kortagu
posted this
30 December 2018

Thanks sir, yes you re right, i have an old laptop (4 processors) and as i remember defectless analysis took about 10 hours even mesh was course.

I dont know whether it keeps pointing down or not but how can i see that works you have an idea about it ? Should i look moment or smt ?

Actually i worry about contact mechanics in cad i created balls with point contact and they seem well but in ansys after mesh you know circular bodies need refine mesh to get that circular shape.

Actually my aim was to observe bpfo which means OUTER RING DEFECT FREQUENCY at spectrum graph (FFT) but i failed (i dont know why) and i decided to signify stresses and waveform graph to complete task. Under real conditions, defect frequency is measured from top center of outer ring or housing of rolling element bearing.

In a nutshell i havent completed yet and i need to see that 161 Hz frequency on spectrum graph.

Do you have any recommend for me ? Now i m using half model and apply symmetry to reduce solving time, finer mesh etc.

161 Hz means;

fbpfo = Z.fs/2 (1-(db/dm).Cos α )

with fs is the shaft frequency, db and dm is ball diameter and pitch diameter respectively. Since in this study assumed that the ball bearing is subjected to a pure radial load, hence the contact angle will be 00.

fs = 3000 cycle/min = 50 cycle/s = 50 Hz

fbpfo = 8.50/2 (1-(7,5/38,5)) = 161 Hz

According to above equation, in this thesis BPFO is 161 Hz.

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