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Confused about units in D(t,X) for AdamsBDF

tloewen
1-Visitor

Confused about units in D(t,X) for AdamsBDF

I'm attaching a simple file that uses AdamsBDF to solve a spring/mass motion problem.  I added units to everything and it worked perfectly, but then I added an "if" statement that generates a ramp function and tried to use it in the D(t,X) matrix and I get a units error even though the ramp function spits out Newtons.

You can reproduce the above by toggling which F(t) is disabled or enabled.

If you want to look at the file (Prime 3.0 format) and provide feedback, I would appreciate it! 

ACCEPTED SOLUTION

Accepted Solutions
StuartBruff
23-Emerald III
(To:tloewen)

Travis Loewen wrote:

I'm attaching a simple file that uses AdamsBDF to solve a spring/mass motion problem.  I added units to everything and it worked perfectly, but then I added an "if" statement that generates a ramp function and tried to use it in the D(t,X) matrix and I get a units error even though the ramp function spits out Newtons.

You can reproduce the above by toggling which F(t) is disabled or enabled.

If you want to look at the file (Prime 3.0 format) and provide feedback, I would appreciate it!

Mathcad is complaining that you are comparing t (second) against scalars.  See fix below.

Stuart

View solution in original post

3 REPLIES 3
StuartBruff
23-Emerald III
(To:tloewen)

Travis Loewen wrote:

I'm attaching a simple file that uses AdamsBDF to solve a spring/mass motion problem.  I added units to everything and it worked perfectly, but then I added an "if" statement that generates a ramp function and tried to use it in the D(t,X) matrix and I get a units error even though the ramp function spits out Newtons.

You can reproduce the above by toggling which F(t) is disabled or enabled.

If you want to look at the file (Prime 3.0 format) and provide feedback, I would appreciate it!

Mathcad is complaining that you are comparing t (second) against scalars.  See fix below.

Stuart

Thanks Stuart!

StuartBruff
23-Emerald III
(To:tloewen)

No problem, Travis.

Stuart

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