Volume 05 Issue 02

2018

 

Investigation of Efficiency of Different Ground Motion Scaling Methods for Estimating Seismic Demands of Steel Moment Frames
Morteza Razi | pp: 52-61 | Download Paper | Show Abstract

Abstract: There are different methods in seismic design codes for scaling earthquake ground motion records for the purpose of performing nonlinear time history analysis. The main objective of this study is to evaluate how different scaling approaches affect the results of nonlinear time history analysis. Reduced the scatter in estimated drift angles was the main criteria to measure the effectiveness of different scaling methods. For this purpose, three steel moment resisting frames with different height (3, 6, and 10 stories) were subjected to Incremental Dynamic Analysis under a suite of twenty near-fault and far-fault ground motions. The results indicate that the scaling method based on UBC 97 causes a more significant dispersion in the responses compared to the other considered methods.

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Experimental Study of Delamination in GFRP during Drilling using Single AE Sensor
J. Sudha, S. Sampathkumar | pp: 62-65 | Download Paper | Show Abstract

Abstract: A Non-destructing testing (NDT) and an unconventional method that is being used for identifying the location and detection and determining the various characteristics of defects in products is Acoustic Emission Technology (AET), which can be applied for understanding the various events associated with drilling process, that occurs from the time when the drill bit comes into contact up to the completion of the drilling process. This paper focusses in finding the maximum thickness to detect drilling related delamination using single AE sensor. Delamination has been artificially induced by placing non-adhesive Teflon tape between the layers at the exit.  Various AE parameters are analyzed to find its relation with the thickness of the composite material.  Peak amplitude and slope of the cumulative RMS curve decreases with the increase in thickness of composite.  Hence, the range of the thickness has been found out beyond which a single AE sensor cannot be used effectively to analyze different events that occur during drilling.

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Modeling & Numerical Analysis of Supersonic Combustor with Double Inclined Ramp-Cavity Fuel Injector
G. Hariharan, N. SenthilKumar, S. Gopalakannan | pp: 66-70 | Download Paper | Show Abstract

Abstract: Sustaining the Supersonic Combustion in Scramjet engine is a very challenging topic of research nowadays. ‘Single-stage-to-orbit’ aerospace vehicles incorporating scramjet engine, is being contemplated to cut down space transportation costs. Propulsion and airframe unit integration, where the vehicle body adds to the thrust generating capacity of the engine besides providing aerodynamic lift, forms an integral part of the design philosophy. This Paper describes some challenges in the modeling of the Supersonic Combustor for proper mixing of air-fuel. Fuel Injectors are a critical component and their design has important effects for sustaining the flame in supersonic combustion as well as overall performance of the engine. Ramp injectors are considered to be a key feature to generate axial vortices. Generation of acoustic oscillations by the cavity injector is also considered to be a better candidate to achieve optimum mixing. Improvement in the performance of ramp and cavity injectors can be improved overall, by combining these injectors properly. Generation of turbulence and 3D flow field for better mixing and proper combustion relies on the combination of cavities and ramps. Ramps will improve the penetration of fuel in to the core and cavities will improve the flame holding characteristics. The ramp generated axial vortices can be utilized to scoop out the hot gases generated at cavities to improve the combustion efficiency. Thus Ramp and cavity combination shows promising characteristics for better scramjet combustor performance. Instead of having a long single inclination in the ramp, two short double inclinations can be made. By this we can prevent the sudden loss of energy. This in-turn increases the flame stabilization during Combustion.

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