A novel micromechanical based theory for the determination of the stress intensity factors (SIFs) of three-dimensional interacting CRACKS is proposed. The pioneering work of Eshelby"s equivalent inclusion method (EIM) in conjunction with Hill"s theorem on discontinuities of elastic fields across the interfaces are utilized in this analytical approach. The important feature of the present theory lies in its generality in treating modes I, II, III, and mixed mode fracture, and handling interacting CRACKS with various geometries subjected to non-uniform far-field applied stress (strain), in a unified manner. For illustrations arbitrarily oriented penny shape CRACKS under far-field normal and shear loading are examined. Comparisons with other analytical solutions, whenever available, established the remarkable accuracy and robustness of the proposed theory.

This paper makes static studies of multiple crack interaction in infinite, elastic, two dimensional bodies applying the Boundary element method. To avoid numerical inaccuracies in crack boundaries the method of Dual boundary element (DBEM) is used here so hyper singular equations are added to the system and this will affect the process of choosing element types. The results in terms of stress intensity factors (SIFs) are presented for a variety of crack arrangements, relative sizes of CRACKS spacing and crack orientations. In order to calculate the so called factors, crack opening displacement method is used. It is found that crack arrangements have significant effects on SIFs.

Imprecise construction work might cause imperfection in the shell of RC. hyperbolic cooling towers. By considering the three directions concrete fracture model and by using elements in Finite Element analysis which could crack in three directions, it could be shown that in imperfect shell, the thickness CRACKS occur at the end of the weight and thermal loads. In the other words, the inside and outside of the concrete shell separate. The number of such CRACKS rises up by increasing the imperfection in the cooling tower shell. This increase in number of CRACKS could multiple when two concavity and convexity imperfections happen consecutively. Since there is not any reinforce bar for preventing of such CRACKS, so it must be avoided by precise construction work and by modifying the participating thermal load factor in combining loads.

This work deals with the interaction of P-waves between a moving central crack and a pair of outer CRACKS situated at the interface of an orthotropic layer and an elastic half-space. Initially, we considered a two-dimensional elastic wave equation in orthotropic medium. The Fourier transform has been applied to convert the basic problem to solve the set of four integral equations. These set of integral equations have been solved to get the analytical expressions for the stress intensity factor (SIF) and crack opening displacements (COD) by using the finite Hilbert transform technique and Cooke’ s result. The main objective of this work is to investigate the dynamic stress intensity factors and crack opening displacement at the tips of the CRACKS. The aims of the study of these physical quantities (SIF, COD) is the prediction of possible arrest of the CRACKS within a certain range of crack velocity by monitoring applied load. SIF and COD have been depicted graphically for various types of orthotropic materials. We presented a parametric study to explore the influence of crack growing and propagation. This result is very much applicable in bridges, roads, and buildings fractures.

This study introduces the free vibration analysis of multilayered symmetric sandwich Timoshenko beams, made of functionally graded materials with two edge cracked, using the finite element method and linear elastic fracture mechanic theory. The FG beam consists of 50 layers, located symmetrically to the neutral plane, whose material properties distribution change along the beam thickness, according to power and exponential laws. The constituent of each layer of the beam is different, but each layer is isotropic and homogeneous. Natural frequency values of a cantilever beam are calculated using a developed MATLAB code. There is good agreement between the present results and the published results from the literature. A detailed study is carried out to observe the effect of crack location, crack depth ratio, power law index and material distribution on the first four natural frequencies.

Pavement inspection is one of the most important steps in implementation of pavement management system and extend efforts have been done to increase the efficiency of this system by using the new technologies. In recent years, transportation agencies focus on creating automatic and more efficient systems for pavement inspection and a large number of researches have been done for this aim. According to progress of computer science, data mining and machine learning as computer-based methods are used more in various areas (such as engineering, medical and economy) and significant results have been achieved. In pavement management area, several researches have been performed with aim of the applying the machine learning especially in pavement distresses evaluation. In this paper, the theoretical concepts have been explained and several models have been created based on deep convolutional networks using transfer learning to detect and classify pavement CRACKS as the most prevalent pavement distress, and the performance of these models has been evaluated considering learning and test speed, and accuracy as the most important performance parameters. The results of this research indicate that the speed of models almost depends on the pre-trained models characteristics that applied in transfer learning process. Also the accuracy of models based on various metrics (Sensitivity, F-score, etc. ) is in range of 0. 94 to 0. 99 and indicates that deep learning method can be used to create expert systems for detection, classification, and quantification of pavement distresses such as cracking.