Qing-fen Li¹, Li Zhu¹, Shi-fan Zhu¹, F-G Buchholz¹

Structural Durability & Health Monitoring, Vol.6, No.3&4, pp. 273-288, 2010, DOI:10.3970/sdhm.2010.006.273

Abstract The fracture behavior in all fracture mode (AFM)-specimen with a single edged crack under different loading conditions is investigated by the aid of the commercial ANSYS code. The separated strain energy release rates (SERRs) along the crack front are calculated by the modified virtual crack closure integral (MVCCI)-method. It is shown that the computational results of the AFM-specimen are in good agreement with some available findings for pure mode I, mode II, mode III, and mixed-mode I+III loading conditions. Furthermore, the crack growth problems under complex mixed-mode II+III loading condition by using the AFM-specimen, are More >

H. Theilig¹

Structural Durability & Health Monitoring, Vol.6, No.3&4, pp. 239-272, 2010, DOI:10.3970/sdhm.2010.006.239

Abstract The aim of this paper is to give an overview to some problems and solutions of the fracture analysis of 2D structures. It will be shown that the common computer-aided two-dimensional fatigue crack path simulation can be considerably improved in accuracy by using a predictor-corrector procedure in combination with the modified virtual crack closure integral (MVCCI) method. Furthermore the paper presents an improved finite element technique for the calculation of stress intensity factors of mixed mode problems by the MVCCI Method. The procedure is devised to compute the separated strain energy release rates by using the… More >

A.P.Cisilino¹, M.H. Aliabadi²

Structural Durability & Health Monitoring, Vol.6, No.3&4, pp. 213-238, 2010, DOI:10.3970/sdhm.2010.006.213

Abstract This paper presents a review of the dual boundary element method for modeling crack growth in two-dimensional and three-dimensional mixed mode problems. The modeling strategy for crack coalescence using the DBEM is presented and comparisons are made with alternative solutions where available. Also presented are three-dimensional multiple crack growth and microcrack growth problems. More >

W. Brocks¹, I. Scheider²

Structural Durability & Health Monitoring, Vol.6, No.3&4, pp. 189-212, 2010, DOI:10.3970/sdhm.2010.006.189

Abstract Material parameters are adjustable coefficients in constitutive equations of the mechanical behaviour. Their identification requires a combined experimental and numerical approach, which results in a generally ill-posed inverse problem. Methods commonly applied in computational mechanics like optimisation and neural networks are addressed, and problems like sensitivity, uniqueness and stability are discussed. The cohesive model for describing ductile tearing is chosen as practical example to substantiate the general considerations. More >

H.A. Richard¹, M. Fulland², G. Kullmer¹, N.-H. Schirmeisen¹

Structural Durability & Health Monitoring, Vol.6, No.3&4, pp. 161-188, 2010, DOI:10.3970/sdhm.2010.006.161

Abstract Fracture processes in real structures are in many cases of a three dimensional (3D) character. In this paper some basic problems of 3D-fracture processes are considered and discussed, in particular for general mixed-mode loading conditions, when modes I and II and III are superimposed. For experimental investigations an AFM-specimen is under consideration, while numerical simulations are carried out with the program ADAPCRACK3D. More >

R. G. Cuntze¹

Structural Durability & Health Monitoring, Vol.6, No.3&4, pp. 123-160, 2010, DOI:10.3970/sdhm.2010.006.123

Abstract The paper deals with the validation of 2D and 3D failure conditions of unidirectional (UD) composites composed of endless fibres and thermoset matrices. The generation of these failure conditions is shortly described and then applied to test cases of the World-Wide-Failure-Exercises WWFE-I and II, organized by Qinetic in the past 20 years. The derivation of the conditions for the brittle fracture failure experiencing UD lamina material was based on the author's so-called Failure Mode Concept (FMC) which basically builds up on the hypotheses of Beltrami and Mohr-Coulomb. The generally applicable FMC is applied here to… More >

S. Hadidi-Moud^1,2, H. Makari¹

Structural Durability & Health Monitoring, Vol.6, No.2, pp. 113-122, 2010, DOI:10.3970/sdhm.2010.006.113

Abstract A comprehensive numerical study has been carried out to investigate and to explore the impact of the presence of part through surface cracks of various size and orientation in a thick welded ferritic steel cylindrical vessel, on the beneficial effect of autofrettage loading. It is well known that autofrettage loading enhances the load carrying capacity of defect free pressure vessels. The results of this study suggest that in presence of cracks, the localised near crack tip residual stress fields interact with in service stresses and influence the enhancement in load carrying capacity of autofrettaged vessel. More >

Zihua Zhao¹, Yu Zhou, Zheng Zhang, Qunpeng Zhong

Structural Durability & Health Monitoring, Vol.6, No.2, pp. 101-112, 2010, DOI:10.3970/sdhm.2010.006.101

Abstract Annex H"Safety assessment method for straight pressure pipeline with local thinning area" of "Safety assessment for in-service pressure vessels containing defects"(GB/T 19426-2004) is briefly introduced. The maximum allowable hanging (unsupported) length of straight pressure pipeline with a local thinning area (LTA) is then determined by using this assessment method. This is the first time that the assessment method has been applied to the long-distance oil pipeline. As a typical case, we have analyzed a length of straight pressure pipeline with LTA and gave the relationship of maximum allowable unsupported length, operating pressure and the depth More >

Fausto Pedro García Márquez¹

Structural Durability & Health Monitoring, Vol.6, No.2, pp. 89-100, 2010, DOI:10.3970/sdhm.2010.006.089

Abstract This paper presents a simple graphic method for detecting and classifying faults in point mechanisms based on the study of some statistical parameters of the force and current signals of the point machine. Principal Components Analysis (PCA) employed in order to reduce the number of these parameters. PCA is utilised in this paper for modifying the parameter dataset, and reducing the coordinate system by linear transformation. It is then possible to plot the new coordinate system in 2 or 3 dimensions, where the faults can be detected and identified. In this work most of the More >

Xue-Ren Wu¹

Structural Durability & Health Monitoring, Vol.6, No.2, pp. 77-88, 2010, DOI:10.3970/sdhm.2010.006.077

Abstract A review of the state-of-the-art is presented on the weight function method for fracture-mechanics-based structural integrity assessment with regard to crack-like defects. The weight function method provides a powerful tool for the determination of key parameters, such as stress intensity factors and crack opening displacements for cracked structural components. For two dimensional (2D) crack problems, weight functions were obtained in closed-form for both centre-and edge-crack configurations. For three dimensional(3D) cases, a combination of the closed-form 2D weight functions and the slice synthesis technique makes it possible for rapid determination of stress intensity factor at any More >