Fatigue Design Evaluation Workshop:
From Materials Testing through Stress Simulation and Experimental Validation

The entire fatigue analysis process will be explored from materials testing to FE life estimation

Andrew Halfpenny, Director of Technology from HBMPrenscia

A small spring clip has been designed as part of a kitchen draw closing mechanism. The clip was found to fail prematurely during qualification test and this has lead to a long delay in production. The manufacturer is keen to avoid similar problems in the future and wants to model this type of component using FE.

In this workshop we consider the entire design process for the spring clip. We start by testing the base material in a fatigue tes trig and derive an SN fatigue curve. The physics of fatigue is introduced and particular attention is paid to the likely statistical spread of life in real components.

An FE model of the component has been produced and a fatigue analysis is run to determine where and when the failure will occur.Practical guidance on FE modelling techniques are given to ensure the best possible fatigue results.

Finally a physical qualification test is run using a working scaled model of a real fatigue test rig. This rig was developed in-house by nCode’s laboratory technicians. It is used to test very small components and to train our apprentices. The correlation between the test life and predicted life is discussed.