This project aims to study and model partial discharge (PD) in a cavity, and induced physical-chemical effects. Among which effects degradation, damage rate, and eventually a life model are the main interests of this project. Different from other PD studies and modelling, this project focuses on detailed physical and chemical phenomenon after each discharge event. Major considerations include the energy spectrum of electron streams impinging into the cavity surface, physical-chemical effects brought on by this process such as polymeric bond breaking, local accumulation of matter, and changes of conductivity. Based on above information, it is hypothesised that damage growth rate can be derived, and a global failure time estimated. During the project, simulation and laboratory studies are carried out simultaneously, aiming at producing comparable and comprehensive result. Simulation studies are based on Matlab and COMSOL modelling, and for laboratory work, insulating materials (XLPE, LDPE, and epoxy) are comprehensively assessed over the life time of the project.