PSI - Issue 13

Evgeny Lomakin et al. / Procedia Structural Integrity 13 (2018) 664–669 Evgeny Lomakin and Boris Fedulov / Structural Integrity Procedia 00 (2018) 000–000

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Let us consider only shear strength characteristic S , and introduce only one damage parameter ψ for clarity and convenience. Assuming shear strength as a function of damage and damage rate parameters, we can write   , S S     . During of active process of damage accumulation in case of shear loading only, we have stress components laying on failure surface, which leads to the equation   12 , S      . Using expression 12 12 12 c G    , where G c corresponds to damaged shear modulus, which according to Fedulov et al. (2018) can be expressed through the damage parameter as 12 12 c G G   , where G - initial shear modulus. The strain component can be written as 12 vt   , where v – strain rate (s -1 ) and t – time (s). Eventually, active process of loading with damage accumulation can be formalized in the following form:   12 , . S G vt      It is possible to split function   , S    into static and dynamic parts:       , QS Dyn S S S        The possible expressions for static and dynamic strength functions can be chosen as:         0 . 1 1 sinh ln , n QS N Dyn S A B S C                           Figure 7 shows the experimental dependencies for carbon/epoxy composite and predicted loading diagrams the use of constants shown in Table 2, which are presented in Fedulov et al. (2018). Table 2. Coefficients for shear failure modelling. ������� ������ n C � � �s -1 � N 75 76 1.5 0.06 0.00002 1.5

Fig. 5. Experimental and predicted inplane shear loading diagrams.