Effects of Structural Ageing on Blast Analyses of a Naval Vessel: A Technical Review

As vessels are being asked to perform over longer service lives and under more intensive operational tempos, it is becoming more pertinent that the effects of structural aging be accounted for. Fatigue is an important aspect of structural aging of a vessel. Currently, fatigue analyses are conducted in order to determine the point at which fatigue failure might occur. However, fatigue can induce changes to the material properties long before full fatigue failure has occurred. These changes in material properties can affect the outcomes of other forms of structural failure. One such form which is of particular importance for naval vessels is failure due to blast loading.

Blast modelling utilising coupled CFD/FEA simulations are conducted when investigating the effects of an internal blast, requiring the use of a constitutive model to account for the material properties. Fatigue damage can result in a reduction of modulus of toughness of some steels, especially so under high strain rate loading conditions. However, these changes in material properties are not currently considered in constitutive models.

This paper reviews experimental investigations conducted into the effects of fatigue on high strain rate loading. It is shown that the effects can be significant, and that further work is required before the allowance of the effects can be introduced to blast analyses.