KwangsooHo¹

CMES-Computer Modeling in Engineering & Sciences, Vol.2, No.3, pp. 351-364, 2001, DOI:10.3970/cmes.2001.002.351

Abstract Negative, zero or positive rate sensitivity of the flow stress can be observed in metals and alloys over a certain range of strain, strain rate and temperature. It is believed that negative rate sensitivity is an essential feature of dynamic strain aging, of which the Portevin-Le Chatelier effect is one other manifestation. The viscoplasticity theory based on overstress (VBO), one of the unified state variable theories, is generalized to model zero (rate independence) and negative as well as positive rate sensitivity in a consistent way. The present model does not have the stress rate term in the evolution law for… More >

Z. Chen¹, W. Hu¹, E.P. Chen²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.4, pp. 57-62, 2000, DOI:10.3970/cmes.2000.001.509

Abstract To simulate the dynamic failure evolution without using nonlocal terms in the strain-stress space, a damage diffusion equation is formulated with the use of a combined damage/plasticity model that was primarily applied to the case of rock fragmentation. A vectorized model solver is developed for large-scale simulation. Two-dimensional sample problems are considered to illustrate the features of the proposed solution procedure. It appears that the proposed approach is effective in simulating the evolution of localization, with parallel computing, in a single computational domain involving different lower-order governing differential equations. More >

H. Jiang^1,2, B. Yang¹, S. Liu³

CMC-Computers, Materials & Continua, Vol.38, No.2, pp. 61-77, 2013, DOI:10.3970/cmc.2013.038.061

Abstract Actin, fibrin and collagen fiber networks are typical hierarchical biological materials formed by bundling fibrils into fibers and branching/adjoining fibers into networks. The bundled fibrils interact with each other through weak van der Waals forces and, in some cases, additional spotted covalent crosslinks. In the present work, we apply Timoshenko's beam theory that takes into account the effect of transverse shear between fibrils in each bundle to study the overall mechanical behaviors of such fiber networks. Previous experimental studies suggested that these fibers are initially loose bundles. Based on the evidence, it is hypothesized that the fibers undergo transitions from… More >

Amiya K. Samanta¹, Somnath Ghosh²

CMC-Computers, Materials & Continua, Vol.8, No.1, pp. 43-52, 2008, DOI:10.3970/cmc.2008.008.043

Abstract A procedure has been described to carry out three-dimensional elastic analysis of reinforced concrete beam employing finite element technique, which uses lower order elements. The proposed procedure utilizes 8-noded isometric solid /hexahedral elements HCiS18 with enhanced assumed strain (EAS) formulation, recently developed in the literature, to predict load-deformation and internal stresses produced in case of a simply supported RC beams in the elastic regime. It models the composite behaviour of concrete and reinforcements in rigid /perfect bond situation and their mutual interaction in bond-slip condition considering continuous interface elements at the material level. Although, bond-slip relation are very much non-linear… More >

C. Nikhare¹, K. Narasimhan²

CMC-Computers, Materials & Continua, Vol.7, No.3, pp. 129-138, 2008, DOI:10.3970/cmc.2008.007.129

Abstract The tube hydroforming process is a relatively complex manufacturing process; the performance of this process depends on various factors and requires proper combination of part design, material selection and boundary conditions. In manufacturing of automotive parts, such as engine cradles, frames rails, sub-frames, cross members, and other parts from circular tubes, pre-bending and per-forming operations are often required prior to the subsequent tubular hydroforming process to fit the tubular blank in the complex die shape. Due to these pre-- hydroforming operations, some of the strains are already developed before going to the actual hydroforming process. Such developed strains before hydroforming… More >

C. Nikhare¹, K. Narasimhan²

CMC-Computers, Materials & Continua, Vol.7, No.1, pp. 1-8, 2008, DOI:10.3970/cmc.2008.007.001

Abstract Hydroforming is a manufacturing process that uses a fluid medium to form a component by using high internal pressure. Tube and sheet hydroforming has gained increasing interest in the automotive and aerospace industries because of its many advantages such as part consolidation, good quality of the formed parts etc. The main advantage is that the uniform pressure can be transferred to every where at the same time. Forming limit is the limit of the component up to that extent it can be formed safely. While analyzing hydroforming process, it is often assumed that the limit strains are identical as that… More >

H. Nguyen-Van¹, N. Mai Duy², T. Tran-Cong ³

CMC-Computers, Materials & Continua, Vol.6, No.3, pp. 159-176, 2007, DOI:10.3970/cmc.2007.006.159

Abstract This paper reports the development of a simple but efficient and accurate four-node quadrilateral element for models of laminated, anisotropic plate behaviour within the framework of the first-order shear deformation theory. The approach incorporates the strain smoothing method for mesh-free conforming nodal integration into the conventional finite element techniques. The membrane-bending part of the element stiffness matrix is calculated by the line integral on the boundaries of the smoothing elements while the shear part is performed using an independent interpolation field in the natural co-ordinate system. Numerical results show that the element offered here is locking-free for extremely thin laminates,… More >

M. Timmel¹, M. Kaliske¹, S. Kolling², R. Mueller³

CMC-Computers, Materials & Continua, Vol.5, No.3, pp. 161-172, 2007, DOI:10.3970/cmc.2007.005.161

Abstract A damage approach based on a material model with microstructural evolution is presented. In contrast to phenomenological constitutive laws, the material response is given by mechanisms at the microscale. At first, a micromechanical substructure is chosen, which represents the overall material behaviour. Then the system is described using a micromechanical model. A geometrical modification of the microstructure is allowed to minimize the total energy. Consequently, the global stiffness is reduced. In this context, thermodynamical considerations are based on configurational forces. With the help of the discussed approach, void growth phenomena of materials, which lead to softening behaviour, can be taken… More >

P. Le¹, N. Mai-Duy¹, T. Tran-Cong¹, G. Baker²

CMC-Computers, Materials & Continua, Vol.5, No.2, pp. 129-150, 2007, DOI:10.3970/cmc.2007.005.129

Abstract This paper presents a numerical simulation of the formation and evolution of strain localization in elasto-thermo-viscoplastic materials (adiabatic shear band) by the indirect/integral radial basis function network (IRBFN) method. The effects of strain and strain rate hardening, plastic heating, and thermal softening are considered. The IRBFN method is enhanced by a new coordinate mapping which helps capture the stiff spatial structure of the resultant band. The discrete IRBFN system is integrated in time by the implicit fifth-order Runge-Kutta method. The obtained results are compared with those of the Modified Smooth Particle Hydrodynamics (MSPH) method and Chebychev Pseudo-spectral (CPS) method. More >

Xiaorui Zhang^1,2,3,*, Jiali Duan¹, Jia Liu², Norman I. Badler³

CMC-Computers, Materials & Continua, Vol.60, No.3, pp. 1055-1071, 2019, DOI:10.32604/cmc.2019.03915

Abstract Current research on suture simulation mainly focus on the construction of suture line, and existing suture simulation systems still need to be improved in terms of diversity, soft tissue effects, and stability. This paper presents an integrated liver suture surgery system composed of three consecutive suture circumstances, which is conducive to liver suture surgery training. The physically-based models used in this simulation are based on different mass-spring models regulated by a special constrained algorithm, which can improve the model accuracy, and stability by appropriately restraining the activity sphere of the surrounding mass nodes around the suture points. We also studied… More >