Hi, There is several definitions of strain, see for instance the page about strain computation in Wikipedia:
http://en.wikipedia.org/wiki/Deformation_(mechanics) If I'am right (but please verify to be sure): ** Log means ln (natural logarithm), ** The way to compute strains in Yade is valid for large strains (or large transformations), whereas the definition epsilon=(length-length0)/length0 is valid under the hypothesis of small strains. ** compare the results given by ln(length/length0) and (length-length0)/length0, it is quasi the same for strains lower than 20% to 30%, when strains become too much important (length-length0)/length0 is no longer valid. Best Luc 张林 a écrit : > Hi everyone > These days I'm a little puzzled with the strain compution in > TriaxialstressController.cpp ,just as follows: > > strain[0] = Mathr::Log(width0/width);//Eq(1) > strain[1] = Mathr::Log(height0/height);//Eq(2) > strain[2] = Mathr::Log(depth0/depth);//Eq(3) > volumetricStrain=strain[0]+strain[1]+strain[2];//Eq(4) > > IIRC,Log means not log10 but ln as usual .Is it right? > Eq(1 to 3) is different from the common compution of strain like: > epsilon=(length-length0)/length0 > and, in PFC3D manuals(V3.0)->users' guide->problem solving with pfc3d > Page 47, I found another Eq for strain compution: > epsilon=(L-L0)/((L0+L)/2) > Are the 3 methods all right? They're designed for different fields? > > Thanks for any suggestion. > Regards. > Zhang Lin > [EMAIL PROTECTED] > 2008-11-25 > > > ------------------------------------------------------------------------ > > _______________________________________________ > Mailing list: https://launchpad.net/~yade-users > Post to : [email protected] > Unsubscribe : https://launchpad.net/~yade-users > More help : https://help.launchpad.net/ListHelp -- Luc Sibille Université de Nantes - Laboratoire GeM UMR CNRS IUT de Saint Nazaire 58, rue Michel-Ange - BP 420 44606 Saint-Nazaire Cedex, France Tel: +33 (0)2 40 17 81 78 _______________________________________________ Mailing list: https://launchpad.net/~yade-users Post to : [email protected] Unsubscribe : https://launchpad.net/~yade-users More help : https://help.launchpad.net/ListHelp
