Current Issue : January - March Volume : 2021 Issue Number : 1 Articles : 5 Articles
The welding procedure for reinforcing bars used in reinforced concrete takes place at fixed\nindustrial installations. The welders must ensure that the reinforcing bar positions are maintained\nthroughout all stages leading up to concreting. Fusion welding offers an alternative procedure that\nentails fewer risks for the workersâ?? health. In this study, we aimed to determine the minimum\nparameters for the intensity, pressure, and time necessary to ensure the level of performance required\nby this assembly welding. A total of 2160 joints were manufactured, comprising the different\nthicknesses. For each thickness measurement, 45 different combinations of parameters were applied.\nThe joints were evaluated based on the resulting dimensions and on the failure force necessary to break\nthe joint. For different thicknesses, the breaking loads were over 7350 N. In addition, the welding\ncycle times did not exceed three seconds. Based on the results obtained in this study, we concluded\nthat assembling rebar (manufacturing reinforcing bars) by electrical resistance welding is a viable\noption. This method is fast, safe, and clean, and reduces the risks to the workersâ?? health....
In order to investigate the effects of fuel distribution on the operation of two-phase pulse detonation engine (PDE), a series of cold\nflow and multicycle PDE experiments was carried out with 9 mixing schemes. Homogeneity degree with fuel distribution\nconsidered in terms of space and time was proposed to quantitatively evaluate the mixing of liquid fuel and air by particle image\nvelocimetry (PIV) in cold flow experiments. Operation stability of multicycle PDE was presented by statistical analysis of peak\npressure at the outlet of a detonation tube. The relationship between operation stability and homogeneity degree was\nquantitatively elaborated. These experimental results indicated that not only using mixing reinforcement devices (such as pore\nplate and reed valve) was fuel distribution improved but also the effect of inlet ways on the homogeneity degree was weakened....
With the rapid development of high-power tractor, the fault diagnosis of high-power tractor has become more and more\nimportant for ensuring the operating safety and efficiency. PSO is an iterative optimization evolutionary algorithm, which can\niterate through different particles to find the optimal solution. However, there is only one population in the standard PSO\nalgorithm, and the information exchange between the populations is relatively single, which can easily lead to the stagnation of the\ndevelopment of the population. In this paper, due to high-power tractor diesel engine fault complexity, fault correlation, and\nmultifault concurrency, a multigroup coevolution particle swarm optimization BP neural network for diesel engine fault diagnosis\nmethod was proposed. First, the USB-CAN device was used to collect data of 8 items of the diesel engine under five different\nworking conditions, and the data was parsed through the SAE J1939 protocol; then, the BP neural network was reconstructed, and\na competitive multiswarm cooperative particle swarm optimizer algorithm (COM-MCPSO) was used to optimize its structure and\nweights. Finally, the data of optimized neural network under five different fault conditions show that, compared with BP neural\nnetwork and PSO optimized BP neural network, the fault diagnosis of COM-MCPSO optimized BP neural network not only\nimproves the network training speed, but also enhances generalization ability and improves recognition accuracy....
Resistance spot welding and hybrid weld bonding have wide applications in\nthe body work construction within the automobile industry. The integrity of\nthe spot welds and applied adhesives determines the body assembly rigidity\nand dynamic performance. Incorporating contact nonlinearity and geometric\nnonlinearity, finite element analysis (FEA) have been carried out to investigate\nthe structural stiffness and strength of both spot-welded and weld-bonded\nassemblies. Topology optimization has been performed to reveal the distributions\nof material effectiveness in the overlap regions and suggest a feasible\nmethod for removing underutilized material for weight reduction. Design\noptimization has been conducted with an aim to reduce the maximum\nvon Mises stress in the assembly to minimum by choosing optimum values\nfor a set of design variables, including the weld spacing, weld diameter and\noverlap width....
At present, high-pressure water jet technology occupies a very important position in the automobile washing industry. Some\nautomatic washers cannot meet the washing requirements in the washing process due to unreasonable arrangement of nozzles on\ntheir spray rods. Based on the theory of computational fluid dynamics (CFD), the internal and external flow field model of the\nnozzle are established in this paper. Fluent is used to simulate and analyze the flow field, and the external parameters of the nozzle\non the side spray bar of the automatic automobile washer are optimized. The simulation results show that after the nozzle and the\nnormal line of the automobile surface are inclined at a certain angle, the target surface is affected not only by normal striking force\nbut also by tangential pushing force, which makes stains easier to remove. The washing effect is the best when the nozzle is inclined\n30° to the normal line of the automobile surface. Increasing the nozzle inlet pressure will increase the dynamic pressure on the\nautomobile surface, but the increase of dynamic pressure will decrease after increasing to a certain pressure. The inlet pressure has\nlittle effect on the area covered by water jet. The reasonable matching results of jet angle, nozzle spacing, and nozzle distance from\nthe automobile surface (target distance) obtained by numerical simulation can not only make the automobile surface completely\ncovered and cleaned but also ensure less jet interference and no waste of water from adjacent nozzles. The above research\nconclusions can provide a basic theoretical basis for the optimal design of automatic automobile washing....
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