$$$$ SIF NOTICE CHAT 11/09/12 21:18:04 7124 DATE 11/09/12 Procedure SIF Voir aussi : ------------- SIF MAT1 DEP1 TAB1 ; TAB1.'FRTFISS' .'LIFIS1' .'LIFIS2' .'MODMIXTE' .'MAILLAGE' .'PFS1' .'DEBOUCH' .'PDEBOUCH' .'EPAI' .'FLEXION' .'MEMBRANE' Description : _____________ This procedure calculates the stress intensity factor in mode I (possibly in mode II) from the displacements of the sides of the crack. The calculated value is a mean of the three points which are closest to the crack tip. This procedure applies in two and three dimensions. IN 2D, the problem relative to a loading in mixed mode can be solved. In 3D with massive elements, for each node of the crack front, the stress intensity factor is calculated from the displacements of the points located in the plane normal to the crack front at the considered node. (before working out the mesh, make sure that you will have these planes normal to the crack front). If the crack is opening,the plane stress formula is applied to the points located at the surface. In 3D with thin shells, the membrane and bending terms of the stress intensity factor can be computed. The bending term is deduced from the knot rotations inducing a strain at the extern skin of the shells. Mixed mode loadings are supported. Contents : _________ Input data : __________ MAT1 : field of material properties DEP1 : displacement field TAB1 : TABLE type object, indexed by words, used to define the calculation options and parameters : Arguments for a two-dimensional problem ________________________________________ index pointed object comments type FRTFISS POINT crack point LIFIS1 MAILLAGE line describing the side of the crack MODMIXTE LOGIQUE VRAI (true) if loading in mixed mode LIFIS2 MAILLAGE if loading in mixed mode, line describing the second side of the crack Arguments for a three-dimensional problem with massive elements _______________________________________________________________ index pointed object comments type FRTFISS MAILLAGE line describing the front crack PSF1 POINT point of the crack surface that does not pertain to the front DEBOUCH LOGIQUE VRAI (true) if the crack is opening PDEBOUCH POINT/MAILLAGE points of the front located at the surface Arguments for a three-dimensional problem with thin shells __________________________________________________________ index pointed object comments type FRTFISS POINT crack point LIFIS1 MAILLAGE line describing the side of the crack MODMIXTE LOGIQUE VRAI (true) if loading in mixed mode LIFIS2 MAILLAGE if loading in mixed mode, line describing the second side of the crack EPAI FLOTTANT shell thickness MEMBRANE LOGIQUE VRAI (true) for membrane term computing FLEXION LOGIQUE VRAI (true) for bending term compting Output data : _____________ On output, TAB1 makes it possible to recover the values of the stress intensity factor index pointed object comments type K1 FLOTTANT/TABLE in 2D, floating : value of K1 in 3D with massive elements, table containing the values of K1 at each node of the front in 3D with thin shells, table containing 3 FLOTTANT (floatings) : MEMBRANE : membrane term FLEXION : bending term TOTAL : sum of both terms K2 FLOTTANT for mixed mode loadings : in 2D, floating : value of K2 in 3D with thin shells, table containing 3 FLOTTANT (floatings) : MEMBRANE : membrane term FLEXION : bending term TOTAL : sum of both terms Example : in order to list the K factor calculated at the node P15 of the crack front, code : LIST (TAB1.K1.P15) Note : _______ If the impi 1 option is used, the straight line plot V**2=f(r) adjusted by the least square method is superimposed on the values of V**2 at the crack first three nodes; the R1 coefficient which stands for the adjustment of the straight line is also specified (R1=1 : perfect adjustment). In addition, the crack opening (curve V=f(r)) is plotted. The sign of K in mode II is conventionnaly given : a positive displacement of the upper crack side in the local coordinate system (or a negative displacement of the lower crack side) implies a positive K II. If the upper crack side is given in 'LIFIS1' and the lower in 'LIFIS2', the sign convention is respected. Otherwise the crack sides are swapped and the folowing message is prompted : ATTENTION! Echange des lignes de fissure!
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