Improvement of  structural damping. The previous implementation of internal forces affected also the matrices used for geometric stiffness, so the convergence of implicit solvers was affected in a bad way. Now the internal damping forces are computed separately, but I avoided building the stiffness matrix K for computing F=-alpha*K*v otherwise it takes more CPU effort than needed, I rather use the factorized version of K (and this also opens the way, in future, to provide custom damping constitutive laws). Now the Reissner element works well also with HHT and I can consider it to be reliable and usable in production. Future changes might be related to speed optimizations.
Improvement of  structural damping. The previous implementation of internal forces affected also the matrices used for geometric stiffness, so the convergence of implicit solvers was affected in a bad way. Now the internal damping forces are computed separately, but I avoided building the stiffness matrix K for computing F=-alpha*K*v otherwise it takes more CPU effort than needed, I rather use the factorized version of K (and this also opens the way, in future, to provide custom damping constitutive laws).
Now the Reissner element works well also with HHT and I can consider it to be reliable and usable in production.
Future changes might be related to speed optimizations.

jcmadsen/chrono,andrewseidl/chrono,andrewseidl/chrono,jcmadsen/chrono,dariomangoni/chrono,projectchrono/chrono,Milad-Rakhsha/chrono,jcmadsen/chrono,dariomangoni/chrono,Milad-Rakhsha/chrono,jcmadsen/chrono,projectchrono/chrono,tjolsen/chrono,tjolsen/chrono,projectchrono/chrono,armanpazouki/chrono,rserban/chrono,amelmquist/chrono,armanpazouki/chrono,rserban/chrono,jcmadsen/chrono,tjolsen/chrono,projectchrono/chrono,jcmadsen/chrono,Milad-Rakhsha/chrono,amelmquist/chrono,Milad-Rakhsha/chrono,Milad-Rakhsha/chrono,Milad-Rakhsha/chrono,andrewseidl/chrono,dariomangoni/chrono,rserban/chrono,rserban/chrono,armanpazouki/chrono,amelmquist/chrono,tjolsen/chrono,projectchrono/chrono,amelmquist/chrono,dariomangoni/chrono,andrewseidl/chrono,amelmquist/chrono,armanpazouki/chrono,dariomangoni/chrono,rserban/chrono,jcmadsen/chrono,tjolsen/chrono,armanpazouki/chrono,rserban/chrono,andrewseidl/chrono,projectchrono/chrono,armanpazouki/chrono,amelmquist/chrono,rserban/chrono,dariomangoni/chrono