I'm trying to remember the title of a science fiction novel I read years ago about a frozen planet onto which some Earth explorers crash land. The natives don't smile except as an act of aggression(?) and the humans and aliens build a large ice ship with which to explore the planet. There was also a sequel to it, in which they explored even farther afield on the planet.
This sounds a lot like Alan Dean Foster's Icerigger.
A ship is crashed on Tran-Ky-Ky and Ethan Fortune and Skua September lead the humans to a base using an iceraft. The sequels are Mission to Moulokin and The Deluge Drivers.
The point is made explicitly that the native Tran do not show their teeth when smiling.