Optional impulsive constraints that resist the relative motions of the two vehicles during a portion of the collision contact. In many impacts, the two colliding vehicles may momentarily interlock, independent of the magnitude of the compressive collision forces and therefore their behavior is not adequately modeled with simple intervehicle friction. This option has been added to permit the modeling of an impulsive constraint on the relative motion. (Input cards 16, 18.)
Inputs for a "Snag" Impulsive Restraint are entered on Cards 16, 18, and 19.

TSWIND 
FSOPO 
XSPI 
YSPI 
AKSP 
DELSPM 
Qembed 
AKSP2 

16 
 
Card: Field 
Variable 

Description 
Original Units 
Metric Units  
16:1 
TSBEG 

"SNAG" Impulsive Restraint Optional Input For SNAG, you specify a point in either V1 (FSOPO=1,2) or V2 (FSOPO=11,12) and at the start time for the snag (TSBEG) the location of the point specified is determined either in the other vehicle (FSOPO=2,12) or in space (FSOPO=1,11). Then an impulsive constraint is applied to the vehicle(s), based on the stiffness AKST, to attempt to minimize the separation of the points during the pusle width (TSWIND). See DISCUSSION – Snag Option Time to begin reaction and to begin use of DTCOLL. 
Sec 
 
16:2 
TSWIND 

Pulse width, or duration of reaction. 
Sec 
 
16:3 
FSOPO 

Option = 0  no reaction. 1  Point specified in V1, reaction point fixed in space. 2  Point specified in V1, reaction point fixed in V2. 5  Point specified in V1, Pole reaction. (If Pole chosen, then must include card 19) 11  Point specified in V2, reaction point fixed in space. 12  Point specified in V2, reaction point fixed in V1. 

 
16:4

XSPI 

X coordinate of force application point in either V1 (FSOPO=1 or 2), in V2 (FSOPO=11,12) or for Pole option (FSOPO=5) the space fixed location X location of the pole center. 
inches 
mm  
16:5 
YSPI 

Y coordinate of force application point in either V1 (FSOPO=1 or 2), in V2 (FSOPO=11,12) or for Pole option (FSOPO=5) the space fixed location X location of the pole center. 
inches 
mm  
16:6 
AKSP 

Linear loaddeflection characteristic of impulsive force. (Only for FSOPO not equal to 5.) 
lb/inch 
N/cm  
16:7 
DELSPM 

Deflection at which saturation of impulsive force occurs. NOTE: Maximum value of Impulse = AKSP*DELPSM*TSWIND 
inches

Mm  
16:8 
Qembed 

For use with Pole Option: Embedment distance. 
inches

Mm  
16:9 
AKSP2 

Normally with DELSPM the force saturates at AKSP*DELPSM. Setting AKSP2 > 0 applies a secondary resistance for deflections > DELSPM. 
Lb/inch

N/cm  
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