Dustin D. Gerrard¹, David T. Fullwood¹, Denise M. Halverson², Stephen R. Niezgoda³

CMC-Computers, Materials & Continua, Vol.15, No.2, pp. 129-152, 2010, DOI:10.3970/cmc.2010.015.129

Abstract The effective properties of composite materials are often strongly related to the connectivity of the material components. Many structure metrics, and related homogenization theories, do not effectively account for this connectivity. In this paper, relationships between the topology, represented via homology theory, and the effective elastic response of composite plates is investigated. The study is presented in the context of popular structure metrics such as percolation theory and correlation functions. More >

Z. Bittnar, L. Vrablik, M. Polak, V. Kristek¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.13, No.2, pp. 43-48, 2009, DOI:10.3970/icces.2009.013.043

Abstract Detail structural and dynamic analysis of concrete suspended bridge structure in Prague which was assessed because of severe damages of parapets and expansion joints is presented. Measured and calculated results are compared and approaches to repairing and stiffening are also recommended. More >

B.K. Raghu Prasad¹, T.V.R.L. Rao¹, A.R. Gopalakrishnan¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.3, pp. 179-196, 2009, DOI:10.3970/icces.2009.009.179

Abstract A simple numerical method namely Initial Stiffness Method using finite element method has been employed to study the size effect which is prominent in concrete structures. Numerous experimental investigations performed on notched plain concrete beams subjected to three point or four-point bending have revealed the fracture process to be dependent on size of the structural member. It was found that, the nominal stress at maximum load decreases as the size of the structure increases. The nominal stress at failure on the characteristic dimension of structure is termed as size effect. This has also been explained More >

Yongchang Cai^1,2, J.K. Paik³, Satya N. Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.54, No.3, pp. 335-368, 2009, DOI:10.3970/cmes.2009.054.335

Abstract This paper presents a simple finite element method, based on assumed moments and rotations, for geometrically nonlinear large rotation analyses of space frames consisting of members of arbitrary cross-section. A von Karman type nonlinear theory of deformation is employed in the updated Lagrangian co-rotational reference frame of each beam element, to account for bending, stretching, and torsion of each element. The Reissner variational principle is used in the updated Lagrangian co-rotational reference frame, to derive an explicit expression for the (12x12)symmetrictangent stiffness matrix of the beam element in the co-rotational reference frame. The explicit expression… More >

Yongchang Cai^1,2, J.K. Paik³, Satya N. Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.53, No.2, pp. 123-152, 2009, DOI:10.3970/cmes.2009.053.123

Abstract This paper presents a simple finite element method, based on simple mechanics and physical clarity, for geometrically nonlinear large rotation analyses of space frames consisting of members of arbitrary cross-section. A co-rotational reference frame, involving the axes of each finitely rotated beam finite-element, is used as the Updated Lagrangian reference frame for the respective element. A von Karman type nonlinear theory of deformation is employed in the co-rotational reference frame of each beam element, to account for bending, stretching, and torsion of each element. An assumed displacement approach is used to derive an explicit expression… More >

H. Altenbach¹, V. A. Eremeyev²

CMC-Computers, Materials & Continua, Vol.9, No.2, pp. 153-178, 2009, DOI:10.3970/cmc.2009.009.153

Abstract Within the framework of the direct approach to the plate theory we consider natural oscillations of plates made of functionally graded materials taking into account both the rotatory inertia and the transverse shear stiffness. It is shown that in some cases the results based on the direct approach differ significantly from the classical estimates. The reason for this is the non-classical computation of the transverse shear stiffness. More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.27, No.3, pp. 137-150, 2008, DOI:10.3970/cmes.2008.027.137

Abstract For the inverse vibration problem, a Lie-group shooting method is proposed to simultaneously estimate the time-dependent damping and stiffness functions by using two sets of displacement as inputs. First, we transform these two ODEs into two parabolic type PDEs. Second, we formulate the inverse vibration problem as a multi-dimensional two-point boundary value problem with unknown coefficients, allowing us to develop the Lie-group shooting method. For the semi-discretizations of PDEs we thus obtain two coupled sets of linear algebraic equations, from which the estimation of damping and stiffness coefficients can be written out explicitly. The present More >

Chein-Shan Liu¹, Jiang-Ren Chang², Kai-Huey Chang², Yung-Wei Chen²

CMC-Computers, Materials & Continua, Vol.7, No.2, pp. 97-108, 2008, DOI:10.3970/cmc.2008.007.097

Abstract For the inverse vibration problem a mathematical method is required to determine unknown parameters from the measurement of vibration data. When both damping and stiffness functions are identified, it is a rather difficult problem. In this paper we will propose a feasible method to simultaneously estimate both the time-dependent damping and stiffness coefficients through three mathematical transformations. First, the second-order equation of motion is transformed into a self-adjoint first-order system by using the concept of integrating factor. Then, we transform these two ODEs into two hyperbolic type PDEs. Finally, we apply a one-step group preserving More >

F. Gao¹, D. Tang^2∗, Z. Guo³, Makoto Sakamoto⁴, T. Matsuzawa⁵

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.1, pp. 21-28, 2007, DOI:10.3970/icces.2007.001.021

Abstract Patients with aortic aneurysm, especially aortic arch aneurysm, are prone to aortic dissection. For investigation of the effects of aneurysm and wall stiffness on wall stress distribution, a nonaneurysm arch model as well as an aneurysm arch model was constructed. The fluid structure interaction was implemented in the arch model of aorta. The results show that the stresses are much higher at inflection points in the aneurysm model than in nonaneurysm model, and the stresses at media in stiffened wall are higher than in unstiffened wall. The high composite stress is located at inflection points More >

Judith Su^∗, Ricardo R. Brau^†, Xingyu Jiang^‡, George M. Whitesides^§, Matthew J. Lang^¶, Peter T. C. So^||

Molecular & Cellular Biomechanics, Vol.4, No.2, pp. 105-118, 2007, DOI:10.3970/mcb.2007.004.105

Abstract During migration, asymmetrically polarized cells achieve motion by coordinating the protrusion and retraction of their leading and trailing edges, respectively. Although it is well known that local changes in the dynamics of actin cytoskeleton remodeling drive these processes, neither the cytoskeletal rheological properties of these migrating cells are well quantified nor is it understand how these rheological properties are regulated by underlying molecular processes. In this report, we have used soft lithography to create morphologically polarized cells in order to examine rheological differences between the front and rear zone of an NIH 3T3 cell posed More >