Effect of dissimilar metal SENB specimen width and crack length on stress intensity factor

Murthy A. Ramachandra,Muthu Kumaran M.,Saravanan M.,Gandhi P. 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.7

Dissimilar metal joints (DMJs) are more common in the application of piping system of many industries. A 2- D and 3-D finite element analysis (FEA) is carried out on dissimilar metal Single Edged Notch Bending (DMSENB) specimens fabricated from ferritic steel, austenitic steel and Inconel e 182 alloy to study the behavior of DMJs with constraints by using linear elastic fracture mechanics (LEFM) principles. Studies on DMSENB specimens are conducted with respect to (i) dissimilar metal joint width (DMJW) (geometrical constraints) (5 mm, 10 mm, 20 mm, 30 mm and 50 mm) (ii) strength mismatch (material constraints) and (iii) crack lengths (16 mm, 20 mm and 24 mm) to study the DMJ behavior. From the FEA investigation, it is observed that (i) SIF increases with increase of crack length and DMJWs (ii) significant constraint effect (geometry, crack tip and strength mismatch) is observed for DMJWs of 5 mm and 10 mm (iii) stress distribution at the interfaces of DMSENB specimen exhibits clear indication of strength mismatch (iv) 3-D FEA yields realistic behavior (v) constraint effect is found to be significant if DMJW is less than 20 mm and the ratio of specimen length to the DMJW is greater than 7.4.

Barriers to Realization of Forestry Mitigation Potential in India

Murthy, Indu K,Prasad KV, Devi Institute of Forest Science 2018 Journal of forest and environmental science Vol.34 No.5

Implementation of mitigation options on land is important for realisation of the goals of the Paris Agreement to stabilize temperature at $2^{\circ}C$. In India, the Intended Nationally Determined Contribution (INDC) targets include a forestry goal of creation of carbon sinks of 2.5 to 3 billion tonnes by 2030. There are however, multiple barriers to implementation of forestry mitigation options in India. They include environmental, social, financial, technological and institutional barriers. The barriers are varied not just across land categories but also for a land category depending on its regional location and distribution. In addition to these barriers is the impeding climate change that places at risk realisation of the mitigation potential as rising temperatures, drought, and fires associated with projected climate change may lead to forests becoming a weaker sink or a net carbon source before the end of the century.

Meta-analysis of GSTM1 and GSTT1 Polymorphisms and Risk of Nasopharyngeal Cancer

Murthy, Archana Krishna,Kumar, Vinod,Suresh, K.P. Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.3

Background: Studies of associations between genetic polymorphism of glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) with risk of nasopharyngeal cancer (NPC) have generated conflicting results. Thus, a meta-analysis was performed to clarify the effects of GSTM1 and GSTT1 polymorphisms on the risk of developing NPC. Materials and Methods: A literature search in two electronic databases namely PubMed and EMBASE up to December 2012 was conducted and eligible papers were finally selected based on the inclusion and exclusion criteria. The pooled odds ratio (OR) and presence of heterogeneity and publication bias in those studies were evaluated. Results: A total of 9 studies concerning nasopharyngeal cancer were evaluated. Analyses of all relevant studies showed increased NPC risk to be significantly associated with the null genotypes of GSTMI (OR=1.43, 95%CI 1.24-1.66) and GSTT1 (OR=1.28, 95%CI=1.09-1.51). In addition, evidence of publication bias was detected among the studies on GSTM1 polymorphism. Conclusions: This meta-analysis demonstrated the GSTM1 and GSTT1 null genotypes are associated with an increased risk of NPC.

Synthesis, Characterization and Bioevaluation of New Tetrahydroquinazolines

Murthy, Y.L.N.,Acharyulu, P.V.N.,Dubey, P.K.,Sundari, T. Tirunala Korean Chemical Society 2008 대한화학회지 Vol.52 No.3

The synthesis, characterization and bioevaluation of five new tetrahydroquinazolines was reported. Initially cyclohexanones were prepared and they were used as synthons to get the target molecules. These were condensed with substituted benzaldehydes and the resulting chalcones were treated with guanidine hydrochloride . All the molecules were non-toxic to human cells and showed significant antibacterial activity.

Production of secondary metabolites from cell and organ cultures: strategies and approaches for biomass improvement and metabolite accumulation

Murthy, Hosakatte Niranjana,Lee, Eun-Jung,Paek, Kee-Yoeup Springer-Verlag 2014 Plant cell, tissue and organ culture Vol.118 No.1

Anther Culture of Niger

Murthy, H.N.,Ashok Kumar, H.G.,Paek, K.Y. The Korean Society of Plant Biotechnology 2000 식물생명공학회지 Vol.27 No.4

Effect of steel fibres and nano silica on fracture properties of medium strength concrete

Murthy, A. Ramachandra,Ganesh, P. Techno-Press 2019 Advances in concrete construction Vol.7 No.3

This study presents the fracture properties of nano modified medium strength concrete (MSC). The nano particle used in this study is nano silica which replaces cement about 1 and 2% by weight, and the micro steel fibers are added about 0.4% volume of concrete. In addition to fracture properties, mechanical properties, namely, compressive strength, split tensile strength, and flexural strength of nano modified MSC are studied. To ensure the durability of the MSC, durability studies such as rapid chloride penetration test, sorptivity test, and water absorption test have been carried out for the nano modified MSC. From the study, it is observed that significant performance improvement in nano modified MSC in terms of strength and durability which could be attributed due to the addition pozzolanic reaction and the filler effect of nano silica. The incorporation of nano silica increases the fracture energy about 30% for mix without nano silica. Also, size independent fracture energy is arrived using two popular methods, namely, RILEM work of fracture method with $P-{\delta}$ tail correction and boundary effect method. Both the methods resulted in nearly the same size-independent $G_F$ irrespective of the notch to depth ratio of the same specimen. This shows evidence that either of the two procedures could be used in practice for analysis of cracked concrete structures.

Evaluation of mechanical properties for high strength and ultrahigh strength concretes

Murthy, A. Ramachandra,Iyer, Nagesh R.,Prasad, B.K. Raghu Techno-Press 2013 Advances in concrete construction Vol.1 No.4

Due to fast growth in urbanisation, a highly developed infrastructure is essential for economic growth and prosperity. One of the major problems is to preserve, maintain, and retrofit these structures. To meet the requirements of construction industry, the basic information on all the mechanical properties of various concretes is essential. This paper presents the details of development of various concretes, namely, normal strength concrete (around 50 MPa), high strength concrete (around 85 MPa) and ultra high strength concrete (UHSC) (around 120 MPa) including their mechanical properties. The various mechanical properties such as compressive strength, split tensile strength, modulus of elasticity, fracture energy and tensile stress vs crack width have been obtained from the respective test results. It is observed from the studies that a higher value of compressive strength, split tensile strength and fracture energy is achieved in the case of UHSC, which can be attributed to the contribution at different scales viz., at the meso scale due to the fibers and at the micro scale due to the close packing of grains which is on account of good grading of the particles. Micro structure of UHSC mix has been examined for various magnifications to identify the pores if any present in the mix. Brief note on characteristic length and brittleness number has been given.

Remaining life prediction of concrete structural components accounting for tension softening and size effects under fatigue loading

Murthy, A. Rama Chandra,Palani, G.S.,Iyer, Nagesh R. Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.3

This paper presents analytical methodologies for remaining life prediction of plain concrete structural components considering tension softening and size effects. Non-linear fracture mechanics principles (NLFM) have been used for crack growth analysis and remaining life prediction. Various tension softening models such as linear, bi-linear, tri-linear, exponential and power curve have been presented with appropriate expressions. Size effect has been accounted for by modifying the Paris law, leading to a size adjusted Paris law, which gives crack length increment per cycle as a power function of the amplitude of a size adjusted stress intensity factor (SIF). Details of tension softening effects and size effect in the computation of SIF and remaining life prediction have been presented. Numerical studies have been conducted on three point bending concrete beams under constant amplitude loading. The predicted remaining life values with the combination of tension softening & size effects are in close agreement with the corresponding experimental values available in the literature for all the tension softening models.

Numerical simulation of an external prestressing technique for prestressed concrete end block

Murthy, A. Rama Chandra,Ganapathi, S. Chitra,Saibabu, S.,Lakshmanan, N.,Jayaraman, R.,Senthil, R. Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.5

This paper presents the details of finite element (FE) modeling and analysis of an external prestressing technique to strengthen a prestressed concrete (PSC) end block. Various methods of external prestressing techniques have been discussed. In the proposed technique, transfer of external force is in shear mode on the end block creating a complex stress distribution. The proposed technique is useful when the ends of the PSC girders are not accessible. Finite element modeling issues have been outlined. Brief description about material nonlinearity including key aspects in modeling inelastic behaviour has been provided. Finite element (FE) modeling including material, loading has been explained in depth. FE analysis for linear and nonlinear static analysis has been conducted for varying external loadings. Various responses such as out-of-plane deformation and slip have been computed and compared with the corresponding experimental observations. From the study, it has been observed that the computed slope and slip of the steel bracket under external loading is in good agreement with the corresponding experimental observations.