The eccentricity coextrusion flow of polymer melt was analyzed based on finite element simulations. Such simulated results as the fields of flow velocity, pressure and shear stress were obtained. Through the analysis of the results, the mechanism of the column interface forming in the axis-symmetry coextrusion flow path was obtained. For the coextrusion flow, if the low viscosity polymer flows near the die wall, the flow would be steady. Whereas, if the polymer with low viscosity is in the core and the high viscosity polymer at the outer region, Which is disadvantage in terms of energy, and the instability flow would occur. This is also accord with the least energy consume theory.
Measurement System Analysis is of vital importance in a Six Sigma project. Variable measurement system takes the advantage of being practical and efficient. This paper focuses on the effect of sample size selection on error estimation of repeatability and reproducibility(R&R). After the discussion about the interval estimation of relevant statistics of R&R, this paper continues to analyze how the confidence interval is influenced by the number of operators, the number of samples and times of repeating measurements and a reasonable sample size in assessing the R&R of a measuring system is established for more effectiveness and efficiency.
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