Observations on the modelling and assessment of dissimilar material brazed joints

At the heart of any procedure for modelling and assessing the failure of dissimilar material brazed joints there must be a basic understanding of the metallurgy and mechanics of the joint. This paper is about developing this understanding and addressing the issues faced with modelling and predicting failure in real dissimilar material brazed joints. A metallurgical investigation has shown that due to a large variation in material properties and transitional zones between the braze and the parent materials, accurately predicting the stress state using FEA will be difficult. Consequently techniques based on experimentally derived test results will be required to predict failure in close proximity to, and at the interface. However, in some instances it may not be necessary to fully capture the stress state at the interface. In cases such as this, if a braze layer with representative properties is used which applies a representative constraint on the model, the converged stresses can be obtained away from the interface which will allow failure to be assessed.