## 5 Conclusions  
This paper adopts a combined approach of experimental testing and simulation analysis to study the sound radiation characteristics of reinforced laminated cylindrical shell structures. The reinforced laminated plate is considered as the research object, and relevant experimental setups are constructed to measure the structural modal properties and sound radiation. At the same time, finite element models are established, and the reliability of the finite element modeling method is verified by comparing experimental and simulation results. Based on this, a finite element model of the reinforced laminated cylindrical shell structure is established, and simulations are performed to discuss the influence of different reinforcement methods, reinforcement quantities, reinforcement lengths, and reinforcement thicknesses on the sound radiation characteristics of the reinforced laminated cylindrical shell structure. The following conclusions are drawn from the study:  
1. In the frequency range of 1-1000 Hz, when comparing the cylindrical shells reinforced with ring ribs and longitudinal ribs, both having 12 ribs, the former has a 16.19 dB lower overall sound power level than the latter. This indicates that the ring rib reinforcement performs better in reducing the structural noise radiation.
2. In the frequency range of 1-1000 Hz, when the number of ring ribs is 4, 10, and 16, the overall sound power level of the structure is 90.1 dB, 80.82 dB, and 80.28 dB, respectively. This indicates that as the number of ring ribs increases, the structure's sound radiation decreases. Additionally, the number of radiation peaks also decreases, and the peak values shift towards higher frequencies. This is due to the increased number of ring ribs, which leads to stronger axial restraint on the cylindrical shell, resulting in a smoother structure sound power level curve and a reduction in radiation peak values.  
Figure 17: Structural sound power level curves for different reinforcement thickness.  
3. In the frequency range of 1-1000 Hz, the total sound power levels of the rib-reinforced cylindrical shell are 80.14 dB, 79.17 dB, and 80.28 dB, respectively, for rib lengths of 28 mm, 30 mm, and 32 mm. This indicates that with the increase in rib length, the overall sound power level shows a trend of an initial increase and then a decrease.
4. In the frequency range of 1-1000 Hz, the total sound power levels of the rib-reinforced cylindrical shell are 82.4 dB, 80.28 dB, and 78.32 dB, respectively, for rib thicknesses of 1.4 mm, 2.0 mm, and 2.6 mm. This indicates that with the increase in rib thickness, the radiated noise of the cylindrical shell structure decreases. This suggests that increasing the rib thickness increases the contact area between the reinforcing ribs and the inner and outer shells to some extent, resulting in a more uniform distribution of excitation forces on the shell, effectively reducing the radiated noise of the structure.  
[PERSON] proposed the ideas, steps, and details of the experiment, and most of the experiments were conducted by [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON], where [PERSON] was instrumental in the proper conduct of the experiments and wrote the article together with [PERSON], and all the authors analyzed the data and discussed the conclusions. All authors have read and agreed to the published version of the manuscript.  
The work is supported by 2022 Knowledge Innovation Dawn Special Plan Project (2022010801020393), Research and Innovation Initiatives of WHPU (2022)04, Natural Science Foundation of Hubei Province (2021 CFB292). This work was finished at Wuhan Polytechnic University, Wuhan.  
Not applicable for studies not involving humans or animals.  
Not new data are created.  
The authors declare no conflict of interest.