弹体高速侵彻混凝土质量侵蚀实验研究

为研究弹体高速侵彻混凝土过程中质量侵蚀规律及特性,开展了一系列实验研究,进行了不同速度(800～1500m/s)侵彻不同强度(C30～C80)混凝土试验,根据试验结果拟合出了既定材料弹体质量侵蚀同侵彻速度之间的对应关系。试验结果还表明:(1)对于该种材料弹体,当侵彻速度小于1200m/s时,弹体侵蚀量不仅同Vs2(动能)呈线性关系,也随混凝土强度的提高而增加;(2)对于材料为60Si2Mn的弹体,其理想侵彻速度为1100m/s～1200m/s之间;高于该速度,质量侵蚀严重,弹体侵彻能力急剧下降;(3)弹体质量侵蚀主要发生在头部,当侵彻速度较低时,磨损是导致弹体质量损失的主要因素;当侵彻速度逐步提高,超过某临界值时,熔融和磨损是导致弹体质量损失主导因素。     

混凝土骨料对高速侵彻弹体质量侵蚀的影响分析

高速侵彻时，弹靶之间发生强烈的局部作用，引起弹体头部发生质量侵蚀，从而影响弹体的侵彻性能。在弹体侵彻过程中，混凝土中的骨料对弹体的质量侵蚀有显著影响。本文通过对高速侵彻混凝土弹体的质量侵蚀实验数据进行分析，进一步分析讨论了混凝土骨料对弹体质量侵蚀的影响。将混凝土靶体视为骨料和砂浆基质混合的二相复合材料，引入混凝土骨料的体积分数χ和骨料的剪切强度τ₁代替骨料的莫氏硬度H，给出无量纲骨料修正因子β，建立了修正的弹体质量损失工程模型。模型预测结果与现有的实验数据符合得很好，更准确地表征了混凝土骨料对弹体质量损失的影响。     

弹体高速侵彻效率的实验和量纲分析

为了研究高速侵彻时弹体撞击速度、材料强度等对质量侵蚀特性和侵彻效率的影响规律，开展了不同材料强度和长径比的弹体高速侵彻半无限厚素混凝土靶实验，弹体撞击速度为880~1 900 m/s，弹头形状为尖卵型(半径口径比为3)，口径为30 mm。由实验发现:弹体撞击速度对侵彻效率的影响呈抛物线分布，最大侵彻效率时的弹体特征撞击速度约1 400 m/s；高速侵彻时弹体的质量侵蚀主要发生在卵形头部，弹身及尾部损伤极少；速度超过特征撞击速度时，弹体侵蚀严重，甚至弯曲变形或解体；弹体强度提高至约2倍时，质量侵蚀率降低约80%。基于实验，利用量纲分析原则建立了量纲一侵彻效率和量纲一弹体撞击速度的函数关系式，可估算出最大侵彻效率对应的弹体撞靶速度，为高速侵彻效应模拟实验提供理论指导。     

考虑头形磨损变化的动能弹侵彻深度研究

质量损失主要发生在弹体头部,讨论残余弹头形状因子的主要影响因素,给出了更为一般化的残余弹头形状因子与初始撞击速度之间的关系.假设在整个侵彻过程中弹体头部形状因子及质量保持瞬时速度平方的线性关系,得到了能够考虑弹体头部质量磨损的侵彻深度计算方法.弹体质量损失将导致其侵彻深度存在上限,该修正模型可以找出达到侵彻深度上限的弹体初始撞击速度.     

高速侵彻混凝土弹体侵蚀效应试验研究

为了探究高速侵彻条件下弹体侵蚀效应及其影响因素,本文利用滑膛炮发射平台,采用次口径发射技术,在800～1800m/s速度范围内,开展了卵形头部弹体高速侵彻混凝土终点效应试验,重点研究了弹体口径、材料、CRH(曲径比)、长径比、屈服强度等因素对侵蚀效应的影响。通过试验获得了高速侵彻条件下弹体侵蚀变形情况,分析了侵彻深度和弹体质量损失率的影响规律,对弹体侵蚀机理进行了探讨。结果发现:通过合理设计弹体结构,提高极限速度大小,增大弹体截面比动能,可以有效增加弹体最大侵彻深度;提高弹体材料动态屈服强度能在一定程度上减小弹体侵蚀效应,提高侵彻深度。     

考虑摩擦因数变化的弹体高速侵彻混凝土质量侵蚀模型研究

弹体在高速侵彻混凝土介质时,由于弹靶之间强烈的局部作用,导致弹体发生质量损失和弹头钝化。为进一步探究弹体高速侵彻混凝土靶质量侵蚀效应及其影响因素,基于热熔化机制及变摩擦因数模型,考虑弹体侵彻过程中头部形状变化,修正了弹体高速侵彻混凝土质量侵蚀模型。为验证模型的可靠性,基于30 mm弹道炮平台,开展了卵形弹体高速(700～1 000 m/s)侵彻典型混凝土靶体实验,获得了弹体高速侵彻质量侵蚀结果。结合理论模型对本文实验及文献实验数据进行了对比分析计算,验证了本文修正模型的可靠性。结果表明:弹体侵彻过程中,滑动摩擦项占总摩擦力的10%～40%,它对弹体侵彻过程的影响不能被忽略;考虑摩擦因数变化的质量侵蚀模型预测结果与已有实验数据吻合得较好;与本文实验数据的最大误差不超过7%,能较准确地预测不同工况下弹体的质量损失。     

头部对称刻槽弹体侵彻半无限厚铝合金靶实验与理论模型

在综合考虑弹体结构稳定性及截面比动能的前提下, 提出一种介于尖卵形弹体及尖锥形弹体间的头部对称刻槽弹体, 以期达到提高侵彻深度的目的。以尖卵形弹体侵彻深度为基准, 开展头部对称刻槽弹体侵彻半无限厚铝合金靶实验。在此基础上, 推导得到可描述头部对称刻槽弹体侵彻2A12铝合金靶过程的局部相互作用模型。同时, 结合头部对称刻槽弹体侵彻后靶体破坏现象, 提出适用于头部对称刻槽弹体的靶体响应力, 进而确立头部对称刻槽弹体的侵彻深度模型。实验结果与理论计算表明, 头部对称刻槽弹体具有相对于尖卵形弹体更好的侵彻能力。头部对称刻槽弹体侵彻深度提高的原因是弹体头部结构截面比动能增加及其侵彻过程中的靶体弱化效应, 其中弱化效应是侵彻深度提高的主控因素。     

动能深侵彻弹的力学设计(Ⅱ):弹靶的相关力学分析与实例

介绍了作者关于动能深侵彻弹研究的部分工作。单纯动能弹侵彻存在侵彻深度上限，在技战术指标一定的前提条件下，弹体结构的优化可令动能深侵彻弹尽可能实现最大侵深。其中弹体结构的力学设计尤为重要，如弹形、弹材、质量比、长径比等。进一步开展弹体结构设计的力学研究，包括头部设计、战斗部后盖、装填比、弹形和弹材、侵彻效应中的尺度律、混凝土靶的设计，最后给出若干实例。     

异型头部弹体增强侵彻性能机理研究

为了了解理想刚性弹丸的高速/超高速动能侵彻中弹体头部形状对侵彻能力的影响,在空腔膨胀理论基础上,基于双卵形异型头部设计,分析了头部形状系数与双卵形特征参数的依赖关系,得到了不同异型头部弹体对侵彻性能的影响规律,提出了具有较小侵彻阻力的异型头部侵彻体设计方案。与不同头部侵彻实验结果对比表明,本文的分析方法合理可行,可为高速侵彻体头部形状设计提供参考。     

SPH算法在长杆弹侵彻多层间隔靶中的应用

基于Autodyn软件,应用SPH算法对长杆弹高速侵彻多层间隔金属靶板的过程进行数值模拟,分析了弹体侵彻靶板后的剩余速度、剩余动能、以及形成的破片及其飞散情况,同时模拟初始速度及弹体质量对侵彻过程的影响.通过与实验结果的比较,表明数值模拟的结果是合理的,能够准确模拟长杆弹对多层间隔靶的高速侵彻过程,对预测弹体侵彻件能以...     

Modeling on mass abrasion of kinetic energy penetrator

An engineering model on mass abrasion of kinetic energy penetrator is presented to predict the nose shape and mass loss of the residual projectile after high-speed penetration into concrete. The experimental analysis indicates that the kinetic energy of penetrator (i.e., mass and velocity of projectile) and the hardness of aggregate of concrete significantly affect the mass abrasion of projectile. A theoretical upper limit exists for the mass loss. More general relationship between mass loss and impact function I of projectile is constructed. Graphical discussion declares that the most mass loss occurs on the nose of the projectile and the eroding nose approaches to an ogival shape with a smaller value of caliber-radius-head (CRH). A relative rate of mass abrasion on ogive-nose is further defined and analyzed. The mass loss from abrasion on kinetic energy (KE) penetrator may be evaluated through the variation of nose shape.     

Parametric study on mass loss of penetrators

Earth penetration weapon （EPW） is applicable for attacking underground targets protected by reinforced concrete and rocks. With increasing impact velocity, the mass loss/abrasion of penetrator increases, which significandy decreases the penetration efficiency due to the change of nose shape. The abrasion may induce instability of the penetrator, and lead to failure of its structure. A common disadvantage, i.e. dependence on corresponding experimen- tal results, exists in all the available formulae, which limits their ranges of application in estimating the mass loss of penetrator. In this paper, we conduct a parametric study on the mass loss of penetrator, and indicate that the mass loss of penetrator can be determined by seven variables, i.e., the initial impact velocity, initial nose shape, melting heat, shank diameter of projectile and density and strength of target as well as the aggregate hardness of target. Further discussion on factors dominant in the mass abrasion of penetrator are given, which may be helpful for optimizing the target or the projectile for defensive or offensive objectives, respectively.     

Analyses of the penetration process considering mass loss

Based on the dynamic cavity-expansion theory and momentum theorem, the key parameters of projectile penetrating into concrete target, i.e., the penetration time and time histories of DOP, deceleration, mass loss, instant mass loss rate and nose shape, are obtained by incremental calculation considering mass loss of projectile. The calculation results are consistent with the experimental results. Due to the mass loss and thus nose blunting effects, the pulse shape of deceleration may be quite different from that obtained in the analysis of a rigid projectile, and then the dissimilarity is analyzed. It is found that the pulse shape of deceleration is determined by the drag force and essentially determined by the performances of target and projectile, i.e., the shear strength of target, the Moh’s hardness of aggregate in concrete and the CRH value of projectile nose. Further analysis indicates that the pulse shape of deceleration is more sensitive to the performance of target than that of projectile.     

Stability analyses of the mass abrasive projectile high-speed penetrating into concrete target. Part Ⅱ： Structural stability analyses

The initial oblique and attacking angles as well as the asymmetrical nose abrasion may lead to bending or even fracture of a projectile,and the penetration efficiency decreases distinctly.The structural stability of a high-speed projectile non-normally penetrating into concrete and the parametric influences involved are analyzed with the mass abrasion taken into account.By considering the symmetrical or asymmetrical nose abrasion as well as the initial oblique and attacking angles,both the axial and the transverse drag forces acting on the projectile are derived.Based on the ideal elastic-plastic yield criterion,an approach is proposed for predicting the limit striking velocity（LSV）that is the highest velocity at which no yielding failure has occurred and the projectile can still maintain its integral structural stability.Furthermore,some particular penetration scenarios are separately discussed in detail.Based on the engineering model for the mass loss and nose-blunting of ogive-nose projectiles established in Part I of this study,the above approach is validated by several high-speed penetration tests.The analysis on parametric influences indicates that the LSV is reduced with an increase in the asymmetrical nose abrasion,thelength-diameter-ratio,and the concrete strength,as well as the oblique and attacking angles.Also,the LSV raises with an increase in the initial caliber-radius-head（CRH）and the dimensionless cartridge thickness of a projectile.     

非对称质量磨蚀导致正侵彻弹体的弯曲屈服

给出了在一定的非对称质量磨蚀条件下垂直于弹体侵彻方向的横向荷载,并结合考虑质量磨蚀的弹体轴向阻力计算方法,得到了正侵彻弹体在压弯联合作用下的屈服分析方法.讨论了影响弹体由于非对称质量磨蚀而弯曲屈服的主要因素.分析表明,弹体的危险截面在承受较大的轴向荷载时,对由非对称质量磨蚀导致的横向荷载极为敏感.     

先进钻地弹高速侵彻实验中质量磨蚀金相分析

开展2组先进钻地缩比弹高速侵彻混凝土实验,侵彻速度在1130~1650m/s之间。针对弹体结 构特点,金相分析了侵彻后剩余弹体,发现弹体与靶接触的表面(包括弹头和壳体段)均存在明显热影响区 (Heataffectedzone,HAZ),而与靶脱离接触部分未发现明显热影响区,因而弹靶相互作用是热影响区产生的 主要原因。在弹尖部位存在少量绝热剪切带(Adiabaticshearingband,ASB),其对弹体质量损失有一定贡献, 但在实验撞击速度范围内其影响有限。ASB可能引起弹尖非对称磨蚀,进而降低弹体侵彻性能。     

基于Archard理论分析弹体质量侵蚀

基于模具与工件磨损中的Archard粘着磨损理论,分析弹体表面微粒的细观塑性变形,建立弹体质量侵蚀表征模型,运用动态空腔膨胀理论得到弹体表面应力,再通过差分计算得到高速侵彻中弹体宏观轮廓的钝化回退过程。计算得到的弹体外部轮廓、质量损失及侵彻深度等参数与实验结果基本吻合。结果表明;弹体侵蚀效应对侵彻时间和深度的影响随着撞击速度的增大愈加显著;弹体侵彻过程中最大过载与刚性条件下有较大区别,提高弹体材料的屈服强度能有效减少侵彻过程中弹体的质量损失,提高最终侵彻深度。