氮化硅陶瓷空心浮力球在内爆临界状态下的失效分析

氮化硅陶瓷具有密度小强度高的优点，在深潜浮力设备领域具有广阔发展前景。然而陶瓷材料固有的脆性以及万米深海严苛的工作环境，使得氮化硅陶瓷空心浮力球在深水环境下面临着内爆的风险。为探究氮化硅陶瓷空心浮力球在内爆临界状态下的失效问题，设计并进行了三点弯曲试验，确定了氮化硅陶瓷材料的力学性能参数，包括弹性模量和破坏应力；随后对氮化硅陶瓷空心浮力球内爆试验的过程及结果进行了回顾总结；基于标准球壳模型与浮力球实物的CT扫描几何模型，对浮力球在内爆临界状态的失效过程进行了有限元仿真分析。结果表明：氮化硅陶瓷空心浮力球的性能存在一定不稳定性；结构内表面局部过大的拉应力是造成失效的主要原因，对内表面进行预加压处理或能提高其抗内爆性能。

Failure of silicon nitride ceramic flotation spheres in critical state of implosion

Silicon nitride ceramic flotation spheres have great potential for use in deep-sea exploration vehicles because they can efficiently provide buoyancy. However, the material characteristics of ceramic and the high-pressure service environment in the deep sea mean that the spheres have a large risk of implosion. This study focuses on the failure of hollow silicon nitride ceramic flotation spheres in the critical state of underwater implosion. First, a three-point bending test of silicon nitride ceramic was conducted to obtain the mechanical property. Next, the implosion experiments of silicon nitride flotation spheres under large hydro-static pressure were examined. Finally, based on the spherical shell model and the spherical geometry model obtained by computed tomographic scanning, the failure process of silicon nitride ceramic flotation sphere in the critical state of implosion was explored. The results show the performance of silicon nitride ceramic flotation spheres is unstable to some degree. Local tension stress is the main reason for the failure of the structure. Since damage begins from the internal surface in the simulation, preload compression treatment of the inner surface might delay the failure of structure.