Frequency effect in short-beam shear fatigue of a glass fiber reinforced polyester composite

• SBS fatigue tests were adequate to study interlaminar shear fatigue.
• The frequency sensitivity was large at low stress amplitude.
• Not significant frequency effect was found at large stress amplitude.
• Temperature increases were large at high stress amplitude and frequencies.

The effect of loading frequency on short-beam shear fatigue behavior of a glass fiber reinforced polyester laminated was studied. Surface specimen temperature increase and macroscopic specimen damage were also evaluated. The tests were performed employing a short-beam device with three amplitude stress levels, four frequencies between 1 and 10 Hz and a shear stress ratio R = 0.1. Specimens with the smallest stress amplitude showed a fatigue life between 105 and 106 cycles and the largest stress amplitude endured approximately 104 cycles. The high stress amplitude tests produced increases in specimen temperature up to 7 °C, 4 °C and 1 °C for 10 Hz, 6 Hz and both 3 and 1 Hz respectively, while no temperature changes were measured in low amplitude tests. According to the statistical analysis performed, the changes in fatigue life were not significant for the frequency range employed in this study.

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