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Hi Avtar,
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<div class="">I am assuming that you are referring to spatial variations of the phase-field variable and that the fracture problem that you are solving is well posed (i.e. displacement controlled, thermal loads, work controlled). As we explained in our 2008
book, force driven problems are often ill posed. You may use an arc-length formulation, of minimize the fracture energy subject to prescribed work, and go back to a force-drive evolution (subject to a safe-load type of condition).</div>
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<div class="">In a staggered scheme (alternate minimizations, block Gauss Seidel, adjoint-based quasi-Newton, call it whatever you like), the elasticity problem can become stiff, but remains really manageable. </div>
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<div class="">Feel free to try my implementation <a href="https://bitbucket.org/bourdin/mef90-sieve" class="">
https://bitbucket.org/bourdin/mef90-sieve</a> for comparison.</div>
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<div class="">Blaise</div>
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<div class="">On Jan 4, 2018, at 12:12 AM, Avtar Singh <<a href="mailto:er.bhullersingh@gmail.com" class="">er.bhullersingh@gmail.com</a>> wrote:</div>
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<div dir="ltr" class="">Hello Petsc Users,
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<div class="">I am solving a fortran framework to simulate phase-field fracture problem. Upto the failure point the code is working fine. But as the crack-phase starts to propagate, there is abrupt changes in the Stiffness Matrix, so determinant becomes nearly
equal to zero. Hence, the code crashes.</div>
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<div class="">I tried with mumps package with pc lu. Also tried, superlu, gmres and fgmres with jacobi, bjacobi, lu. But the problem still persist.</div>
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<div class="">Can anyone suggest, Which solver and preconditioner should i use?<br class="">
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<div class="">Thank you</div>
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<div class="">Avtar Singh</div>
<div class="">Research Scholar </div>
<div class="">Multiscale Mechanics and Multiphysics Lab</div>
<div class="">IIT Roorkee, Roorkee</div>
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Department of Mathematics and Center for Computation & Technology</div>
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Louisiana State University, Baton Rouge, LA 70803, USA</div>
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Tel. +1 (225) 578 1612, Fax +1 (225) 578 4276 <a href="http://www.math.lsu.edu/~bourdin" class="">
http://www.math.lsu.edu/~bourdin</a></div>
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