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Jyoti Mazumder - One of the best experts on this subject based on the ideXlab platform.
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control of melt Pool Temperature and deposition height during direct metal deposition process
The International Journal of Advanced Manufacturing Technology, 2012Co-Authors: Lijun Song, Vijayavel Bagavathsingh, Bhaskar Dutta, Jyoti MazumderAbstract:This paper presents a hybrid control system that is able to improve dimensional accuracy of geometrically complex parts manufactured by direct metal deposition process. The melt Pool height is monitored by three high-speed charged couple device cameras in a triangulation setup. The melt Pool Temperature is monitored by a dual-color pyrometer. A two-input single-output hybrid control system including a master height controller and a slave Temperature controller is used to control both height growth and melt Pool Temperature at each deposition layer. The height controller is a rule-based controller and the Temperature controller uses a generalized predictive control algorithm with input constraints. When the melt Pool height is above a prescribed layer thickness, the master height controller blocks control actions from the Temperature controller and decreases laser power to avoid over-building. When the melt Pool height is below the prescribed layer thickness, the Temperature controller bypasses the height controller and dynamically adjusts laser power to control the melt Pool Temperature. This hybrid controller is able to achieve stable layer growth by avoiding both over-building and under-building through heat input control. A complex 3-D turbine blade with improved geometrical accuracy is demonstrated using the hybrid control system.
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feedback control of melt Pool Temperature during laser cladding process
IEEE Transactions on Control Systems and Technology, 2011Co-Authors: Lijun Song, Jyoti MazumderAbstract:Laser cladding is a multiple-parameter-dependent process, and a feedback control is critical for the process stabilization. This paper presents a generalized predictive control strategy with input constraints to stabilize the melt Pool Temperature during a high-power diode laser cladding process. A dual-color pyrometer was used to monitor the melt Pool Temperature. A state-space dynamic model relating the laser drive signal (laser power) to the melt Pool Temperature was identified experimentally using the subspace method. A generalized predictive controller with input constraints was implemented in real time using the state-space model. The closed-loop process was able to track the melt Pool Temperature to a reference Temperature profile. Laser cladding of H13 tool steel on a substrate with uneven surface showed that the closed-loop process was able to compensate for an under-fill with 3-mm depth after 40-layer depositions.
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Robust sensing and control of direct metal deposition
Pacific International Conference on Applications of Lasers and Optics, 2008Co-Authors: Lijun Song, Jyoti MazumderAbstract:Direct metal deposition is one of the rapid manufacturing technologies to fabricate geometrically complicated, dense, near-net-shape components. Deposition process involves a large number of parameters, among which the laser power is considered as the primary variable. In order to develop a control system for the process, molten Pool Temperature during deposition was monitored by a two-color pyrometer. Laser power and molten Pool Temperature form a single-input single-output system, whose dynamics were identified using a linear state space model. A generalized predictive control system with input constraints was designed for controlling the direct metal deposition process. To demonstrate the use of the proposed sensor and control algorithm, closed-loop experiments were conducted to adjust the laser power in order to track molten Pool Temperatures to the reference values.Direct metal deposition is one of the rapid manufacturing technologies to fabricate geometrically complicated, dense, near-net-shape components. Deposition process involves a large number of parameters, among which the laser power is considered as the primary variable. In order to develop a control system for the process, molten Pool Temperature during deposition was monitored by a two-color pyrometer. Laser power and molten Pool Temperature form a single-input single-output system, whose dynamics were identified using a linear state space model. A generalized predictive control system with input constraints was designed for controlling the direct metal deposition process. To demonstrate the use of the proposed sensor and control algorithm, closed-loop experiments were conducted to adjust the laser power in order to track molten Pool Temperatures to the reference values.
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Robust sensing and predictive control of direct metal deposition
International Congress on Applications of Lasers & Electro-Optics, 2008Co-Authors: Lijun Song, Jyoti MazumderAbstract:Direct metal deposition is one of the rapid manufacturing technologies to fabricate geometrically complicated, dense, near-net-shape components. Deposition process involves a large number of parameters, among which the laser power is considered as the primary variable. In order to develop a control system for the process, molten Pool Temperature during deposition was monitored by a two-color pyrometer. Laser power and molten Pool Temperature form a single-input single-output system, whose dynamics were identified using a linear state space model. A generalized predictive control system with input constraints was designed for controlling the direct metal deposition process. To demonstrate the use of the proposed sensor and control algorithm, closed-loop experiments were conducted to adjust the laser power in order to track molten Pool Temperatures to the reference values.Direct metal deposition is one of the rapid manufacturing technologies to fabricate geometrically complicated, dense, near-net-shape components. Deposition process involves a large number of parameters, among which the laser power is considered as the primary variable. In order to develop a control system for the process, molten Pool Temperature during deposition was monitored by a two-color pyrometer. Laser power and molten Pool Temperature form a single-input single-output system, whose dynamics were identified using a linear state space model. A generalized predictive control system with input constraints was designed for controlling the direct metal deposition process. To demonstrate the use of the proposed sensor and control algorithm, closed-loop experiments were conducted to adjust the laser power in order to track molten Pool Temperatures to the reference values.
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Predictive control for direct metal deposition
International Congress on Applications of Lasers & Electro-Optics, 2007Co-Authors: Lijun Song, Jyoti MazumderAbstract:Direct metal deposition plays an important role in rapid manufacturing industry to fabricate geometrically complicated, dense, near-net-shape components. A large number of parameters are involved in the deposition process. Its present development stagnates in its control. A good understanding of the laser material processing and a well designed controlling system are essential for the system reliability. This paper addresses the development of a linear model based generalized predictive control system for direct metal deposition. The molten Pool Temperature during the direct metal deposition process was monitored by a two-colour pyrometer. A single-input single-output linear system that describes the dynamics between the molten Pool Temperature and the laser power was considered. The incremental generalized predictive control algorithm with Kalman filter estimation was used to control the molten Pool Temperature. The performance of the controller was compared with the on-off controller.Direct metal deposition plays an important role in rapid manufacturing industry to fabricate geometrically complicated, dense, near-net-shape components. A large number of parameters are involved in the deposition process. Its present development stagnates in its control. A good understanding of the laser material processing and a well designed controlling system are essential for the system reliability. This paper addresses the development of a linear model based generalized predictive control system for direct metal deposition. The molten Pool Temperature during the direct metal deposition process was monitored by a two-colour pyrometer. A single-input single-output linear system that describes the dynamics between the molten Pool Temperature and the laser power was considered. The incremental generalized predictive control algorithm with Kalman filter estimation was used to control the molten Pool Temperature. The performance of the controller was compared with the on-off controller.
Lijun Song - One of the best experts on this subject based on the ideXlab platform.
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control of melt Pool Temperature and deposition height during direct metal deposition process
The International Journal of Advanced Manufacturing Technology, 2012Co-Authors: Lijun Song, Vijayavel Bagavathsingh, Bhaskar Dutta, Jyoti MazumderAbstract:This paper presents a hybrid control system that is able to improve dimensional accuracy of geometrically complex parts manufactured by direct metal deposition process. The melt Pool height is monitored by three high-speed charged couple device cameras in a triangulation setup. The melt Pool Temperature is monitored by a dual-color pyrometer. A two-input single-output hybrid control system including a master height controller and a slave Temperature controller is used to control both height growth and melt Pool Temperature at each deposition layer. The height controller is a rule-based controller and the Temperature controller uses a generalized predictive control algorithm with input constraints. When the melt Pool height is above a prescribed layer thickness, the master height controller blocks control actions from the Temperature controller and decreases laser power to avoid over-building. When the melt Pool height is below the prescribed layer thickness, the Temperature controller bypasses the height controller and dynamically adjusts laser power to control the melt Pool Temperature. This hybrid controller is able to achieve stable layer growth by avoiding both over-building and under-building through heat input control. A complex 3-D turbine blade with improved geometrical accuracy is demonstrated using the hybrid control system.
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feedback control of melt Pool Temperature during laser cladding process
IEEE Transactions on Control Systems and Technology, 2011Co-Authors: Lijun Song, Jyoti MazumderAbstract:Laser cladding is a multiple-parameter-dependent process, and a feedback control is critical for the process stabilization. This paper presents a generalized predictive control strategy with input constraints to stabilize the melt Pool Temperature during a high-power diode laser cladding process. A dual-color pyrometer was used to monitor the melt Pool Temperature. A state-space dynamic model relating the laser drive signal (laser power) to the melt Pool Temperature was identified experimentally using the subspace method. A generalized predictive controller with input constraints was implemented in real time using the state-space model. The closed-loop process was able to track the melt Pool Temperature to a reference Temperature profile. Laser cladding of H13 tool steel on a substrate with uneven surface showed that the closed-loop process was able to compensate for an under-fill with 3-mm depth after 40-layer depositions.
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Robust sensing and control of direct metal deposition
Pacific International Conference on Applications of Lasers and Optics, 2008Co-Authors: Lijun Song, Jyoti MazumderAbstract:Direct metal deposition is one of the rapid manufacturing technologies to fabricate geometrically complicated, dense, near-net-shape components. Deposition process involves a large number of parameters, among which the laser power is considered as the primary variable. In order to develop a control system for the process, molten Pool Temperature during deposition was monitored by a two-color pyrometer. Laser power and molten Pool Temperature form a single-input single-output system, whose dynamics were identified using a linear state space model. A generalized predictive control system with input constraints was designed for controlling the direct metal deposition process. To demonstrate the use of the proposed sensor and control algorithm, closed-loop experiments were conducted to adjust the laser power in order to track molten Pool Temperatures to the reference values.Direct metal deposition is one of the rapid manufacturing technologies to fabricate geometrically complicated, dense, near-net-shape components. Deposition process involves a large number of parameters, among which the laser power is considered as the primary variable. In order to develop a control system for the process, molten Pool Temperature during deposition was monitored by a two-color pyrometer. Laser power and molten Pool Temperature form a single-input single-output system, whose dynamics were identified using a linear state space model. A generalized predictive control system with input constraints was designed for controlling the direct metal deposition process. To demonstrate the use of the proposed sensor and control algorithm, closed-loop experiments were conducted to adjust the laser power in order to track molten Pool Temperatures to the reference values.
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Robust sensing and predictive control of direct metal deposition
International Congress on Applications of Lasers & Electro-Optics, 2008Co-Authors: Lijun Song, Jyoti MazumderAbstract:Direct metal deposition is one of the rapid manufacturing technologies to fabricate geometrically complicated, dense, near-net-shape components. Deposition process involves a large number of parameters, among which the laser power is considered as the primary variable. In order to develop a control system for the process, molten Pool Temperature during deposition was monitored by a two-color pyrometer. Laser power and molten Pool Temperature form a single-input single-output system, whose dynamics were identified using a linear state space model. A generalized predictive control system with input constraints was designed for controlling the direct metal deposition process. To demonstrate the use of the proposed sensor and control algorithm, closed-loop experiments were conducted to adjust the laser power in order to track molten Pool Temperatures to the reference values.Direct metal deposition is one of the rapid manufacturing technologies to fabricate geometrically complicated, dense, near-net-shape components. Deposition process involves a large number of parameters, among which the laser power is considered as the primary variable. In order to develop a control system for the process, molten Pool Temperature during deposition was monitored by a two-color pyrometer. Laser power and molten Pool Temperature form a single-input single-output system, whose dynamics were identified using a linear state space model. A generalized predictive control system with input constraints was designed for controlling the direct metal deposition process. To demonstrate the use of the proposed sensor and control algorithm, closed-loop experiments were conducted to adjust the laser power in order to track molten Pool Temperatures to the reference values.
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Predictive control for direct metal deposition
International Congress on Applications of Lasers & Electro-Optics, 2007Co-Authors: Lijun Song, Jyoti MazumderAbstract:Direct metal deposition plays an important role in rapid manufacturing industry to fabricate geometrically complicated, dense, near-net-shape components. A large number of parameters are involved in the deposition process. Its present development stagnates in its control. A good understanding of the laser material processing and a well designed controlling system are essential for the system reliability. This paper addresses the development of a linear model based generalized predictive control system for direct metal deposition. The molten Pool Temperature during the direct metal deposition process was monitored by a two-colour pyrometer. A single-input single-output linear system that describes the dynamics between the molten Pool Temperature and the laser power was considered. The incremental generalized predictive control algorithm with Kalman filter estimation was used to control the molten Pool Temperature. The performance of the controller was compared with the on-off controller.Direct metal deposition plays an important role in rapid manufacturing industry to fabricate geometrically complicated, dense, near-net-shape components. A large number of parameters are involved in the deposition process. Its present development stagnates in its control. A good understanding of the laser material processing and a well designed controlling system are essential for the system reliability. This paper addresses the development of a linear model based generalized predictive control system for direct metal deposition. The molten Pool Temperature during the direct metal deposition process was monitored by a two-colour pyrometer. A single-input single-output linear system that describes the dynamics between the molten Pool Temperature and the laser power was considered. The incremental generalized predictive control algorithm with Kalman filter estimation was used to control the molten Pool Temperature. The performance of the controller was compared with the on-off controller.
Milan Brandt - One of the best experts on this subject based on the ideXlab platform.
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Melt Pool Temperature and its effect on clad formation in pulsed Nd:yttrium-aluminum-garnet laser cladding of Stellite 6
Journal of Laser Applications, 2007Co-Authors: Shoujin Sun, Yvonne Durandet, Milan BrandtAbstract:The effective melt Pool Temperature in pulsed Nd:yttrium-aluminum-garnet laser cladding of Stellite 6 was measured with a two-color pyrometer. The pulse peak Temperature (Tp) and durations when the melt Pool Temperature is above the melting point of Stellite 6 powder (t1) and substrate (t2) in each pulse have been calculated and averaged. The effects of laser operating parameters (pulse energy, pulse frequency, spot overlap, powder mass flow rate, and pulse length) on these values have been investigated. It is found that Tp depends on the peak laser power, pulse length and determines the maximum size of melt Pool (DM), whereas both t1 and t2 increase with peak power, pulse frequency (f), pulse length, and spot overlap. The prediction of the clad area, the total area of a single-track clad layer, based on Tp, t1, and t2 is given for pulsed laser cladding of Stellite 6. Comparison between the experimental data and prediction has been made with a correlation coefficient of 0.99. In order to produce a larger single-track clad area, the higher value of the product of f⋅t1 and longer beam interaction time (τ) are required.The effective melt Pool Temperature in pulsed Nd:yttrium-aluminum-garnet laser cladding of Stellite 6 was measured with a two-color pyrometer. The pulse peak Temperature (Tp) and durations when the melt Pool Temperature is above the melting point of Stellite 6 powder (t1) and substrate (t2) in each pulse have been calculated and averaged. The effects of laser operating parameters (pulse energy, pulse frequency, spot overlap, powder mass flow rate, and pulse length) on these values have been investigated. It is found that Tp depends on the peak laser power, pulse length and determines the maximum size of melt Pool (DM), whereas both t1 and t2 increase with peak power, pulse frequency (f), pulse length, and spot overlap. The prediction of the clad area, the total area of a single-track clad layer, based on Tp, t1, and t2 is given for pulsed laser cladding of Stellite 6. Comparison between the experimental data and prediction has been made with a correlation coefficient of 0.99. In order to produce a larger ...
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melt Pool Temperature control using labview in nd yag laser blown powder cladding process
The International Journal of Advanced Manufacturing Technology, 2006Co-Authors: Dariush Salehi, Milan BrandtAbstract:In laser cladding, the substrate Temperature increases as the process progresses, which can lead to excessive dilution, the formation of a heat-affected zone (HAZ), thermal distortion and cracking due to the build-up of residual stresses. The feasibility of controlling heat build-up and dilution through on-line Temperature control during Nd:YAG laser cladding is investigated using a LabVIEW graphical program with a real-time proportional, integral and derivative (PID) controller to control the Temperature of the melt Pool. Cladding trials were performed with and without Temperature control. The effects of laser cladding conditions such as the substrate scan rate and powder feed rate on clad dilution and HAZ were determined by quantitative metallography. Results indicate that while the LabVIEW system can control the melt Pool Temperature, this does not necessarily result in a quality clad layer and highlights the need for multi-parameter process control.
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Correlation between melt Pool Temperature and clad formation in pulsed and continuous wave Nd:YAG laser cladding of stellite 6
Pacific International Conference on Applications of Lasers and Optics, 2004Co-Authors: Shoujin Sun, Yvonne Durandet, Milan BrandtAbstract:The melt Pool Temperature in pulsed laser cladding of stellite 6 was measured with a two-colour pyrometer. The pulse peak Temperature (Tp), durations when the melt Pool Temperature is above the melting points of stellite 6 powder (t1) and substrate (t2) in each pulse have been calculated and the effects of laser operating parameters (pulse energy, pulse frequency and spot overlap) on these values have been examined.It is found that Tp only depends on the pulse energy and determines the melt Pool size (DM), whereas the ratios of both t1 and t2 to the pulse length increase with pulse energy, pulse frequency (f) and spot overlap. The predictions of clad height, the total thickness of clad layer and dilution by Tp, t1 and t2 are given for both pulsed and continuous wave (CW) laser cladding of stellite 6. Comparison between the experimental data and prediction has been made. Thick clad layer with low level of dilution requires higher value of the product of t1·f, longer beam interaction time (τ) and large DM.
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Comparison between continuous wave and pulsed Nd:YAG laser cladding of stellite 6
International Congress on Applications of Lasers & Electro-Optics, 2004Co-Authors: Shoujin Sun, Milan BrandtAbstract:The comparison of melt Pool Temperature and the clad formation between continuous wave and pulsed Nd:YAG laser cladding of stellite 6 on stainless steel was made. The melt Pool Temperature in the CW laser cladding is roughly constant and increases with laser power, whereas the melt Pool Temperature in the pulsed laser cladding shows large fluctuation. Both pulse peak Temperature ( Tp ) and the duration ( t1 ) when the melt Pool Temperature is above the melting point of stellite 6 powder increase with laser power.Clad height of the CW laser cladding increases smoothly with the laser power due to the increase of melt Pool Temperature (size), however, the increase of clad height of the pulsed laser cladding with the laser power is faster because of the increases of both Tp and t1 . For the same average power, the clad height in pulsed laser cladding at high pulse frequency is higher than that at the lower pulse frequency, and the total clad thickness in pulsed laser cladding is higher than that in CW laser cladding due to the effect of peak power. Therefore, higher powder mass flow rate is required for pulsed laser cladding.The comparison of melt Pool Temperature and the clad formation between continuous wave and pulsed Nd:YAG laser cladding of stellite 6 on stainless steel was made. The melt Pool Temperature in the CW laser cladding is roughly constant and increases with laser power, whereas the melt Pool Temperature in the pulsed laser cladding shows large fluctuation. Both pulse peak Temperature ( Tp ) and the duration ( t1 ) when the melt Pool Temperature is above the melting point of stellite 6 powder increase with laser power.Clad height of the CW laser cladding increases smoothly with the laser power due to the increase of melt Pool Temperature (size), however, the increase of clad height of the pulsed laser cladding with the laser power is faster because of the increases of both Tp and t1 . For the same average power, the clad height in pulsed laser cladding at high pulse frequency is higher than that at the lower pulse frequency, and the total clad thickness in pulsed laser cladding is higher than that in CW laser c...
Baek-min Kim - One of the best experts on this subject based on the ideXlab platform.
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Understanding ENSO Regime Behavior upon an Increase in the Warm-Pool Temperature Using a Simple ENSO Model
Journal of Climate, 2011Co-Authors: Baek-min KimAbstract:The regime behavior of the low-order El Nino-Southern Oscillation (ENSO) model, according to an in- crease in the radiative-convective equilibrium sea surface Temperature (SST; Tr), is studied to provide a possible explanation for the observed increase in ENSO irregularity characterized by decadal modulation. During recent decades, a clear increasing trend of the warm-Pool SST has been observed. In this study, the increase in the warm-Pool maximum SST is interpreted as an increase in Tr following previous studies. A bifurcationanalysiswithTrasacontrolparameterisconductedtorevealthatthedegreeofENSOirregularity in the model is effectively controlled by the equilibrium states of the model. At a critical value of Tr, bi- furcation analysis reveals that period-doubling bifurcation occurs and an amplitude-modulated ENSO emerges. At this point, a subcycle appears within the preexisting ENSO cycle, which initiates decadal modulation of ENSO. AsTr increases further, nested oscillations are successively generated, illustrating clear decadal modulation of ENSO. The qualitative regime changes revealed in this study are supported by the observation of regime shifts in the 1970s. With increasing Tr, the mean zonal SST gradient increases, and the model adjusts toward a ''La Nina-like'' mean state. Further constraint with shoaling of the mean thermocline depth and increasing stratification causes ENSO to exhibit stronger amplitude modulation. Furthermore, the timing of the period-doubling bifurcation advances with these two effects.
Jiann C. Yang - One of the best experts on this subject based on the ideXlab platform.
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The influence of liquid Pool Temperature on the critical impact Weber number for splashing
Physics of Fluids, 2003Co-Authors: Samuel L. Manzello, Jiann C. YangAbstract:An experimental study is presented to determine the influence of liquid Pool Temperature on splashing behavior. Water droplets with initial diameter of 3.1 mm±0.1 mm impacted a water Pool 40 mm in depth. The impaction process was recorded using a high-speed digital camera at 1000 frames/s. The impinging droplet was fixed at room Temperature and the liquid surface was heated using a hotplate. To determine the critical Weber number for splashing, the impact velocity was varied. The critical impact Weber number for splashing was found to be dependent on liquid Pool Temperature, decreasing with an increase in liquid Temperature.