Indian Journal of Science and Technology

Abstract

Background/Objectives: Current importance of the study is stipulated by the high costs associated with ASTM E-399 field trials. The aim is to develop the new method to avoid or reduce them. Methods: The principle methods applied to the investigation of this problem are as follows: calculation of the critical value of stress intensity factor (SIF) employing analytical method and making use of the phySIFal and mechanical properties of the materials; calculation of SIF critical value experimentally, according to standard ASTM E-399 requirements. The study is accomplished with the verification tasks that prove the workability of the method and with the results of its implementation within the prototype software (PS). The PS belongs to Computer-Aided Engineering (CAE) systems and is applied to solve the issues of fracture strength and cracking resistance. Findings: The study presents the new method founded on the application of the modified Murakami formula to calculate the critical value of SIF. There is a new algorithm that explains the functions of the PS. The algorithm consists of two parts. The first part considers the structure without cracks; the second part describes the structure with a crack. The second part of the algorithm has a block that includes the modified formula for calculating the critical value of SIF. The new method of analytical calculation of the critical SIF holds for quasi-brittle materials (plasticity zone at the top of the crack is no larger than 20 %), and it takes into account the cracks in continual three-dimensional environment. It is used for the 1st type crack. This method in combination with the relevant PS is an innovation in the sphere of strength and cracking resistance analysis, insofar as it helps either reduce or avoid the costs associated with the field tests. Applications/Improvements: The materials of the study are of practical importance for industrial companies, educational and scientific institutions that study the issues of fracture strength and cracking resistance.

Keywords: Fracture Mechanics, Critical Stress Intensity Factor, Finite Elements Method, Crack, Computer-Aided Engineering Systems, LEFM