VT commodore fan belt keeps shredding

hi so im new here and im not sure exactly how this works so here it goes,

so yesterday i noticed this sound coming from the engine and didn't think much of it until today when we were fixing up something that i noticed that our fan belt was shredded around the front edge , so we replaced it and took it for a test drive and within maybe 15 mins it shredded our new belt as well.
And yes the belt was put on correctly so the grooved bits went were they were meant to.

does anyone have any idea what it could be ?