A group multicriteria decision making with ANOVA to select optimum parameters of drilling flax fibre composites: A case study

Abstract

Composite parts are often drilled during assembly. However, it has been well established that drilling process can damage long-fibre composites, and the ideal process parameters need to be investigated based on each given material system, yet under different conflicting design criteria. Here, a multi-criteria decision making (MCDM) approach along with the analysis of variance is aimed to find the best-compromised solution for drilling parameters of a flax fibre composite plate; namely to minimize the top and bottom surface delamination factors while simultaneously maximizing the residual tensile strength of the drilled laminate. Different criteria importance weights along with different MCDM techniques have been modeled to capture different practical design scenarios. Overall, the majority of employed methods suggested a higher spindle speed, a lower feed rate, and a step drill bit geometry. Among the design factors, the feed rate by far played a statistically significant role (>95% confidence level) in controlling the damage outcome and is deemed of prime design concern. It is also shown that the inclusion of subjective weights by experts is a key in such design problems to avoid statistical overinterpretation.