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The paper presents a fast online predictive method to solve the task-priority differential inverse kinematics of redundant manipulators under kinematic constraints. It implements a task-scaling technique to preserve the desired geometrical task, when the trajectory is infeasible for the robot capabilities. Simulation results demonstrate the effectiveness of the methodology. [ABSTRACT FROM AUTHOR]

We present new results where free parameters in spurious oscillations at layers diminishing (SOLD) method are adaptively chosen. Provided numerical results are for conforming piecewise linear finite element space with free parameters from piecewise constant finite element space. We focus on a higher order convergence we discovered in previous paper by Lukáš (2015). [ABSTRACT FROM AUTHOR]

Nowadays, the widespread use of resistance spot welding (RSW) in various industries is evidence for the importance of this manufacturing process. In this paper, the finite element method (FEM) is utilized to model the weld nugget geometry and tensile-shear strength in RSW process of the galvanized interstitial free (IF) and bake hardenable (BH) steel sheets. Computational results have good agreement with experimental data. The investigation of input parameters influence, namely welding current, welding time, and electrode force on nugget size variations reveals that welding current is the most influential parameter. The examination of input parameters interaction on joint strength indicates that increase in welding current and time and also reduction in electrode force result in larger nugget size and bigger joint strength. Although by increasing the nugget size, at first, the joint strength is raised, after reaching the maximum strength, increase in nugget size results in decreasing the joint strength, and it may lead to expulsion phenomenon. The analysis of variance (ANOVA) results of response surface methodology (RSM) modeling demonstrate that beside the welding parameters, their interactions have significant effect on nugget geometry and tensile-shear strength. The relative error between RSM predicted and FEM calculated maximum strength is attained about 3% that specifies the efficiency of RSM. [ABSTRACT FROM AUTHOR]

This paper proposes a robust optimization algorithm, enabling global optimum tracking and manufacturing uncertainty factors handling, for high-speed permanent magnet motor design. A new robustness criterion is introduced, considering effectively the impact of the construction tooling uncertainties on the design variables in all objectives. An adaptive-network-based fuzzy inference system is adopted acting as a surrogate for the time-consuming finite-element (FE) analyses and results in computationally fast robust electric machine design procedure. The procedure has been validated through FE high-speed motor design. [ABSTRACT FROM AUTHOR]

This paper focuses on the optimization of a linear actuator by the “output space mapping (OSM)” method. The underlying objective of this work lies in the minimization of the time required for the achievement of this optimal design. Indeed, in addition to the sole costs of optimization processes strictly speaking, the time needed for the developpement of the models is taken into account. In the context of OSM, two different finite-element models of the same actuator are used. This paper presents these modeling solutions and considers their corresponding accuracy. Results of this multi-objective optimization method are presented and compared with those obtained by the sequential simplex (SS) method based solely on the fine model. Both approaches give similar results. However, the comparison of their performances clearly shows that the OSM algorithm is an effective technique for reducing the computation time of optimization studies, even in the case of relatively simple electromagnetic structures. Hence, this approach leads to an original and effective optimization methodology. [ABSTRACT FROM AUTHOR]

In this paper, we consider an inverse problem of identifying a space-dependent source in the parabolic equation which is a classical ill-posed problem. The inverse source problem is formulated into a regularized optimization problem. Then, a non-iterative algorithm based on a sequence well-posed direct problems solved by the finite element method is proposed for solving the optimization problem. In order to obtain a reasonable regularization solution, we utilize the damped Morozov discrepancy principle together with the linear model function method for choosing regularization parameters. Numerical results for one- and two-dimensional examples show that the proposed method is efficient and robust with respect to data noise, especially for reconstructing the discontinuous source functions. Furthermore, the proposed method is successfully used to solve a real example of identifying the magnitude of groundwater pollution source. [ABSTRACT FROM AUTHOR]

In this paper, based on the previous research experiences in the lumped parameter modeling and study of active control mounts (ACM) model, an analytical model of active ACM in powertrain is developed and implemented in MATLAB. In order to validate this newly developed model in this work, a finite element analysis (FEA) method is conducted in ANSYS and the results of FEA is compared with analytical model for validation. After the validation, the control strategy is integrated into the analytical model by using the linear quadratic regulator (LQR) method. Numerical results show a good control performance. Furthermore, this work examines the application of genetic algorithms (GA) in optimizing the weight matrices of LQR. An optimal configuration is obtained and thus this approach could help the practical design of ACM systems. [ABSTRACT FROM AUTHOR]

In this paper, a rectangular plenum internally equipped with two crossed baffles within a fixed space is assessed. To simplify the optimization process, a simplified objective function (OBJ) is constructed using the finite element model (FEM) in conjunction with the polynomial neural network model (ANNM). To assess an optimal plenum, the best OBJ will be numerically searched using a genetic algorithm (GA). Before the GA operation is performed, the accuracy of the FEM is verified using the analytical data. In addition, a case study of shape optimization on a space-constrained plenum at three targeted tones (1950 Hz, 2450 Hz, and 2850 Hz) has been introduced and carried out. The results reveal that the maximum value of the sound transmission loss (STL) can be accurately obtained at the desired frequencies. Consequently, the algorithm proposed in this study provides an efficient way to develop optimal rectangular plenums internally equipped with two crossed baffles. [ABSTRACT FROM AUTHOR]

Abstract: This study reports on energy efficiency optimization regarding bottom trawls. Efficient fishing gear uses up only a small amount of energy per fish caught. Drag and mouth area during trawling operations affect energy efficiency. Drag causes the energy consumption and the trawl mouth area impacts the quantity of fish caught, hence an energy efficient gear has a low ratio drag on the mouth area. A novel numerical optimization technique using spatial fish distribution is presented in this work. The tool is based on a FEM mechanical model for trawls which consist mostly of netting panels sewn together. This tool is adapted to minimize an objective function namely the drag-to-mouth area ratio. This technique consists in modifying the design of all the panels of the trawl. In this paper the modifications are constant and quantified in terms of mesh number. Moreover the trawl mouth area takes into account the presence of fish within a given depth with respect to sea bottom and the value of the depth is adapted to the fish species of interest. Trawl design optimization with two uniform fish distributions at a given depth (6m and 3m above the sea bed) and one linear distribution at 6m above the sea bed are compared. The application of this tool when designing a bottom trawl for research vessels leads to an energy economy ranging from 16% to 52% under certain assumptions. [Copyright &y& Elsevier]

Abstract: This paper describes a new numerical method for the design of multi-step stamping tools, in which the optimization approach is based on the Response Surface Method (RSM) with Kriging interpolation as well as the Sequential Quadratic Programming (SQP) algorithm. The present work attempts to provide a reliable methodology for the optimum design of the forming tools in order to produce a desired part by multi-step stamping within a severe tolerance (0.1mm). The numerical method has been proposed to reduce the number of forming steps and therefore increasing the process productivity. To reach this goal, an integrated optimization approach, using the commercial finite element code ABAQUS© together with an optimization algorithm was developed. The optimization algorithm consists in constructing an explicit form of the objective function according to the design variables. To search the global optimum of the objective function, the SQP algorithm has been used. A thin metallic part formed by manual press and without blank-holder has been considered, to demonstrate the effectiveness of the optimization approach to get the optimal tools shape in a few iterations. [Copyright &y& Elsevier]

Abstract: Non-linear finite element analyses were carried out to evaluate and optimize the seismic characteristics of knee-braced cold formed steel shear walls using software ANSYS. Different structural characteristics including: material nonlinearity, geometric imperfection, residual stresses and perforations are taken into account. The numerical models were verified based on experimental tests. Agreement of the numerical simulations and the test results showed that finite element analysis can be used effectively to predict the ultimate capacity of knee-braced CFS shear panels. A total of 12 models with a various ranges of knee-elements'' lengths were investigated. Of particular interests were the specimens'' maximum lateral load capacity and deformation behavior in addition to a rational estimation of the seismic response modification factor. Preliminary conclusions presented in this paper, refer to the optimum seismic characteristics of knee-braced CFS shear walls and the corresponding dimensions and configuration. [Copyright &y& Elsevier]

Abstract: In this paper, single and bi-layered tube hydroforming processes were numerically simulated using the finite element method. It was found that the final bulges heights resulted from the models were in good agreement with the experimental results. Both types of modeling have been kept with the same geometry, tube material, and process parameters to compare between the obtained hydroformed products (branch height, thickness reduction, and wrinkling) using different loading path types. Results were discussed. [Copyright &y& Elsevier]

Abstract: This paper introduces a method which allows the calculation of the optimal radial interference and the optimal mandrel shape on a cold-expanded bushing–hole connection commonly used in aerospace structures, in order to obtain the desired values of the residual stresses on the hole surface. This method has been developed by an extended campaign of FE analysis, planned and evaluated with statistical techniques on the basis of a previous presented closed-form method to determine the residual stress field. The method will give the possibility to reduce the zone of the hole surface subject to negligible residual radial stresses, obtaining also compressive residual circumferential stresses on the entire hole surface. An experimental axial fatigue test plan on aeronautical components with optimized cold-expanded bushing–hole connections and subjected to cyclic loads showed a substantial improvement in fatigue life. [Copyright &y& Elsevier]

Based on a numerical study by means of three-dimensional finite-element analysis, this paper discusses investigations of the bearing behavior of piled rafts in overconsolidated clay. It is shown that the interaction between piles and rafts is a major influence. The potential savings of an optimized foundation design are demonstrated for a simple example. [ABSTRACT FROM AUTHOR]