G. Dhondt¹, D. Bremberg²

Structural Durability & Health Monitoring, Vol.6, No.3&4, pp. 305-328, 2010, DOI:10.3970/sdhm.2010.006.305

Abstract In a previous article the K-distritubion along the crack front of several mixed-mode specimens was investigated [Dhondt, Chergui, and Buchholz (2001)]. Both the modified virtual crack closure integral method and the quarter point element stress field method yielded results close to the available reference solutions in the literature [Murakami (1987)]. The present paper extends these results in two aspects. First, the meshing procedure used to obtain a focused mesh at the crack front is modified in order to deal with highly curved cracks. Secondly, the K-distribution along the initial crack is used to perform a crack propagation calculation. The form… More >

Masanori Kikuchi¹, Kazuhiro Suga¹

Structural Durability & Health Monitoring, Vol.6, No.3&4, pp. 289-304, 2010, DOI:10.3970/sdhm.2010.006.289

Abstract Crack closure effect on interaction of two surface crack growth processes by fatigue is studied. At first, change of C value in Paris' law along crack front of single surface crack is measured experimentally. It is shown that C value decreases near specimen surface. Crack closure effect is studied numerically for a surface crack by elastic-plastic cyclic analyses. It is found that closure effect appears more strongly near specimen surface than the maximum-depth point. By determining effective stress intensity factor including closure effect, it is shown that change of C value is equal to the change of closure effect along… More >

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 investigated and results show that… 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 convergence of two separate… 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 UD material. Essential topics of… More >

Ugo Galvanetto, Paul Robinson, Agostino Cerioni, Carlos Lopez Armas

Structural Durability & Health Monitoring, Vol.5, No.2, pp. 161-190, 2009, DOI:10.3970/sdhm.2009.005.161

Abstract This paper presents a simple mathematical model to investigate various formulations of interface elements which are used to simulate fatigue driven delamination in composite materials. To illustrate the effectiveness of the model it is used to evaluate the performance of several different static constitutive laws and damage definitions coupled with a particular fatigue degradation strategy. It is shown that the model can be used to readily assess the robustness and reliability of the different formulations by examining hundreds of thousands of sets of parameter values in a rational and efficient manner. More >

E. Viola¹, F. Tornabene²

Structural Durability & Health Monitoring, Vol.1, No.2, pp. 155-170, 2005, DOI:10.3970/sdhm.2005.001.155

Abstract In this paper, generalized differential quadrature techniques are applied to the computation of the in-plane free vibrations of thin and thick non-uniform circular arches in undamaged and damaged configurations, when various boundary conditions are considered. Structural damage is represented by one crack in different positions and with various damage levels. The crack present in a structural member can be considered as a local stiffness reduction at the fracturing section, which changes the dynamic behaviour of the structure. Much effort has been devoted to dealing with in-plane free vibration analysis of circular arches, but only a few researchers have studied cracked… More >