Mechanical and temperature contact in fuel rod cladding

For the mechanical contact between fuel and cladding a slip criterion relating contact shear stresses to the slip between fuel and cladding is introduced. Because of irreversibility an incremental formulation is made. With this slip criterion with associated slip rule it is possible to simulate different types of frictional behaviour of the fuel cladding interface. It is also possible to allow for eventual welding between fuel and cladding. The transient temperature problem is also solved by means of the finite element method. The paper presents results for the effect of different types of slip rules on the contact stress distribution. It is shown that the contact shear stress is smaller for the hardening model than for the ideal model. It is also shown that a crack in the fuel increases the contact stresses and that at temperature decrease high tensile stresses arise after eventual welding. It is also shown how particles between fuel and cladding influence the stresses. Also here the effect of eventual welding is studied. (Auth.)