Update Regression approach and Tolerance bands power law authored by Jamie Engelhardt Simon's avatar Jamie Engelhardt Simon
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title: Regression approach and Tolerance bands - power law title: Regression approach and Tolerance bands - power law
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## Dependency ## Dependency
It is assumed that the data can be described by a power law, expressed as Y or X-dependent (referring to the second and first axes on a fatigue curve). It is assumed that the data can be described by a power law, expressed as Y or X-dependent (referring to the second and first axes on a fatigue curve).
...@@ -99,7 +100,7 @@ The purpose is to sort the difference between the prediction and the data and de ...@@ -99,7 +100,7 @@ The purpose is to sort the difference between the prediction and the data and de
E = Y_{\textrm{p,s}} - Y_{\textrm{d,s}} E = Y_{\textrm{p,s}} - Y_{\textrm{d,s}}
``` ```
**b)** Extract the data with a positive error. We are only interested in the positive difference, as these are an indication of the points below the mean line. **b)** Extract the data with a positive error. We are only interested in the positive difference, as these are an indication of the points below the mean line
```math ```math
E = E\left[E > 0\right], \quad X_{\textrm{d,s}} = X_{\textrm{d,s}}[E>0], \quad Y_{\textrm{d,s}} = Y_{\textrm{d,s}}[E>0] E = E\left[E > 0\right], \quad X_{\textrm{d,s}} = X_{\textrm{d,s}}[E>0], \quad Y_{\textrm{d,s}} = Y_{\textrm{d,s}}[E>0]
...@@ -141,7 +142,7 @@ Compute the adjustment coefficient associated with the tolerance limit of intere ...@@ -141,7 +142,7 @@ Compute the adjustment coefficient associated with the tolerance limit of intere
\textrm{if}\;\textrm{X-dependent}\;\Rightarrow C_{\alpha} = \frac{X_{\alpha}}{Y_{\alpha}^m} \textrm{if}\;\textrm{X-dependent}\;\Rightarrow C_{\alpha} = \frac{X_{\alpha}}{Y_{\alpha}^m}
``` ```
The end results for an X- or Y dependent fit using $\alpha=0.75$ and $\alpha=0.95$ are illustrated below The end results for an X or Y-dependent fit using $\alpha=0.75$ and $\alpha=0.95$ are illustrated below
<br> <br>
<div align="center"> <div align="center">
![XdependentFit](uploads/323df7b64a177ce36648ef6ad6f4a191/XdependentFit.png){width=45%} ![XdependentFit](uploads/323df7b64a177ce36648ef6ad6f4a191/XdependentFit.png){width=45%}
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