Interface TYPE6 (/INTER/TYPE6)

Interface TYPE6 is used to simulate contact between two rigid bodies.

This interface is similar to interface TYPE3, except for the stiffness. The relationship between the contact force and the penetration is provided by a user-defined function. This interface is used particularly in vehicle occupant simulations, for example: knee bolsters. The main limitation of this interface is that surface 1 must be part of one rigid body, and also for surface 2. Moreover, both surfaces must be oriented so that normals are facing each others.

The stiffness used corresponds to the curve Force versus Penetration input by you. The instantaneous interface stiffness is the slope of the input curve at the given penetration; therefore, the time step can be affected since the interface stiffness is used to compute a stable time step:(1)
Δ t = 0.1 M K MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqqHuoarca WG0bGaeyypa0JaaGimaiaac6cacaaIXaWaaOaaaeaadaWcaaqaaiaa d2eaaeaacaWGlbaaaaWcbeaaaaa@3DB8@
Where,
M MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGnbaaaa@3731@
The min (Mass of the first rigid body and Mass of the second rigid body)
K MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGnbaaaa@3731@
Slope of Force vs Penetration curve


Figure 1. Interface TYPE6 - Normal Orientation