A method for optimizing a welding process to produce a weld joint having a predetermined strength includes measuring a plurality of melt layer thicknesses of weld joints for a plurality of sample assemblies formed by the welding process, measuring a plurality failure loads of weld joints for the plurality of sample assemblies, each of the measured plurality of failures loads being associated with one of the measured plurality of melt layer thicknesses, selecting a first failure load from the plurality of measured failure loads responsive to determining that the first failure load corresponds to a predetermined weld strength, and selecting a first melt layer thickness from the plurality of measured melt layer thicknesses that is associated with the selected first measured failure load.