# Parameter Study for the Ice Adhesion Centrifuge Test
## 3 Results
### Data Analysis  
Ice adhesion test results are often accompanied by comparably high data scattering, which is caused by the high sensitivity of the ice-substrate interface to fluctuations in temperature, pre-conditioning parameters, and icing durations. Additionally, contaminations in the water and on test substrates may occur, and mechanical disturbances during ice formation and sample handling affect the measurement values. Finally, the test devices and also the staff need to work under harsh lab conditions (in this case, at a temperature of \(-8~{}^{\circ}\)C), resulting in higher stress levels for man and machine. To account for this, limited overall test times and detailed and robust test protocols are defined. Test repetitions increase the data points and help to identify single measurement errors. In this study, a minimum of 10 data points per coating material for tests with impact ice and 8 data points for tests with static ice were assessed. For the exploratory data analysis of the ice adhesion test results, box plots were used to achieve a high data quality. To identify extreme values/outlier candidates in the data sets, the \(1.5~{}\times\) IQR rule was selected (interquartile range IQR multiplied by 1.5 and added to the third quartile or subtracted from the first quartile) as an established statistical tool [22]. Data points outside this calculated range were defined as outliers and subsequently removed prior to the final calculation of the medians, means, and standard deviations per material and parameter set [23]. Tables 5-10 summarize the results of the data analysis, including boxplots that indicate outliers as dots outside the whiskers. The resulting medians, means, and standard deviations for the ice adhesion strength are given prior to and after the removal of identified outliers. The latter are indicated as \"cleaned\" values. For impact ice, accreted at a wind speed of 95 m/s in the ice wind tunnel, clear differences between the surfaces were observed (Table 5). For PUR C25, the lowest ice adhesion was observed in this parameter set. The difference between the median and mean value is negligible for the evaluation. No outliers were identified. Standox represents an example where two outliers were observed (dots outside the whiskers). They were removed from the data set, resulting in a reduced standard deviation (\"cleaned\" data set  
Figure 5: Test result reproducibility for ice adhesion tests over the complete test period: (**a**) for impact ice 95 m/s (200 rpm/s); (**b**) for static ice (200 rpm/s) (the given lines indicate the resulting means per material). used for the following assessments). For PTFE-tape, the highest ice adhesion strength for this parameter set was observed. Here, the data distribution was comparably high, with equal mean and median values. The results for impact ice, accreted at 60 m/s, are summarized in Table 6. The PUR C25 material again showed the lowest ice adhesion. One identified outlier was removed from the data set, resulting in a slight reduction in the mean and standard deviation. Tests with PTFE-tape showed higher ice adhesion strength data compared to PUR C25. For Standox, data dispersion was high, preventing a clear ranking between PTFE-tape and Standox. However, there was a trend that for tests with the Standox material, higher ice adhesion strength data were observed. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Impact Ice 60 m/s** & **Standox** & **PUR C25** & **PTFE-Tape** \\ \hline box plots & 160 & 140 & 140 \\ box plots & 120 & 120 & 120 \\ box plots & 80 & 100 & 100 \\ box plots & 40 & 100 & 100 \\ box plots & 80 & 100 & 100 \\ box plots & 100 &  
A further general increase in the ice adhesion strength was observed for impact ice, accreted at 40 m/s velocity (Table 7). For the material ranking, PUR C25 again showed the lowest ice adhesion strength. Standox and PTFE-tape were on comparable higher levels.