How to Calculate Internal Volumes in SOLIDWORKS

It can be tricky to calculate internal volumes, especially when we’re dealing with non-uniform cross-sections.

Fortunately, SOLIDWORKS is capable of handling volume calculations easily thanks to the Intersect tool. Alongside its usual application in surface modelling, this tool allows you to generate solids from negative space.

So let’s show you how to quickly calculate volumes of fluids in SOLIDWORKS using it.

A SHORTCUT FOR ADDING NEW PLANES

This water bottle design needs some water level markers adding to the translucent window on the side.

There are two unmerged bodies in this model, so we’ll need to use the intersect command, a new plane, and a little bit of iterative design.

Firstly, we’ll add the new plane by selecting the top plane and CTRL + dragging one of the blue points to create a parallel copy.

An offset of 100mm will do us for now – we’ll use this plane to evaluate the volume at this height, so we’ll also rename it to ‘Fill Level’.

USING INTERSECT TO FIND VOLUMES IN SOLIDWORKS

We’ll access our Intersect tool by searching for it on our shortcut bar. Hit the ’S’ key on your keyboard and search for ’Intersect’.

We then need to select all the relevant bodies and planes. We’ll pick the Window and the Bottle bodies, and also the Fill Level plane we just created.

’Create both’ should be selected from the property manager to ensure we create an internal volume up to the level of the plane, and we’ll click ‘Intersect’.

There are 7 regions created between the intersecting geometry. We’re only interested in one, however.

We’ll check the region we want to keep and hit Invert Selection. As there’s only one body we’re keeping, merge result is irrelevant.

Confirming the command leaves us with the internal volume, and we can evaluate this solid geometry to find the exact volume.

Our Mass Properties command on the Evaluate tab tells us we’re sitting at 725 ml, a little off the litre we’re after. Conveniently, there’s no need to modify the intersect feature to find the correct value.

Simply by editing the offset dimension of the plane, SOLIDWORKS automatically rebuilds and we can check our value again in the Mass Properties.

After a few iterations, our 1L mark comes in at 134.40mm.