The effect of “hardening in the cut” with a single incision and cuts depending on the initial level of strength

Yu. P. Gul, A. V. Ivchenko, P. V. Kondratenko, V. S. Chmeleva, I. Perchung

Abstract


Purpose. On the basis of analytical and experimental studies to identify and summarize quantitative regularities of the influence of geometry of cuts and especially of the system of cuts and the source strength to the magnitude of the hardening effect in  the  incision. Methodology. Analytical  study  on  the  systematization  of  literature  data  on  the  quantitative  influence  of  different factors on the hardening effect in the incision in comparison with experimental data influence of single cuts and a system of notches of different  geometry objects in model and full-scale products with different  level of structural hardening when  tested in a static uniaxial tensile tests. Findings. Confirmed and obtained new data on the quantitative impact of single cuts and systems of cuts at different  initial level of structural  hardening of the facilities that do not have single cuts  and system cuts,  and found that when  a single  cuts  with  the  growth  of  structural  hardening  in  the  investigated  range – the  value  of  the  hardening  effect  in  the  incision increases, the system cuts the influence of the level of extreme structural hardening: the hardening effect in the incision first increases and then decreases. The proposed explanation of observed in experiments effects of various factors on the effect of hardening in the cut, in the corresponding generic expression. Originality. First shown and interpreted an ambiguous impact of the system of cuts, compared with a single incision, the hardening effect of the incision at different levels of structural hardening: in the case of a single incision geometric hardening in the overall fixed effect of hardening in the notch acts as a cofactor for structural hardening, as in the case of a system of cuts at a certain level of structural hardening effect of the cuts is again reinforcing factor. Also for the first time formalized the influence of various factors on the hardening effect in the incision in the form of equations that do not contradict to experimental data. Practical value. On the basis of the results developed recommendations for updating the object type subjected to acceptance tests, in particular bolts in classes 8.8 and higher. They can be used to optimize the geometry of the system cuts metal with functional cuts, and in general creating objects with positive use of the hardening effect in the incision.


Keywords


a single cut; the system of cuts; hardening in the cut; the stress concentration factor; the degree of stiffness of the stress state; the level of structural hardening.

References


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