Automatic Contact Setup in Explicit Analysis

OptiStruct – Automatic Contact Setup in Explicit Analysis

Product: OptiStruct


Product Version: OptiStruct 2021.2 or above

Topic Objective


Automatic Contact Setup in Explicit Analysis

Topic Detail


  1. Introduction


  1. Automatic Contact Definition


    1. Create Contact


    1. AUTO options


  1. References




  1. Introduction


In explicit analysis setup, OptiStruct offers a way to automatically define contact interfaces between components/parts.  With this option, users don’t need to manually define contact pairs among components/parts that potentially contact with each other.  This option is defined using AUTO option in CONTACT card.  The subsequent sections will show how this is setup in HyperWorks.  The automatic contact definition is currently not available for implicit analysis.



  1. Automatic Contact Definition


    1.  Create CONTACT


The CONTACT card which defines the contact interface between components/parts can be created by right click on Groups entity in model browser as shown in Figure 1 below.




Figure1: CONTACT creation



    1.  AUTO options


After CONTACT card is created, go to Property Option, select Property Type and set TYPE to AUTO as shown in Figure 2. 






Figure 2: CONTACT AUTO Options



There are 4 options to be defined after TYPE is set to AUTO.  They are ACTIVA, DEACTIVA, PCONT and PSURF as shown in right image of Figure 2.  


Users can check the ACTIVA and DEACTIVA options to activate or deactivate automatic contact definition for components/parts in model.  By default, the ACTIVA_IDS is set to ALL after ACTIVA option is checked as shown in Figure 3.  This indicates that the automatic contact interface is applied to all components/parts in the model.  Users can also choose to manually define components/parts pairs that the automatic contact interface should be applied to.  This is done by setting the ACTIVA_IDS to INDIVIDUAL, define the number of contact pairs in ACTIVA_NUM_IDS and select the master/slave surface sets as shown in right image of Figure 3.  If ACTIVA option is not checked, OptiStruct will use ACTIVA ALL option by default.  Also, it is not recommended to use shell or membrane skins on top of solid elements in automatic contact definition. 


Similarly, DEACTIVA can be used to exclude specified components/parts pairs from automatic contact interface by defining the DEACTIVA_NUM_IDS and select the master/slave surface sets as shown in Figure 4.  User can select same surface set for IDSi and IDMi.  This will exclude self-contact interaction in the selected surface set.





Figure 3: ACTIVA Options




Figure 4: DEACTIVA Options



The properties of automatic contact interface are defined by checking the PCONT option and referring a PCONT card as shown in Figure 5.  Stiffness, friction, clearance, and other properties defined in the PCONT will then be used by the automatic contact interface.  For more information about PCONT, please refer to OptiStruct online help, Reference Guide>Input Data>Bulk Data Section>PCONT. 


Users can also define surface edges that will be included in automatic contact definition by checking the PSURF option and referring to a PSURF card.  The edge criteria angle in the PSURF card is the angle between the normal vectors of two surfaces connected by an edge.  It implies edges on surface when the angle greater than or equal to the specified values.  It is recommended to use the default edge criteria angle, 45 degrees, in the PSURF card.  Smaller value in angle criteria will include more edges in automatic contact definition.  This could lead to slower performance without significant improvement on the result accuracy.  In OptiStruct 2022.2, if PSURF is not defined, the default angle criteria will be used.




Figure 5: PCONT and PSURF options




  1. Reference

[1] Altair OptiStruct 2022.2 Help, Altair Engineering Inc, Troy MI USA