shapes - What do you call this kind of design with stripes with rounded corners

What's the name that classifies this style (the black rounded lines)?

(Source)

I've also made a variant without actually knowing what it's called.

Answer

Most of the time it's refered to as The Rounded Wavy Pattern, but it has no real name as far as I know.

It was used for the first time, or at least its popularity started in 2013 with this illustration by Nina Geometrieva :

(Dribbble shot)