Design for reliability methodology for micro laser welding of pigtail fibres

This paper discusses the effect of five process parameters on the generation of post weld stresses in the pigtail fibre optic. The alignment of the fibre optic and the laser in the butterfly module become misaligned during the laser welding process of the sleeve to the ferrule. This is primarily due to post welding stresses in the fibre optic which develop during the cooling process. The mechanical stresses resulting in the post welded fibre optic are estimated using Finite Element Analysis and response surface methodology. Integrated Design of Experiments (DoE) and Finite Element Analysis (FEA) are used to determine the distribution of the post welding stresses in the fibre optic. The DoE data is used to construct an explicit reduced order model to perform a sensitivity analysis. The influence of the manufacturing tolerances and variation of the design variables on the residual stresses in fibre is assessed using a Monte Carlo simulation. The initial design of the fibre optic is used to evaluate the important process parameters and to assess the capability of the welding process. A particle swarm optimisation algorithm is used to undertake design optimisation of fibre optic and to determine the optimal process conditions.