Design Advisor output report

[Paul Welch]

I haven't done very much simulation, but am starting to use the Design Advisor module.

My report from my first study shows some fields for the calculated reaction force, with a Magnitude (Min & Max) and also the specific components (Min & Max) in U,V, and W.

However, the individual componts in U,V,& W (all max values) don't result in the max magnitude answer. Using vector addition, they add up to less than the max magnitude of total force.

How can this be?


Reaction Force[N] Min. Max.
Magnitude 1.19058e-016 1.40247
Force U -0.193135 0.231557
Force V -1.07646 0.224953
Force W -0.172479 0.898692

Any ideas?

Thanks,

Paul

[waynef]

First of all, in order to get the total reaction force due to an enforced displacement easily, I would recommend you use version 11.0 or greater of OneSpace Designer Modeling. In this version we have added the capability to sum the reaction force (or applied force) over the length of an edge or the area of a face.



Next, make sure that you have the results turned on to calculate Reaction Force in the Analysis menu. Reaction force is defined as the NODAL forces that occur at the constraints or enforced displacements. For instance, if you constrain a face in the X direction. All nodes on that face are held with zero displacement in the X direction. The reaction force reported in the HTML report is the maximum nodal force to hold zero or other displacement at that node. It is not really a useful quantity until you sum the nodal forces over an edge or face.



Applied force is the nodal force where a Load (force) is applied. Applied forces only appear in the dataset choices when you have an applied load in your model.



You must use the new capability to sum the force over the topology, which is referred to as "sum topo" in the PostProcess>Inquire menu. This command sums the force component (force U, V, or W) over the length of an edge for the case of an enforced displacement applied to an edge, or over a face for the case of a constraint applied to a face. Please see the attached image. First you must choose Reaction Force as the Dataset, then choose a component of force in a direction. Then the Sum Topo check box will become available. Then choose the By LBC button pick the enforced displacement or constraint from the viewport. These will be equal and opposite forces in your case in the direction you would expect (W or Z).