Effects of fatigue damage on the high strain-rate performance of DH36 steel

An experimental investigation has been undertaken to determine the effects of fatigue on the high strain-rate material properties of high-performance steel used in modern naval vessel structures. A novel methodology to conduct tensile testing at low and high strain-rates on fatigued specimens was developed. A bespoke Split Hopkinson’s Tension Bar clamping arrangement was designed to undertake the necessary high strain-rate testing of flat dog-bone specimens. Analysis of the microstructure of the specimens was performed alongside a comparison on the strain-rate sensitivity of the tested DH36 steel against other literature sources. Testing revealed no statistically significant effect of high cycle fatigue at high strain-rate as determined by a two-sample t-test, but revealed a possible effect on quasi-static material properties. The findings of this novel comparison between fatigued and virgin material properties of shipbuilding steel provides decision-makers and researchers with an understanding on the effect of fatigue on high strain-rate material properties.