Two nonlinear transient dynamic analyses (ANTYPE,TRANS) are performed on the digger-arm assembly.
Finite-deformation and large-rotation effects are included in the analysis (NLGEOM).
An analysis is performed for each of the following cases:
The connecting rods are modeled as flexible with SOLID185 elements.
The flexible connecting rods are now modeled as CMS superelements.
In general, automatic time-stepping schemes are preferred over fixed-time stepping schemes, as the program is allowed to cut back when the problem does not converge; when the convergence rate is good, larger time increments are used to achieve faster convergence. For this problem, however, fixed time-stepping with a time increment of 0.2 seconds is used so that the results at additional time points can be captured. Three load steps, each having a 10-second duration, are used, for a total analysis time of 30 seconds.
A default numerical damping of 0.1 is set (TINTP), and the HHT time-integration method is selected (TRNOPT).
The following example input performs the essential tasks in the analysis process:
/solu antype,4 ! transient analysis nlgeom,on ! activate large-deformation effects trnopt,full,,,,,hht ! HHT time-integration method tintp,0.1 ! numerical damping autots,off ! automatic time-stepping disabled deltim,0.1,0.1,0.1 ! set time increments time,10. ! set total time timint,on ! activate time-integration effects outres,all,all ! output all results at all time points ! solve ! solve for 1st load step time, 20. solve ! solve for 2nd load step time, 30. solve ! solve for 3rd load step finish