Yongfeng Zhang¹, Hanchen Huang^1,2, Satya N. Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.35, No.3, pp. 215-226, 2008, DOI:10.3970/cmes.2008.035.215

Abstract Molecular dynamics simulations reveal the asymmetrical yield strength of twinned copper nanowires under tension and compression. The simulation results show that the strength of nanowires depends on loading conditions, morphologies, and twin spacing. Under tensile loading condition the Schmidt factor of the leading partial is larger than that under compression. Effectively, the yield strength under tension is smaller than that under compression. When the cross-section is circular in morphology, dislocation nucleation requires larger stress, and the asymmetry of yield strength depends on the nucleation stress. When the cross section is square in morphology, dislocation nucleation More >

H. T. Wang¹, Z. H. Yao²

CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.1, pp. 1-14, 2008, DOI:10.3970/cmes.2008.029.001

Abstract Carbon nanotubes (CNTs) may provide ultimate enhancement in stiffness and strength for composite materials. This paper presents a rigid-fiber-based boundary integral equation formulation for the numerical simulation of debonding process and the corresponding strength of CNT reinforced composites. The CNT/matrix interfaces are assumed to fail when the interfacial shear force reaches a prescribed threshold, and the CNTs and matrix are considered to be detached in the failed areas. The matrix with one or several tens of originally well-bonded CNTs is subjected to an incremental tensile load and the effective stress-strain relations are readily obtained by… More >

Asif Husain¹, M. Guniganti², D. K. Sehgal², R. K. Pandey²

CMC-Computers, Materials & Continua, Vol.8, No.3, pp. 133-150, 2008, DOI:10.3970/cmc.2008.008.133

Abstract This paper describes an approach to identify the mechanical properties i.e. fracture and yield strength of steels. The study involves the FE simulation of shear punch test for various miniature specimens thickness ranging from 0.20mm to 0.80mm for four different steels using ABAQUS code. The experimental method of the miniature shear punch test is used to determine the material response under quasi-static loading. The load vs. displacement curves obtained from the FE simulation miniature disk specimens are compared with the experimental data obtained and found in good agreement. The resulting data from the load vs.… More >

Ralf G. Cuntze¹

Structural Durability & Health Monitoring, Vol.3, No.2, pp. 87-106, 2007, DOI:10.3970/sdhm.2007.003.087

Abstract The paper deals with the application of phenomenological, invariant-based strength conditions (fracture failure) and their interrelationships. The conditions have been generated and are just applied here for a variety of materials. These might possess a dense or a porous consistency, and belong to brittle and ductile behaving isotropic materials, brittle unidirectional laminae and brittle woven fabrics. The derivation of the conditions was based on the author's so-called Failure Mode Concept (FMC) which basically builds up on the hypotheses of Beltrami and Mohr-Coulomb.
Essential topics of the paper are: 'global fitting' versus 'failure mode fitting', a short… More >

Y. Kato, Y. Yamamura

The International Conference on Computational & Experimental Engineering and Sciences, Vol.4, No.2, pp. 87-92, 2007, DOI:10.3970/icces.2007.004.087

Abstract The purpose of this study is to investigate the deformational behavior and strength of the catheter which is made from the soft nylon resin and is reinforced with thin stainless wires called braid. When we image the usage conditions of catheter in the actual surgical operation, it is expected that the multi-axial loading for tension, torsion and the bending are applied and deformations occurring in the catheter become very complicated. As the first step of this study to reveal these phenomena, the combined loadings for tension and torsion are chosen as the subject of this More >

Doo Kie Kim¹, Seong Kyu Chang¹, Sang Kil Chang¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.1, pp. 29-34, 2007, DOI:10.3970/icces.2007.002.029

Abstract Accurate and realistic strength estimation before the placement of concrete is highly desirable. In this study, the advanced probabilistic neural network (APNN) was proposed to reflect the global probability density function by summing the heterogeneous local probability density function automatically determined in the individual standard deviation of variables. Currently, the estimation of the compressive strength of concrete is performed by a probabilistic neural network (PNN) on the basis of concrete mix proportions, and the PNN is improved by the iteration method. However, an empirical method has been incorporated to specify the smoothing parameter in the More >

J. Toribio ¹

Structural Durability & Health Monitoring, Vol.2, No.4, pp. 239-248, 2006, DOI:10.3970/sdhm.2006.002.239

Abstract This paper reviews the fracture performance in air and aggressive environment (stress corrosion cracking) of eutectoid prestressing steel wires with different levels of cold drawing. In air environment, a micromechanical model of fracture is proposed to rationalize the results on the basis of the microstructure of the steels after drawing and the model of Miller & Smith of fracture of pearlitic microstructure by shear cracking of the cementite lamellae. In hydrogen assisted cracking (HAC), a microstructure-based model is proposed on the basis of the Miller & Smith model and the mechanism of hydrogen enhanced decohesion or, more More >

G. Milani¹, T. Rotunno², E. Sacco³, A. Tralli^1,4

Structural Durability & Health Monitoring, Vol.2, No.1, pp. 29-50, 2006, DOI:10.3970/sdhm.2006.002.029

Abstract Aim of the present work is the evaluation of the ultimate load bearing capacity of masonry panels reinforced with FRP strips. The investigation is developed performing both experimental and numerical studies. In particular, several panels subjected to different loading conditions are tested in the Tests Laboratory of the University of Florence (Italy). Then, numerical models based on combined homogenization and limit analysis techniques are proposed. The results obtained by numerical simulations are compared with experimental data. The good agreement obtained shows that the proposed numerical model can be applied for the evaluation of the ultimate More >

E. Takai¹, R. Landesberg², R.W. Katz², C.T. Hung³, X.E Guo^1,4

Molecular & Cellular Biomechanics, Vol.3, No.1, pp. 1-12, 2006, DOI:10.3970/mcb.2006.003.001

Abstract Osteoblast interactions with extracellular matrix (ECM) proteins are known to influence many cell functions, which may ultimately affect osseointegration of implants with the host bone tissue. Some adhesion-mediated events include activation of focal adhesion kinase, and subsequent changes in the cytoskeleton and cell morphology, which may lead to changes in adhesion strength and cell responsiveness to mechanical stimuli. In this study we examined focal adhesion kinase activation (FAK), F-actin cytoskeleton reorganization, adhesion strength, and osteoblast responsiveness to fluid shear when adhered to type I collagen (ColI), glass, poly-L-lysine (PLL), fibronectin (FN), vitronectin (VN), and serum… More >

W. Brocks¹

Structural Durability & Health Monitoring, Vol.1, No.4, pp. 233-244, 2005, DOI:10.3970/sdhm.2005.001.233

Abstract A review on phenomenological fracture criteria is given, based on the energy balance for cracked bodies, and the respective toughness parameters are related to micromechanical processes. Griffith's idea of introducing a "surface energy" and Barenblatt's concept of a "process zone" ahead of the crack tip build the foundation of modern cohesive models, which have become versatile tools for numerical simulations of crack extension. The cohesive strength and the separation energy used as phenomenological material parameters in these models appear to represent a physically significant characterisation of "fracture toughness". Micromechanical interpretations of these parameters can be More >