大型柔性起竖臂的有限元建模与分析

针对使用中的振动问题,基于ANSYS软件平台建立某大型柔性起竖臂合理的有限元模型,获得其固有振动特性、刚度和强度等设计数据。分析表明,使用中出现的振动现象是由于外载荷频率接近起竖臂一阶固有频率所致,而起竖臂刚度和强度设计整体合理,但存在局部应力集中和强度设计偏于保守的问题。     

India’s nuclear counter-revolution: nuclear learning and the future of deterrence

ABSTRACT

The India–Pakistan near war of February–March 2019 highlights India’s ongoing evolution in strategic thought and practice since its emergence in 1998 as an overt nuclear-weapon possessor. These changes, involving an increasing willingness to engage in the intentional escalation of conflict with a nuclear-armed rival willing to be the first to use nuclear weapons, challenge certain academic assumptions about the behavior of nuclear-weapon states. In particular, they undermine the expectations of the nuclear-revolution theory—which anticipates nuclear and conventional restraint among nuclear-armed rivals through fear of mutual assured destruction—and the model of nuclear learning which underpins this theory, in which new nuclear-weapon states gradually absorb this restraint through policy-maker learning. This article explores how India’s learning pathway since 1998 has deviated from these expectations. India is instead pursuing its own “revolution,” in the direction of creating capabilities for flexible response and escalation dominance. It concludes by illuminating the similarities between Indian strategic behavior and contemporary practices of other nuclear-armed states, and suggests that New Delhi’s emerging de facto nuclear doctrine and posture is part of a broader empirical challenge to our current conceptions of the nuclear revolution and of nuclear learning.