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coatkuanteen

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  1. I have tried to optimize ply angles to reach min. nonlinear axial displacement (DRESP3). However ply angles varied very slightly throughout the optimization process and non-optimal solution was found when it stopped. It works fine when I optimize thicknesses instead of ply angles. Any comments on this issue? I use SENSOPT AUTO option for gradient calculation.
  2. Thank you! But why do we need the correction factor if we are still in the linear stress-strain relation? ESLs based on displacement should produce strains very close to the ones from (geometrical) nonlinear analysis with linear material property.
  3. Could you please forward this query to the development department? Kind regards, Tanut
  4. Hi, Small deviation because of different solvers is acceptable, but the difference I am pointing out is more than 100% ! For instance, in the attached files, we look at strain response of the first outer loop iteration (initial design, no optimization yet): NORMAL STRAIN XX, PLY 1, Time=1.0s or equivalent static Subcase 90008 Element ID 40477: RADIOSS value=-6.344E-04, DRESP value=-1.628E-03, Difference=157% Element ID 40245: RADIOSS value=-6.388E-04, DRESP value=-1.587E-03, Difference=148% Element ID 36632: RADIOSS value=-6.276E-04, DRESP value=-1.465E-03, Difference=133% Regards, V55s_t_REF_STRN.eslout V55s_t_REF_STRN_01.h3d
  5. When I impose ply strain responses, which can be derived directly from displacement ESLs of the same nonlinear loadcase, as design constraints for a nonlinear loadcase, there are differences between strain response values outputted in .out file and strain contour in .h3d file. In theory, design responses from these two files should match each other but strain values in .out file (optimization values) tend to be larger than what is plotted in .h3d file (analysis values). What could be the reason behind this? Any suggestion on how I can use .h3d strain output as design responses? V55s_t_REF_STRN.fem
  6. Hi, I would like to know whether OptiStruct ESLM allows the utilization of DRESP3 in static subcases or nonlinear static subcase or both. Thank you very much,
  7. Answer from Altair Development Engineer: "We basically check the number of outer loops w/o any change or improvement in objective/constraint. This is consistent with regular OS optimization. For example, if the number of outer loop w/o any change (see below tolerance) => 2, then convergence is satisfied. Tolerance for maximum constraint violation change – default = 5.0E-3 Tolerance for objective function value change – default = 5.0E-3"
  8. I have used OptiStruct nonlinear-response optimization via Equivalent Static Load Method (ESLM) extensively in my research but would like to know more regarding its stopping criteria of the outer loop i.e. How are convergence criteria defined in order to stop the ESLM (besides ESLMAX max.no. of iteraitons reached)? I know OBJTOL is used in the inner loop (linear static opt. loop), but not sure whether the outer nonlinear-response loop deploys the same criteria. I have not found this info in the User’s Guide. I appreciate your kind support in this matter. Mr.ESLM
  9. Hi, Is the current Optistruct 13.0 ESLM capable of handling stress/strain constraints from nonlinear analysis i.e. correct generation of ESLs to produce identical stress/strain responses in linear static environment? regards, Mr.ESLM
  10. I have solved the error by deleting all unused design variables. Thanks anyway! Tanut
  11. Hi, I ran it on OptiStruct 13.0. 210, windows machine but still got the same error. Could you please try running the following .fem file again? It will take less than one hour. https://www.dropbox.com/sh/0nqezeb8q95cbf1/AACjXJYzpkCudD8KOG0Sz2Gva?dl=0 Kind regards, Tanut Here are my solver versions on the Windows OS: OptiStruct Version 13.0.210.001 Time of build : 23:21:01 Date of build : Jan 12 2015 Build tag : 0751393_5533130_Ce64RBW8UH12M:96526 Supported H3D : v12.0 Radflex name : radflex_13_win64.exe Use version : 130131112 or higher RADIOSS Starter version 13.0 Platform release : win64 Platform info : Windows 64 bits, Intel compiler Radflex name : radflex_13_win64.exe Use Radflex version : 130131112 or higher Time of build : 11:53:56 Date of build : 05/27/14 Build tag : 0718847_1233513.000_1020_0029780_10 RADIOSS Engine version 13.0 Platform release : win64 Platform info : Windows 64 bits, Intel compiler Radflex name : radflex_13_win64.exe Use Radflex version : 130131112 or higher Time of build : 11:50:02 Date of build : 05/27/14 Build tag : 0718847_1233513.000_2020_0029780_10 RAD2RAD version 13.0 Platform release : win64 Platform info : Windows 64 bits, Intel compiler Time of build : 11:53:24 Date of build : 05/27/14 Build tag : 0718847_1233513.000_1020_0029780
  12. Hi Rahul, Could you ask your experts on these stopping criteria? I have taken a look at ref documents but still have not found a conclusion on how stopping criteria in Optistruct ESLM are defined. Best regards, Tanut
  13. OptiStruct Version 13.0.0 RADIOSS Engine version 13.0 Linux OS I've tried OptiStruct Version 13.0.210.001 but did not work out as well.
  14. In ESLM nonlinear-response optimization, I have a buckling constraint (LAMA) as well as a displacement constraint from IMPDYN analysis while min. mass is the design objective. PARAM, ALTBUCK, 0 is specified. CSTRESS is not requested in IMPDYN subcase. However, after the 1st inner loop I experience: *** INTERNAL PROGRAMMING ERROR *** in file "tabscr.F", at location # 1000. **** ABORTING RUN DUE TO AN INTERNAL ERROR **** Please see the attached files for more info. Many thanks, Tanut MT_H_ESLM_2_fem.txt MT_H_ESLM_2_out.txt
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