Spacecraft Survivability To Space Debris Risk

The space debris has causing serious threat to the spacecraft running on the orbit.More and more countries have treat the debris' influence as the important problem at the beginning of the space mission.Among them,the technology of space debris impact risk assessment for spacecraft is mature.Risk assessment techniques are based on critical perforation failure analysis of protective structures,however,for the spacecraft with large payload,the subsequent impact of the debris breakdown protection structure may cause damage or functional degradation of the components,and the survivability of the spacecraft in the space debris environment is also affected.Therefore,the damage pattern and the function reduction of the component directly affect the spacecraft system's normal operation,which directly determines the survivability of the spacecraft in the space debris environment.To study the survivability of spacecraft,we can accurately obtain the impact of debris on the space system,and then take specific measures to solve and optimize.Based on risk assessment technology,this paper draws on the concept of aircraft survivability and applies it to spacecraft systems.The components of spacecraft survivability and their influencing factors are analyzed.The influence factors are analyzed from two aspects: external factors and spacecraft characteristics.The influencing factors are modeled and the expression forms are given.The overall assessment of viability was conducted from two aspects of sensitivity and vulnerability.Firstly,based on the occlusion algorithm,the calculation method and evaluation flow of spacecraft impact sensitivity are given from the point of view of finite element.Secondly,the vulnerability analysis method is developed,and the overall vulnerability analysis scheme is presented.Vulnerability analysis is carried out from two aspects of function failure and function reduction of parts / components.The classification of functional failure and its research scheme are expounded in detail.Hierarchical classification of functional reductions is carried out,and the evaluation methods of different grades are summarized and the research ideas are given.At the same time,based on the existing research techniques and purposes,the equivalent aluminum plate analysis method is adopted to evaluate the vulnerability,and the simplified "0-1" distribution model is used to characterize the vulnerability.The relation between the components and the system is established.The damage probability of the system is calculated by establishing the damage tree model for different grades and different failure modes.Based on survivability algorithm,this paper designs and implements a spacecraft survivability evaluation software“S3DE-Survivability of Spacecraft in Space Debris Environment”,realize the transformation of engineering oriented practical software,standardize the software structure and improve its scalability.The software is composed of space debris data module,spacecraft geometry module,spacecraft module,the spacecraft structure model module,component vulnerability module,function model of spacecraft module and visualization output module 7 modules.Illustrates the functional characteristics of each module and the key technologies of data transfer and connection.The software effectively embeds the model of space debris environment,implements the connection of various interfaces and applies survivability algorithm to space engineeringIn this paper,three kinds of standard operating conditions,typical components(batteries,electronic boxes)and the analogue satellite “Mozi” are verified respectively.The three standard operating conditions are compared with those of BUMPER and MDPANTO,and the sensitivity and vulnerability of the working conditions are calculated respectively.The minimum error is 0.14%,and the maximum error is 2.26%.The maximum error of the failure number is 12.09%,and the minimum error is 0.49%.The accuracy of the sensitivity calculation method and the feasibility of calculating the fragility of the equivalent aluminum plate are explained in the reasonable range.In addition,two typical components of battery and electronic box are designed,and their failure probability and survivability under different damage modes are calculated.Finally,a simplified model is designed based on the structure of the “Mozi” satellite,which consists of 37 components on the satellite and 32 damage modes of 16 main components.On the basis of the assumed equivalent thickness,the viability probability of the 7 subsystems and the total system is analyzed.The results show that the failure probability and the survivability of the system can be initially calculated by using different equivalent thickness to characterize the different damage modes of the components.In the same minimal cut,the more the number of damage patterns,the higher the probability of survival.Therefore,in order to improve the survivability of spacecraft,various damage modes and equivalent aluminum plate thickness should be taken into account in the early stage of spacecraft system design.