" Universe " by Robert A Heinlein is a story along these lines.
Like most of RAF's work it is well worth reading.
scifi.stackexchange.com/users/97/Matthew Nichols
" Orphans of The Sky " by Robert A Heinlein.
It is very different from most of his other books and does not seem to connect into his "universe".
It has a fast plot with a space opera feel to it.
scifi.stackexchange.com/users/70/benstraw
" Non-Stop " by Brian Aldiss takes place aboard a generation ship.
scifi.stackexchange.com/users/240/Dan Geiser
And in the " Helliconia " trilogy by Aldiss there is a spaceship, where the inhabitants lose contact with earth.
Their society degenerates as well.
scifi.stackexchange.com/users/2439/Jennifer
" Mayflies " by Kevin O'Donnell tells the story of a generation ship, built as an escape from a dying Earth. Without going into too many spoilers, the central computer fails and shuts off the main drive, making the journey take much longer than expected.
The passengers don't handle this well.
scifi.stackexchange.com/users/113/Bevan
Hull Zero
Three by Greg Bear is quite similar to Pandorum.
Many people have remarked on the similarities, which has cause some bad reviews.
On the other hand, plenty of good reviews on Amazon too, so it's still on my list.
Product Description HULL ZERO
THREE is an edge of your seatthrill-ride through the darkest reaches of space, from one of thegenre's biggest names.
Perfect for fans of Arthur C. Clarke's RAMA orthe film EVENT HORIZON.
A starship hurtles through the emptiness ofspace.
Its destination - unknown.
Its purpose?
A mystery.
Its history?Lost.
Now, one man wakes up.
Ripped from a dream of a new home, a newplanet and the woman he was meant to love in his arms, he findshimself wet, naked, and freezing to death.
The dark halls are full ofmonsters but trusting other survivors he meets might be the greaterdanger.
All he has are questions: Who is he?
Where are they going?What happened to the dream of a new life?
What happened to the womanhe loved?
What happened to Hull 03?
All will be answered, if he cansurvive.
Uncover the mystery.
Fix the ship.
Find a way home.
scifi.stackexchange.com/users/3698/Martijn Heemels
I'd add The Book of the Long Sun tetralogy by Gene Wolf.
scifi.stackexchange.com/users/4224/Gray Gaffer
Is there a novelization of Pandorum?  If not, did anyone else write about the inhabitants of a  generation ship  going feral?
Is there a novelization of Pandorum?
scifi.stackexchange.com
<generation-ship><pandorum>
scifi.stackexchange.com/questions/598
scifi.stackexchange.com/users/10/MatthewMartin
Suggestions include"Universe" and"Orphans of The Sky" by Robert A Heinlein;  and "Non-Stop" by Brian Aldiss, which takes place aboard a generation ship. "Hull Zero,  Three"  by Greg Bear is quite similar to Pandorum. Some may add  "The Book of the Long Sun" tetralogy by Gene Wolf. “Universe" by Heineken, "Orphans of the Sky" by Heineken, "Non-Stop" by Aldiss and "The Book of the Long Sun" by Wolf are all novelisations. Moreover, "Hull Zero" and "Three" by Bear are also novelisations of Pandorum. 
“Universe" by Heinelen, "Orphans of the Sky" by Heinelen, "Non-Stop" by Aldiss and "The Book of the Long Sun" by Wolf are all novelisations. "Hull Zero" and "Three" by Bear are also novelisations of Pandorum. 