In this lecture, we'll cover the following:

• Creating a Boolean mask to isolate and visualise shear within a central strip of the slab
• Defining and controlling strip width as a fraction of slab dimensions using interactive widgets
• Applying masks to contour plots by replacing excluded values with NaN
• Extracting and displaying meaningful maximum shear values from masked data
• Implementing an additional perimeter mask to remove edge effects and improve visual clarity

In this lecture, we focus on refining shear force visualisations by selectively masking regions of the slab to highlight the most meaningful data. We begin by constructing a Boolean mask that isolates a central strip of the slab, allowing us to examine transverse shear behaviour away from boundary effects. By defining the strip width as a fraction of the slab dimensions and controlling it through interactive widgets, we gain flexible control over how much of the domain is included in the visualisation. The masking process is implemented by evaluating distances from the slab’s centreline and using logical conditions to retain or discard values.

We then enhance the visual output by replacing excluded regions with NaN values, ensuring they are omitted from contour plots. This enables clearer interpretation of shear distributions and prevents edge discontinuities from distorting the colour scale. We also compute and display the maximum shear value within the visible region, improving the usefulness of the plot for comparison and validation. Finally, we introduce a perimeter mask to remove boundary effects entirely, combining it with the central strip mask to produce a highly controlled and informative visualisation of shear behaviour.

Next up

Next, we will add magnitude clipping to the shear plots, giving us finer control over which values are displayed.