3D crack modeling using CTMOPT macro in ANSYS

Hello Everybody..

I am MS student in University of cincinnati, Oh, USA. I am working on
fractures in thin film and for  that i need to model 3D cracks. Problem
is i cant just use extrude comand becuase, crack is not throughout tht
length of the film ( So i cant use th eapproch mentioned above). there
is CTMOPT macro in ansys which allows to desgin meshing at the crack
tip. I am struggling with the ewxplanation given there. If anybody has
detail information in how to implelment this macro, please let me
know. 

Thanknig you,

Sagar Bhamare

The physics associated with self-affine crack formation and propagation is discussed. Some novel concepts are suggested for the mechanics of self-affine cracks. These concepts are employed to model the crack face morphology and, in turn, to solve various problems with self-affine cracks. It is shown that linear elastic fracture mechanics (LEFM) is a special case of self-affine crack mechanics and should be used only in length scales larger than the self-alfine correlation length. The theoretical results are confirmed by available experimental data.

Hello everybody,

I am searching precision of crack propogation in a bonded wafer double.I wrote a code but the problem is that when I want to solve it in ANSYS, the program is shutdown. I need help about it. Thanks for your helps...

 Greetings

 Volkan DALMISLI

P.S:The code is given below. 

finish
/title,sphere wafer
/filname,sphere wafer
/clear,start

*CFOPEN,volkan,dat           ! deletes the data file
*CFWRITE,releaserate     ! table heading of the data file
*CFCLOS
/PNUM, volu, 1 
/prep7

 It seems that within the field of fracture mechanics, some authors use "fracture" to refer to the mechanism of creating new surfaces within a body by breaking the material bonds and reserve the word "crack" for the sharp-tipped discontinuity that results from fracture of a brittle material. But it does not appear that this distinction is followed consistently throughout the literature, and perhaps different research areas within the fracture mechanics field use the two words in different ways.

Hello Everybody

I´ve got problem with propagating the crack in two regions at the same time in Franc3d. I initialized the crack in one region and propagated it, but the crack is propagating only in one region, although the crack should be propagated also in second region. Can anyone help me, pleease? Which steps do I need to take to obtain the propagation in first and second region? It´s imposibble to initialize the same crack in two regions? 

Thanx 

Dear Mechanicians,

I am reading some papers on the surface effects of nano-sized elements(bars,beams, plates, films) or defects(inhomogeneities, inclusions, cavities) these days. Some researchers have studied the surface effects on the stress state around a circular hole or an elliptic hole. I wonder if there is any research work on the surface effect around a nano-sized crack. Thank you!

When the dielectric constant of an insulator in an interconnect is reduced, mechanical properties are often compromised, giving rise to significant challenges in interconnect integration and reliability. Due to low adhesion of the dielectric an interfacial crack may occur during fabrication and testing. To understand the effect of interconnect structure, an interfacial fracture mechanics model has been analyzed for patterned films undergoing a typical thermal excursion during the integration process. It is found that the underlayer pattern generates a driving force for delamination and changes the mode mixity of the delamination. The implications of our findings to interconnect processes and reliability testing have been discussed.

Zhen Zhang and Zhigang Suo

For a crack impinging upon a bimaterial interface at an angle, the singular stress field is a linear superposition of two modes, usually of unequal exponents, either a pair of complex conjugates, or two unequal real numbers. In the latter case, a stronger and a weaker singularity coexist (known as split singularities). We define a dimensionless parameter, called the local mode mixity, to characterize the proportion of the two modes at the length scale where the processes of fracture occur. We show that the weaker singularity can readily affect whether the crack will penetrate, or debond, the interface.