Card 16 - Impulsive Constraint "Snag" – Veh1, Veh2

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 inter-vehicle 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.

 

TSBEG

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 load-deflection 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

 


More:

Card 16, Seq 1 - Impulsive Restraint "Snag" - Veh3