PSI - Issue 28

Behzad V. Farahani et al. / Procedia Structural Integrity 28 (2020) 226–233 Behzad V. Farahani et al./ Structural Integrity Procedia 00 (2020) 000–000

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stress field near a crack face would be discarded in engineering structures. Therefore, such region could be eliminated from the initial structural component, which lead to suppress the crack tip singularity. Consequently, assuming a plate with a width of W submitted to a unidirectional loading with a magnitude of P , therefore, for any crack length of , the mode I SIF for finite plates with central oriented cracks would be calculated as; � � � ���� � � �� � �� � ���� � . (2) Where is the remote stress and � � ⁄��� . Regarding � , it is a parameter related to the stress dead-zone hypothesis, which could be derived from the following equation: � � �.��� ��.������ � ����� � � . (3) In the case of infinite plate including oriented central cracks with an angle of to the loading direction, the following equation is valid for the SIF calculation: � � � √2 ���� . (4) For a simplified case of infinite plates with a horizontal notch, � � , the mode I SIF can take the below form: � � � √2 � . (5) Furthermore, Farahani et al. (Farahani, Eslami, et al. 2019) carried out a hybrid experimental/numerical approach on the SIF determination for Middle Tension (MT) fracture specimens with a central horizontal notch upon uniaxial tensile test. A new analytical solution was proposed following the stress dead-zone concept and therefore a relationship was established for the SIF based on the compliance function. The mathematical procedure follows the energy-balance approach proposed by Griffith (Griffith 1921). Hence, mode I SIF for the finite MT plates would be acquired through the compliance function associated to the stress dead-zone, as; � �� � � � � ��� � � � ��� . (6) In which, is the plate thickness and denotes the remote load. Considering as the plate width, thus, � � . Moreover, is a geometrical characteristic associated to the stress dead-zone, which has been verified as � 1.2 for the studied benchmark. 6. Conclusions This review work focuses on new approaches to determine the Stress Intensity Factor, SIF, in the cracked structures. Advanced optical techniques, applicable on the structural components dealing with integrity monitoring to obtain the SIF, were reviewed. Thus, DIC approach, which permits to acquire the deformation variation on the structural components under various loading conditions, was surveyed. The obtained DIC data enables to experimentally characterize the SIFs. Additionally, Thermoelastic Stress Analysis, TSA, relying on the temperature variations on materials, was also reviewed in details. It allows measuring the stress field function resulting from thermal effects on a variety of material behaviours consisting of metals, polymers and composite constructions. It can be concluded that it is possible to use the optical tools to link the experimental data to the computational analyses in the field of LEFM. Amongst all, the reviewed works prove that the DIC and TSA have revealed to be efficient optical tools led to verify the numerical studies performed by the advanced discretization techniques resorting to FEM and meshless methods. Moreover, this work reviews a novel analytical solution on SIF calculation for the infinite/finite plates including oriented central cracks with an angle to a loading direction. Thus, stress dead-zone concept was taken into account to implement the compliance function. Therefore, a set of equations was suggested for the mode I SIF.