Finite element analysis and optimization of the rubber diaphragms in type-120 relief valves

Purpose Type-120 relief valves are critical components of locomotive braking systems, and they rapidly discharge the air pressure during brake release to enable swift pressure relief. In order to develop type-120 relief valve rubber diaphragms with long life and high performance, the damaged faulty samples were analyzed and studied. Design/methodology/approach Finite element analysis (FEA) was used to investigate the stress distribution and failure mechanism of the rubber diaphragms within the type-120 relief valves under dynamic loading conditions. The Ogden hyperelastic constitutive model was used to fit the diaphragm data obtained from the uniaxial tensile tests, and its suitability for the modeling of large deformations was confirmed. Findings The FEA results indicated that, when the rubber diaphragms reached their maximum deformation, the peak stress on their upper surfaces was 5.44 MPa. Thus, this region is highly susceptible to fatigue damage. The service life of the rubber diaphragms could be extended by using rubber compounds with high tensile moduli or a fabric-reinforced rubber diaphragm. Originality/value This study provides valuable data and experience for the development of the rubber diaphragms in the type-120 valves and other long-life rubber products in the railway field.