Adhesion in VR

Like so much of WebVR it is currently bleeding edge and works only on special versions of Chrome and Firefox. Later this year the standard Chrome, Firefox and Edge will handle WebVR natively. The app works with the HTC Vive and the Oculus Touch, using the gui.datVR tool for menu items.

Here we get a chance to look at the difference in adhesive strength between mere "intermingling" and strong "entanglement". Thanks to the amazing physijs-2 physics engine from Chandler Prall you get a vivid sense of what happens when polymers get entangled as a crack tries to tear an interface apart.

Instructions are below. For those who can't (yet) run VR, a YouTube video is available.

Adhesion Demo VR

Adhesion depends on the degree of entanglement. Set % Tangled to 0 for no tangles (except, as you will find, by chance, as in the real world) and 100% for only tangles. The number of chains is a substitute for density of chains (Σ) in the real world and N-Links is the length of the polymer chain. In both intermingling and entanglement, the work of adhesion is ΣNU where U is an energy of 3.5kJ/mole for intermingling and 350kJ/mole for entanglement which requires bond breaking. Each time a bond breaks you see a big increase in the pseudo work of adhesion value that is continually displayed as the interface is pulled apart.

Unlike the other apps, "flying" isn't an option because I don't (yet?) know how to move things when there's live physics going on. To get things into a comfortable position for your setup, change Position and hit reset. You select parameters from the data.guiVR interface by point and click/drag - and you start running by un-setting Pause. You can also use the Thumbpad to toggle pause and the Menu button to reset.

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