# OntoIMM: An Ontology for Product Intelligent Master Model
## 5 Case Study: Design and Analysis of Gun-Barrel
### Parameter Variant Modifying
#### 5.2.2 Compromise Decision-Based Parameter Modifying  
For the determination of the wall thickness which forms the theoretical shape of barrel, strength calculation is needed to be conducted based on compromise decision. It refers to gaining the relationship between chamber pressure, bullet velocity and bullet range, time based on interior ballistic calculation with a certain shoot condition of loading and bullet. In this step, chamber pressure characteristics are acquired to draw the calculated chamber pressure curve (P-L curve) with MATLAB, and wall thicknesses are determined based on the view data (internal diameters of three main sections) with calculation code. According to the compromise decision model described in Section 3.6, the information needed for design decision calculation is automatically extracted from the existing product information, as shown in Table 5.  
Figure 9: Parameter modifying based on design knowledge.  
Table 5 describes the decision elements of the strength calculation. The nomenclatures in the template are defined in Table 6.  
The compromise decision code for strength calculation is automatically called to visually show the optional parameters (the wall thickness of critical locations) and variant sensitivity, and the shape parameters are obtained.  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Nomenclatures** & **Description** \\ \hline BL & Barrel length (mm) \\ r\({}_{\text{2C}}\) & External diameter in section of chamber (mm) \\ r\({}_{\text{2 MBP}}\) & External diameter in section of MBP (mm) \\ r\({}_{\text{2M}}\) & External diameter in section of muzzle (mm) \\ FG & Goal function \\ n & Safety Factor \\ W & Barrel weight (kg) \\ \(\omega_{1}\) & Weight associated with the r\({}_{2}\) goal \\ \(\omega_{2}\) & Weight associated with the W goal \\ r\({}_{1}\) & Internal diameter (mm) \\ p & Pressure of the gunpowder gas in the chamber (kpa) \\ p & Material density (g/cm\({}^{3}\)) \\ \(\sigma_{\text{s}}\) & Material yield limit (N/mm\({}^{2}\)) \\ ST & The shape type of the rifling cross section \\ P–L & Calculated bore pressure curve \\ \hline \hline \end{tabular}
\end{table}
Table 6: Nomenclatures in the template.  
\begin{table}
\begin{tabular}{l l l l l l} \hline \hline \multirow{2}{*}{DTemplateInfo} & **Name** & **Type** & **Object** & **OtherInfo** \\ \cline{2-5}  & Strength calculation & compromise decision & Barrel &... \\ \hline \multirow{4}{*}{Parameter} & **Name** & **Type** & **Unit** & **Value** & **Input/Output** \\ \cline{2-5}  & os & numerical & N/mm\({}^{2}\) & 50 & Input \\ BL & numerical & mm & 600 & Input \\ P–L curve & Matlab file & Unit & P–L-mat & Input \\ r1 & numerical & mm & 12.7 & Input \\ FG & numerical & — & FG =\(\omega_{1}\)*\({}_{2}\) +\(\omega_{2}\)*W & Input \\ \hline \multirow{4}{*}{Variable} & **Name** & **Type** & **Unit** & **Value** & **Behavior** \\ \cline{2-5}  & r2C & numerical & mm & Output & Output \\ r2 MBP & numerical & mm & Output & Output \\ r2M & numerical & mm & Output & Output \\ \hline \multirow{4}{*}{Constraint} & **Name** & **Type** & **Constraint description** & \\ \cline{2-5}  & \multirow{2}{*}{n} & \multirow{2}{*}{hard} & 0.9–1 in chamber section & \\  & & & 1.2–1.3 in MBP section & \\  & & & 3–5 in muzzle section & \\ \hline \multirow{2}{*}{Goal} & **Name** & **Type** & **Description** & **Weight** & **Formula** \\ \cline{2-5}  & r2 & Max & Max r2 & \(\omega 1\) & r2 = f (r1,os, n, p) \\ W & Min & Min weight & \(\omega 2\) & W = f (r2, r1, BL, ST, p) \\ \hline \hline Analysis & \multicolumn{2}{l}{Algorithm of multi-objective analysis, Process of barrel strength calculation} \\ \hline Driver & Matlab for P–L curve, Code for barrel strength calculation & \\ \hline Preference & Design rule 1, Design rule 2,... & \\ \hline History & \multicolumn{2}{l}{Previous experience} \\ \hline Response & \multicolumn{2}{l}{Optional parameters} \\ \hline \hline \end{tabular}
\end{table}
Table 5: The compromise decision template for strength calculating.