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A. Rama Chandra Murthy,Smitha Gopinath,G.S. Palani,Nagesh R. Iyer 사단법인 한국계산역학회 2008 Computers and Concrete, An International Journal Vol.5 No.3
This paper presents methodologies for remaining life prediction of plain concrete structural components considering tension softening effect. 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. A methodology to account for tension softening effects in the computation of SIF and remaining life prediction of concrete structural components has been presented. The tension softening effects has been represented by using any one of the models mentioned above. Numerical studies have been conducted on three point bending concrete structural component under constant amplitude loading. Remaining life has been predicted for different loading cases and for various tension softening models. The predicted values have been compared with the corresponding experimental observations. It is observed that the predicted life using bi-linear model and power curve model is in close agreement with the experimental values. Parametric studies on remaining life prediction have also been conducted by using modified bilinear model. A suitable value for constant ‘k’ of modified bilinear model is suggested based on parametric studies.
XFEM for fatigue and fracture analysis of cracked stiffened panels
M.R. Nanda Kumar,A. Ramachandra Murthy,Smitha Gopinath,Nagesh R. Iyer 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.1
This paper presents the development of methodologies using Extended Finite Element Method (XFEM) for cracked unstiffened and concentric stiffened panels subjected to constant amplitude tensile fatigue loading. XFEM formulations such as level set representation of crack, element stiffness matrix formulation and numerical integration are presented and implemented in MATLAB software. Stiffeners of the stiffened panels are modelled using truss elements such that nodes of the panel and nodes of the stiffener coincide. Stress Intensity Factor (SIF) is computed from the solutions of XFEM using domain form of interaction integral. Paris’s crack growth law is used to compute the number of fatigue cycles up to failure. Numerical investigations are carried out to model the crack growth, estimate the remaining life and generate damage tolerant curves. From the studies, it is observed that (i) there is a considerable increase in fatigue life of stiffened panels compared to unstiffened panels and (ii) as the external applied stress is decreasing number of fatigue life cycles taken by the component is increasing.
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.
A. Ramachandra Murthy,Rakhi Sara Mathew,G.S. Palani,Smitha Gopinath,Nagesh R. Iyer 국제구조공학회 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 (Al2014A) plate panels with concentric stiffener by varying sizes and positions under fatigue loading. Tensioncoupon tests and compact tension tests on 2014A have been carried out to evaluate mechanical propertiesand 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 ofstiffener and size. From the study, it can be concluded that the remaining life for stiffened panel for particularsize and position can be estimated by knowing the remaining life of corresponding unstiffened panel.