Torsional Vibration-Matrix Method

[thunderscot]

Hello there, I was looking for some help in calculating the second moment of area (I) value of a compressor blade. The I value changes throughout the section of the blade. The tip is at an angle of 15degrees from the base. I have used bd^3/12 for my base and INTy^2.dA for the tip(where y =sin15deg.s)I have tried to do it but the answers I get when put into my matrix spreadsheet do not tie in with initial Ansys analysis

Any help would be great

Thanks Jim

 

[CESSNA1]

THUNDERSCOT: The equation you are using is for rectangles. I am assuming that the turbine blade is airfoil shape. The methods I suggest a dpeending upon the axis about which you want it are:

1. Divide the blade into sections and do a calculation for each section about the axis of interest, then sum them up.

2. Do it experimentally

Regards
Dave