Mohd Idris Shah Ismail

Neural Network Modeling for Prediction of Weld Bead Geometry in Laser Microwelding

Laser microwelding has been an essential tool with a reputation of rapidity and precision for joining miniaturized metal parts. In industrial applications, an accurate prediction of weld bead geometry is required in automation systems to enhance productivity of laser microwelding. The present work was conducted to establish an intelligent algorithm to build a simplified relationship between process parameters and weld bead geometry that can be easily used to predict the weld bead geometry with a wide range of process parameters through an artificial neural network (ANN) in laser microwelding of thin steel sheet. The backpropagation with the Levenberg-Marquardt training algorithm was used to train the neural network model. The accuracy of neural network model has been tested by comparing the simulated data with actual data from the laser microwelding experiments. The predictions of the neural network model showed excellent agreement with the experimental results, indicating that the neural network model is a viable means for predicting weld bead geometry. Furthermore, a comparison was made between the neural network and mathematical model. It was found that the developed neural network model has better prediction capability compared to the regression analysis model.

Determination of Heat Flux Intensity Distribution and Laser Absorption Rate of AISI D2 Tool Steel

The prediction of fluctuated temperature distribution generated by pulsed wave laser in laser assisted micro milling (LAMM) is crucial. The selection of processing parameter by minimize the effect on the processing characteristic is decisive to ensure the machining quality is high. Determining the effect of heat generated in underneath surface is important to make sure that the cutting tools are able to cut the material with maximum depth of cut and minimum defects in term of tool wear and tool life. In this study the simulation was carried by using Ansys APDL. In order to confirm the actual and distribution irradiation of temperature from simulation, an experimental was done to validate the results. The experiment was conducted by using Nd:YAG laser with wavelength 1064 nm.

Thermo-Mechanical Analysis on Thermal Deformation of Thin Stainless Steel in Laser Micro-Welding

In the present study, a three-dimensional finite element model has been developed to simulate the temperature, stress and deformation fields in continuous wave (CW) laser micro-welding of thin stainless steel sheet. The welding deformation was experimentally evaluated using a single-mode fiber laser with a high-speed scanning system. Application of developed thermal model demonstrated that the laser parameters, such as laser power, scanning velocity and spot diameter have a significant effect on temperature field and the weld pool. In the case of welding deformation, numerical simulation was carried out by an uncoupled thermo-mechanical model. The welding stress and deformation are generated by plastic deformation during the heating and cooling periods. It was confirmed that the residual stress is higher than yield strength and has strongest effect upon the welding deformation. The numerical simulated results have proved that the developed finite element model is effective to predict thermal histories, thermally induced stresses and welding deformations in the thin material.

Mechanical and microstructure characterization of aluminium-copper (Al-Cu) reinforced with in-situ titanium diboride (TiB2)

Aluminium based in-situ metal matrix composites (MMCs) have better properties and performance when compared to ex-situ MMCs. In this research, aluminium-copper (Al-Cu) alloy was reinforced with 1 to 6wt.% titanium diboride (TiB2). Al-MMCs has been fabricated with salt route reaction process at 800 °C via potassium hexafluorotitanate (K2TiF6) and potassium tetrafluoroborate (KBF4) salts. Al-Cu composites reinforced with 1,2, 3 and 6wt.% TiB2 then will be characterized their mechanical properties and microstructure. From results obtained, increased TiB2 contents will increased the value of tensile and hardness properties of Al-Cu alloy. The composites synthesized using in-situ techniques exhibit the presence a uniform distribution of reinforcement that tends to be fine and associated with a clean interface with the metallic matrix. In order to achieve a good mechanical and wear properties it is important to control Al3Ti phase formation during the synthesis of in situ Al-Cu/TiB2 composites.

Wear Properties of Metal Matrix Composite Al-Cu and Al-Cu-TiB2

Tensile and wear properties of aluminium (Al) based metal matrix composites (MMCs) was prepared by added titanium diboride (TiB2) with in-situ technique by salt route. The salts used in this research were potassium hexafluorotitanate (K2TiF6) and potassium tetrafluoroborate (KBF4). Nanocomposite samples were prepared by casting technique associated with incorporating 3 and 6 wt.% of TiB2 into matrix of Al-6wt.%Cu. Instron and wear tests machine were used to characterize the tensile and wear Al-Cu alloys properties. Results showed that increase in TiB2 content gave the high properties of tensile and wear behavior. The study indicates that TiB2 particles have giving improvement the wear performance of the Al–6wt.%Cu alloy. For a constant load and sliding speed, the wear rate decreases as a function of amount of TiB2 in the composite. The wear rate decrease with increasing in wt.% TiB2 particles for the all loads applied. However, addition of TiB2 particle to the Al–6 wt%.Cu matrix has show the coefficient value of wear decreases regardless of applied load. Study of the wear surfaces both alloy and composites by optical microscope suggests that the improvement in wear resistance is mainly due to the formation of finer groove or debris by content of TiB2.

A prediction of laser spot-to-cutting tool distance in laser assisted micro milling Inconel 718

Abstract Laser assisted micro milling (LAMM) is one of the techniques used to enhance the ability to manufacture microscale products. Laser is used to preheat the workpiece materials prior the machining process. Compared with conventional machining, LAMM is a green manufacturing method due to reduction in cutting force during machining process. However, it needs to be controlled to avoid the melting and changing of materials properties. Determining the processing parameters and their effects on the processing characteristics, temperature measurement and the laser spot-to-cutting tool distance are crucially important. In this study, finite element analysis using ANSYS software was used to predict the heat distribution to characterise the melting and heat affected zone formation. The data at the centre of laser spot were recorded to obtain the appropriate distance between laser spot-to-cutting tool. From the results, the estimations of laser spot-to-cutting tool distance of Inconel 718 together with the allowable depth of cut were determined and applied in the actual LAMM experiment. Meanwhile, the analyses of cutting force and tool wear as an evidence in conjunction with the laser heating application to reduce the materials strength were performed.

Micro-Welding of Super Thermal Conductive Composite by Pulsed Nd:YAG Laser

The diffusion of generated heat in the electronic devices is an important issue. The heat would be diffused from electronic devices by passive strategies, which would be carried out by the use of high thermal conductivity materials as a heat sink. The development of advanced materials with the superior high-thermal properties and the high strength-toweight ratio has led to new metal matrix composites (MMCs) as a great attractive material in the electrical and electronic industries. Aluminum and its alloys are widely used for the manufacturing of MMCs, which have reached the industrial stage in some areas (Barekar et al., 2009). In order to manufacture practical components from MMCs, a technique for joining MMCs to other similar composites or to monolithic materials is strongly required. Therefore, the development of reliable and economic joining technique is important for extending the applications of MMCs. It is well-known that laser welding is the most flexible and versatile welding technology, and it has succeeded in the welding of MMCs (Niu et al., 2006; Bassani et al., 2007).

Corrosion characterization of in-situ titanium diboride (TiB2) reinforced aluminium-copper (Al-Cu) alloy by two methods: Salts spray fog and linear polarization resistance (LPR)

Aluminium-copper (Al-Cu) alloys is the one of most Metal Matrix Composites (MMCs) have important high-strength Al alloys. The aluminium (Al) casting alloys, based on the Al-Cu system are widely used in light-weight constructions and transport applications requiring a combination of high strength and ductility. In this research, Al-Cu master alloy was reinforced with 3 and 6wt.% titanium diboride (TiB2) that obtained from salts route reactions. The salts used were were potassium hexafluorotitanate (K2TiF6) and potassium tetrafluoroborate (KBF4). The salts route reaction process were done at 800 °C. The Al-Cu alloy then has characterized on the mechanical properties and microstructure characterization. Salts spray fog test and Gamry-electrode potentiometer instruments were used to determine the corrosion rate of this alloys. From results obtained, the increasement of 3wt.%TiB2 contents will decrease the value of the corrosion rate. In corrosion test that conducted both of salt spray fog and Gamry-electrode potentiometer, the addition of 3wt.%TiB2 gave the good properties in corrosion characterization compare to Al-Cu-6wt.%TiB2 and Al-Cu cast alloy itself. As a comparison, Al-Cu with 3wt.%TiB2 gave the lowest value of corrosion rate, which means alloy has good properties in corrosion characterization. The results obtained show that in-situ Al-Cu alloy composites containing the different weight of TiB2 phase were synthesized successfully by the salt-metal reaction method.Aluminium-copper (Al-Cu) alloys is the one of most Metal Matrix Composites (MMCs) have important high-strength Al alloys. The aluminium (Al) casting alloys, based on the Al-Cu system are widely used in light-weight constructions and transport applications requiring a combination of high strength and ductility. In this research, Al-Cu master alloy was reinforced with 3 and 6wt.% titanium diboride (TiB2) that obtained from salts route reactions. The salts used were were potassium hexafluorotitanate (K2TiF6) and potassium tetrafluoroborate (KBF4). The salts route reaction process were done at 800 °C. The Al-Cu alloy then has characterized on the mechanical properties and microstructure characterization. Salts spray fog test and Gamry-electrode potentiometer instruments were used to determine the corrosion rate of this alloys. From results obtained, the increasement of 3wt.%TiB2 contents will decrease the value of the corrosion rate. In corrosion test that conducted both of salt spray fog and Gamry-electrode ...

Features of Laser Tube Bending processing based on Laser Forming: A Review

Laser forming of materials can help produce the desired shapes from sheets or tubes, which is not possible through conventional methods. Molds, dies, and external force are not needed for the laser forming of materials. Furthermore, the process is flexible and can be controlled by making changes to the materials, their geometry, and the laser parameters, either individually or in combination with each other. Investigations into laser tube bending are scarce in the literature pertaining to this field of study despite its potential and industrial importance. In contrast, much research has been conducted on laser sheet forming, which employs the same mechanism. In this study, laser tube bending is compared with laser sheet forming in order to develop a better understanding of the laser forming process. This review elucidates upon the mechanisms employed in laser forming (in general) and laser tube bending (in particular). A number of investigation methods are reviewed and analytical models of the process are also described. The principle of laser tube bending is explained, and the influence of various parameters (such as materials, geometry, laser, edge, and cooling effects) on the process is analyzed. Additionally, large tubes bending and preloading, or laser assistance, are examined.

Design and Analysis of Computer Experiments Using Polynomial Regression and Latin Hypercube Sampling in Optimal Design of PID Controller

Computational complexity and time-consuming iteration of simulation for tuning of Proportional-Integral-Derivative (PID) controller is a common drawback in many types of existing methods. This paper aims to propose a new method for achieving an optimal design for PID gains parameters with the least number of simulation runs. To achieve this purpose, we combine polynomial regression and Latin Hypercube Sampling (LHS) in order to Design and Analyze of Computer Experiments (DACE). In this method, the LHS is performed three times to design the associated sample points for different usage that includes training sample points to fit polynomial regression as a common surrogate model; validating sample points to scale standardized residuals; grid search sample points for investigating optimal point over whole design space. To show the flexibility and applicability of the proposed method, we serve a numerical case in the tuning of PID controller for linear speed control of Direct Current (DC) motor. Four different polynomial regression fit input/output (I/O) data over separately four model’s performances that includes Integral-Square-Error (ISE), Integral-Absolute-error (IAE), Integral-Time-Square-Error (ITSE), and Integral-Time-Absolute-Error (ITAE). Comparison of the result with two existing approaches such as traditional Zeigler-Nichols method and Taguchi-Gray Relational Analysis (Taguchi-GRA) confirms the reliability and superiority of the proposed method.