Ok, you did not post the model or the age of the system. My guess is that the hinges are stiffening up putting strain on the case. If you are under warranty I would strongly suggest calling Dell tech support. If not under warranty parts may be available here at Parts-People.

@JOcean​ Mine has the exact same damage., and is out of warranty. Inspiron 15 5000 series, what can I do to stop further damage .

@Lynndilou​ My wife had an Inspiron with the same problem. I loosened the retaining nut on the hinge which put less strain on the hinge and prevented further damage. But at some point you may have to have the hinge and case replaced if the damage becomes worse.

It is dell i5 processor 8th generation laptop. How can I fix this crack on laptop case , please provide some suggestions.