PSI - Issue 16

Cristian Alejandro de León Gómez et al. / Procedia Structural Integrity 16 (2019) 265–272 Cristian Alejandro de León Gómez et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Table 1. Constants of "material – environment" and the criterion values of SIF.

Constants of system "material – environment"

th K 

System "material – environment"

C

n

0 mT – air

1.90 E-8 4.16 E-8 3.18 E-8

0.582 0.568 0.677

17.285

0 mT – seawater 3 mT – seawater

4.675 5.448

Values Δ K th given in the Table 1 were the base for determination of the characteristic values a th . Along with these values obtained on the base of experimental data processing, values of a fc were calculated using the technique of Dmytrakh et al. (2005) that corresponds to characteristics value ( a / t ) * determined on the base of relation (6). Also, it should be noted that in the investigated object 45  45  5 mm it was taken into consideration is the parameter of 5 mm angle, all further calculations are given for this case, when the crack propagates perpendicularly to the main axis of this parameter. Assessments of the durability of the investigated element of the construction with potentially possible crack like defects of various forms and geometry is performed on the base of the relation by Dmytrakh et al. (1999), that provides the attainment conditions of spontaneous destruction of the structural elements, i.e.

a

    F K da fc

N



(8)

fc

I

a

th

where N fc – number of load cycles prior to destruction of structural elements; F (Δ K I ) – known function of SIF Δ K I . To results of calculation of durability are given in Table 2.

Table 2. Data for calculating of the durability of investigation object 45 × 45 × 5 mm with defects of various form System "material – environment" a th ,. mm a fc , mm N fc , loadcycles Model No. 1 0 mT – air 1.22 1.78798 9.1577 E+6 0 mT – seawater 0.10 7.86497 E+6 3 mT – seawater 0.13 7.32972 E+6

0 mT – air

0.20 0.01 0.02 0.20 0.02 0.22 0.01 0.02 0.20 0.01 0.02 0.27 0.15 0.25

1.00934 E+7 6.04617 E+6 5.3397 E+6 1.27968 E+7 7.31996 E+6 6.48981 E+6 9.1577 E+6 5.93539 E+6 5.33695 E+6 1.16696 E+7 6.79095 E+6 5.33695 E+6 9.76859 E+6 6.2387 E+6 5.62347 E+6

Model No. 2

0 mT – seawater 3 mT – seawater

1.92487

0 mT – air

Model No. 3

0 mT – seawater 3 mT – seawater

0.015

2.43187

0 mT – air

Model No. 4 ( a/c=0.15 ) Model No. 5 ( a/c=0.1 ) Model No. 6 ( a/c=0.1 )

0 mT – seawater 3 mT – seawater

1.67381

0 mT – air

0 mT – seawater 3 mT – seawater

2.18112

0 mT – air

0 mT – seawater 3 mT – seawater

1.78798