## 6 Concluding Remarks  
The lightweight technology of the pressurized capsule structure is a critical technology and bottleneck in the MDSEM. In this study, research was conducted from two perspectives: the development of pressurized capsule structure technology and the demand-driven traction of the MDSEM. The analysis led to the following conclusions:  
1. As an essential section of the manned spacecraft, the pressurized capsule structure is the key to realize the functions of bearing and sealing. With the stiffer requirements of the life and reliability of the pressurized capsule structure, the panel pressurized capsule structure represented by the WPPCS instead of the semi-monocoque shell type is the current mainstream pressurized capsule structure. 2. The MDSEM requires the pressurized capsule structure to have extremely low structural weight, long space service life of more than 15 years, reusability and adaptability to the harsh deep space environment. The conventional WPPCS has inherent shortcomings such as low bearing efficiency, large structural weight and conservative strength criterion, which makes it unable to be widely used in MDSEMs. As a method to meet the new requirements, the new structure of the IPPCS replaces the frame by the local panel structure, eliminates the segmentation of the weld zone, realizes the global stiffener continuity of the capsule, overcomes the shortcomings of the WPPCS and significantly improves the lightweight level of the pressurized capsule structure. 3. The key technology research progress of the IPPCS is rapid and has the engineering application conditions. The technical progress is organized as follows: Firstly, through the internal pressure cyclic loading experiment, the validity of the numerical analysis technology of the internal pressure shakedown limit of the pressurized capsule structure is verified. The bearing safety of the pressurized capsule structure with local plastic deformation can be evaluated by the shakedown analysis. A strength criterion of the pressurized capsule structure is added, that is, the allowable stress level of the local area of the pressurized capsule structure in the shakedown state should be higher than the yield strength of the material. Secondly, the IPPCS design method is proposed including four steps of shell cross-section, basic stiffener configuration, transition zone stiffener configuration and local structure, which guides the full realization of the optimization-based structural design in engineering applications and provides a tool guarantee for the structural design of the IPPCS. Thirdly, the 5B70 has excellent comprehensive performance, with the advantages of medium strength, weldability and corrosion resistance. It also meets the material selection requirements of the pressurized capsule structure, and can be widely used in the pressurized capsule structure instead of 5A06. Fourthly, the spinning process of large-size ultra-thick plates can realize the structural integrity manufacturing of the pressurized capsule structure, which provides a process guarantee for the development of the IPPCS. The progress of the IPPCS technology has initially reserved the structural technology for MDSEMs. In view of the long-term service requirements of the pressurized capsule structure in the harsh deep space environment in the future, it is recommended to further strengthen basic research as follows:  
1. The quantitative prediction method of internal pressure shakedown limit load of the pressurized capsule structure will be studied: The calculation time of numerical methods for the shakedown limit load is long, and sometimes it does not meet the need of rapid evaluation of bearing capacity. The establishment of approximate prediction formulas can quickly calculate the shakedown limit prediction load. 2. The structural technology of lightweight pressurized capsule structures with large temperature gaps will be studied: Extreme high and low temperature alternation is one of the challenges of MDSEMs.