| In space missions,point-explosive unlocking devices are widely used to connect and unlock the rocket and spacecraft.In the process of unlocking,high-frequency and strong transient shock waves are generated to impact the equipment mounted inside the spacecraft and may cause damage to electronic components.Therefore,spacecraft impact response caused by explosive bolt unlocking must be considered in aerospace engineering.In this paper,the impact environment and stress wave propagation law of a certain explosive bolt in the process of unlocking are studied by means of combining numerical simulation and experimental verification,and three buffer schemes of the explosive bolt are designed.The best one of the three buffer schemes is selected for establishing the spacecraft explosion unlocking model with multiple bolts initiating simultaneously.Finally,the impact response characteristics of spacecraft in the process of point explosion unlocking are explored.Firstly,in this paper,the finite element models corresponding to a typical internal explosion in literatures are established by using coupling Euler-Lagrange(CEL)method.The pressure responses at corresponding positions are measured and compared with the test results of a typical internal explosion,respectively,which verify the effectiveness of CEL method in solving the coupling problem between explosion load and structure.Secondly,after verifying the validity of the numerical method,the impact load characteristics during explosive bolt unlocking are studied in this paper.Firstly,a numerical model of single explosion bolt unlocking is established based on CEL method,and the impact environment generated in the explosion unlocking process is analyzed.It is found that the unlocking process of explosion bolt could be divided into two processes in time domainexplosion and impact.Then,comparing the peak values of shock spectra of explosion and impact processes with the experimental results,the effectiveness of the numerical model of explosion unlocking for single bolt based on CEL method is verified.Because of the use of sets of explosive bolts in space,based on the single bolt explosive unlocking model,a numerical model of multiple bolt simultaneous unlocking is established in this paper.And several measuring points are arranged on the docking frame in the multiple bolt simultaneous unlocking model to obtain the circumferential distribution of stress wave and shock spectra peak values along the docking frame.Thirdly,due to the large impact environment generated in the process of unlocking,three buffer schemes are designed in this paper,that is,adding rubber or PTFE damping pad to joint surface of the spacecraft and rocket and increasing the length of the collection box.Then the impact response and stress wave transmission characteristics of the three buffer schemes are studied.The peak values of impact spectra are compared with the corresponding test results to verify the feasibility of each buffer scheme.Then the buffering effects of the three buffer schemes are compared and the best one is selected.Finally,after selecting the optimal buffer scheme,the numerical model of spacecraft explosion unlocking is established by combining the multiple bolt simultaneous unlocking model.Firstly,stress wave and shock spectra peaks at typical locations such as docking surface and intermediate frame are analyzed.At the same time,several measuring points were arranged in the axial and circumferential directions of the spacecraft,then extracting the peak stress waves and impact spectra at each measuring point.The distribution of stress wave and impact environment along the spacecraft and the attenuation law after passing through the T-beam and intermediate frame inside the spacecraft are studied to reveal the impact response characteristics of the spacecraft in the process of point-explosion unlocking. |
