【作者】 王莹；

【导师】 姚熊亮；

【作者基本信息】 哈尔滨工程大学 ， 船舶与海洋结构物设计制造， 2023， 博士

【摘要】 随着人类对极地科学研究的深入,其政治、经济和军事价值日益突出,成为世界各国争夺的重要战略要地。潜艇在北极冰盖下发射战略导弹攻击陆地上的目标仍面临挑战。新型破冰技术利用水下爆炸产生的高压冲击波和气泡脉动对冰层进行损伤破坏,削弱其结构强度,为潜艇上浮创造有利条件。在民用领域,冰下定点爆破和无人机载弹破冰在我国高寒地区的河流湖泊防凌实践中发挥重要作用,保障人民的生命财产安全。然而,由于冰层受爆炸与碰撞冲击的复杂物理过程影响,对冰层的损伤破坏特性尚不成熟,仍有待解决的机理性问题。由于冰的特殊属性和多种因素的影响,冰的力学性能研究面临巨大困难和挑战,如密度、温度、盐度、孔隙率和晶体尺寸等,以及加载速率和边界条件的影响。本文首先概述了冰的力学特征和研究方法,并总结了爆炸与碰撞冲击下冰层损伤特性的研究进展。然而,以往的研究主要集中在水下爆炸冲击波传播规律和冰结构破坏范围的影响,缺乏对冲击波、气泡脉动、射流与冰结构相互耦合机理研究。对于炸药选型、形状和联合布放方式等参数对冰层损伤破坏效应影响的研究也相对不足。在工程应用中,除了水下定点爆破,还可以使用破冰弹远程投射破冰,但对于碰撞冲击下冰层的损伤机理研究还较少。针对以上问题,本文以工程需求为导向,重点研究了爆炸和碰撞冲击载荷对冰层损伤的特性,旨在揭示其损伤机理和破坏特性。本文针对冰结构行为的数值研究现状,分析了描述冰结构动响应和失效的4种典型本构模型:弹脆性模型、各向同性弹塑性断裂模型、动力损伤脆性模型和各向同性高应变率弹塑性模型。通过在动力学分析软件LS-DYNA中对冰体梁四点弯曲进行数值模拟,发现不同加载速率下冰体梁的失效特性具有相似性和差异性,尤其失效模式呈现出不同的典型特征。针对水下爆炸的多种载荷作用,包括冲击波、气泡脉动和水冢冲击,进行了小尺度气泡破冰机理试验和大尺度海上爆炸破冰试验研究。小尺度气泡破冰机理试验关注气泡载荷对不同厚度冰板的相互作用和破坏特性,结果显示,相对薄冰板在气泡脉动载荷下容易产生大面积的小块破裂冰,相对中厚冰板则易形成大块碎冰,而气泡与厚冰板的相互作用仅对冰层造成冲击,无法造成破坏。随后进行了大尺度海上爆炸破冰试验,观察到冰层在水下爆炸载荷作用下产生明显的鼓包和散射现象,形成了破碎区和裂隙区。研究结果表明,气泡脉动载荷和水冢冲击载荷在水下爆炸破冰过程中发挥着重要作用。为了进一步研究水下爆炸载荷对冰层的损伤破坏机理,建立了冰-水-气泡全耦合数值模型,采用LS-DYNA软件进行流固耦合计算,并与试验结果进行对比验证,验证结果高度吻合,证明该数值模型能够准确模拟水下爆炸载荷作用下冰层的损伤破坏过程,真实还原试验现象,验证了模型的有效性。在实际爆炸破冰工程中,药包爆炸形式、炸药选型、药包形状和布置方式等因素对水下爆炸破冰的效果有着重要影响。对不同类型炸药、炸药形状以及柱形炸药长径比对爆炸破冰效率的影响进行了对比分析。研究结果表明,采用HMX炸药、OCTOL炸药以及RDX(0.36)炸药可以充分利用水下爆炸能量对冰层造成相对较大的损伤破坏范围。分析结果表明,双药包垂直布置的破冰效率低于等当量的单药包水下爆炸破冰效率;当双药包水平布置且炸药间距小于0.8倍冰损伤半径时,破冰效应范围小于等当量的单药包水下爆炸破冰;选择2倍冰损伤半径作为双药包水平布放间距可使破冰破坏效应范围达到最高,从而形成贯穿的冰层裂隙区以实现冰层损伤破坏范围的最大化。分析还指出,在双药包水下微差爆炸时,可以选择同时起爆或者大微差时间起爆,以充分利用爆炸能量造成更大的冰层损伤破坏范围。针对碰撞冲击载荷对冰层的损伤破坏特性问题,采用动力损伤本构模型描述了冲击压缩载荷下冰材料的脆性破坏特性。首先验证了动力损伤本构模型在模拟高速加载冲击下冰材料脆性失效方面的适用性和可靠性。在验证有效性的基础上,利用LS-DYNA中的侵蚀接触算法和冰材料动力损伤模型,建立了冰层受刚性弹体冲击的数值模型,并总结了刚性弹体在碰撞冲击载荷下对冰层动态损伤失效的一般规律。通过对比分析平头、半圆头和锥头形状的刚性弹体在冲击冰层时的损伤破坏特性,发现刚性弹体的头部形状对冰层的冲击效能有较大影响。在三种头部形状的弹体都可以穿透冰层的情况下,平头弹对冰层的冲击损伤范围最大,其次是半圆头弹,再次是锥头弹。此外,冲击速度和质量也对结果产生影响。最后,破冰弹是当前受到关注的一种碰撞冲击载荷破冰方式。为实现这一目标,关键技术之一是设计高效穿透冰层的破冰弹。本文提出了基于冰层靶标目标特性的破冰弹结构初步设计方案,并对比评估了常规弹头、锥形弹头和异形头部弹头三种破冰弹的冲击破坏效能。研究发现,相对于其他两种头部形状的破冰弹,异形头部破冰弹具有更好的冲击破坏冰层效能。基于本文的研究基础,旨在为破冰技术的开发提供参考。更多还原

【Abstract】 With the deepening of human exploration and scientific research in polar regions,their political,economic,and military significance has become increasingly prominent,turning them into important strategic locations contested by countries around the world.Submarines still face challenges when launching strategic missiles from beneath the Arctic ice cap to target objectives on land.New ice-breaking technologies utilize the high-pressure shockwaves and pulsating bubbles generated by underwater explosions to damage and weaken the ice,thereby reducing its structural strength and creating favorable conditions for submarine ascent.In the civilian sector,fixed underwater explosions and drone-delivered ice-breaking bombs play a crucial role in preventing ice jams and ensuring the safety of lives and property in the cold regions of our country’s rivers and lakes.However,due to the complex physical processes influenced by the effects of explosions and collision impacts on the ice,the understanding of the damage characteristics of the ice is still immature,presenting unresolved mechanistic issues.Due to the unique properties of ice and the influence of various factors such as density,temperature,salinity,porosity,crystal size,as well as loading rate and boundary conditions,the study of ice’s mechanical behavior faces significant difficulties and challenges.This paper provides an overview of the mechanical characteristics and research methods of ice,and summarizes the research progress on the damage characteristics of ice under explosion and collision impacts loads.However,previous studies have mainly focused on the propagation laws of underwater explosion shockwaves and the extent of ice structural damage,lacking research on the coupled mechanisms between shockwaves,pulsating bubbles,jet,and ice structure.There is also relatively limited research on the effects of parameters such as explosive selection,shape,and combined deployment on the damage effects on ice.In engineering applications,in addition to fixed underwater explosions,remote projection of icebreaking projectiles can be used.However,research on the damage mechanisms of ice under collision impacts is still limited.Addressing the aforementioned issues,this paper takes engineering requirements as its guidance and focuses on studying the characteristics of ice damage under explosion and collision impact loads,aiming to reveal their damage mechanisms and destructive characteristics.This article addresses the current status of numerical research on ice structural behavior and analyzes four typical constitutive models used to describe the dynamic response and failure of ice structures:brittle elasticity model,isotropic elastoplastic fracture model,dynamic brittle damage model,and isotropic high-strain-rate elastoplastic model.By conducting numerical simulations of four-point bending tests on ice beams using the dynamic analysis software LS-DYNA,it was observed that the failure characteristics of ice beams exhibit both similarities and differences under different loading rates,particularly in terms of distinct failure modes displaying typical features.In response to various loading effects of underwater explosions,including shock waves,bubble pulsations,and water spike impact,small-scale bubble ice-breaking mechanism experiments and large-scale offshore explosion ice-breaking tests were conducted.The smallscale bubble ice-breaking mechanism experiments focused on the interaction and damage characteristics of bubble loads on ice plates of different thicknesses.The results showed that relatively thin ice plates were prone to large-area small fragmentations under bubble pulsation loads,while relatively medium-thick ice plates tended to form large fragmented ice pieces.The interaction between bubbles and thick ice plates only caused impact on the ice layer without causing damage.Subsequently,large-scale offshore explosion ice-breaking tests were conducted,and noticeable bulging and scattering phenomena were observed on the ice layer under the influence of underwater explosion loads,resulting in fractured and damaged areas.The research findings indicated that bubble pulsation loads and water spike impact loads play significant roles in the process of underwater explosion ice-breaking.To further investigate the damage and failure mechanisms of ice layers under underwater explosion loads,a fully coupled numerical model of ice-water-bubble was established.Fluid-structure interaction coupling calculations were performed using LS-DYNA software,and the results were compared and validated against experimental data,demonstrating a high degree of agreement and confirming the accuracy of the numerical model in simulating the damage and failure process of ice layers under underwater explosion loads.The model effectively replicated the experimental phenomena and validated its effectiveness.In practical explosive ice-breaking engineering,factors such as the explosive form,explosive selection,explosive shape,and arrangement have significant effects on the effectiveness of underwater explosion ice-breaking.A comparative analysis was conducted on the effects of different types of explosives,explosive shapes,and length-to-diameter ratios of cylindrical explosives on the efficiency of explosive ice-breaking.The research findings showed that using HMX explosives,OCTOL explosives,and RDX(0.36)explosives could effectively utilize the energy of underwater explosions to cause relatively large damage and destruction to ice layers.The analysis results indicated that the ice-breaking efficiency of vertically arranged double charges was lower than that of single charges with equivalent explosive yields in underwater explosion ice-breaking.When horizontally arranged double charges had a spacing less than 0.8 times the ice damage radius,the ice-breaking effect range was smaller than that of single charges with equivalent explosive yields in underwater explosion ice-breaking.Selecting a spacing of 2 times the ice damage radius for horizontally arranged double charges resulted in the highest ice-breaking destruction effect range,thus forming a continuous fractured zone in the ice layer to maximize the damage and destruction range of the ice layer.The analysis also pointed out that in the case of slight time differences in the detonation of double charges underwater,simultaneous detonation or detonation with a large time difference could be chosen to fully utilize the explosive energy and cause a larger range of damage and destruction to the ice layer.To address the issue of damage and destruction characteristics of ice layers under collision impact loads,a dynamic damage constitutive model was used to describe the brittle failure characteristics of ice materials under impact compression loads.Firstly,the applicability and reliability of the dynamic damage constitutive model in simulating the brittle failure of ice materials under high-speed loading were validated.Based on the validation of effectiveness,a numerical model of ice layers subjected to impact from rigid projectiles was established using the erosion contact algorithm and the dynamic damage model of ice materials in LS-DYNA.The general patterns of dynamic damage and failure of ice layers under collision impact loads from rigid projectiles were summarized.Through comparative analysis of the damage and destruction characteristics of rigid projectiles with flat heads,semi-spherical heads,and conical heads when impacting ice layers,it was found that the head shape of the rigid projectile had a significant impact on the impact efficiency on the ice layer.When all three head shapes of projectiles were able to penetrate the ice layer,the flat-headed projectile had the largest range of impact damage on the ice layer,followed by the semispherical head projectile,and then the conical head projectile.Additionally,the impact velocity and mass also had an influence on the results.Finally,icebreaking bombs have emerged as a notable method for achieving damage and destruction of ice layers under impact loads.One of the key technologies for realizing this goal is the design of efficient ice-penetrating projectiles.This paper proposes a preliminary design scheme for icebreaking projectiles based on the target characteristics of ice layers and conducts a comparative evaluation of three types of projectiles:conventional warhead,conical warhead,and irregular-shaped warhead,in terms of their impact destruction efficiency on ice layers.The study reveals that the irregular-shaped warhead exhibits better efficiency in impacting and destroying ice layers compared to the other two head shapes.Building upon the findings of this research,aiming to provide reference for the development of icebreaking techniques.更多还原