A link between the peak stresses and the averaged strain energy density for cracks under mixed-mode (I+II) loading
Journal Title: Frattura ed Integrità Strutturale - Year 2015, Vol 9, Issue 34
Abstract
In this work, a link between the averaged strain energy density (SED) approach and the peak stress method in the case of cracks subjected to mixed mode (I+II) loading has been investigated. Some closed-form expressions of the strain energy density, averaged in a volume of radius R0, as function of the stress intensity factors are provided for plane strain conditions under mixed mode I+II loadings. On the basis of the peak stress method (PSM) some expressions useful to estimate the mode I and mode II stress intensity factors (SIFs) have been recently derived. These relationships take advantage of the elastic peak stresses from FE analyses carried out by using a given mesh pattern where the element size and type are kept constants. The evaluation of the SIFs from a numerical analysis of the local stress field usually requires very refined meshes and then large computational effort. The usefulness of the PSM-based expressions is that (i) only the elastic peak stresses numerically evaluated at the crack tip are needed and not a set of stress–distance data; (ii) the employed meshes are rather coarse if compared to those necessary for the evaluation of the whole local stress field. By substituting the PSM-based relationships in the closed-form expressions of the averaged SED it appears that the latter can be directly estimated by means of the elastic peak stresses evaluated at the crack tip. Several FE analyses have been carried out on cracked plates subjected to tension loading considering different geometrical combinations, varying the length 2a and the inclination ϕ of the crack (i.e. the mode mixity) as well as the size d of the adopted finite elements, with the aim to evaluate the local SED and the elastic peak stress components σpeak and τpeak. In all cases the numerical values of the SED derived from the FE analyses have been compared with those analytically obtained by using the expressions for the SED based on the elastic peak stresses, in order to verify the range of applicability of the proposed relationships.
Authors and Affiliations
G. Meneghetti, B. Atzori, A. Campagnolo, F. Berto
Keywords
Related Articles
- EP ID EP106598
- DOI 10.3221/IGF-ESIS.34.11
- Views 77
- Downloads 0
Damage propagation in a masonry arch subjected toslow cyclic and dynamic loadings
In the present work, the damage propagation of a masonry arch induced by slow cyclic anddynamic loadings is studied. A two-dimensional model of the arch is proposed. A nonlocal damage-plasticconstitutive law is ado...
A research on detecting and recognizing bridge cracks in complex underwater conditions
The method aims to recognize and extract the characteristic parameters of bridge cracks based on images of the cracks obtained through the application of preprocessing technologies, such as graying, graphical enh...
Numerical homogenization of piezoelectric textileswith electrospun fibers for energy harvesting
Piezoelectric effects are exploited in an increasing number of micro- and nano-electro-mechanicalsystems. In particular, energy harvesting devices convert ambient energy (i.e. mechanical pressure) into electricalen...
L’infragilimento da idrogeno. Un caso di studio in una barra di comandi di un velivolo dell’aviazione generale.
La degradazione delle caratteristiche meccaniche di un materiale di impiego aeronautico ha pesanti ricadute sulla sicurezza del volo. Tale degradazione si può manifestare sia per l’effetto combinato tra l’ambiente...
Combining experimental and numerical analysis to estimate stress fields along the surface crack front
Combining experimental and computational method for determination of the singular and the non-singular stress terms along the front of the 3D surface crack is proposed. Evaluation of the terms is based on comprehen...