Application of ANN concepts for prediction of crack growth and remaining life of circumferentially cracked piping components under different loading scenarios

Murthy A. Ramachandra,Kale Divyansh,Saravanan M.,Vishnuvardhan S. 한국원자력학회 2025 Nuclear Engineering and Technology Vol.57 No.4

This paper presents the details of Artificial Neural Network (ANN) based models to predict crack depth and remaining life of circumferentially part-through cracked piping components used in the nuclear industry. Crack growth data from experimental studies on (i) straight pipes made up of SA 312 Type 304 LN stainless steel having part-through circumferential notch under combined bending and torsion and (ii) dissimilar metal pipe weld joints having circumferential through-wall crack in the weld were used. The dissimilar metal pipe weld joint is made up of SA312 Type 304 LN austenitic stainless steel and SA508 Gr. 3 Cl. 1 low alloy carbon steel and joined by Nickel-rich Inconel alloy weld. About 75 % of the mixed experimental data has been used for development of model and the remaining data for validation. For the development of ANN model, (i) back propagation technique (ii) sigmoidal transfer functions and (iii) Levenberg-Marquardt algorithm are used. The maximum percentage difference observed between the predicted and the experimental results for crack depth and remaining life was 19.59 % and 15.78 % respectively. The efficiency of the developed model was verified using several statistical parameters. The developed models are useful for the structural integrity assessment of piping components under different loading scenarios.

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.

Prediction of flexural behaviour of RC beams strengthened with ultra high performance fiber reinforced concrete

Murthy A, Ramachandra,Aravindan, M.,Ganesh, P. Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.3

This paper predicts the flexural behaviour of reinforced concrete (RC) beams strengthened with a precast strip of ultra-high performance fiber-reinforced concrete (UHPFRC). In the first phase, ultimate load capacity of preloaded and strengthened RC beams by UHPFRC was predicted by using various analytical models available in the literature. RC beams were preloaded under static loading approximately to 70%, 80% and 90% of ultimate load of control beams. The models such as modified Kaar and sectional analysis predicted the ultimate load in close agreement to the corresponding experimental observations. In the second phase, the famous fatigue life models such as Papakonstantinou model and Ferrier model were employed to predict the number of cycles to failure and the corresponding deflection. The models were used to predict the life of the (i) strengthened RC beams after subjecting them to different pre-loadings (70%, 80% and 90% of ultimate load) under static loading and (ii) strengthened RC beams after subjecting them to different preloading cycles under fatigue loading. In both the cases precast UHPFRC strip of 10 mm thickness is attached on the tension face. It is found that both the models predicted the number of cycles to failure and the corresponding deflection very close to the experimental values. It can be concluded that the models are found to be robust and reliable for cement based strengthening systems also. Further, the Wang model which is based on Palmgren-Miner's rule is employed to predict the no. of cycles to failure and it is found that the predicted values are in very good agreement with the corresponding experimental observations.

COMMON FIXED POINTS FOR A RATIONAL INEQUALITY UNDER WEAK COMPATIBLE MAPS OF TYPE (A) (DEDICATED TO THE LATE P. V. LAKSHMAIAH)

Murthy, P.P.,Olaleru, J.O. The Youngnam Mathematical Society 2009 East Asian mathematical journal Vol.25 No.1

In this paper, we present a unique common xed point theorem under weak compatible mappings of type(A), which extends and generalizes a result of Achari [1].

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.

Implications of Impacts of Climate Change on Forest Product Flows and Forest Dependent Communities in the Western Ghats, India

Murthy, Indu K.,Bhat, Savithri,Sathyanarayan, Vani,Patgar, Sridhar,M., Beerappa,Bhat, P.R.,Bhat, D.M.,Gopalakrishnan, Ranjith,Jayaraman, Mathangi,Munsi, Madhushree,N.H., Ravindranath,M.A., Khalid,M., Institute of Forest Science 2014 Journal of forest and environmental science Vol.30 No.2

The tropical wet evergreen, tropical semi evergreen and moist deciduous forest types are projected to be impacted by climate change. In the Western Ghats region, a biodiversity hotspot, evergreen forests including semi evergreen account for 30% of the forest area and according to climate change impact model projections, nearly a third of these forest types are likely to undergo vegetation type change. Similarly, tropical moist deciduous forests which account for about 28% of the forest area are likely to experience change in about 20% of the area. Thus climate change could adversely impact forest biodiversity and product flow to the forest dependent households and communities in Uttara Kannada district of the Western Ghats. This study analyses the distribution of non-timber forest product yielding tree species through a network of twelve 1-ha permanent plots established in the district. Further, the extent of dependence of communities on forests is ascertained through questionnaire surveys. On an average 21% and 28% of the tree species in evergreen and deciduous forest types, respectively are, non-timber forest product yielding tree species, indicating potential high levels of supply of products to communities. Community dependence on non-timber forest products is significant, and it contributes to Rs. 1199 and Rs. 3561/household in the evergreen and deciduous zones, respectively. Given that the bulk of the forest grids in Uttara Kannada district are projected to undergo change, bulk of the species which provide multiple forest products are projected to experience die back and even mortality. Incorporation of climate change projections and impacts in forest planning and management is necessary to enable forest ecosystems to enhance resilience.

aarvee associates

Murthy, M 서울행정학회 2014 서울행정학회 학술대회 발표논문집 Vol.2014 No.7

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.

Fracture analysis and remaining life prediction of aluminium alloy 2014A plate panels with concentric stiffeners under fatigue loading

Murthy, A. Ramachandra,Mathew, Rakhi Sara,Palani, G.S.,Gopinath, Smitha,Iyer, Nagesh R. Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.4

Fracture analysis and remaining life prediction has been carried out for aluminium alloy (Al 2014A) plate panels with concentric stiffener by varying sizes and positions under fatigue loading. Tension coupon tests and compact tension tests on 2014A have been carried out to evaluate mechanical properties and crack growth constants. Domain integral technique has been used to compute the Stress intensity factor (SIF) for various cases. Generalized empirical expressions for SIF have been derived for various positions of stiffener and size. From the study, it can be concluded that the remaining life for stiffened panel for particular size and position can be estimated by knowing the remaining life of corresponding unstiffened panel.

Crack growth analysis and remaining life prediction of dissimilar metal pipe weld joint with circumferential crack under cyclic loading

Murthy, A. Ramachandra,Gandhi, P.,Vishnuvardhan, S.,Sudharshan, G. 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.12

Fatigue crack growth model has been developed for dissimilar metal weld joints of a piping component under cyclic loading, where in the crack is located at the center of the weld in the circumferential direction. The fracture parameter, Stress Intensity Factor (SIF) has been computed by using principle of superposition as K_H + K_M. K_H is evaluated by assuming that, the complete specimen is made of the material containing the notch location. In second stage, the stress field ahead of the crack tip, accounting for the strength mismatch, the applied load and geometry has been characterized to evaluate SIF (K_M). For each incremental crack depth, stress field ahead of the crack tip has been quantified by using J-integral (elastic), mismatch ratio, plastic interaction factor and stress parallel to the crack surface. The associated constants for evaluation of K_M have been computed by using the quantified stress field with respect to the distance from the crack tip. Net SIF (K_H + K_M) computed, has been used for the crack growth analysis and remaining life prediction by Paris crack growth model. To validate the model, SIF and remaining life has been predicted for a pipe made up of (i) SA312 Type 304LN austenitic stainless steel and SA508 Gr. 3 Cl. 1. Low alloy carbon steel (ii) welded SA312 Type 304LN austenitic stainless-steel pipe. From the studies, it is observed that the model could predict the remaining life of DMWJ piping components with a maximum difference of 15% compared to experimental observations.