Moment curvature units

[aisan]

Hi all,

I have a question regarding moment curvature units. I have defined my units library as below:

set m 1.; # Define Basic Unit - Length
set kg 1.; # Define Basic Unit - Mass
set sec 1.; # Define Basic Unit - Time
set rad 1.; # Define Basic Unit - Radians

set N [expr $kg*$m/pow($sec,2)]; # Define Engineering Units - Newton
set kN [expr $N*1000]; # Define Engineering Units - Kilo Newton
set Pa [expr $N/pow($m,2)]; # Define Engineering Units - Pascals
set MPa [expr $Pa*1000000]; # Define Engineering Units - Mega Pascal
set cm [expr $m/100]; # Define Engineering Units - Centimeter
set mm [expr $m/1000]; # Define Engineering Units - Milimeter

and in my section and analysis file I have entered all the values in Mpa, N, and mm.
Knowing this what is the unit for moment and curvature?

aisan

[silvia]

this is the problem with the metric units that i can't figure out.
you define kg as a mass, then N as 1.*$kg, does this mean that g is one?
i think the first kg is kg force not mass.
what happened to 9.8?

the units will then be force*length for moment and 1/length for curvature, whatever the basic units result there.

in these cases you should define forces as basic units, not masses.

[aisan]

Hi silvia,

thanks for the response. I didn't post the complete library file. my bad.
here it is:
et m 1.; # Define Basic Unit - Length
set kg 1.; # Define Basic Unit - Mass
set sec 1.; # Define Basic Unit - Time
set rad 1.; # Define Basic Unit - Radians

set N [expr $kg*$m/pow($sec,2)]; # Define Engineering Units - Newton
set kN [expr $N*1000]; # Define Engineering Units - Kilo Newton
set Pa [expr $N/pow($m,2)]; # Define Engineering Units - Pascals
set MPa [expr $Pa*1000000]; # Define Engineering Units - Mega Pascal
set cm [expr $m/100]; # Define Engineering Units - Centimeter
set mm [expr $m/1000]; # Define Engineering Units - Milimeter

#Constants
set g [expr 9.81*$m/pow($sec,2)]; # Gravitational Acceleration
set PI [expr 2*asin(1.0)]; # PI constant 3.14159
et Ubig 1.e10; # a really large number
set Usmall [expr 1/$Ubig]; # a really small number

Would you please let me know how would you revise this file if you were supposed to write a unit file in SI? Can you please include in your examples SI units as well.

Thanks,
aisan

[silvia]

you have to talk to someone who knows more about si units.
i don't think that N = 1*kg

i think 1kg-force = 1kg-mass * g.