轮压载荷下夹层板直升机平台结构响应特性

以直升机平台甲板为研究对象,基于数值仿真方法,考虑弹性工况和塑性工况,分别采用动态冲击、轮胎准静态压载、刚体准静态压载和均布压载4种处理方式模拟轮压载荷,分析夹层板上面板、夹芯层和下面板的响应特点,讨论载荷处理方式对轮压压力分布和结构响应的影响规律,并初步探讨4种载荷处理方式间的内在关系。研究结果表明:在轮压载荷作用下,板架产生高应力、高变形的局部结构响应,采用动态冲击、轮胎准静态压载和均布载荷3种处理方式均能较好地反映夹层板响应,这3种载荷处理方式之间存在联系,轮压载荷可通过等效处理达到一定程度的简化。     

铝合金加筋板轮印载荷的简化等效模型

将轮印载荷等效处理为接触区域内的均布压力是目前大多数研究通常采用的方法,但简化的均布压力与实际的接触压力明显不同。基于此,本文以子午线轮胎-铝合金加筋板为研究对象,模拟现实中不同轮胎压载方式下产生的轮印载荷。基于能量法提出使用补偿系数β的圆形均布压力代替实际轮印载荷的等效简化方法,讨论不同加载工况、轮印位置、加筋板结构参数对补偿系数β的影响,最后通过具体的工况算例分别从加载区域、加筋板的最大应力值、加筋板上应力状态分布,验证均布加载补偿系数β的合理性。研究结果表明,本文提出的方法可以有效替代为轮印载荷的简化等效模型,并且与基于规范的计算相比,该方法的计算精度更高。本文提出的补偿系数β用于加筋板最大应力值的预测时,预测精度平均提升33.99%,对此类甲板设计以及强度计算有较好的实际工程应用价值。     

基于一阶zigzag理论的软芯复合夹层板冲击载荷下的动态响应分析（英文）

本文提出一种简化的用于求解软芯复合材料夹层板的一阶zigzag理论模型，该模型能精确求解外载荷作用下软芯复合材料夹层板的静态和动态响应。软芯复合材料夹层板的上下面板采用一阶剪切变形理论，芯材运用线性函数模拟横向和面内位移。模型充分考虑芯材厚度方向的应力和应变，能很好满足横向剪切应力和位移界面边界条件。基于此模型，运用Newmark法求解控制方程分析冲击载荷作用下简支软芯复合夹层板的动态响应，将提出的一阶zigzag理论模型与公开发表的文献结果进行了准确性对比验证。在验证的基础上进行了一系列的参数研究，并详细研究了各种参数对夹层板动态响应的影响。计算结果能为船用软芯复合材料夹层板提供理论设计指导。     

轮印载荷下I型夹层板架结构静强度力学性能试验研究

现代舰船的直升机起降时会通过轮胎将载荷作用于飞行甲板的板架上,这种载荷通常被称为轮印载荷。除此之外,相对于传统加筋板结构形式,I型夹层结构具有轻质、高比强度等优点,是一种可以应用于船舶飞行甲板的新型结构形式。本文针对轮印载荷局部重载和位置不确定的特点,设计了合理的试验贴片方案及加载程序,并将试验数据与理论值对比,分析误差原因,研究I型夹层板架结构的板格在四种典型位置轮印载荷作用下的静强度力学性能。试验结果表明,夹层板架结构在载荷附近测点的应力水平较大,同时其上面板沿船宽方向的弯曲应力大于沿船长方向的弯曲应力,而下面板2个方向的弯曲应力特性与上面板相反。这些结论对于I型夹层板架结构在轮印载荷下的力学性能研究具有重要意义。     

填充超弹性材料夹层板的抗爆性能研究

夹层板是一种比刚度大、比强度高的结构形式,根据文献将典型加筋板等效为最优夹层板,采用非线性数值方法,对爆炸冲击波作用下方形蜂窝夹层板及填充超弹性材料的方形蜂窝夹层板响应进行数值计算,分析填充超弹性材料夹层对夹层板各部位加速度、速度及位移响应的影响,对比不同爆距下夹层板响应,并分析填充超弹性材料对夹层板吸能的影响。从计算结果可知填充超弹性材料可有效减小爆炸载荷作用下夹层板的响应,减小夹层板面、背板间相对变形。     

填充超弹性材料夹层板的抗爆性能研究

夹层板是一种比刚度大、比强度高的结构形式,根据文献将典型加筋板等效为最优夹层板,采用非线性数值方法,对爆炸冲击波作用下方形蜂窝夹层板及填充超弹性材料的方形蜂窝夹层板响应进行数值计算,分析填充超弹性材料夹层对夹层板各部位加速度、速度及位移响应的影响,对比不同爆距下夹层板响应,并分析填充超弹性材料对夹层板吸能的影响。从计算结果可知填充超弹性材料可有效减小爆炸载荷作用下夹层板的响应,减小夹层板面、背板间相对变形。     

填充超弹性材料夹层板的抗爆性能研究

夹层板是一种比刚度大、比强度高的结构形式,根据文献将典型加筋板等效为最优夹层板,采用非线性数值方法,对爆炸冲击波作用下方形蜂窝夹层板及填充超弹性材料的方形蜂窝夹层板响应进行数值计算,分析填充超弹性材料夹层对夹层板各部位加速度、速度及位移响应的影响,对比不同爆距下夹层板响应,并分析填充超弹性材料对夹层板吸能的影响。从计算结果可知填充超弹性材料可有效减小爆炸载荷作用下夹层板的响应,减小夹层板面、背板间相对变形。     

填充超弹性材料夹层板的抗爆性能研究

夹层板是一种比刚度大、比强度高的结构形式,根据文献将典型加筋板等效为最优夹层板,采用非线性数值方法,对爆炸冲击波作用下方形蜂窝夹层板及填充超弹性材料的方形蜂窝夹层板响应进行数值计算,分析填充超弹性材料夹层对夹层板各部位加速度、速度及位移响应的影响,对比不同爆距下夹层板响应,并分析填充超弹性材料对夹层板吸能的影响。从计算结果可知填充超弹性材料可有效减小爆炸载荷作用下夹层板的响应,减小夹层板面、背板间相对变形。     

船用泡沫铝夹层板在低温下的冲击动态响应研究

泡沫铝夹层板具有良好的动态能量吸收性能,在极地船舶抗冲击防护方面具有巨大的潜在应用前景。文章利用ABAQUS有限元软件,结合准静态拉伸压缩材料试验,建立了船用泡沫铝夹层板的低温动态冲击数值仿真模型,研究了其动态冲击响应与抗冲击性能,并采用Instran 9350落锤冲击试验机对数值仿真模型进行了试验验证。在此基础上,研究了低温和冲击能量对船用泡沫铝夹层板动态冲击响应的影响。结果表明,随着冲击能量的增加,常温和低温条件下船用夹层板的冲击力峰值、最大挠度和最终挠度遵从乘幂增长规律。与常温相比,低温下船用泡沫铝夹层板的面板变形较小,且随着冲击能量的增加,低温的影响更为显著,即船用泡沫铝夹层板在低温下具有更好的抗冲击性能。     

轮印载荷作用下波纹型夹层板格强度特性分析

针对轮印块状载荷下的波纹型夹层板格结构,建立了应力分析计算方法。该方法基于Mindlin-Reissner板理论的夹层板格整体弯曲计算和经典板理论的芯材间上面板的局部弯曲计算,并将二者叠加得到轮印载荷下夹层板格总的弯曲特性。开发了基于MATLAB的计算程序,能方便地调整夹层板格尺寸及轮印块载荷的位置、尺寸和载荷值,计算相应的板格变形和各特征点应力值。讨论了结构尺寸参数、轮印载荷尺寸参数等对上面板局部弯曲应力及板格整体弯曲应力的影响特性,为这类结构的设计和优化提供有益的参考。     

Ice impact response and energy dissipation characteristics of PVC foam core sandwich plates: Experimental and numerical study

In this paper, the dynamic responses and energy dissipation characteristics of polyvinyl chloride (PVC) foam core sandwich plates under ice impact are investigated. The ice impact tests of PVC foam core sandwich plates were conducted by employing the horizontal impact experimental apparatus. The finite element simulations were conducted to analyze the dynamic response of PVC foam core sandwich plates based on soil and concrete material model for ice impactor. It was demonstrated that numerical results were in good agreement with experimental results. The deformation modes of the top facesheets were coupling of local indentation with global bending deformation, while the deformation modes of bottom facesheets were overall bending deformation. The permanent deformation of face sheets show that the impact resistance of sandwich plate is better than that of equivalent weight hull plate (EWHP). In addition, based on the actual navigation environment of ship, the effect of impact angle and ice floe shape on dynamic response and energy dissipation are analyzed.     

Research on the dynamic buckling of a typical deck grillage structure subjected to in-plane impact Load

The dynamic buckling of the main deck grillage would result in the total collapse of the ship hull subjected to a far-filed underwater explosion. This dynamic buckling is mainly due to the dynamic moment of the ship hull when the ship hull experiences a sudden movement under impact load from the explosion. In order to investigate the ultimate strength of a typical deck grillage under quasi-static and dynamic in-plane compressive load, a structure model, in which the real constrained condition of the deck grillage was taken into consideration, was designed and manufactured. The quasi-static ultimate strength and damage mode of the deck grillage under in-plane compressive load was experimentally investigated. The Finite Element Method (FEM) was employed to predict the ultimate strength of the deck grillage subjected to quasi-static in-plane compressive load, and was validated by comparing the results from experimental tests and numerical simulations. In addition, the numerical simulations of dynamic buckling of the same model under in-plane impact load was performed, in which the influences of the load amplitude and the frequency of dynamic impact load, as well as the initial stress and deflection induced by wave load on the ultimate strength and failure mode were investigated. The results show that the dynamic buckling mode is quite different from the failure mode of the structure subjected to quasi-static in-plane compressive load. The displacements of deck edge in the vertical direction and the axial displacements are getting larger with the decrease of impact frequency. Besides, it is found that the dynamic buckling strength roughly linearly decreased with the increase of initial proportion of the static ultimate strength P₀. The conclusions drawn from the researches of this paper would help better designing of the ship structure under impact loads.     

Equivalent design pressure for ship plates subjected to moving slamming impact loads

When a ship navigates at sea, the slamming impact can generate significant load pulses which move up along the hull plating. The effect of the moving pressure has so far not been explicitly considered in the Rules and Regulations for the Classification of Ships. Based on a modal superposition method and the Lagrange equation, this paper derives analytical solutions to study the elastic dynamic responses of fully clamped rectangular plates under moving pressure impact loads. The spatial variation of the moving slamming impact pressure is simplified to three types of impact loads, i.e. a rectangular pulse, a linearly decaying pulse and an exponentially decaying pulse. The dynamic responses of fully clamped rectangular plates under the moving slamming impact pressure are calculated in order to investigate the influence of the load pulse shapes and moving speed on the plate structural behaviour. It is found that the structural response of the plate increases with the increase of the moving speed. The response of the plate subjected to a moving pressure impact load is smaller than the case when the plate is subjected to a spatially uniform distributed impact load with the same load amplitude and load duration. In order to quantify the effect of the moving speed on the dynamic load, a Dynamic Moving Load Coefficient (DMLC) is introduced as the ratio between the dynamic load factor for the moving impact load and that under the spatially uniform distributed impact load. An expression for DMLC is proposed based on analyses of various scenarios using the developed analytical model. Finally an empirical formula which transforms the moving impact loads to an equivalent static load is proposed.     

冲击载荷下加筋板非线性瞬态分析

本文用半解析的方法分析了横向冲击载荷下加筋板的非线性瞬态响应。考虑膜力的存在，忽略筋截面上的剪切应力，引入板的应力函数，采用离散加筋板模型，运用能量原理建立加筋板的动响应控制方程。假设挠度为双级数形式，运用迦辽金法，将加筋板的动响应方程转化为一个多自由度的动力系统，采用数值方法来求解。本文最后给出了几个模型的计算结果。     

超大型浮体柔性夹层连接器力学性能研究

考虑连接器作为超大型浮体最为薄弱的构件之一,研究带有柔性夹层连接器的力学特性,旨在明确柔性夹层对连接器的刚度和应力变化的影响.通过建立钢与柔性夹层的本构模型,采用接触力学分析手段,对连接器进行力学分析,分别获得超弹性橡胶和尼龙作为柔性夹层时连接器的力学特性和刚度变化曲线,并获得不同厚度,初始弹性模量和泊松比对这一结果的影响程度.分析发现,超弹性橡胶与尼龙对于连接器的应力大小具有显著影响,采用超弹性橡胶和尼龙夹层时,连接器的应力水平与应力分布也明显不同,同时材料参数的变化对于连接器的刚度变化影响较大.可根据实际需要,对柔性夹层材料进行参数优化,既得到合理的连接器刚度,又将连接器应力水平控制在合理范围内.     

船用夹层板芯材的动态力学性能实验研究

基于分离式霍普金森压杆实验装置,对船用夹层板系统(SPS)的芯材-聚氨酯弹性体的动态力学性能进行了实验分析。在实验满足一维、均匀性的前提下,计算得到了聚氨酯弹性体在不同应变率下的应力—应变关系,讨论了试样尺寸对结果的影响;考虑聚氨酯弹性体不同于金属的动态力学性能,以及准静态力学性能与动态力学性能的差异,确定运用朱—王—唐(ZWT)方程描述聚氨酯弹性体的本构关系,能够准确反应聚氨酯弹性体的非线性粘弹性特性,拟合结果与实验结果吻合较好。     

典型舱内爆炸载荷对加筋板的毁伤特性

[目的]为研究典型舱内爆炸载荷对加筋板的毁伤特性,将舱内爆炸载荷分为初始爆炸冲击波载荷和准静态气压载荷,利用有限元分析软件LS-DYNA开展爆炸载荷下固支单向加筋板毁伤特性的数值模拟.[方法]主要模拟载荷冲量相等和载荷峰值相等时固支单向加筋板的变形特性,以及加筋板分别在初始爆炸冲击波载荷、准静态气压载荷及2种载荷联合作...     

面内流固冲击载荷下板结构的弹塑性动态屈曲及失效

一种简单的半解析方法用来研究板结构的动态弹塑性屈曲及失效.考虑材料和几何非线性,忽略面内位移和面内惯量,运用能量变分原理以及增量伽辽金方法得到面内流固冲击载荷下板以及加筋板的弹塑性动态屈曲增量控制方程,采用数值方法求解,并通过算例分析了几何参数以及冲击载荷的影响.     

结构动态稳定性数值模拟研究

采用有限元方法计算了加筋板在流固冲击下的动态稳定性,研究的目的是对舱壁结构受水下爆炸冲击时的动态稳定性提供参考和依据.详细分析了影响加筋结构动态屈曲的各种因素:加筋与筋的厚度、初始几何缺陷的形式与大小、冲击载荷的脉宽和幅值、边界条件、筋的分布以及板的厚度.在分析研究的基础上提出了改善加筋板抗失稳的方法,以利于工程设计中具体应用.