# Simcenter 3D Solutions How to (associatively) measure distance between two nodes (points) using Result Probe

2021-06-10T16:36:19.000-0400
Simcenter 3D

## Summary

Measure Simple Distance in Postprocessing can measure distance between two nodes, but it can't be maintained. This is possible using Result Probe. If the nodes have underlying points, this can be done associatively using look-up functions. Otherwise (with no points) the workaround is to use multiple Result Probes.

## Details

 Attachments: Distance_DummyCantilever_ResultProbe_1899.7z (1 MB)
The drawback of using Measure Simple Distance is that it can’t be saved nor can it follow a change/modification of the model (non-associative).  If we have underlying points for the nodes that are to be measured (e.g. by making them mesh points), we can make use of the lookup functions (expression). These functions are ready to be used in Result Probe. Below please find links from our online documentations about this and the tutorial for the application in result probe:

https://internal.docs.sw.siemens.com/en-US/product/289054037/doc/PL20200601120302950.xid1753663/html/xid1926527

If we would like to measure the effective distance (considering all three axes), we could extend the formula as shown below:
sqrt( ((X("PT2")+DX("PT2"))-(X("PT1")+DX("PT1")))^2 + ((Y("PT2")+DY("PT2"))-(Y("PT1")+DY("PT1")))^2 + ((Z("PT2")+DZ("PT2"))-(Z("PT1")+DZ("PT1")))^2) To the time this article is created it is not yet possible to use the look-up functions on nodal-based. At least not using a single formula as provided above. Because in Result Probe it is not possible to differentiate the input for two different nodes. We can select the two nodes in Result Probe and use “Combine Across Entities : Difference” to generate the difference, but we still need to define this for each direction.

The workaround is to generate the end position for each direction and for each node e.g. (X_Node1 = X+Displ_x) and assign each as a single Result Probe.

Since we can do operations between result probes, to generate the final distance we’ll create the final result probe as shown below:
sqrt((fd("X_Node1")-fd("X_Node2"))^2+(fd("Y_Node1")-fd("Y_Node2"))^2+(fd("Z_Node1")-fd("Z_Node2"))^2) A simple model (from v.1899) attached to this article was created to demonstrate the two different methods, using points and using nodes (pls. see screenshot below). For the nodal method, in total we will require seven result probes. We can cut it into four result probes (one instead of two result probes for each direction) if for each direction we select directly the two nodes and use “Combine Across Entities : Difference” to directly generate the difference for that axis.

The point method is more stable and associative, whereas for the nodal method we might have to make sure the result probes are using the same nodes (ID) after a re-mesh or to reassign them.

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