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INVESTIGATION OF THE ROLE OF RESIDUAL STRESSES IN THE WARM PRESTRESS (WPS) EFFECT. PART II—ANALYSIS
Author(s) -
Reed P. A. S.,
Knott J. F.
Publication year - 1996
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/j.1460-2695.1996.tb00985.x
Subject(s) - materials science , extrapolation , residual stress , fracture (geology) , structural engineering , welding , superposition principle , composite material , mathematics , engineering , mathematical analysis
— Curry's model of the WPS effect has been applied to the results of a previous paper, and is extended to treat warm prestressing in blunt notched test‐pieces. The effect of more complex prestress cycles is also predicted by an extrapolation of the model. The effects of the load‐cool‐fracture, LCF, cycle can be reasonably predicted for both sharply precracked and blunt notched specimens. For the sharply precracked specimens the effects of the load‐unload‐cool‐fracture, LUCF, cycle at — 196°C are consistently overpredicted and this may be due to a decrease in the cleavage fracture stress at — 196°C of the material at the crack tip which has been subjected to repeated plastic straining by the combination of loading cycles. Modifications to the model are suggested which reduce the overproduction but a wide degree of scatter is observed in the experimental observations. Blunt notched specimens show a reasonable correlation between prediction and theory for the tensile LUCF cycle. Problems have been found in predicting the effect of various prestress cycles in different specimens due to the inherent variability in baseline fracture behaviour of the weld metal. It is concluded that the general trend of results is adequately explained by superposition models but that a greater understanding of local flow properties at a crack tip is required to achieve reasonable predictive success for weld metals such as A533BW.