Force analysis of two reconstruction schemes of the driving wheel in Su Song's astronomical clock-tower
[Objective]The driving wheel is a challenge during the reconstruction of Su Song's astronomical clock-tower.Two approaches,the"flip-scoop"and"fixed-scoop"methods,have been identified based on whether the scoop can turn independently.Recent research reports that both options are inevitably inconsistent with the original text,indicating that conformity with the original text is no longer the only criterion for evaluating the merits of these approaches.Therefore,future models should not solely follow these options.New schemes can be designed by learning from their advantages while addressing their shortcomings and components that do not match the original text.Additionally,for museum exhibitions,long-term model stability is crucial.The force data of key components exactly determine the overall stability of the whole model.Therefore,in this study,the force data of some key components in the two schemes are obtained by constructing models in the software and calculations,which will provide valuable references for the reconstruction process.[Methods]This study establishes two models in the software based on the"flip-scoop"and"fixed-scoop"methods according to the original size in Song Dynasty.The force data between the forward upper lock and the driving wheel are calculated using the laws of a rigid body in rotational motion.Subsequently,the pressure between the forward upper lock and the driving wheel is analyzed.[Results]The results revealed that the force between the forward upper lock and the driving wheel was nearly three times higher in the"flip-scoop"model compared with the"fixed-scoop"model.The reason for this disparity was the different structural characteristics between the two schemes.The"fixed-scoop"model incorporated buffering components that reduced the rotation speed of the driving wheel and thus weaken the force between the forward upper lock and the driving wheel.However,the"flip-scoop"model lacked components to help achieve similar effects.More critically,while the driving wheel periodically struck the forward upper lock,it was also subjected to the reaction force of the forward upper lock.In the"fixed-scoop"model,the forward upper lock struck the bottom of the scoop,while in the"flip-scoop"model,the forward upper lock struck the edge of the spoke on the side of the driving wheel.This results in a much smaller spoke impacted contact area in the"flip-scoop"model than in the"fixed-scoop"model,leading to higher pressure on the driving wheel in the"flip-scoop"model than that in the"fixed-scoop"model.Furthermore,this increased pressure exacerbated the potential risk of deformation and damage to the spokes.Additionally,once the pivot wheel was damaged,the influence on the stability of the entire model would be irreversible.[Conclusions]In summary,the differences in the buffering components and the contact areas between the driving wheel and forward upper lock make the driving wheel and forward upper lock in the"fixed-scoop"model suffer less impact and render its operational stability.Future reconstruction models can be designed based on this advantage.
Su Song's astronomical clock-towerdriving wheelreconstructionforce analysis
万方数据
维普
