I used FEA to optimize this PETG bracket down to 49 gram. But is there a mathematical way to simulate long-term plastic 'creep' so I know when it will fail?(holding a 5kg load)

I used FEA to optimize this PETG bracket down to 49 gram. But is there a mathematical way to simulate long-term plastic 'creep' so I know when it will fail?(holding a 5kg load)