# Mechanics of Screw Joints Solved as Beams Placed in a Tangential Elastic Foundation
## 4 Experiment (Pull-Out Test for Screws) and Its Evaluation
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & & & & & \\ \hline \multirow{2}{*}{
\begin{tabular}{c} **Measurement** \\ **Number** \\ \end{tabular} } & \multirow{2}{*}{**Screw Type**} & \multirow{2}{*}{**Screw Material**} & \multirow{2}{*}{**Pre-Dilled Hole**} & \multicolumn{2}{c}{**Limit State**} & \multirow{2}{*}{**Damage Limit State**} \\  & & & **Material** & & **Diameter [m]** & \(F_{E}\) [N] & \(u_{E}\) [m] & **Description** \\ \hline \multirow{2}{*}{1} & \multirow{2}{*}{HB 6.5} & 1.4441 & \multirow{2}{*}{0.0032} & \multirow{2}{*}{8634} & \multirow{2}{*}{0.001405} & \multirow{2}{*}{Pulling the screw out} \\  & & (AISI 316L) & & & & \\ \hline \multirow{2}{*}{2} & \multirow{2}{*}{HB 6.5} & 16.414V & \multirow{2}{*}{0.004} & \multirow{2}{*}{7475} & \multirow{2}{*}{0.001666} & \multirow{2}{*}{of the wood} \\ \hline \multirow{2}{*}{3} & \multirow{2}{*}{HB 7} & 1.4441 & \multirow{2}{*}{0.004} & \multirow{2}{*}{8541} & \multirow{2}{*}{0.001527} & \multirow{2}{*}{Screw breakage} \\  & & (AISI 316L) & & & & \\ \hline \multirow{2}{*}{4} & \multirow{2}{*}{HB 7} & 16.414V & \multirow{2}{*}{0.0045} & \multirow{2}{*}{8649} & \multirow{2}{*}{0.001638} & \multirow{2}{*}{Pulling the screw out} \\  & & (AISI 316L) & & & & \\ \hline \multirow{2}{*}{5} & \multirow{2}{*}{HB 6.5} & 1.4441 & \multirow{2}{*}{0.004} & \multirow{2}{*}{8770} & \multirow{2}{*}{0.001707} & \multirow{2}{*}{of the wood} \\  & & (AISI 316L) & & & & \\ \hline \multirow{2}{*}{6} & \multirow{2}{*}{HB 6.5} & 1.4441 & \multirow{2}{*}{0.004} & \multirow{2}{*}{8942} & \multirow{2}{*}{0.001468} & \multirow{2}{*}{Screw breakage} \\  & & (AISI 316L) & & & & \\ \hline \multirow{2}{*}{7} & \multirow{2}{*}{HB 6.5} & 1.4441 & \multirow{2}{*}{0.004} & \multirow{2}{*}{8279} & \multirow{2}{*}{0.00114} & \multirow{2}{*}{} \\  & & (AISI 316L) & & & & \\ \hline \multirow{2}{*}{8} & \multirow{2}{*}{HB 7} & 1.4441 & \multirow{2}{*}{0.005} & \multirow{2}{*}{7390} & \multirow{2}{*}{0.001385} & \multirow{2}{*}{} \\  & & (AISI 316L) & & & & \\ \hline \multirow{2}{*}{9} & \multirow{2}{*}{HB 7} & 1.4441 & \multirow{2}{*}{0.005} & \multirow{2}{*}{7606} & \multirow{2}{*}{0.001544} & \multirow{2}{*}{of the wood} \\  & & (AISI 316L) & & & & \\ \hline \multirow{2}{*}{10} & \multirow{2}{*}{HB 6.5} & 16.414V & \multirow{2}{*}{0.005} & \multirow{2}{*}{7322} & \multirow{2}{*}{0.001906} & \multirow{2}{*}{} \\  & & & & & & \\ \hline \multirow{2}{*}{11} & \multirow{2}{*}{HB 6.5} & 16.414V & \multirow{2}{*}{0.005} & \multirow{2}{*}{7381} & \multirow{2}{*}{0.001339} & \multirow{2}{*}{} \\  & & & & & & \\ \hline \multirow{2}{*}{12} & \multirow{2}{*}{HB 7} & 16.414V & \multirow{2}{*}{0.0055} & \multirow{2}{*}{9105} & \multirow{2}{*}{0.001804} & \multirow{2}{*}{} \\  & & & & & & \\ \hline \multirow{2}{*}{13} & \multirow{2}{*}{HB 7} & 16.414V & \multirow{2}{*}{0.0055} & \multirow{2}{*}{9481} & \multirow{2}{*}{0.002157} & \multirow{2}{*}{Screw breakage} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Pull-out test results (_Picaa abies_ wood, moisture about 10%). The variability of the results of measured variables \(\mathrm{F_{E}}\), \(u_{\mathrm{E}}\) given in Table 3 is therefore primarily due to a combination of material properties of dry spruce wood, screw materials, type of screws and pre-drilling and screwing operations. The aim was to have \"diverse\" results for more general verification options for the designed tangential elastic foundation models. According to the medical point of view, the variability of pre-drilled hole diameters (0.0032 to 0.0055 m) was chosen (i.e., connection to the future pull-out tests of bone joints in bovine and human femurs). It is clear from the nature of the measured quantities and the knowledge of mechanics that the normal force at point B must be equal to the loading force, i.e., \(N_{\mathrm{B}}=\mathrm{F}\). The presented results are similar to the work of other scientists, for example, see [3, 24].