How do I find the positive normal of a shell element in ABAQUS?

For shells the positive normal is given by the right-hand rule going around the nodes of the element in the order they are given in the element-nodal connectivity data line (datalines which follow the keyword *ELEMENT line). 

*ELEMENT, TYPE=S4R5
30, 101, 102, 202, 201

If using the ABAQUS/CAE click on Tools and choose Query... option and from the new form select Shell/Membrane Normals then click on the component in the viewport. 

 Colour coding :   Brown - Positive   Magenta - Negative

Click on Done when finished. 

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If you using ABAQUS Viewer with an *.odb file then Plot Material Orientation icon in the Visualization module can be used to plot the normal. The Red line indicates the Normal direction of the shell. The local-1 direction is drawn in Cyan and the local-2 direction in Yellow.