Emission of CO2 into atmosphere has been the main reason behind global warming. Production of one tonne of cement approximately emits one tonne of CO2, the Greenhouse gas and major culprit for global warming, into atmosphere. Global warming is a great concern to humankind, and Scientists throughout the world do extensive researches to find out alternate green materials that could help in reducing the effect of global warming. Fly ash, once considered a waste material, has found usefulness in replacing cement up to 60% and experiments are conducted to determine the fracture parameter of plain cement concrete (OPC) and high volume fly ash concrete (HVFAC). The Beams of size 1200mm long x 100mm wide x 200mm deep are cast for the experiment. The critical Crack Tip Opening Displacement for plain cement concrete (OPC) and high volume fly ash concrete (HVFAC) are determined. Four numbers of M30 grade concrete notched beam specimens are cast with OPC concrete as reference specimens and four specimens each for 50% and 60% replacement of cement with fly ash are also cast. All the beams are tested under three point loading until failure. The parametric study of notch to depth ratio is kept as 0.2 and 0.3. From the test results, the rupture load of the specimens decreased with the increase in fly ash content.

Fracture toughness is usually used as a generic term for measures if materials resistance to expansion of a crack in engineering applications such as petrochemical industries and oil and gas pipelines. The concept of fracture toughness received profound importance in engineering design and applications, after the destruction of liberty ships in the World War II. In this paper, fracture toughness test methods, evaluation and standardization of metal materials are reviewed based on linear elastic and elastic-plastic fracture mechanics. The general principles and methods of testing developed by the American Society for Testing and Materials are explained. The main parameters of fracture mechanics such as elastic energy release rate (G), stress intensity factor (K), J integral, crack tip opening displacement (CTOD) and crack tip opening angle (CTOA) are defined. Finally, the scientific and computational foundations of the two factors (K) and CTOD, as the most widely used industrial factors will be examined in detail.

The effect of cyclic loading on fatigue crack growth in plastically compressible solids is investigated at negative stress ratio under plane strain and small scale yielding conditions. The material is characterized by a finite strain elastic viscoplastic constitutive model with hardening and hardening-softening-hardening hardness functions. Displacements corresponding to the isotropic linear elastic mode I crack field are prescribed on a remote boundary. The plastic crack growth, crack tip opening displacement (CTOD) and near crack tip stress fields are presented using finite element method. Material hardening/ softening has a major relevance on crack growth, CTOD and the evolution of stress distribution. It is revealed here that the negative stress ratio can significantly influence the loading conditions at the crack tip and thereby increase the crack growth for tension– compression loading for hardening material whereas the fatigue crack growth of plastically compressible hardening-softening-hardening material is only slightly affected by the negative stress ratio albeit it is accepted in literature that compressive loads contribute to fatigue crack growth significantly. In the present studies, the CTOD variation with applied load and the near stress distribution are also very unusual in nature.

Experimental and numerical studies are carried out in this study to characterize the flexural properties of ultra-high-performance fiber-reinforced concrete (UHPFRC) beams with and without an initial notch reinforced with micro steel fibers in overall ratios of 2% by volume. Dimensions of the notch were 5 mm in width, and 25 mm in height. For this purpose, three-point bending tests were carried out on UHPFRC specimens. Thereafter, numerical studies were carried out to validate experimental findings and in subsequent, sensitivity analyses were carried out to provide better insight with regard to the investigated parameters. Variables of the study were: mesh size, width, height, length, overall size of the beam, tensile strength, compressive strength, modulus of elasticity, crack mouth-opening displacement (CMOD), and crack tip-opening displacement (CTOD). Furthermore, vertical deflection-CMOD findings were compared against available equations in the literature and discussions were made where relevant. Results showed that finer mesh leads to negligible stiffer results with similar observations for the maximum sustained stress by the modulus of elasticity, compressive strength, and width variations. Moreover, 40% increase in the tensile strength led to 47% increase in the sustained stress and doubling the clear span led to 5.5% increase in the sustained stress and 20% peak deflection.; depth variations led to size effect phenomenon and  nonlinear regression analyses successfully captured the flexural load-deflection, load-CMOD, and load-CTOD trends of the flexural beams with coefficient of correlation values ( ) close to unity. Finally, a brief cost analysis was given for the fabrication of 1  of UHPFRC.

Offshore pipelines are usually constructed by the use of girth welds, while welds may naturally contain flaws. Currently, fracture assessment procedures such as BS 7910 are based on the stress-based methods and their responses for situations with large plastic strain is suspicious. DNV-OS-F101 with limited modifications proposes a strain-based procedure for such plastic loads. In this paper 3D nonlinear elastic-plastic finite element analyses using the ABAQUS software are performed in order to compare existing stress- and strain-based procedures beside newly strain-based method which is called CRES approach in order to improve the criteria used in current guidelines particularly at large plastic strains. It is concluded that although BS 7910 values are closer to finite element results than other methods in elastic region, but it is still conservative. In the area of large plastic strain, CRES method is very less conservative in both case of with and without internal pressure in comparison to others. The comparison of numerical simulation results with those available experimental data reveals a good agreement.

Experiments have indicated that the fracture properties of rocks change with variations of loading rate. In this study, the microstructural properties of two marbles are characterized by three different microscopic techniques including petrographic thin sections method, fluorescent replacement technique, and scanning electron microscopy (SEM). An experimental investigation is conducted to study the quasi-static fracture behavior in different microstructural features of crystalline rocks. The hollow center cracked disc (HCCD) method is employed to determine the fracture parameters with variations of loading rates using a hydraulic machine. Microscopic studies on microstructure deficits reveal that fractal dimension in Maroon marble is higher than in Baghat marble. Variations of toughness, crack propagation speed, and crack tip opening displacement (CTOD) with changes of loading rate are also investigated. The results indicate that toughness and crack propagation speed increase with loading rate, but the effect of microstructure in two marbles reduces the rate of growth. The fracture toughness in Baghat marbles is higher than in Maroon marble, and difference of fracture toughness is magnified with the loading rate.