams by in-process varying of spindle speed and cutting depth." Advances in Manufacturing 6, no. 3 (June 14, 2018): 272–79. http://dx.doi.org/10.1007/s40436-018-0225-x.

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48

Rempel, J., P. Jacobi, J. Friedrich, A. Prof Verl, P. Prof Wiederkehr, and D. Prof Biermann. "Simulationsbasierte Fräsprozessauslegung*/Simulation-based design of milling-processes - Sensitivity analysis of stability lobe diagrams for automotive large-scale production." wt Werkstattstechnik online 107, no. 11-12 (2017): 841–46. http://dx.doi.org/10.37544/1436-4980-2017-11-12-65.

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In diesem Fachartikel werden die Einflüsse von Unsicherheiten in den Modellparameterwerten auf die Stabilitätsgrenze einer Stabilitätskarte aufgezeigt. Dazu wird an einem Beispielsystem eine Sensitivitätsanalyse für ein Verfahren zur Erzeugung von Stabilitätskarten durchgeführt. Zur Bestimmung des dynamischen Verhaltens der Werkzeugmaschine kommt eine Methode der Frequenzgang-Kopplung zum Einsatz.   To estimate the effect of uncertainties on the prediction of stability limits, a sensitivity analysis was conducted for a procedure to determine stability lobe diagrams for an example system. Thereby, a method of receptance coupling to identify the dynamic behavior of the tool center point was applied.

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Fong, Z. H., F. C. Huang, and H. S. Fang. "Evaluating the inter-lobe clearance of twin-screw compressor by the iso-clearance contour diagram (ICCD)." Mechanism and Machine Theory 36, no. 6 (June 2001): 725–42. http://dx.doi.org/10.1016/s0094-114x(01)00018-0.

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Guo, Y. Y., H. Lei, C. Zhao, and C. T. Sun. "Research on Stability of High Speed Milling System." Advanced Materials Research 670 (March 2013): 137–42. http://dx.doi.org/10.4028/www.scientific.net/amr.670.137.

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Machining instability is often the limiting factor on metal removal rate. So the stability of cutting system is an important research in high-speed machining area. It is widely used in engineering practice. In this paper, the stability of high-speed milling was studied by the numbers aiming at the dynamic milling process model of ball-end mill. The dynamic model of high-speed milling process was established. On the basis of Altintas’s theory, the formula about the limit axial depth of cut was derived. Besides, the model parameters of the system were obtained and the accuracy of the stability lobes diagram was verified through the experiments. From this research, it was learned that structure parameters of machine tool-cutting tool system, cutting force coefficients, spindle speed and axial depth of cut were factors affecting the stability in high-speed cutting. And the obtained stability lobes diagram provided a reliable basis in selecting cutting parameters during tool path planning.

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Journal articles on the topic 'Lobe diagramy'

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