Effects of surface quality and loading history on fatigue life of laser-machined poly(methyl methacrylate)

•Polishing of laser-machined surfaces can enhance the tensile strength up to 5%.•Polishing can enhance fatigue life of laser-machined samples by a factor of ten.•Loading sequence has a definite effect on the remaining life of PMMA.•Manson–Halford and Otani–Song models can be used to estimate fatigue life of PMMA.

In this research the effects of surface quality and loading history on fatigue behavior of CO2 laser-machined poly(methyl methacrylate) are investigated. It is found that polishing of laser-machined surfaces can enhance the tensile strength up to 5% while significantly elongating the fatigue life of specimens. Microscopic observations reveal that defects on lateral laser machined surface and heat affected zone lead to a reduction of fatigue life by a factor of ten compared to samples with polished lateral surfaces. In the second part of this research it is observed that the loading sequence has a definite effect on the remaining life of poly(methyl methacrylate). Finally the ability of several cumulative damage formulations for modeling the fatigue life in multi-stage loading is evaluated, out of which Manson–Halford and Otani–Song models outperformed the others.