Frictional stress with CONTA174 elements in ANSYS

[Pablo]

Hi,

I'm trying to compute the frictional stress at a node which is attached to a
six CONTA174 elements. I have already created the ETABLE which contains the
TAUR et TAUS tangential contact stress for each vertex of the six elements
coincident with the node. Having the tangential contact stress for the
vertex (coincident with the node) of the six elements, I would like to know
how ANSYS compute the tangential contact stress in R direction (TAUR) and in
S direction (TAUS)? After computing these two stresses, I will use the
frictional stress formula which is available in the ANSYS help:

Frictional stress = SQRT (TAUR**2+TAUS**2)

Also I would like to know if there is a way to compute the direction of the
tangential contact stress for the R and S direction?

I have created a macro which computes the normal contact pressure at a
specific node and have verified the results obtained by this macro by
plotting the results for the specific node. When I compare the results for
the normal contact pressure obtained with the CONTA174 elements and the
normal stress obtained for the solid elements beneath the CONTA174 there is
always a small difference... Does someone knows the reason of this
difference?

Thanks for taking the time to read and reply in advance.

Pablo,

[Pablo]

Hi,

I was able to compute (mimic) the tangential contact stress for a specific
node and get the same result shown in the results graphics of ANSYS. What
ANSYS does is that it computes the tangential contact stress (CONT:SFRIC)
for every vertex coincident to the specific node, then it computes an
average tangential contact stress with all the tangential contact stress of
each vertex. In other words ANSYS computes the resultant (tangential contact
stress) for each vertex and computes an average of the resultants even
thought the resultants directions are not the same...(very strange manner of
computing the average of resultants that do not have the same direction... I
may be forgetting something here...) Any comments are welcome.

Pablo,

Post by Pablo
Hi,
I'm trying to compute the frictional stress at a node which is attached to
a six CONTA174 elements. I have already created the ETABLE which contains
the TAUR et TAUS tangential contact stress for each vertex of the six
elements coincident with the node. Having the tangential contact stress
for the vertex (coincident with the node) of the six elements, I would
like to know how ANSYS compute the tangential contact stress in R
direction (TAUR) and in S direction (TAUS)? After computing these two
stresses, I will use the frictional stress formula which is available in
Frictional stress = SQRT (TAUR**2+TAUS**2)
Also I would like to know if there is a way to compute the direction of
the tangential contact stress for the R and S direction?
I have created a macro which computes the normal contact pressure at a
specific node and have verified the results obtained by this macro by
plotting the results for the specific node. When I compare the results for
the normal contact pressure obtained with the CONTA174 elements and the
normal stress obtained for the solid elements beneath the CONTA174 there
is always a small difference... Does someone knows the reason of this
difference?
Thanks for taking the time to read and reply in advance.
Pablo,