SHOCK ANALYSIS OF ENERGY DISTRIBUTION CENTRE AS PER NSS-2

SHOCK ANALYSIS OF ENERGY DISTRIBUTION CENTRE AS PER NSS-2 : 

GE POWER CONTROLS- INDIA “One Team Committed To Customer Success” g SHOCK ANALYSIS OF ENERGY DISTRIBUTION CENTRE AS PER NSS-2 EXTERNAL GUIDE : INTERNAL GUIDE Mr. Sabu John Dr.Jagannath K Senior Manager, Professor, Design & Development, Mechanical & Manufacturing Dept, Plot.No.42/1 & 45/14, Manipal Institute of Technology, Electronics City-Phase 2, Manipal-576104, Bangalore-560100 jagan.korody@manipal.edu John.sabu@ge.com jagan.korody@yahoo.com Ph.no: 9900199476 Ph.no: +919448162655

CONTENTS : 

CONTENTS INTRODUCTION LITERATURE REVIEV PROBLEM DEFINITION OBJECTIVES OF THE PROJECT METHODOLOGY SHOCK CALCULATION FOR EDC MODELLING OF THE STRUCTURE ANALYSIS OF THE STRUCTURE SIESMIC TEST OF THE STRUCTURE CONCLUSION

STATEMENT OF THE PROBLEM : 

STATEMENT OF THE PROBLEM The objective of the analysis is to carry out the shock analysis on the panel and find out the amplification in displacement in all three directions. To see the effect of the acceleration loading on the Energy Distribution Centre structure at an induced frequency (from the NSS Grade 2 Graph). To see the effect of the structure for the given operating frequency and acceleration. To see the effect of the Required response spectrum of Energy Distribution Centre.

OBJECTIVES OF THE PROJECT : 

OBJECTIVES OF THE PROJECT The objective of the analysis is to carry out the shock analysis on the panel and find out the amplification in displacement in all three directions. The Analysis conducted here are: Modal Analysis Harmonic Analysis Transient Analysis Spectrum Analysis The NSS grade 2 code is used for checking amplifications.   To calculate the natural frequency of the Energy Distribution Centre Structure.   To see the effect of the acceleration loading on the Emergency Distribution Centre structure at an induced frequency (from the NSS Grade 2 Graph).   To see the effect of the Required response spectrum of Energy Distribution Centre.

SCOPE OF THE STUDY : 

SCOPE OF THE STUDY Since , for distributing the power in ships, we have to use diesel generators depending on the loading of the ships, for distributing power to the various components within the ship , we have to use the distribution centre known as Energy Distribution Centre. , we are using is widely used in Indian navy applications, especially in war ships. Therefore , its widely used in marine applications. Because of this the structure as to be designed as per NSS 2 grade.

Literature Review : 

Literature Review Seismic Analysis of an Axial Blower using ANSYS Equipment used at nuclear power plants requires robust and reliable designs because in case of disaster, such as earthquake, small damage can turn into an unpredictable result. In order to conduct seismic analysis, it is necessary to perform modal analysis and calculate RRS from the FRS. In this paper, desired data from the modal analysis will be obtained from ANSYS using axial blower Model. Those data will be used in numerical analysis for calculating RRS, which is essential data for designing axial blower. Therefore, it was possible to determine whether the axial blower is safe through RRS.

Finite element model using ANSYS : 

Finite element model using ANSYS

Slide 8: 

In order to conduct FEA on the axial blower, each part should be modeled properly prior to analysis. The structural base and fan casing of the fan was modeled using Shell63 element in ANSYS 5.5. Young’s modulus is 2.07×1011 Pa and density is 7.8×103 kg/m3. Element Lumped Mass21 was used for the impeller and valve. Motor was modeled with Beam4 element with surface area of 0.1649m2 and moment of inertia of I z = 1.2164×10−3m4 , I x = 2.4328×10−3m4 Figure . is the modeled axial blower with total elements of 7620. As most of earthquake wave have frequencies less than 33 Hz, if the resonance frequency of the axial blower is less than 33 Hz, overloaded stress from resonance may happen. In this case, stress value calculated by Square Roots of Sums of Square (SRSS) method should be compared to allowed stress value in order to assure the safety of the structure.

Slide 9: 

Stress distribution subject to pressure Fundamental mode shapes of the axial blower Stress distribution subject to dead weight

Required response spectrum at node 1306 in (a) the x-direction (b) the y-direction(c) the z-direction : 

Required response spectrum at node 1306 in (a) the x-direction (b) the y-direction(c) the z-direction

Conclusion : 

Conclusion By obtaining RRS, it was possible to determine the safety of the axial blower used in the nuclear power plant. In this paper, RRS of the axial blower exhibits stable condition and didn’t exceed 10G under most earthquakes. However, when Y-direction frequency is above 50 Hz, RRS value exceeds 10G. It is known that frequency of the earthquake waves seldom go above 33 Hz, but the structural safe should be thought. As the axial blower is weak in Y-direction frequency, it is desirable to reinforce the mounting bolt to the surface in order to ensure safety.

METHODOLOGY : 

METHODOLOGY FEM model was generated using 3D beam Element. Modal Analysis of the Emergency Distribution Centre was carried out to determine the natural frequency of the structure. First ten natural frequencies were determined from the modal analysis. Harmonic analysis was carried over a frequency range to see the effect of the structure for the given operating frequency and acceleration

PRELIMINARY MODELING DETAILS : 

PRELIMINARY MODELING DETAILS

Slide 14: 

Preliminary Modeling of EDC

STRUCTURE THICKNESS FOR FE ANALYSIS : 

STRUCTURE THICKNESS FOR FE ANALYSIS

MATERIAL PROPERTIES : 

MATERIAL PROPERTIES

Meshing of the Model : 

Meshing of the Model

Applying Boundary Conditions : 

Applying Boundary Conditions We have to constrained model at base of the EDC in X,Y & Z Directions

FE Model of EDC : 

FE Model of EDC The FE model of the panel is shown below. The model is made up of : Beam Elements Mass Elements

MODAL ANALYSIS OF ENERGY DISTRIBUTION CENTRE : 

MODAL ANALYSIS OF ENERGY DISTRIBUTION CENTRE Modal analysis is carried out to determine the vibration characteristics (natural frequencies and mode shapes) of a EDC or a machine component while it is being designed . First ten natural frequencies were determined from the modal analysis. . The natural frequencies and mode shapes are important parameters in the design of a structure for dynamic loading conditions. To calculate the natural frequency of the Energy Distribution Centre structure. The modal analysis is conducted to find whether the natural frequency of panel fall in the range of operating frequency (15 to 25Hz). The First ten frequencies and first five modes are given below

Mode shapes : 

Mode shapes

Mode shapes : 

Mode shapes

HARMONIC ANALYSIS OF ENERGY DISTRIBUTION CENTRE : 

HARMONIC ANALYSIS OF ENERGY DISTRIBUTION CENTRE Harmonic response analysis is a technique used to determine the steady state response of a EDC to loads that vary sinusoidally (harmonically) with time. Harmonic response analysis of an EDC gives you the ability to predict the sustained dynamic behavior of switch board thus enabling to verify whether or not our designs will successfully overcome resonance and other harmful effects of forced vibrations. The idea is to calculate the structure's response at several frequencies and obtain a graph of some response quantity (usually displacements) versus frequency. "Peak" responses are then identified on the graph and stresses reviewed at those peak frequencies.

Details for Harmonic Analysis of Structure of EDC : 

Details for Harmonic Analysis of Structure of EDC

Harmonic Analysis For Vertical Acceleration : 

Harmonic Analysis For Vertical Acceleration

Maximum displacement in panel X direction due to vertical acceleration : 

Maximum displacement in panel X direction due to vertical acceleration

Maximum displacement in panel Y direction due to vertical Acceleration : 

Maximum displacement in panel Y direction due to vertical Acceleration

Maximum displacement in panel X direction due to vertical acceleration : 

Maximum displacement in panel X direction due to vertical acceleration

VON-MISES STRESS : 

VON-MISES STRESS

Harmonic Analysis For Horizontal Acceleration : 

Harmonic Analysis For Horizontal Acceleration

Maximum displacement in panel X direction due to Horizontal acceleration : 

Maximum displacement in panel X direction due to Horizontal acceleration

Maximum displacement in panel y direction due to Horizontal acceleration : 

Maximum displacement in panel y direction due to Horizontal acceleration

Maximum displacement in panel Z direction due to Horizontal acceleration : 

Maximum displacement in panel Z direction due to Horizontal acceleration

VON-MISES : 

VON-MISES

Harmonic Analysis For Combined Acceleration : 

Harmonic Analysis For Combined Acceleration

Maximum displacement in panel X direction due to Combined acceleration : 

Maximum displacement in panel X direction due to Combined acceleration

Maximum displacement in panel Y direction due to Combined acceleration : 

Maximum displacement in panel Y direction due to Combined acceleration

Maximum displacement in panel Z direction due to Combined acceleration : 

Maximum displacement in panel Z direction due to Combined acceleration

VON-MISES STRESS : 

VON-MISES STRESS

TRANSIENT ANALYSIS OF EDC : 

TRANSIENT ANALYSIS OF EDC Transient dynamic analysis (sometimes called time history analysis) is a technique used to determine the dynamic response of a EDC structure under the action of any general time dependent loads. We can use this type of analysis to determine the time varying displacements, strains, stresses, and forces in a structure as it responds to any combination of static, transient, and harmonic loads. The time scale of the loading is such that the inertia or damping effects are considered to be important

Details for Transient Analysis of Structure of EDC : 

Details for Transient Analysis of Structure of EDC

TRANSIENT ANALYSIS CARRIED OUT FOR VERTICAL ACCELERATION : 

TRANSIENT ANALYSIS CARRIED OUT FOR VERTICAL ACCELERATION Displacement Vs Time for Vertical Acceleration Velocity Vs Time for Vertical Acceleration

Slide 44: 

Acceleration Vs Time for Vertical Acceleration

TRANSIENT ANALYSIS CARRIED OUT FOR HORIZONTAL ACCELERATION : 

TRANSIENT ANALYSIS CARRIED OUT FOR HORIZONTAL ACCELERATION Displacement Vs Time for Horizontal Acceleration Velocity Vs Time for Horizontal Acceleration

Acceleration Vs Time for Horizontal Acceleration : 

Acceleration Vs Time for Horizontal Acceleration Acceleration Vs Time for Horizontal Acceleration

SPECTRUM ANALYSIS : 

SPECTRUM ANALYSIS A spectrum analysis is one in which are used with a known spectrum to calculate displacements and stresses in the EDC Model. It is mainly used in place of a time-history analysis to determine the response of EDC structures to random or time-dependent loading conditions such as earthquakes, wind loads, ocean wave loads.

SIESMIC TEST : 

SIESMIC TEST Axis of vibration : X, Y& Z –axis simultaneously Frequency range : 0.5 Hz to 50 Hz Duration : 30 Seconds Damping Coefficient : 5% Required Response Spectrum : Zone 4 of 1997 Uniform Building Code Status of test sample during testing : Non-energized, Breaker and MCCB’s Were in ON position

CALIBRATION : 

CALIBRATION Equipment Used : Tri-axial Shaker System DCS 2000 control system with data acquisition system Accelerometers, Mounting Details : EDC was welded to 16mm thick MS plate and mounted on shake table Three numbers of accelerometers and four numbers of strain gauges were mounted on test specimen.

EDC Mounted on the Shakable table : 

EDC Mounted on the Shakable table

Observations : 

Observations After seismic test, LV Panel (EDC) GEM Panel was subjected to visual inspection . Following observations were made: (a) No permanent deformations, dislocations , breakage or cracks. (b )No cracks in weld and (c) No loosening of components / equipments from original mounting. Doors did not open during test. ACB was kept in mechanically ON condition during test. No change in status noticed. No damage to shutter assembly of draw out ACB noticed. Racking mechanism of ACB was in operational state before and after seismic test. Draw out module MCCB’s were in operational state before and after seismic test

Design Response Spectrum-1997 Uniform Building Code Zone : 

Design Response Spectrum-1997 Uniform Building Code Zone

Resonance search test, Z-axis,accelerometer, No resonance found by data acqisition system : 

Resonance search test, Z-axis,accelerometer, No resonance found by data acqisition system

Resonance search test, Z-axis,accelerometer, No resonance found : 

Resonance search test, Z-axis,accelerometer, No resonance found

CALCULATION FOR MECHANICAL WITHSTANDING DUE TO SHORT CIRCUIT CURRENT FOR BUSBARS FOR 800A : 

CALCULATION FOR MECHANICAL WITHSTANDING DUE TO SHORT CIRCUIT CURRENT FOR BUSBARS FOR 800A The reference formula’s and various parameters are taken from MERLIN GERIN formula F = 1.53 x K x n² x Isc² x L _________ _____ d x 10² Where, F is the force , in N K = 0.95 (It is a coefficient depending upon the size of conductors and the Distance between them). n = 2.2 for Isc= > 50KA rms, 105 KA rms peak Isc is the r.m.s. short circuit current, in KA L is the distance between the supports. d is the distance between the axis of phases.

Slide 56: 

F = 1.53 x 0.95 x 2.2²x 105² x 420 / 120x 10 ² =2714.64 N. The admissible shearing Force, for one phase is given by : Ra = S*R Ra is the maximum admissible force, in N. S is the total section (for 1 phase and for 1 element) subject to the Shearing, and given in cm². = 8 x 1 = 8 cm2 R is the resistance against shearing by tearing the material, given in N/cm². For SMC material - R = 400 N. Ra = 8 x 400 = 3200 N For all busbars including one or several bars per phase (with same width), we get: F1 = F/2 =2714.64/ 2 =1357.32 N As Ra >> F1 Since Ra found much greater than F1 the busbar and supports choose for the above is in order for the requirement of 50 kA rms short time and 105 KA SHORT CIRCUIT CURRENT.

SCOPE FOR FUTURE WORK : 

SCOPE FOR FUTURE WORK The similar shock analysis carried out using shell elements. Electro-magnetism can be carried out. Calculation for thermal withstand capability of busbars rated 800 a due to short circuit current. Time Response spectrum of Energy Distribution Centre can be carried out.

CONCLUSIONS : 

CONCLUSIONS Analysis results showed that the component is able to withstand the induced shock of gh =20.38 & gv =71.35 at operating frequency specified in NSS graph grade-2. By obtaining Time Response Spectrum, it was possible to determine the safety of the Energy distribution centre used in naval ships. By obtaining Required Response Spectrum, it was possible to determine the safety of the Energy distribution centre used in naval ships.

REFERENCES : 

REFERENCES J. Lee, J. Kim, P, Jung, J, Jung, Seismic analysis of axial blower for nuclear power plant use, Journal of Korean Society for Noise and Vibration Engineering, Vol. 9, pp535 – 543, 1999.  William T. Thomson, Marie Dillon Dahleh, Theory of Vibration with Application, 5th Ed., Prentice Hall, 1993, Englewood Cliffs, New Jersey.   3. Zienkiewicz O. C. and Cheung Y. K. The Finite Element Method in Structural and Continuum Mechanics. – McGraw-Hill: London, 1967.   4. Argyris J. H. Energy theorems and structural analysis // Aircraft Engineering, 1954, Vol. 26, Part 1 (Oct. – Nov.), 1955, Vol. 27, Part 2 (Feb. – May). 5.  K. Bathe, Finite Element Procedures in Engineering Analysis, Prentice-Hall, Inc.Englewood Cliffs, New Jersey 07632, and ISBN 0-13-317305-4, 1982.