K. Garikipati¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.2, pp. 175-184, 2002, DOI:10.3970/cmes.2002.003.175

Abstract The embedding of micromechanical models in the macromechanical formulation of continuum solid mechanics can be treated by a variational multiscale method. A scale separation is introduced on the displacement field into coarse and fine scale components. The fine scale displacement is governed by the desired micromechanical model. Working within the variational framework, the fine scale displacement field is eliminated by expressing it in terms of the coarse scale displacement and the remaining fields in the problem. The resulting macromechanical formulation is posed solely in terms of the coarse scale displacements, but is influenced by the fine scale; thereby it has… More >

F. Simonetti¹, R. M. Ardito Marretta²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 81-90, 2000, DOI:10.3970/cmes.2000.001.383

Abstract Advanced propellers are being developed to improve the performance and fuel economy of future transport aircraft. To study them, various aerodynamic prediction models and systems (from theory to experiment) have been developed via several approaches (Free Wake Analysis, helicoidal source methods, scale model tests). This study focuses on the development of an efficient numerical method to predict the behaviour of rotor or propeller in forward flight. Based on a variational approach, the present numerical technique allows a significant reduction of computer resources used in the calculation of instantaneous velocities to determine the wake geometry and the three-dimensional vortex flow streaming… More >

Yu Yang^1,2,*, Yuwei Chen^1,2, Yuling Chen², Wei Bi^3,4

CMC-Computers, Materials & Continua, Vol.56, No.2, pp. 261-272, 2018, DOI: 10.3970/cmc.2018.02736

Abstract The state-of-the-art universal steganalysis method, spatial rich model (SRM), and the steganalysis method using image quality metrics (IQM) are both based on image residuals, while they use 34671 and 10 features respectively. This paper proposes a novel steganalysis scheme that combines their advantages in two ways. First, filters used in the IQM are designed according to the models of the SRM owning to their strong abilities for detecting the content adaptive steganographic methods. In addition, a total variant (TV) filter is also used due to its good performance of preserving image edge properties during filtering. Second, due to each type… More >

Zhengzheng Cao¹, Ping Xu^1,*, Zhenhua Li², Minxia Zhang¹, Yu Zhao¹, Wenlong Shen²

CMC-Computers, Materials & Continua, Vol.54, No.2, pp. 137-159, 2018, DOI:10.3970/cmc.2018.054.137

Abstract In the traditional mining technology, the coal resources trapped beneath surface buildings, railways, and water bodies cannot be mined massively, thereby causing the lower coal recovery and dynamic disasters. In order to solve the aforementioned problems, the roadway backfilling mining technology is developed and the joint bearing mechanism of coal pillar and backfilling body is presented in this paper. The mechanical model of bearing system of coal pillar and backfilling body is established, by analyzing the basic characteristics of overlying strata deformation in roadway backfilling mining technology. According to the Ritz method in energy variation principle, the elastic solution expression… More >

Chih-Ping Wu^1,2, Ruei-Yong Jiang¹, Sheng-Yao Tu¹

CMC-Computers, Materials & Continua, Vol.41, No.2, pp. 111-152, 2014, DOI:10.3970/cmc.2014.041.111

Abstract Exact three-dimensional stability and free vibration analyses of simply-supported, multilayered functionally graded material (FGM) circular hollow cylinders and laminated composite ones under axial compression are presented. The material properties of each FGM layer are assumed to obey a power-law distribution of the volume fractions of constituents through the thickness coordinate. The Pagano method, which is based on the principle of virtual displacement and is conventionally used for the analysis of laminated composite structures, is modified to be feasible for the study of multilayered FGM cylinders, in which Reissner's mixed variational theorem, the successive approximation and transfer matrix methods, and the… More >

L.B. Borkowski¹, K.C. Liu¹, A. Chattopadhyay¹

CMC-Computers, Materials & Continua, Vol.37, No.3, pp. 161-193, 2013, DOI:10.3970/cmc.2013.037.161

Abstract The microstructural variation in fiber-reinforced composites has a direct relationship with its local and global mechanical performance. When micromechanical modeling techniques for unidirectional composites assume a uniform and periodic arrangement of fibers, the bounds and validity of this assumption must be quantified. The goal of this research is to quantify the influence of microstructural randomness on effective homogeneous response and local inelastic behavior. The results indicate that microstructural progression from ordered to disordered decreases the tensile modulus by 5%, increases the shear modulus by 10%, and substantially increases the magnitude of local inelastic fields. The experimental and numerical analyses presented… More >

E. Ferretti¹

CMC-Computers, Materials & Continua, Vol.36, No.3, pp. 293-322, 2013, DOI:10.3970/cmc.2013.036.293

Abstract The Cell Method is applied in order to model the debonding mechanism in ceramic floor tiles subjected to positive thermal variation. The causes of thermal debonding, very usual in radiant heat floors, have not been fully clarified at the moment. There exist only a few simplified analytical approaches that assimilate this problem to an eccentric tile compression, but these approaches introduce axial forces that, in reality, do not exist. In our work we have abandoned the simplified closed form solution in favor of a numerical solution, which models the interaction between tiles and sub-base more realistically, when the positive thermal… More >

Sanjeev Saxena¹, Raghvendra Singh², Geeta Agnihotri²

CMC-Computers, Materials & Continua, Vol.36, No.3, pp. 257-270, 2013, DOI:10.3970/cmc.2013.036.257

Abstract The present numerical study is an attempt to understand the dependency of characteristic distance on the fracture specimen thickness and temperature. The presented work will be useful to establish the characteristic distance prediction methodology using three dimensional FEM model. Based on the methods proposed for the numerical prediction of characteristic distance, it comes out that it depends on fracture specimen thickness and finally it converges after a specified thickness of fracture specimen. In Armco iron material, characteristic distance varies in temperature ranges where dynamic strain ageing phenomenon is observed, initially decrease and then increases again. More >

L. Dong¹, S. N. Atluri²

CMC-Computers, Materials & Continua, Vol.24, No.1, pp. 61-104, 2011, DOI:10.3970/cmc.2011.024.061

Abstract A simple procedure to formulate efficient and stable hybrid/mixed finite elements is developed, for applications in macro- as well as micromechanics. In this method, the strain and displacement field are independently assumed. Instead of using two-field variational principles to enforce both equilibrium and compatibility conditions in a variational sense, the independently assumed element strains are related to the strains derived from the independently assumed element displacements, at a finite number of collocation points within the element. The element stiffness matrix is therefore derived, by simply using the principle of minimum potential energy. Taking the four-node plane isoparametric element as an… More >

Q. S. Yang¹, B. S. Liu, L. T. Meng

CMC-Computers, Materials & Continua, Vol.12, No.1, pp. 39-56, 2009, DOI:10.3970/cmc.2009.012.039

Abstract Coupling and interaction of multi-physical fields exist in hydrogel consisting of a fluid and a solid under external stimulus. In this paper, a phenomenological theory for chemo-mechanical coupling behavior and finite element formulation are developed, based on the thermodynamic laws. The free energy function is constructed and used to derive the constitutive equations and governing equations for a linear coupling system including a chemical effect. Equivalent integral forms of the governing equations and coupled finite element equations are obtained by a variational principle. Numerical examples demonstrate the interaction of chemical and mechanical effects of hydrogel under external force loadings and… More >