PSI - Issue 33

O.B. Naimark et al. / Procedia Structural Integrity 33 (2021) 1115–1122

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Naimark O.B. et al / Structural Integrity Procedia 00 (2021) 000–000

PMMA specimen

CRACK

LASER

GAGE

polarizer 1

polarizer 2

(a)

(b)

Fig.1 Scheme of stress recording (a) and stress dynamics for different crack velocity (b)

The influence of two attractors related to different scenarios of failure was studied under the recording of the stress dynamics using the polarization scheme coupled with the laser system, Fig.1.

(a)

(b)

Fig. 2. The Poincare cross-section for the phase variables

: a -

, b -

The temporal stress history was measured at the marked point fixedly spaced 4 mm apart from the main crack path on the distance. This allowed the nonlinear properties of the system to be investigated using the stress phase portrait for observable variables for slow and fast cracks, Fig. 1. These portraits display the “hyperbolic” stress dynamics (Fig.1a) for and the stochastic dynamics (Fig.1b) for corresponding to the set of singular blow-up modes (5) responsible for numerous daughter crack origin. These phase portraits represent the Poincare cross-sections in the phase space, when the dynamics of a nonlinear system depends on stress and damage variables. The phase portraits in Fig 2a, b demonstrate the presence generally two characteristic dynamics due to the influence of two singular self-similar solutions.