JSOL

About: JSOL is a based out in . It is known for research contribution in the topics: Finite element method & Welding. The organization has 83 authors who have published 106 publications receiving 680 citations.

Baggage Transportation and Navigation by a Wheeled Inverted Pendulum Mobile Robot

Abstract: Our goal is to configure an automatic baggage-transportation system by an inverted pendulum robot and realize a navigation function in a real environment. The system consists of two cooperative subsystems: a balancing-and-traveling control subsystem and a navigation subsystem. Position errors of the inverted pendulum robot are often caused by a drift error in the gyro sensor and a change in the center of gravity by a loaded baggage when applying the linear state feedback control method for balancing and traveling. We have reduced the position errors for navigation by resetting the balance position occasionally while traveling with simple methods without an external observer or alternative sensors. In this paper, we state the method and show the experimental results of navigation in a real environment by the implemented robot system.

Iterative substructure method employing concept of inherent strain for large-scale welding problems

Abstract: When structures such as ships, automobiles, and bridges are assembled by welding, distortion and residual stress are produced as unavoidable consequence of local shrinkage due to welding. The dimensional error deteriorates the performance of the structures and becomes an obstacle to achieve smooth manufacturing if the error exceeds the tolerable limit. On the other hand, residual stress plays an important role in crack initiation and fatigue life. Thus, it is necessary to predict the welding distortion and stress beforehand, so that effective measure and control can be taken. Since the welding is a highly nonlinear problem, it is difficult to predict the distortion quantitatively. For accurate prediction, finite element analysis (FEA) can be a powerful tool. In this research, an enhanced FEA scheme namely i-ISM is developed based on the inherent strain concept and iterative substructure method (ISM). Its capability of solving large-scale practical problems is demonstrated through typical models.

Machine design optimization based on finite element analysis in a high-throughput computing environment

Abstract: Although finite element (FE) analysis is a powerful analytical tool for electric machines, it is rarely used in iterative machine design optimization programs since it is computationally intensive, requiring excessive calculation times. This paper describes an approach for overcoming this obstacle using a high-throughput computing (HTC) environment that harnesses the parallel processing capabilities of large numbers of computers to evaluate many candidate designs simultaneously. Differential evolution has been selected as the optimization algorithm that applies FE analysis to maximize the electromagnetic performance according to an objective function in a computationally-efficient manner. This software has been applied using available HTC resources to optimize the design of a 30 kW (continuous) fractional-slot concentrated winding (FSCW) surface permanent magnet (SPM) machine for high torque density. Tests comparing the computational speeds achieved using the same optimization software with the HTC resources and a single computer have demonstrated a major reduction (approx. 30∶1) of the computation time using the HTC approach.

FPGA permanent magnet synchronous motor floating-point models with variable-DQ and spatial harmonic Finite-Element Analysis solvers

Abstract: This paper explains the FPGA implementation of a Permanent Magnet Synchronous Motor (PMSM) model using the latest JMAG-RT Finite-Element-Analysis software's real-time models: variable-DQ and Spatial Harmonic. In the variable-DQ (VDQ) model, the DQ inductances are varied according to the saturation level and a sinusoidal back-EMF is assumed. In the Spatial Harmonic (SH) model, the instantaneous magnetisation state is used to integrate the model; differential inductance and nonsinusoidal back-EMF are considered for all possible points of operation, resulting in improved precision, especially in transient states. The SH model also includes torque and current harmonics contents induced by machine slots and back-EMF spatial configurations. Both VDQ and SH models are implemented in a ML605 FPGA board running in the RT-LAB real-time simulation environment.

Microstructural Characteristics and Mechanical Properties of Friction Stir Welded Thick 5083 Aluminum Alloy

Abstract: Joining thick sections of aluminum alloys by friction stir welding (FSW) in a single pass needs to overcome many challenges before it comes to full-scale industrial use. Important parameters controlling the structure-properties relationships both across weld cross-section and through thickness direction were investigated through mechanical testing, electron backscatter diffraction technique, transmission electron microscopy, and occurrence of serrated plastic flow. The evolution of the properties in the weld cross-section shows that the presence of undissolved and fragmented Al $$_6$$ MnFe particles cause discrepancies in establishing the Hall-Petch relationship, and derive the strengthening from the Orowan strengthening mechanism. A ‘stop action’ friction stir weld has been prepared to understand the role of geometrical features of the tool probe in the development of the final microstructure after complete weld. Sectioning through the ‘stop action’ weld with the probe in situ displays the individual effect of thread and flat on the grain structure formation. The material at the thread surface experiences more severe deformation than the material at flat surface. Both the high-angle boundaries and mean grain size are found to be higher at the thread surface. The strain hardening capacity, stress serration amplitude, and frequency are observed to be higher in the stir zone than other weld regions.