The influence of hole quality on mechanical behavior and strain distribution of open-hole CFRP laminates subject to different machining processes

Machining process is generally required for cutting composite material of structural components prior to final assembly in aerospace industry. This study aimed to investigate surface quality and mechanical behavior of open-hole composite laminates following different machining processes including abrasive waterjet cutting, high power fiber laser machining, conventional drilling and ultraviolet laser machining. Hole quality was quantified for further understanding the correlation between surface damage and mechanical behavior. Experimental results demonstrated that the hole geometrical accuracy and mechanical property were highly dependent on the machining methods. Digital image correlation technique was implemented to capture the strain distribution and strain evolution around open holes during tensile loading. Machining methods exhibited significant impact on epsilon yy$$ {\varepsilon}_{yy} $$, epsilon xx,$$ {\varepsilon}_{xx}, $$ and epsilon xy$$ {\varepsilon}_{xy} $$ strain levels around hole edges, while limited influence on strain distribution patterns. epsilon yy$$ {\varepsilon}_{yy} $$ and epsilon xx$$ {\varepsilon}_{xx} $$ concentrated in the regions consisting of fibers perpendicular to and along the loading direction respectively, and shear strain epsilon xy$$ {\varepsilon}_{xy} $$ featured with X shape around hole edge.