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Hull form optimization for the roll motion of a high-speed fishing vessel based on NSGA-II algorithm
Published in Pentti Kujala, Liangliang Lu, Marine Design XIII, 2018
Dan Qiao, Ning Ma, Xiechong Gu
The entire optimization process is controlled by NSGA-II algorithm running on iSight optimization platform, which is effective and robust for single/ multi-objective optimization problems. The input movable values of movable control points at the given degree of freedom of motion are set as the optimization variables. The RBF transformation method is utilized to conduct the ship hull form reconstruction and preparation for the seakeeping motion response calculation. The ship displacement constraints and GM constrains are employed for the fast elimination of the abnormal intermediate results to ensure the rationality of the iteration process. The seakeeping motion response calculations are carried on HydroStar based on 3-D potential theory. The maximum steps of iteration are installed as the stopping criterion, which is defined according to the population size and the number of generations in NSGA-II algorithm. The calculation, verification and confirmation of the level 2 vulnerability criteria for surf-riding and broaching, as well as the calm water resistance at service Froude number Fn = 4.0 are conducted after the completion of the ship hull form optimization process, where the appropriate intermediate results during the iteration should be selected strategically through constructions of the convex hull.
Uncertainty analysis and time-dependent reliability estimation for the main shaft device of a mine hoist
Published in Mechanics Based Design of Structures and Machines, 2022
Shuang Cao, Guoan Chen, Yuxing Peng, Hao Lu, Fengbin Ren
To develop an appropriate random response surface of the MSD as a metamodel, it is essential to analyze the random variables affecting the stress response of the MSD. The selection of random variables should not only reflect the randomness of response, but also disclose the fluctuation range of random variables. Random variables affecting safe operation of the MSD include machine-finishing precision, assembly tolerance and loads, among which the former two are reflected in the randomness of the MSD geometry (Figure 3). In this paper, the parameters of structures and loads are considered as random variables, including seven structure variables and three load variables, which are shown in Table 1. Latin hypercube sampling (LHS) is adopted to generate design matrices of random variables in hope of decreasing the experimental scale. In order to obtain the corresponding responses of the design matrix, a three-dimensional model of the MSD is established through equation modeling with random variables. The parametric model can be easily rebuilt by modifying the parameters of design variables in equation script, and each rebuilt model is subjected to the FE analysis to obtain the corresponding response. The above process can be realized via the multidisciplinary design optimization software iSIGHT integrated with SOLIDWORKS and ANSYS. The details of the integration process are summarized below:
Shape optimization of bi-directional flow passage components based on a genetic algorithm and computational fluid dynamics
Published in Engineering Optimization, 2018
Xueping Gao, Ye Tian, Bowen Sun
According to the survey of previous research studies, one of the most widely used methods to optimize the shapes of fluid devices is to combine the optimization algorithm and CFD (Smolka 2013a; Malkawi et al. 2005; Palacz et al. 2016; Ghosh et al. 2010; Amirante and Tamburrano 2016; Amirante et al. 2014). The optimization platform was built using iSight software (iSight 2009), with which simulation codes of different disciplines can be coupled. The following software are coupled to evaluate the objective function through CFD analysis: FLUENT (FLUENT 2006), GAMBIT (GAMBIT 2000) and MATLAB (Demuth and Beale 2010). This simulation is configured through a graphical interface, with which one can set up, monitor and analyse a design problem.
Multi-objective optimization design of wheel based on the performance of 13° and 90° impact tests
Published in International Journal of Crashworthiness, 2019
Dengfeng Wang, Shuai Zhang, Wenchao Xu
Therefore, taking a type wheel as research objects, united topology optimization was performed based on dynamic bending and radial fatigue tests, and an assembled wheel with a magnesium alloy rim and an aluminum alloy disc was designed. Measuring the magnesium and aluminum alloy stress–strain curves of the wheel in different strain rates by universal tensile testing machine, finite element models of assembled wheel were established for 13° impact tests with the Mooney–Rivlin tire material model. The effective plastic strains of the wheel under two conditions of the hammer impacting the spoke and the window were analyzed respectively and the relationship between the 13° impact performance and the wheel structure was studied. And established finite element models of the assembled wheel for 90° impact tests, analyzed the deformation of the inner wheel flange and the effective plastic strain of the rim and disc when the hammer impacted facing the window, and analyzed the failure range of the wheel and the effective plastic strain of the rim and disc beyond the 25% circumferential range (90°) of the impact position when the hammer impacted facing the valve window. Then studied the relationship between these performances and the wheel structure. The parametric models of the assembled wheel under four finite element conditions were established by mesh morphing technology. Multi-objective optimization model was built in Isight software platform where the DEP-Mesh Works and LS-DYNA software were integrated. Using the established surrogate model, Non-dominated Sorting Genetic Algorithm-II (NSGA-II) was adopted to perform the multi-objective optimization of the wheel to realize the lightweight.