H. S. Kazemi, S. M. Tavakkoli, R. Naderi,
Volume 6, Issue 2 (6-2016)
Abstract
The Isogeometric Analysis (IA) is utilized for structural topology optimization considering minimization of weight and local stress constraints. For this purpose, material density of the structure is assumed as a continuous function throughout the design domain and approximated using the Non-Uniform Rational B-Spline (NURBS) basis functions. Control points of the density surface are considered as design variables of the optimization problem that can change the topology during the optimization process. For initial design, weight and stresses of the structure are obtained based on full material density over the design domain. The Method of Moving Asymptotes (MMA) is employed for optimization algorithm. Derivatives of the objective function and constraints with respect to the design variables are determined through a direct sensitivity analysis. In order to avoid singularity a relaxation technique is used for calculating stress constraints. A few examples are presented to demonstrate the performance of the method. It is shown that using the IA method and an appropriate stress relaxation technique can lead to reasonable optimum layouts.
S. Fallahian, A. Joghataie , M.t. Kazemi,
Volume 8, Issue 3 (10-2018)
Abstract
An effective method utilizing the differential evolution algorithm (DEA) as an optimisation solver is suggested here to detect the location and extent of single and multiple damages in structural systems using time domain response method. Changes in acceleration response of structure are considered as a criterion for damage occurrence. The acceleration of structures is obtained using Newmark method. Damage is simulated by reducing the elasticity modulus of structural members. Three illustrative examples are numerically investigated, considering also measurement noise effect. All the numerical results indicate the high accuracy of the proposed method for determining the location and severity of damage.