Fatigue Crack Propagation Property of YB-DM-10 Directional PMMA

Abstract

The threshold value of stress intensity factor range was acquired according the study of fatigue crack propagation property of directional PMMA (YB-DM-10). It was found that the plot of fatigue crack propagation rate is accordance with Pairs Law and Walker Law. The effect of angles in plane, frequency and stress ratio on the fatigue crack propagation was studied. According the comparison of coefficient in Pairs Law, Walker Law and morphology SEM in fracture surface under test conditions with different parameters, the effect of different parameters on fatigue crack propagation rate was analysed. Results show that the fatigue crack propagation rates of test specimens with different cutting angle in XY plane of PMMA sheet are nearly the same. The frequency has slight effect on the fatigue crack propagation, except that data become separate in the third region of da/dN-△K plot. On the condition of same stress intensity factor range, the fatigue crack propagation rate accelerates as the stress ration increases. The result of the study established foundation for the application of directional PMMA and the research on the damage tolerance of transparent materials used in aircraft cockpit canopies.

Keywords

• directional PMMA
• fatigue crack propagation
• threshold
• cutting angle
• frequency
• stress ratio