## 3 Analysis and Design of Key Components
### High-Temperature and Ultrahigh-Pressure Simulation Test Cabin
#### 3.1.3 Analysis and Calculation of Wall Thickness  
(1) Material selection  
The materials used in the design and manufacture of the simulation test cabin must be provided by the manufacturer with the required material parameters. Key parameters for materials used in ultrahigh-pressure vessels have been stipulated in the literature [40] and are shown in Table 2.  
According to the requirements for materials used in the simulation test cabin and the need for economy, the material chosen for the test chamber designed in this paper was 35 CrNi3 MoVR. The mechanical properties of the material at room temperature are shown in Table 3, and the mechanical properties at 150 \({}^{\circ}\)C are shown in Table 4 [40]. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Structural Style** & **Characteristic** & **Scope of Application** \\ \hline \multirow{5}{*}{Single-layer cylinder} & \multirow{2}{*}{Integral forging} & Due to the limitation of forging conditions and high & The diameter of the cylinder is between \\  & & cost, it is suitable for steel with poor welding & 300 mm and 800 mm, and the length does not exceed 12 mm \\  & & performance & \\  & & & \\  & & & \\  & & & \\  & & & \\  & & & \\  & & & \\ \end{tabular} \begin{tabular}{c} Simple process, short cycle, high efficiency; however, it \\ cannot be used when the cylinder diameter is too small \\ \(110\) mm \\ \end{tabular} \begin{tabular}{c} The diameter of the cylinder is greater than \\ \(400\) mm, and the maximum thickness is \\ \(110\) mm \\ \end{tabular} \\  & \begin{tabular}{c} Segentally welded \\ cylinder \\ Seamless tubular cylinder \\ \end{tabular} & \
\begin{tabular}{c} Does not need large coil equipment; low productivity \\ The source of raw materials is convenient, the \\ manufacturing efficiency is high, and the cycle is short \\ \end{tabular} &
\begin{tabular}{c} The larger the diameter is, the longer the manufacturing time \\ The diameter of the cylinder should not \\ exceed 500 mm \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Structural characteristics and application range for each cylinder form. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Percent Elongation after Fracture** & **Charyy Impact Work** & **Fracture Toughness** & **Area Reduction** \\ \hline \(\geq\)16\% & \(\geq\)41 \(\downarrow\) & \(\geq\)120 MPa & \(\geq\)40\% \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Material property specifications for ultrahigh-pressure vessels. Figure 5: Bearing capacities of various cylindrical structures. According to the performance parameters given for 35 CrNi3 MoVR in Tables 3 and 4, the wall thickness of the rock cabin and drill pipe cabin were designed to provide a room temperature yield strength of R\({}_{p0,2}\) = 960 MPa and a tensile strength of R\({}_{m}\) = 1070 MPa. At a design temperature of 150 \({}^{\circ}\)C, the yield strength and tensile strength were \(R_{p0,2}^{t}\) = 857 MPa and \(R_{m}^{t}\) = 1060 MPa, respectively. In this paper, the tensile test data for materials were used to calculate the thickness of the cylinder. The strength reduction coefficient of materials at 150\({}^{\circ}\)C was calculated as shown in Equation (1), which is 0.9. \[\phi = 1-\frac{T-50}{1000} \tag{1}\]  
where \(\phi\) is the strength reduction coefficient of materials, and \(T\) is the temperature. (2) Calculation of wall thickness  
The failure criteria for pressure vessels mainly include elastic failure, plastic failure, and blasting failure criteria. The elastic failure criterion has been widely used and is poorly understood. Container elastic failure indicates that when the cylinder is subjected to internal pressure or other complex working loads, the stress on the cylinder wall is higher than the yield strength, and the container cannot continue to work normally.