Structural design is a process of determining an optimal solution by repeating hypotheses and verification processes with numerous design variables. To acquire a more appropriate solution, a ...mathematical model for structural design is proposed to find the optimal solution. While many studies have proposed the minimum weight design for steel frames, a mathematical model should be considered in the manufacturing and installation process in order to solve practical issues. In this study, a multi-objective model was proposed to consider not only the cost of materials, but also processing and welding costs. A penalty function was also used to reflect the constructability and on-site applicability of the structure. A genetic algorithm was used to determine the optimal solution, and the results of the optimal design analysis were compared and analyzed based on a three-story numerical example. Analysis of the numerical example resulted in offering a smaller number of types of materials whose size and arrangement allowed for easier construction, compared to that of the optimal design that only considered weight. Furthermore, the welding cost allowed for the optimum design with improved on-site constructability was also considered.
•We have developed a more comprehensive structural design support scheme.•The cost function has been considered by adding the manufacturing and welding cost for the connections.•The constraint relevant to constructability was added in order to develop a practical optimum design scheme.
Flux-cored arc welding (FCAW) is an innovative semi-automatic assembly process that is increasingly used in the industrial sector. However, the achievement of quality welds on steels with a low ...weldability index often and inevitably rhymes with high production costs. Therefore, the optimization of welding conditions in order to find a compromise between economic and technological criteria is of great interest. This document proposes the determination of optimal welding parameters, which minimize the total welding cost and maximize weld penetration simultaneously under maximum allowable hardness limitation in the heat-affected zone (HAZ) of high-strength low alloy steel (HSLA) grade S460. The decision variables chosen are welding current, welding speed, voltage and preheating temperature. For this purpose, a mathematical model of the total welding cost for the FCAW process has been developed. Then, the optimization problem is implemented with Matlab™ software and solved using a non-dominated sorting genetic algorithm (NSGA-II). The near optimal solutions are presented as a Pareto front. The choice of optimal welding parameters according to the operator’s objective is made simple and practical. The study highlighted the major role of preheating in reducing the total welding cost and preserving the quality of the weld joint for HSLA steel.
Conventional welding techniques for complex structures often rely on human involvement, which can be prone to errors when deviations from the planned process occur. In contrast, robotic welding is ...highly precise and effective, particularly in the assembly of complex structures such as double-bottom ships. Therefore, this paper presents a comprehensive technical and economic analysis comparing robotic welding to conventional welding in the assembly process of a ship’s block panels. The study aims to evaluate and compare the strategies employed in robotic welding and conventional welding, with a specific focus on the ship double-bottom context. Furthermore, an economic value analysis is conducted to assess the cost effectiveness of each approach. The analysis reveals that robotic welding can achieve a significantly faster welding speed, completing the process approximately 3.85 times quicker compared to conventional methods. Moreover, the ratio of electricity and man-hours between robot welding and conventional welding is 1:2.75. These findings highlight the potential for cost savings by implementing robotic welding processes. The analysis reveals a significant difference in operational costs, highlighting the efficiency and cost effectiveness of robotic welding compared to conventional methods.
Laser welding and nanocomposites are finding increasing applications in industries. The polypropylene/ethylene-propylene-diene-monomer/clay nanocomposite has wide application in many industries. In ...this study, the effect of laser power, standoff distance, scan velocity, and clay content as input parameters on tensile and impact strengths of laser welds and welding operation cost as output parameters has been investigated using response surface methodology. The Box–Behnken design was employed to establish proper mathematical models relating input to output parameters. Morphology and dispersion of clay in the above nanocomposite have also been evaluated by X-ray diffraction and transmission electron microscopy. The results have been presented numerically and graphically. The results show that with laser power of 108.84–110.90 W, scan velocity of 566.18–597.19 mm/min, standoff distance of 8 mm, and clay content of 0.35–0.83 wt%, optimum values for tensile strength of 9.3 MPa, impact strength of 67.2 J/m, and welding cost of 30 cents/m are obtained. A minimum cost weld (18.5 cents/m) can be achieved when a proper combination of laser power of 108.53–109.80 W, scan velocity of 874.27–893.09 mm/min, standoff distance of 8 mm, and clay content of 0.75–0.94 wt% is selected.
Structural design is usually carried out with a number of repetitive processes in which trial and error between assumptions at each stage on the structural system is done toward the selection of ...final solutions with an enormous effort of engineers. The authors proposed a design supporting scheme which could center their ability on the essential design processes by saving time for the selection with the use of Multi-Objective Genetic Algorithm (MOGA). In addition, through the various analyses of the steel structure models such as rigid-frame, X-type braced frame and K-type braced frame, it has been clearly shown that we can obtain other alternative design solutions with lower cost and proper drift angle in the proposed structural system. In this paper, the proposed supporting design scheme will be extended and confirmed its validity with considering not only manufacture cost in the process for making steel members and the welding cost for connecting beams and columns as well as steel cost which is considered until now in the scheme but also the penalty function which is given to the optimization problem in order to ensure the constructability of the beam-column connection for more practical use of the supporting design scheme.
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