Papers by Keyword: Optimization

Abstract: Optimization procedures can be considered useful for machining applications. Most commonly, the optimization method is applied to search a trade-off between costs and profits, and it allows searching for the optimum cutting parameters to maximize the useful tool-life, minimize the time of production, etc. The selection of the optimal machining conditions which could maximize the process sustainability performance and the fatigue life of the machined product is the objective of the work presented. The numerical model developed is useful to have integrated results as input for the optimization algorithm in order to drastically reduce the number of experimental tests needed. In the present work, the optimization of the performance measures is carried out using a self-written Genetic Algorithm code implemented using the MATLAB software.

Abstract: For the purpose of determining the optimal value for the technological parameters from the experimental results when evaluating the forming ability through the processing time during the processing of SUS 304 sheet material by SPIF technology. The article has conducted experiments to collect parameters and experimental planning to establish a mathematical model; at the same time, determine the optimal value for the parameters of the machining process such as tool diameter, tool feed and tool running speed which directly affect the machining time. The optimal technological parameters have practical applicability to improve the efficiency and productivity of the processing process for SUS 304 sheet metal in particular and other sheet metal materials in general.

Abstract: Tungsten Inert Gas welding process (TIG) has been widely used in industries. A robotic arm has been adopted in the industry with objectives to replace or efficiently improved some severe welding conditions where it is dangerous for human and to increase productivity and quality. This research is aimed to find the optimal conditions of TIG welding process on AISI 304 stainless steel. The design of experiments used a statistical method to determine the optimal TIG welding conditions providing the strongest tensile strength across the weldment. The fractional factorial experimental design and then the central composite design were used as a response surface method to find the optimal TIG welding conditions for AISI 304 stainless steel using robotics system. The statistically significant factors and their optimal values are the welding current (136 Ampere), welding speed (13 cm/min), wire feed rate (93 cm/min), and the arc gap (2.5 mm). After that, the residual stress caused by TIG welding at the optimal condition was measured by X-ray diffraction (XRD) technique. The results showed that the weldment obtained from the optimal welding conditions provides compressive residual stresses which cause the materials to be stronger.

Abstract: This paper presents the development of a three degrees-of-freedom (DOF) compliant parallel mechanism (CPM) with spatial motions, i.e., two rotations about the X and Y axes and one translation along the Z axis (θX-θY-Z). Such CPM is synthesized by the improved beam-based structural optimization method. The obtained results suggest that the proposed CPM is able to produce totally decoupled motions illustrated by a diagonal stiffness/compliance matrix, a large workspace of ±22,5 degrees × ±22,5 degrees × ±9,6 mm, fast dynamic response with the first natural frequency of ~100 Hz and high stiffness ratios between actuating and non-actuating directions (with stiffness ratios of 6210 and 2706 for translations and rotations respectively). Finite element analysis (FEA) is employed to evaluate the actual performance of the synthesized CPM with Ti6Al4V material in order to verify the correctness of the synthesis method. The effectiveness of the improved beam-based structural method is demonstrated by the good agreement between the simulation and predicted data with the highest deviations are 8.8% and 6.7% for the stiffness and dynamic properties respectively. In addition, some comparisons are carried out to investigate the advantages as well as disadvantages of the proposed CPM and existing designs. The comparison results show that the 3-DOF CPM presented in this paper has many merits compared to its counterparts. It can be used in various applications, e.g., the micro/nano positioners and alignment systems in precision engineering field due to its good mechanical properties (high stiffness ratios and fast dynamic behavior), large work range and fully-decoupled motion characteristic.

Abstract: Paper presents the results of factorial experiments made to establish the influence of technological parameters of 3D printing using the Fused Deposition Modeling (FDM) Technology, on the mechanical properties of the material deposited with ULTRA PLA filaments. By planning the experiments and the statistical processing of the results, mathematical relations were established regarding the dependence between the objective functions, the controllable factors and their interactions. To obtain high tensile strengths of the components made by 3D printing, regimes are required to allow the deposition of layers as thin as possible (h = 0.1 mm) and temperatures as high as possible, close to 300°C. The choice of inappropriate values of these process parameters can lead to a significant decrease in tensile strength, reaching even up to 30-40% of the maximum possible value to be reached. The experiments reveal that the printing speed does not have a major influence on the mechanical properties. Practical, the printing speed is limited by the technical characteristics of the printer used. The results of the experimental research obtained on a number of 30 process variants led to the establishment of optimal 3D printing variants that correspond to the requirements imposed on the objectively analysed functions (tensile strength, dimensional accuracy, speed of execution, surface quality).

Abstract: This paper will present the mechanical capacity of 3D printed test specimens, in direct correlation with their infill pattern, that were made from polyamide (also called nylon) reinforced with carbon fibers (in proportion of 20%). Nylon is a flexible, but strong material, and carbon fibers give it increased mechanical strength, which will be shown by the mechanical test’s results. The infill’s density is 50%, which gives enough strength for most prototyping applications and reduces the print time considerably. The geometries of infill tested in this paper are lines, honeycomb and gyroid. Preliminary results showed that the higher the printing temperature, the better the layers weld and bond, thus the mechanical properties increase.

Abstract: This study presents a numerical method for optimizing the quantity and the placement of reinforcements along the principal-stress trajectories. The model representing carbon fiber composite structures consists of solids and embedded one-dimensional beam elements. Based on the Runge-Kutta method, the reinforcing structure is optimized considering the manufacturability of additive manufacturing (AM). For a case study, the optimization method is performed on an open-hole specimen. The Young’s modulus and the tensile strength of the optimized structure show an increase of more than 30 % and ~50 % in the simulation, respectively, compared to the reference specimen from another study. Robotic additive manufacturing is used to fabricate the specimen for experimental validation. The prediction of absolute values of tensile strength are reliable comparing to the experimental test, however, there is a deviation of more than 30 % in the linear-elastic behavior possibly due to the presence of voids in the printed part.

Abstract: This paper presents an investigation of the dimension variations on modular magnetorheological (MR) valve with meandering flow path structure. The size variations including the inner and outer radius of the valve at radial path. The first step is conducting FEMM (Finite Element Method Magnetics) to find out the density of magnetic flux on MR valve. The obtained magnetic field density is applied to steady state models to predict pressure drop. To determine the best configuration, pressure drop and operation range are the objective of the selection process. Based on the results, MR valve with 2.75 mm inner radius radial and 9 mm outer radius radial was chosen as the best MR valve design if compared to the other MR valve designs. The results obtained from the MR valve with 2.75 mm inner radius radial and 9 mm outer radius radial are 1.79 Mpa for the pressure drop and 6.68 for the operational range. Keywords: modular magnetorheological valve, optimization, objective function, smart materials

Abstract: One of the laminated bamboo production processes uses a bamboo planer machine. The use of this technology creates great opportunities for improving the quality of the bamboo processing process. Existing equipment still requires improvements to the power transfer mechanism and system, which affects the frame's shape. Therefore it was necessary to design and retest the frame design so that the machine can produce good shavings. The frame design comprises 50 mm × 50 mm × 5 mm angled steel with ASTM A36 material standardization. The testing method was finite element analysis (FEA) using SolidWorks. The frame was tested using static loading simulation to take mass, maximum stress, deflection, and safety factors. From the simulation, the safety factors value was 6,513. It was too high compared with the predetermined criteria, so the thickness of the frame was changed to 4 mm. The optimization increases material efficiency by 18,227% resulting in reduced frame mass to 76,576 kg. The result of the safety factor becomes 5.930. Keywords: FEA; Frame; Bamboo; Optimization; Strength Analysis; Planer Machine

Abstract: This study was carried out to ascertain the optimum parameters for maximum total acid number (TAN) reduction via catalytic esterification using chicken eggshell ash as catalyst. A central composite design (CCD) was created to optimize TAN reduction by varying temperature and catalyst weight %. The chicken eggshell ash was calcined and reactivated in a furnace at 900 °C for an hour. An oil solution (referred to as synthetic solution) of diesel was adulterated with the organic acid m-toluic which served as a representation for highly acidic oil. Titration using alcoholic potassium hydroxide (KOH) and an indicator (phenolphthalein) was used to deduce the total acid number of the synthetic solution before and after esterification. The optimum parameters for maximum TAN reduction obtained from the model were a temperature of 56.90 °C, a catalyst weight % of 11.45%, and a maximum TAN reduction of approximately 94%. Fourier Transform Infrared (FTIR) Spectroscopy also confirmed that TAN reduction had taken place as the peaks that represent the carbonyl group (C=O stretch at ~1605 cm-1) was reduced significantly.