My 10node tet (SOLID168) model seems to output the wrong CG
(center of gravity) information in the d3hsp file for each part. Why?
This appears to be an obvious bug in the 5434 build of LS970. LSTC Technical Support was notified on February 3rd, 2005. This should be fixed in an upcoming build of LSDYNA, if possible. There may be some inherent limitation with the element that prevents outputting the correct value. The good news is that the mass calculation seems to be accurate and the CG information that is printed out is probably not used internally by the code. If additional details become known concerning this issue, they will be posted in this solution. In the example below, there are two blocks, one centered at (0,1.5,0) and made of bricks and one at (0,1.5,0) and made of tets. The 1st is fine, and gives even better results in double precision, but the 2nd (tet block) gives poor results and shows no improvement in double precision. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = fini /clear /view,,1,2,3 /plopts,info,1 /title, CG Test in ANSYS LSDYNA /prep7 et,1,SOLID164 et,2,SOLID168 r,1 mp,ex,1,30.0e6 ! Young's modulus, psi. mp,nuxy,1,0.30 ! Poisson's ratio, unitless. mp,dens,1,0.0007 ! mass density, lbfsec^2/in^4 block,1,1,2,1,1,1 ! CG at (0,1.5,0) block,1,1,1,2,1,1 ! CG at (0,1.5,0) esize,0.25 type,1 vmesh,1 type,2 vmesh,2 eplot fini /solu time,0.0001 edrst,10 edhtime,10 edopt,add,,both d,all,ux,0.0,,,,uy,uz eddbl,double ! comment out for single precision ... save solve save fini /eof = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Single Precision Results: ========================= Date: 02/03/2005 Time: 16:34:30 ___________________________________________________   Livermore Software Technology Corporation    7374 Las Positas Road  Livermore, CA 94551   Tel: (925) 4492500 Fax: (925) 4492507   <a target=_blank href="http://www.lstc.com">http://www.lstc.com</a>http://www.lstc.com  _________________________________________________    LSDYNA, A Program for Nonlinear Dynamic   Analysis of Structures in Three Dimensions  Version: 970 Date: 07/30/2004   Revision: 5434 Time: 15:01:01     Features enabled in this version:   ANSYS Database format   Shared Memory Parallel     Licensed to:     Platform :   OS Level : WINDOWS XP   Hostname : pghxpdciabat4   Precision : Single precision (I4R4)     Unauthorizeduse infringes LSTC copyrights  _________________________________________________ ******************************************************************************** m a s s p r o p e r t i e s o f p a r t # 1 total mass of part = 0.27999885E02 xcoordinate of mass center = 0.20423112E07 ycoordinate of mass center =0.15000001E+01 zcoordinate of mass center =0.12992835E08 inertia tensor of material row1= 0.1225E02 0.8555E10 0.6821E12 row2= 0.8555E10 0.1925E02 0.2071E09 row3= 0.6821E12 0.2071E09 0.1225E02 principal inertias i11 = 0.1225E02 i22 = 0.1925E02 i33 = 0.1225E02 principal directions row1= 0.1000E+01 0.1222E06 0.1465E02 row2= 0.1226E06 0.1000E+01 0.2957E06 row3= 0.1465E02 0.2959E06 0.1000E+01 ******************************************************************************** m a s s p r o p e r t i e s o f p a r t # 2 total mass of part = 0.27999992E02 xcoordinate of mass center =0.18247974E02 ycoordinate of mass center =0.73751835E02 zcoordinate of mass center =0.40418007E02inertia tensor of material row1= 0.8649E04 0.1336E06 0.9997E06 row2= 0.1336E06 0.7841E04 0.2711E06 row3= 0.9997E06 0.2711E06 0.9025E04 principal inertias i11 = 0.8624E04 i22 = 0.7841E04 i33 = 0.9051E04 principal directions row1= 0.9701E+00 0.1384E01 0.2422E+00 row2= 0.8161E02 0.9997E+00 0.2442E01 row3=0.2424E+00 0.2172E01 0.9699E+00 ******************************************************************************** m a s s p r o p e r t i e s o f b o d y total mass of body = 0.55999998E02 xcoordinate of mass center =0.91239851E03 ycoordinate of mass center =0.75368762E+00 zcoordinate of mass center =0.20209064E02 inertia tensor of body row1= 0.4431E02 0.3947E05 0.1010E05 row2= 0.3947E05 0.2003E02 0.8175E05 row3= 0.1010E05 0.8175E05 0.4434E02 principal inertias of body i11 = 0.4430E02 i22 = 0.2003E02 i33 = 0.4435E02 principal directions row1= 0.9706E+00 0.1627E02 0.2406E+00 row2= 0.2389E02 0.1000E+01 0.2873E02 row3= 0.2406E+00 0.3363E02 0.9706E+00 *****************02 zcoordinate of mass center =0.40418134E02 inertia tensor of material row1= 0.8649E04 0.1336E06 0.9997E06 row2= 0.1336E06 0.7841E04 0.2711E06 row3= 0.9997E06 0.2711E06 0.9025E04 principal inertias i11 = 0.8624E04 i22 = 0.7841E04 i33 = 0.9051E04 principal directions row1= 0.9701E+00 0.1384E01 0.2422E+00 row2= 0.8162E02 0.9997E+00 0.2442E01 row3= 0.2424E+00 0.2172E01 0.9699E+00 ******************************************************************************** m a s s p r o p e r t i e s o f b o d y total mass of body =0.56000000E02 xcoordinate of mass center =0.91239862E03 ycoordinate of mass center =0.75368759E+00 zcoordinate of mass center =0.20209067E02 inertia tensor of body row1= 0.4431E02 0.3947E05 0.1010E05 row2= 0.3947E05 0.2003E02 0.8175E05 row3= 0.1010E05 0.8175E05 0.4434E02 principal inertias of body i11 = 0.4430E02 i22 = 0.2003E02 i33 = 0.4435E02 principal directions row1= 0.9705E+00 0.1627E02 0.2411E+00 row2= 0.2390E02 0.1000E+010.2872E02 row3= 0.2411E+00 0.3364E02 0.9705E+00 ******************************************************************************** = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = . 

