Abstract : A parallel system consisting of two components will continue to work until both the components fail. However, it is possible that at the failure of one of the components, the surviving component has to shoulder extra load and its survival function will change at this point. Independence of component lifetimes also comes in question, even if acceptable initially. This phenomenon has been considered in the literature for more than 50 years. Certain parametric bivariate survival functions (such as the Freund or the Gumbel distribution) have been proposed to model it.

In this work (still under progress jointly with Uttara Naik-Nimbalkar and Isha Dewan) we carry out non/semi parametric modelling through relevant considerations. We also propose goodness-of-fit tests to verify whether the phenomenon actually follows any of the above models.