*FRPRO

Data format:

An arbitrary number of lines with up to 12 values each

IPRO XMU NX NY NZ XKN XKT COFRIC T1 T2 T3 EPSZ

Status : mandatory when friction elements are used

Purpose : to define properties of a set of friction elements with by default an isotropic friction coefficient. A special coefficient may be defined in a specified direction.

Restriction : **the total number of friction elements properties sets is limited to MAXPRO (version dependent).

Details :

Parameter	Description
IPRO	identification number of the following set of
properties
XMU	friction coefficient
NX,NY,NZ	normal vector co-ordinates
KN	normal stiffness(Def = 1.e+08). When doing static analysis only, it is better to use 1.e+15.
XKT	longitudinal stiffness(Def = XMU * XKN)
COFRIC	Additional friction coefficient (Def. = 0)
TX,TY,TZ	vector co-ordinates defining the direction with the friction coefficient COFRIC. If Tx=Ty=Tz=0, the direction is given by the tangent vector of the structure.
EPSZ	Limit authorised penetration relative to a quadratic variation of the normal reaction force. Above this limit, the reaction force is proportional to the penetration. (Def= 1e-4)

Notes :

If the friction element is to be used for the ground the normal vector is the vector normal to the ground.

Examples : *FRPRO

c[.]  [.]    [.]   [.]   [.]   [N/m]    [N/m]   [.]    [.]    [.]    [.]    [m]

  1   0.5     0     0     1   1.e+08    1.e+07   0.7    0      0      0     1e-4

Friction element on the ground with an anisotropic friction coefficient. Xm=0.5 in normal direction and Xmu=0.7 in the tangent direction of the structure