• Steel and Composite Structures
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• 제45권2호
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• pp.205-218
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• 2022

Proper calculation of splitting tensile strength (STS) of concrete has been a crucial task, due to the wide use of concrete in the construction sector. Following many recent studies that have proposed various predictive models for this aim, this study suggests and tests the functionality of three hybrid models in predicting the STS from the characteristics of the mixture components including cement compressive strength, cement tensile strength, curing age, the maximum size of the crushed stone, stone powder content, sand fine modulus, water to binder ratio, and the ratio of sand. A multi-layer perceptron (MLP) neural network incorporates invasive weed optimization (IWO), cuttlefish optimization algorithm (CFOA), and electrostatic discharge algorithm (ESDA) which are among the newest optimization techniques. A dataset from the earlier literature is used for exploring and extrapolating the STS behavior. The results acquired from several accuracy criteria demonstrated a nice learning capability for all three hybrid models viz. IWO-MLP, CFOA-MLP, and ESDA-MLP. Also in the prediction phase, the prediction products were in a promising agreement (above 88%) with experimental results. However, a comparative look revealed the ESDA-MLP as the most accurate predictor. Considering mean absolute percentage error (MAPE) index, the error of ESDA-MLP was 9.05%, while the corresponding value for IWO-MLP and CFOA-MLP was 9.17 and 13.97%, respectively. Since the combination of MLP and ESDA can be an effective tool for optimizing the concrete mixture toward a desirable STS, the last part of this study is dedicated to extracting a predictive formula from this model.

• Steel and Composite Structures
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• 제48권1호
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• pp.1-17
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• 2023

The main goal of this paper is to study vibration of damaged core laminated sectorial plates with Functionally graded (FG) face sheets based on three-dimensional theory of elasticity. The structures are made of a damaged isotropic core and two external face sheets. These skins are strengthened at the nanoscale level by randomly oriented Carbon nanotubes (CNTs) and are reinforced at the microscale stage by oriented straight fibers. These reinforcing phases are included in a polymer matrix and a three-phase approach based on the Eshelby-Mori-Tanaka scheme and on the Halpin-Tsai approach, which is developed to compute the overall mechanical properties of the composite material. Three complicated equations of motion for the sectorial plates under consideration are semi-analytically solved by using 2-D differential quadrature method. Using the 2-D differential quadrature method in the r- and z-directions, allows one to deal with sandwich annular sector plate with arbitrary thickness distribution of material properties and also to implement the effects of different boundary conditions of the structure efficiently and in an exact manner. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. The sandwich annular sector plate is assumed to be simply supported in the radial edges while any arbitrary boundary conditions are applied to the other two circular edges including simply supported, clamped and free. Several parametric analyses are carried out to investigate the mechanical behavior of these multi-layered structures depending on the damage features, through-the-thickness distribution and boundary conditions.

• 대한기계학회논문집B
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• 제35권5호
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• pp.481-486
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• 2011

회전하는 실린더 주변의 액막 거동을 예측하는 것은 제철 산업에서 판재의 부식을 방지하기 위한 박막 코팅 과정에 매우 중요하게 적용될 수 있다. 판재 코팅에 사용할 박막을 만들기 위하여 실린더를 회전하는 경우, 실린더 주변 액막의 거동은 실린더 지름 및 회전 속도, 중력, 유체의 물성에 따라 영향을 받는다. 이러한 변수의 영향으로 실린더를 따라 상승하는 액막의 거동 특성 및 실린더 주변 액막 두께가 결정된다. 본 연구에서는 회전하는 실린더 주변 액막 거동에 대한 경계면을 갖는 이상유동에 대해 VOF 방법을 사용하여 수치해석하였다. 다양한 회전 속도, 실린더 지름, 유체 점성, 표면장력에 따른 액막 거동의 이상유동에 대한 수치해석을 통해 액막 두께를 예측할 수 있었다. 이를 통해, 회전 속도, 실린더 지름 및 유체 점성이 증가함에 따라 더 많은 액막을 상승시켜 두꺼운 액막을 형성하였으며, 이러한 액막 두께에 대한 수치해석 결과는 기존 실험 및 이론적 상관식과 일치하는 결과를 보였다.