G. Dhondt¹

Structural Durability & Health Monitoring, Vol.1, No.1, pp. 21-34, 2005, DOI:10.3970/sdhm.2005.001.021

Abstract An algorithm is described which allows for the automatic calculation of crack propagation due to cyclic loading under mixed-mode conditions. The core of the procedure deals with the insertion of an arbitrarily formed crack into a virgin 20-node brick element mesh, thereby generating new quadratic bricks. One especially difficult aspect is the extension of the triangulation of the crack surface up to the boundary of the crack front elements. In the present article the technique is applied to linear elastic calculations using the stress intensity factor concept and a Paris-type law. However, other crack propagation parameters and crack propagation laws… More >

S. N. Atluri¹

Structural Durability & Health Monitoring, Vol.1, No.1, pp. 1-20, 2005, DOI:10.3970/sdhm.2005.001.001

Abstract The solution of three-dimensional cracks (arbitrary surfaces of discontinuity) in solids and structures is considered. The BEM, developed based on the symmetric Galerkin BIEs, is used for obtaining the fracture solutions at the arbitrary crack-front. The finite element method is used to model the uncracked global (built-up) structure for obtaining the stresses in an otherwise uncracked body. The solution for the cracked structural component is obtained in an iteration procedure, which alternates between FEM solution for the uncracked body, and the SGBEM solution for the crack in the local finite-sized subdomain. In addition, some crack growth models are used to… More >

Leiting Dong^1,2, Satya N. Atluri^1,3

CMC-Computers, Materials & Continua, Vol.33, No.2, pp. 111-154, 2013, DOI:10.3970/cmc.2013.033.111

Abstract In this study, SGBEM Voronoi Cells (SVCs), with each cell representing a grain of the material at the micro-level, are developed for direct micromechanical numerical modeling of heterogeneous composites. Each SVC can consist of either a (each with a different) homogenous isotropic matrix, and can include micro-inhomogeneities such as inclusions, voids of a different material, and cracks. These inclusions and voids in each SVC can be arbitrarily-shaped, such as circular, elliptical, polygonal, etc., for 2D problems. Further, the cracks in each SVC can be fully-embedded, edge, branching, or intersecting types, with arbitrary curved shapes. By rearranging the weakly-singular boundary integral… More >

L. Susmel^1,2, D. Taylor², R. Tovo¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.2, pp. 81-86, 2007, DOI:10.3970/icces.2007.001.081

Abstract This paper investigates some practical aspects related to the use of the Theory of Critical Distances (TCD) when employed to estimate notch fatigue limits. The accuracy of different formalisations of the theory was checked by using experimental data taken from the literature. This exercise allowed us to confirm that the simplest formalisation of the TCD, in which both critical distance and critical stress are material constants [1], is also the most accurate one, giving predictions falling within an error interval of about ±20%. The TCD is also accurate when applied to notches having large opening angles. More >

Z. D. Han¹, S. N. Atluri¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.6, pp. 699-716, 2002, DOI:10.3970/cmes.2002.003.699

Abstract As shown in an earlier work, the FEM-BEM alternating method is an efficient and accurate method for fracture analysis. In the present paper, a further improvement is formulated and implemented for the analyses of three-dimensional arbitrary surface cracks by modeling the cracks in a local finite-sized subdomain using the symmetric Galerkin boundary element method (SGBEM). The finite element method is used to model the uncracked global (built-up) structure for obtaining the stresses in an otherwise uncracked body. The solution for the cracked structural component is obtained in an iteration procedure, which alternates between FEM solution for the uncracked body, and… More >

Kaito Watanabe¹, Masaki Izawa¹, Ayumi Takahashi¹, Kazuhito Misaji^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.114, No.2, pp. 191-207, 2018, DOI:10.3970/cmes.2018.114.191

Abstract Under the aim of finding effective rehabilitation solutions, the difference between the extents of fatigue of each muscle used in different motions are compared. Previous research suggested methods for estimating muscle torque and muscle tension on the basis of a musculoskeletal model. As a result, it has become possible to quantitatively identify the extent of fatigue in each muscle during motion. Therefore, to evaluate muscle fatigue more quantitatively, driving power and angular momentum are focused on. Based on the driving torque of joints and the muscle torque calculated by using a three-dimensional musculoskeletal model, a method for calculating the driving… More >

N. Yan, N. Kawagoishi, Y. Maeda, Q. Chen

The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.4, pp. 103-104, 2011, DOI:10.3970/icces.2011.017.103

Abstract Fatigue tests under rotating bending and ultrasonic loading were carried out using plain specimens with different grain sizes of Ni-base super alloy, Inconel 718, in order to investigate the effects of grain size and loading frequency on fatigue properties. Fatigue strength was increased with decreasing in grain size under both tests. Moreover, the fatigue strength under ultrasonic loading was higher than that under rotating bending. The resistance to crack initiation was larger in smaller grain sized alloy under both tests, and larger under ultrasonic loading than under rotating bending. Effects of loading frequency and grain size on crack initiation were… More >

Youshi Hong, Chengqi Sun, Aiguo Zhao

The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.3, pp. 91-92, 2011, DOI:10.3970/icces.2011.016.091

Abstract The researches on the behavior of very-high-cycle fatigue (VHCF) for high strength steels have become a new branch in the field of metal fatigue since 1980s. The characteristics of crack initiation and propagation for high strength steels in VHCF regime differ from those in low cycle and high cycle fatigue regimes. One of the most distinct phenomena for VHCF regime is the interior or subsurface crack initiation at inclusions or at other inhomogeneities. In fact, the period of crack initiation and early growth dominates the fatigue life, which is extremely evident for the fatigue process containing VHCF regime. This paper… More >

T. Sakai, W. Li, B. Lian, N. Oguma

The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.1, pp. 7-8, 2011, DOI:10.3970/icces.2011.016.007

Abstract Long term use of mechanical products provides us a lot of positive environmental effects such as saving resources, saving energy, reducing environmental load to globe and reducing the industrial wastes. Thus, fatigue property of metallic materials in very high cycle regime such as gigacycles has been a new important subject to ensure the long durability of actual mechanical structures during the latest decades. From this point of view, fatigue tests in the long life regime were performed for various kinds of metallic materials by many researchers and a series of experimental results were reported. One of most typical aspect in… More >

LIU Yong-jie, TIAN Ren-hui, OUYANG Qiao-lin, WANG Qing-yuan

The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.1, pp. 5-6, 2011, DOI:10.3970/icces.2011.016.005

Abstract Ti-6Al-4V is widely used in biology engineering as well medical implant. Clinical investigations show that TC4 implant could have rupture of passivation film and visible corrosion. To predict service life of the Ti-6Al-4V implant, it is necessary to study its ultra-high cycle fatigue behaviors in physiological environment exceeding 10⁷ cycles. In this paper, using the ultrasonic fatigue testing technique, the high cycle and ultra-high cycle fatigue properties of Ti-6Al-4V subjection to simulated body fluid (SBF) in body temperature were studied and compared with that of normal Ti-6Al-4V. The experimental results show that SBF subjection has slight influence on the ultra-high… More >