What is the function of cartilage in the lung? Where is cartilage tissue found in the lung?

It's to keep the bronchi open.

The cartilage is found lining the bronchi in order to keep them open. This isn't like the cartilage in the rest of your body. It's actually a lot thinner, and smaller, but it's extremely durable.

Basically, it acts like a door prop, keeping the door open so people could get through.