Patran 2010.2 has a new direct results access (DRA) capability which supports MD Nastran SOL 400 and which included several results access upgrades, particularly relating to new contact and multi-step SOL 400 analysis results quantities such as rigid body motions and contact status. The DRA capability upgrade means that Nastran contact analysis results can be displayed and the contact quantities can be plotted. These capabilities include rigid body animation along with the deformation results (must request contact results output to be able to see rigid body motion), contact status throughout the analysis. In the case of permanent glued contact, Nastran only displays the contact status in increment 0. This represents the ability to see the initial contact condition which persists throughout the analysis.

The capability to display rigid body results is new in Patran 2010.2, and the contact results output quantities are only available when using the MASTER/DBALL or OP2NEW output formats. By default Patran will write the Nastran input to produce MASTER/DBALL for a SOL 400 analysis. Patran 2010.2 will also write the Nastran input such that, if OP2 is the selected results format, the old form of OP2 (Patran writes PARAM,POST,-1) is produced. Thus, to obtain the new OP2 results output you must insert PARAM,POST,1 into the bulk data section, either by hand editing the input or using direct text input. You can also attach the new OP2 file using DRA the same way you can attach the MASTER/DBALL file. To do this, simply use the Analysis - Attach Results - Attach MASTER form and change the file suffix filter on the Select Results File form to *.op2 and select the new format OP2 file.

You can still use the legacy DRA by typing the following command in the PCL command window:

 set_dra_legacy_flag(FALSE)

Conversely, the legacy DRA can be turned off using:

set_dra_legacy_flag(TRUE) 

In previous versions, Patran only supported the linear versions of the 2D solid elements. Starting with Patran 2010.2 Patran provides you with the option to specify whether linear or nonlinear elements are used. The default is to use the automatic option which causes Patran to write the linear elements unless the elements are part of a contact body or reference an elastic-plastic material (3D elements have had this automatic options for several releases), in which case Patran will write the nonlinear version of the 2D axi-symmetric or plane elements.

Patran 2010.2 also added support for the new MD Nastran large strain solid-shell element. If this property type is selected Patran will write the PSLDN1 entry along with the PSOLID entry which causes MD Nastran to use the new solid shell element.

A second enhancement added to Patran 2010.2 supports two new features in MD Nastran 2010 Solution 400. The first is the NLSTEP adaptive load incrementation method. This was a significant enhancement to MD Nastran because it will allow Nastran to adapt the load increment in a way that will effectively overcome contact and other significant loading changes to the model in a way that will provide load step sizes that will lead to a converged solution.

If you specify that you want fixed load incrementation on the Analysis - Subcase - Load Incrementation form, then Patran will write the NLPARM entry using the values on that form. However, by default, Patran will write the NLSTEP entry using the Nastran defaults. The NLSTEP adaptive load incrementation method is the same algorithm used by Marc by default and is much more robust than previous load incrementation methods available in Nastran. Thus, using the defaults when setting up a SOL 400 nonlinear analysis is highly recommended as it will provide a robust solution method.

Patran 2010.2 also added support for the new Nastran 2010 BOLT bulk data entry available to do cross-section preloads. The BOLT entry replaces the previous MBOLTUS entry which was only available for SOL 600. The BOLT entry works for both SOL 400 and SOL 600 and allows users to specify bolt, or other cross-section preloads. The BOLT entry will be written out based on the Patran MPC menu "Overclosure" MPC type. Using these MPC types users can specify bolt pre-loads and "locking" of the bolt after preload to simulate the analysis of bolted-joint assemblies. Bolt modeling can be done in Patran using the Tools - Modeling - Bolt Preload menu which combines the actions (mesh-splitting and mpc and LBC creation) required to do the complete cross-section loading.

Another significant enhancement to the Nastran preference contact pre-processing capability is a change that allows users to explicitly control the master-slave relationships of the contact bodies. By default Nastran assigns the master-slave relationships based on the contact body ID order.

In previous versions of the Nastran preference in Patran, the contact bodies were numbered and written to the input file in the chronological order in which they were created in the modeling process (based on the Patran internal ID). While Patran did allow the user to control the order in which the contact bodies appeared in the contact table, this was not adequate to control the master-slave relationship of the individual contact pairs because, by default, MD Nastran defined the master-slave relationship based on the contact body number. Since Patran assigned this contact body ID number based on the chronological order in which the body was created, the user had no control over the master-slave contact relationship except by the use of the 1st - 2nd, and 2nd - 1st controls.

A much better method has been implemented in Patran 2010.2 by causing Patran to write the contact bodies and assign their ID's according to the alphanumeric order of the contact body names. This way the user has complete control over the master-slave relationships simply be selecting or modifying the contact body names.

Patran 2010.2 provides users with the means to control the linear contact convergence criteria by providing access to the form that controls the NLPARM bulk data entry from the Solution Parameters forms of the linear solution sequences. The NLPARM entry is required to be in the input for any linear contact solution.