# Engineering Sample: Control of Manufacturing Processes

Problem 1-1. INFLUENCE OF GYROSCOPIC EFFECT ON FLUCTUATIONS OF THE CENTRIFUGE SHAFT

CL = 35329.81 σ = 778.7 LCL= 34551.11 UCL = 36108.51

The standard model of calculations of the natural resonant frequencies of a system gives an approximate result, that can be different from experimental result on a higher frequencies of rotation.

Standard_model_resonant_frequency = 35329.81 rad/sec

Experimental_resonant_frequency = 26512 rad/sec

Solution 1-1.

CL = 26517.98 σ = 778.7 LCL= 25739.28 UCL = 27296.68

To reduce error we have to use more accurate models for calculations. One of these models allows us to take into account gyroscopic effect of fluctuations. The main idea of this approach is to include influence of the elastic deformations on angular speed.

Accurate_model_resonant_frequency = 26517.98 rad/sec

Experimental_resonant_frequency = 26512 rad/sec

Problem 2-1. FITTING AN S-N CURVE

Standard approach for fatigue life-cycle has a large spread of statistical value results. It was necessary to find more optimal and easier approach to deal with experimental data.

Solution 2-1.

One of the most optimal approaches was offered by S. Maddox, who decided to make a logarithmic dependence between number of cycles and stress value of failure:

log(N) = log (A) – m*log(S)

Besides, he offered to take into account that N value is also depends on different factors (e.g. surface treatment, detail size etc). Standard approach has assumption that N is independent value.

References

Schneider, C. (2003). Best practice guide on statistical analysis of fatigue data, 9.

Maddox, S. (2000). Fatigue design rules for welded structures. Prog. Struct. Engng. Mater., 2(1), 102-109.

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