Current Issue : July - September Volume : 2015 Issue Number : 3 Articles : 5 Articles
This work describes the development of a structural optimization framework adept at accommodating diverse customer\nrequirements. The purpose is to provide a framework accessible to the optimization research analyst. The framework integrates\nthe method of moving asymptotes into the finite element analysis program (FEAP) by exploiting the direct interface capability\nin FEAP. Analytic sensitivities are incorporated to provide a robust and efficient optimization search. User macros are developed\nto interface the design algorithm and analytic sensitivity with the finite element analysis program. To test the optimization tool\nand sensitivity calculations, three sizing and one topology optimization problems are considered. In addition, flutter analysis of a\nheated panel is analyzed as an example of coupling to nonstructural discipline. In sizing optimization, the calculated semianalytic\nsensitivities match analytic and finite difference calculations. Differences between analytic designs and numerical ones are less\nthan 2.0% and are attributed to discrete nature of finite elements. In the topology problem, quadratic elements are found robust at\nresolving checkerboard patterns....
This paper presents a decision framework that highlights the integration of manufacturing strategy (MS) and sustainability\nalong with strategic responses as a significant component. This integration raises complexity and uncertainty in decision-making\nfollowing the number of subjective components with their inherent relationships that must be brought into context and the huge\namount of required information in eliciting judgments.Thus, a proposed hybridmulticriteria decision-making (MCDM) approach\nin the form of an integrated probabilistic fuzzy analytic network process (PROFUZANP) is adopted in this work. In this method,\nanalytic network process (ANP) serves as the main framework in identifying policy options of manufacturing strategy. Fuzzy set\ntheory (FST) is used to describe vagueness in decision-making which is carried out by eliciting judgments in pairwise comparisons\nusing linguistic variables with corresponding triangular fuzzy numbers (TFNs). Probability theory is used to handle randomness\nin aggregating judgments of multiple decision-makers. Results show that a stakeholder-oriented approach is considered the most\nrelevant strategic response in developing a sustainable manufacturing strategy. The contribution of this work lies in identifying the\npolicies which constitute a sustainable manufacturing strategy using an integrated MCDM approach under uncertainty...
Metal materials can inevitably show deteriorated properties by the factors of stress, temperature, and environmental erosion in\ndistinct operating environments. Without proper protection, the service life would be shortened or even deadly danger would\nbe caused. This study aims to apply Finite Element Method and Boundary Element Method to analyzing the effects of corroded\npetrochemical pipes on the fatigue life and the fracture form.The research results of nondestructive testing and software analyses\nshow that cracked oil pipes with uniform corrosion bear larger stress, mainly internal pressure, on the longitudinal direction than\nthe circumferential direction. As a result, the maximal fatigue loading cycle of a circumferential crack is higher than that of a\nlongitudinal one. From the growing length and depth of a crack, the final aspect ratio of crack growth appears in 2.42ââ?¬â??3.37 and\n2.71ââ?¬â??3.42 on the circumferential and longitudinal direction, respectively.Meanwhile, the ratios of loading cycles of circumferential\nand longitudinal crack are 26.23 on uncorroded and 20.54 on general metal loss oil pipe. The complete crack growth and the\ncorrespondent fatigue loading cycle could be acquired to determine the service life of the oil pipe being operated as well as the\nsuccessive recovery time....
This paper proposes a redundantly actuated parallel manipulator 4-UPS-S that is applicable for orientation adjustment in the\ngathering process of solar power. A thorough analysis involving the kinematic issues is performed. Inverse kinematic problems\nare solved in the close-loop. The Jacobian matrix and some performance indexes are analytically derived. The multiobjective\noptimization model is established, and the determinacy optimization is completed on the basis of previous research works. Six-\nSigma robust analysis is performed on the basis of the determinacy optimal solution. Results show that 4-UPS-S does not satisfy\nthe quality requirement. Therefore, it is necessary to implement Six-Sigma robust optimization, and select optimial solution of\nrobustness to complete the nondeterminacy optimization.The research results show that the proposed methodology has a simple\noperation and high optimization efficiency. The methodology commodiously obtains robustness parallel manipulator that satisfies\nthe quality requirement....
Incompressible large eddy simulation and direct numerical simulation of a low-pressure turbine atRe = 5.18Ã?â??104 and 1.48Ã?â??105 with\ndiscrete incoming wakes are analyzed to identify the turbulent kinetic energy generation mechanism outside of the blade boundary\nlayer.The results highlight the growth of turbulent kinetic energy at the bow apex of the wake and correlate it to the stress-strain\ntensors relative orientation.The production rate is analytically split according to the principal axes, and then terms are computed\nby using the simulation results.The analysis of the turbulent kinetic energy is followed both along the discrete incoming wakes and\nin the stationary frame of reference. Both direct numerical and large eddy simulation concur in identifying the same production\nmechanism that is driven by both a growth of strain rate in the wake, first, followed by the growth of turbulent shear stress after.The\npeak of turbulent kinetic energy diffuses and can eventually reach the suction side boundary layer for the largest Reynolds number\ninvestigated here with higher incidence angle. As a consequence, the local turbulence intensity outside the boundary layer can grow\nsignificantly above the free-stream level with a potential impact on the suction side boundary layer transition mechanism....
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