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

Forum|Forum|10 years ago
September 16, 2015
3 replies
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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!

1_Program-mcdx.zip

Other

Best answer by StuartBruff

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

S

StuartBruff

Answer

23-Emerald V

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