# Weibull++ Equation Fit Solver Example

Weibull++ Equation Fit Solver Example

The Equation Fit Solver can be used to perform linear and nonlinear regression. For example, assume that an engineer collected the following degradation data.

 Time Reading 5 8.08 10 13.52 15 21.86 20 31.96 25 37.86 30 46.67 35 53.35 40 62.29 45 71.62 50 80.37 55 91.43 60 104.00

From the physical mechanism, the engineer knows that the degradation path follows the following equation:

$y=a+bx+c\ln (x)$

where:

• x is the time

This model is not a standard degradation model in Weibull++; however, the problem can be solved by using the Equation Fit Solver.

Solution:

Step 1: Insert an Equation Fit Solver folio in your project and enter the given data in the folio, as shown next.

Step 2: Enter the degradation equation in the control panel and name it “My Degradation Equation,” as shown next.

Step 3: Click Calculate. The following picture shows the results.

Step 4: You can use the Calculate Y given X area on the control panel to make predictions. For example, the predicted Y value at X=100 is 176.2424.

Step 5: The following plot shows the fitted model and the observed values.