【作者】 盖芳芳；

【导师】 庞宝君； 管公顺；

【作者基本信息】 哈尔滨工业大学 ， 固体力学， 2010， 博士

【摘要】 随着人类航天活动的日趋频繁,空间碎片环境日益恶化,严重地威胁着在轨航天器的安全运行。航天器上的各种压力容器是航天器用来储存液体或含能高压气体的部件,在空间碎片超高速撞击下,可能导致其发生泄漏,甚至发生爆炸等灾难性破坏,使航天器任务提前终止或失效。目前,虽然已对超高速撞击下压力容器破损过程进行了有益的探索,但通常定性分析多于定量计算,并且尚未针对在超高速撞击下压力容器的损伤破坏行为建立出一个相对系统的理论预报模型。压力容器的损伤破坏特性及其失效预报分析是航天器空间碎片风险评估与防护结构设计的一个重要关键技术和前沿课题。本文以航天器上的圆柱形充气压力容器为研究对象,以速度范围为1.0km/s~7.0km/s的球形铝制弹丸模拟空间碎片,采用数值模拟和理论分析相结合的技术手段,对空间碎片超高速撞击充气压力容器的破损过程、破损机理开展系统研究,建立了包括容器前壁破损预报及容器后壁破损预报的压力容器破损预报模型,并与实验结果进行了对比。应用AUTODYN-2D,采用Lagrange方法确定了压力容器前壁穿孔尺寸、裂纹尺寸与气体压力、撞击条件的关系。根据压力容器前壁穿孔的形态特征,将其简化为含双裂纹的圆孔,建立了压力容器前壁穿孔的简化模型。基于线弹性断裂力学的Bueckner原理,建立了前壁穿孔尺寸、裂纹尺寸及气体压力与裂纹应力强度因子之间的关系式。应用该关系式,并基于断裂力学的K准则,对在气体介质压力作用下压力容器前壁的断裂行为进行了分析,建立了压力容器前壁破损预报模型,获得了压力容器前壁发生灾难性破坏的临界条件。研究结果表明,压力容器前壁穿孔孔边是否有裂纹裂纹产生对容器前壁发生灾难性破坏的临界气体压力有较大的影响。应用AUTODYN-2D,采用SPH方法对前壁撞击穿孔而产生的二次碎片与内充气体介质的相互作用过程建立计算模型并进行了数值模拟分析,通过与实验结果相比较,验证了数值模拟方法的有效性。根据二次碎片形态特点,建立了不同弹丸破碎模式的二次碎片初始模型。在此基础上,应用流体动力学、冲击波及气固两相流理论,结合数值模拟研究结果,对不同弹丸破碎模式下二次碎片与气体介质的相互作用过程进行了分析,建立了二次碎片与气体介质的相互作用模型,并通过与数值模拟结果、实验结果相比较验证了模型的有效性,确定了压力容器内二次碎片的运动特性及气体冲击波的传播规律。针对不同弹丸破碎模式,根据已获得的二次碎片运动特性及气体冲击波的传播规律,将二次碎片及气体冲击波对容器后壁的作用简化为局部均布冲击载荷对固支圆板的作用,建立了不同弹丸破碎模式下二次碎片及气体冲击波对压力容器后壁作用的简化模型,获得了局部冲击载荷的作用半径及在二次碎片与冲击波共同作用下容器后壁产生的初速度。基于前人对局部冲击载荷作用下圆板的破坏分析,确定了在二次碎片与气体冲击波作用下容器后壁产生穿孔的临界条件及穿孔半径。将穿孔半径等效为贯穿直裂纹,根据线弹性断裂力学,并考虑容器壁曲率的影响,获得了容器后壁发生灾难性破坏的临界条件。最后,集成上述研究成果建立了超高速撞击下充气压力容器的破损预报模型,并讨论了预报模型的适用范围。针对具体的实验工况应用建立的预报模型进行了计算,给出了预报流程,并通过与实验结果的比较验证了预报模型的有效性。本文建立的球形弹丸超高速撞击充气压力容器破损预报模型对航天器防护结构的设计具有指导意义,揭示了压力容器在超高速撞击下的破损机理,为压力容器类部件空间碎片撞击风险评估及开发研制先进的压力容器防护方案具有工程应用参考价值。更多还原

【Abstract】 With the unceasing development of space activity, the total number of space debris is ever increasing, which greatly threatens orbiting space vehicles. Spacecraft often employ pressure vessels to contain gases and liquids. A pressure vessel subjected to hypervelocity impact by meteoroids and space debris can represent a significant hazard to a space vehicle because of the energy stored within the vessel. Vessel can occur venting through the impact hole. Catastrophic rupture of the vessel can send high-velocity fragments in all directions and secondary debrisary damage becomes a serious threat to the spacecraft. The damage characteristic of pressure vessel by space debris and prediction of catastrophic failure are the important basic of shield structure design and risk evaluation of spacecraft in space debris environment.At present, the quantitative investigation on damage process of pressure vessel under hypervelocity impact is still very limit. Systemic prediction model for damage and failure of pressure vessels under hypervelocity impact has not built.Based on the background mentioned above, this paper investigates the damage process of pressure vessel under hypervelocity impact. The impact velocity is ranging from 1.0 km/s to 7.0 km/s, the impact condition limits to fragmentation and melt of materials. The gas-secondary debris interaction process and propagation process of shock wave are investigated, and the prediction model for damage and failure of pressure vessels under hypervelocity impact is built.Lagrange methods in AUTODYN-2D is used for investigate the relationships between impact hole size, crack size, gas pressure and impact conditions. According to characteristics of impact hole, initial model of secondary debris is built. The model is presented by postulates the existence of two-radial cracks that emanate at the boundary of a circular hole. The relationships of impact hole size, crack size, gas pressure and the stress intensity factor which is determined by simplified linear elastic fracture mechanics are obtained. The damage process of the front wall is analyzed. The prediction model for damage and failure of front wall is built. The critical stress value is obtained.SPH methods in AUTODYN-2D is used for investigate the gas-secondary debris interaction process. The numerical simulation results are consistent with experimental results very well. The fragmentation process of projectile is introduced. According to characteristic of secondary debris, initial model of secondary debris is built. The gas-secondary debris interaction process is analyzed. The model of the gas-secondary debris interaction is built. The calculational results are compared to experimental results to verify the usefulness of the model. The motion characteristics of secondary debris and the rules of shock wave propagation are obtained.the paper assumes that the rear wall is subjected to uniform load when impacted by the debris cloud and shock wave. Initial velocity of the rear wall under a localized pulse loading is obtained. Based on the closed from deflection solution for thin plates subjected to localize explosive loading, the radius of discing and petalling is obtained. The prediction model for damage and failure of rear wall is built. The critical condition of catastrophic rupture of rear wall under a localized gas pressure is obtained.Last, based on the previous study, the prediction model for damage and failure of pressure vessels under hypervelocity impact is built. The applicable scope of prediction model is discussed. The calculational results are compared to experimental results to verify the usefulness of the model. The paper gives the prediction process.The result of this paper has some significant meanings and is valuable in engineering applications and providing theoretical guidelines. It reveals the physical process of pressure vessel damage and mechanism of damage. It provides technical foundation for risk assessment of pressure vessel and shielding design applications of pressure vessel.更多还原