Dynamic analysis of the DN350 squib valve shear cap

Background: DN350 squib valve is introduced into the third generation passive nuclear power plant. Purpose: In squib valve design, the required piston kinetic energy for valve opening is need to be calculated, and used to determine the right propellant quantity. Methods: LS-DYNA is used for the dynamic simulation of the piston impacting the shear cap. A multi-parts FEM model is created for calculation. The effects of strain rate and failure criteria are considered in the material models. Dynamic relaxation method is used to apply inner pressure and screw pre-tension loads. An equivalent material model for the crush tube assembly is set up with appropriate contact algorithm applied. Results: Calculation results such as kinetic energy, velocity and valve body loads are obtained. The calculated piston velocity is in good agreement with the test data. Conclusions: The simulation methods and models can be applied in valve structure design and type approval. (author)