1. A system for a user to simulate the degraded operation of a circuit, comprising: a circuit degradation simulator; a user defined circuit simulator, wherein said user defined circuit simulator allows the user to input a user selected circuit simulator and user data comprising: a netlist representation of the circuit; and a circuit stress time value; and an interface for connecting the user defined circuit simulator to the circuit degradation simulator, whereby the circuit degradation simulator determines the operation of the circuit at the circuit stress time value utilizing said netlist representation in the user selected circuit simulator.