金属托盘面板弯曲力学性能研究及有限元分析

目的确认以镀锌钢为材质的面板是否适合物流金属托盘包装,并对其弯曲变形力学性能进行研究。方法通过SolidWorks软件对金属面板进行建模,利用力学相关知识建立面板的形心位置模型及惯性矩求解方法。同时在Ansys Workbench中对长度为600~1200 mm之间的面板进行位移弯曲变形仿真,及对面板的最大挠度理论计算过程进行推导。结果得到了面板的精确形心位置y_p=10.334 mm,惯性矩I_(zp)=1.372×10~(-8) m~4,以及不同长度面板的最大位移变形理论与仿真数值。结论提供了金属托盘面板弯曲变形的理论计算方法,进一步确认了金属托盘面板在物流包装中的耐用性、实用性,该研究为金属托盘力学性能探讨、结构优化提供依据。     

圆柱形破片侵彻纤维增强复合材料三明治板的弹道极限模型EI北大核心CSCD

分析了圆柱形破片侵彻纤维增强复合材料三明治板的过程,基于能量守恒定律分别对圆柱形破片侵彻面板、复合材料夹层和背板三个阶段中消耗的能量进行了理论推导,建立了圆柱形破片侵彻纤维增强复合材料三明治板的计算模型,并得到了剩余速度的计算公式,令剩余速度等于零,即可得到弹道极限。将计算模型得出的结果与试验结果进行了对比,验证了计算模型的可行性与有效性。该计算模型可以为钢/纤维增强复合材料/钢复合装甲结构的抗侵彻设计提供指导。     

圆柱形破片侵彻纤维增强复合材料三明治板的弹道极限模型

分析了圆柱形破片侵彻纤维增强复合材料三明治板的过程,基于能量守恒定律分别对圆柱形破片侵彻面板、复合材料夹层和背板三个阶段中消耗的能量进行了理论推导,建立了圆柱形破片侵彻纤维增强复合材料三明治板的计算模型,并得到了剩余速度的计算公式,令剩余速度等于零,即可得到弹道极限。将计算模型得出的结果与试验结果进行了对比,验证了计算模型的可行性与有效性。该计算模型可以为钢/纤维增强复合材料/钢复合装甲结构的抗侵彻设计提供指导。     

剪切变形下橡胶支座压缩刚度比分析研究

为了研究不同截面形状橡胶支座在剪切变形下的压缩刚度,该文分别基于双弹簧模型与有效面积模型推导了四种截面形状（环形、圆形、方形及矩形）支座的压缩刚度比公式,然后采用ABAQUS建立七个支座有限元模型,结合已有的支座压缩及剪切试验,验证所建立的有限元模型能够准确模拟橡胶支座的实际受力情况,在此基础上,结合理论模型对比分析了不同支座的压缩性能。分析结果表明:压缩及剪切试验中,支座刚度计算值与试验值相差均在5%以内;支座压缩刚度比只与剪切变形与截面惯性半径比值有关,与截面形状及截面尺寸大小无关;该文建立的模型及拟合刚度比公式能够有效模拟橡胶支座在不同剪切变形下的压缩刚度变化情况。     

金属橡胶/橡胶复合叠层耗能器动力学模型

针对橡胶常温低频段的阻尼性能差,设计开发了一种新型的金属橡胶／橡胶复合叠层耗能器。采用电液伺服材料试验机的位移加载方式,对该复合叠层耗能器进行了动态特性研究。在试验研究的基础上结合理论分析,建立了耗能器的动力学模型,并提出了一种迟滞回线分解识别算法,利用试验数据辨识出了模型中的未知参数。对比仿真与试验结果表明,所建模型可靠且参数识别精度能够满足工程应用的要求。     

斜向三维隔震支座的非线性力学性能试验及数值模拟研究

该文针对三维隔震结构较高竖向承载力和减震效果的需求,基于铅芯橡胶支座提出了斜向三维隔震支座,并基于铅芯橡胶支座的非线性力学本构模型,建立了考虑压缩应力及刚度衰减影响的三维隔震支座非线性竖向刚度计算模型。进行了倾斜角度分别为12°和15°的三维隔震支座模型力学性能试验,试验结果得到了该三维隔震支座滞回模型呈现出加载和卸载非平行特征,竖向刚度呈现非线性变化,以及角度和竖向位移对力学性能的影响规律。进一步对理论与试验结果进行对比分析,三维隔震支座的试验结果与理论计算值吻合。最后利用通用有限元软件建立不同倾斜角度的三维隔震支座数值分析模型,基于计算理论、静力试验及数值仿真结果分析了摩擦系数、剪应变、倾斜角度对三维隔震支座非线性竖向刚度的影响。     

低速冲击下金属面夹芯板性能分析

用实验、有限元及理论分析相结合方法对金属面夹芯板抗冲击性能进行研究。用实验方法研究金属面夹芯板在落锤冲击下的动力性能及破坏情况,并用有限元方法对实验进行模拟分析,验证有限元计算方法的适用性;用理论方法对夹芯板局部变形进行分析,将局部变形势能与外力功建立体系总势能,用势能驻值原理获得集中力与局部变形关系,以面板拉伸断裂为破坏条件,获得夹芯板开裂冲击力;建立有限元模型计算夹芯板开裂破坏时的冲击力,并与公式计算值比较。分析表明,夹芯板开裂冲击力随面板强度、厚度及锤头半径、开裂应变的增加而增大,落锤质量、芯材强度、芯材厚度对开裂冲击力基本无影响。     

浮冰碰撞下蜂窝金属夹芯板动态响应研究EI北大核心CSCD

采用非线性有限元软件ANSYS/LS-DYNA,结合混凝土冰材料数值模型,建立了楔形冰碰撞下蜂窝金属夹芯板动态响应数值仿真模型,得到了碰撞过程的冲击力时间曲线和冲击力位移曲线、蜂窝金属夹芯板的变形以及冲击能量分配情况,并开展了楔形冰-蜂窝金属夹芯板碰撞冲击试验验证。研究结果表明,楔形冰碰撞下蜂窝金属夹芯板上面板表现为局部凹陷与整体弯曲的耦合变形模式,下面板表现为整体弯曲变形模式,冲击能量转化为蜂窝金属夹芯板的变形能和楔形冰的回弹动能以及冰体破碎耗散能量,数值仿真与试验结果吻合较好,验证了数值计算模型的准确性。在此基础上,研究了浮冰碰撞冲击位置以及蜂窝芯层厚度对其动态响应及能量分配的影响规律。     

新型集成装甲对EFP侵彻性能的影响

根据平板装药和陶瓷复合装甲与爆炸成型弹丸（EFP）相互作用的原理，提出了新型集成装甲与EFP作用的计算模型；据此模型进行了EFP残余速度计算，证明了在相同面密度的新型集成装甲和陶瓷复合装甲防护下，EFP的残余速度有明显差异；根据该计算模型可进行集成装甲的优化和EFP的反装甲目标设计。     

金属橡胶Mooney-Rivlin修正模型试验

目的研究金属橡胶的本构关系,建立一种适用于工程计算和数值仿真的金属橡胶Mooney-Rivlin修正模型。方法基于金属橡胶变形过程中刚度非线性、可压缩的特点,将金属橡胶试件的变形分为“等容部分”和“体积部分”这2个部分,采用正交试验法研究加载速度、固相体积分数、丝径对金属橡胶变形“体积部分”的影响程度。结果试验因素对Mooney-Rivlin模型描述金属橡胶本构关系误差的影响顺序为固相体积分数>丝径>加载速度,其中加载速度对误差值的影响程度远小于固相体积分数和丝径。结论修正后的Mooney-Rivlin模型有较好的拟合效果,可以更好地反映金属橡胶非线性刚度的特性,为金属橡胶的实际应用提供了理论参考。     

Nonlinear Finite Element Analysis of Rubber Composite Shells

A finite-element solution for rubber composite shells is presented. Sandwich laminates with a rubber core have also been studied. Incompressibility of a rubber matrix and complexity of composite shells bring forth the need for a sound numerical model to describe the behavior of such engineering materials. The developed model was applied to a degenerate shell element within the limits of the first- and third-order shear deformation theories. The model allows to predict with a sufficient accuracy the nonlinear behavior of sandwich shells with composite skins and rubber cores and composite shells with a rubber matrix.     

结构形状对密闭胞元抗射流侵彻性能的影响

针对液态复合装甲抗射流侵彻性能与胞元的结构形状密切相关性,研究了密闭胞元的结构形状对抗射流侵彻性能的影响。利用LS-DYNA有限元软件进行了数值仿真,分析了结构形状为四边形、圆形、六边形的3种密闭胞元对射流冲击波的反射能力和密闭胞元受到的压力、射流断裂时间及速度区间、剩余穿深、胞元内壁变形等参量,得出圆形密闭胞元反射冲击波的能力最优;圆形密闭胞元的抗射流侵彻能力最强,表现为剩余穿深最小,干扰射流头部速度区间最大;六边形密闭胞元的抗射流干扰能力稍小,干扰射流颈部速度区间最大,吸能最大,变形小且稳定性好;四边形密闭胞元的抗射流侵彻能力最差,内壁变形的振动幅度最大。为研究多胞结构液态复合装甲提供了结构上的设计依据。     

Affordable processing of thick section and integral multi-functional composites

The use of multi-functional integral armor is of current interest in armored vehicles and military carriers. In the present study, thick-section laminated composites and multi-layered integrated composites have been processed/manufactured with the aim of providing multi-functionality including easy reparability, quick deployment, enhanced ballistic damage and fire protection, as well as lightweight advantages. The design of an integral armor utilizes a combination of thick-section structural composite, ceramic tiles, resilient rubber, fire retardant laminate liner and a composite durability cover. Processing techniques such as automated fiber placement and/or autoclave molding are traditionally used to process dissimilar multi-layered structure, but prove to be expensive.This work focuses on emerging cost-effective liquid molding processes such as vacuum assisted resin transfer/infusion molding (VARTM) for the production of thick-section and integral armor parts (up to 50 mm thick). While thick-section composites have applications in a variety of structures including armored vehicles, marine bodies, civil infrastructure, etc. in the present work they refer to the structural laminate within the integral armor. The processing steps of thick-section composite panels and integral armor have been presented. The integrity of the interfaces has been evaluated through scanning electron microscopy (SEM). Representative results on static and dynamic response (high strain rate, HSR and ballistic impact) of the VARTM processed thick-section composite panels are presented. Wherever applicable, comparisons are made to conventional closed-mold resin transfer molding (CMRTM). Process sensing by way of flow and cure monitoring of the resin in the fiber perform has been conducted using embedded direct current (DC)-based sensors in the thick-section preform and integral armor interfaces. The feasibility of cost-effective VARTM for producing thick-section composites and integral armor has been demonstrated.     

弹体侵彻陶瓷/金属复合靶板问题的研究

针对弹体侵彻陶瓷/金属复合靶板的问题,将弹体的墩粗变形、陶瓷面板碎裂及陶瓷锥的形成变化和金属背板的变形结合起来,建立了可变形弹体垂直侵彻陶瓷/金属靶板的理论分析模型。利用大型非线性有限元程序LS-DYNA3D,对平头弹侵彻陶瓷/金属复合靶板的问题进行数值模拟,得到了陶瓷/金属复合靶板受弹体侵彻的变形过程。最后给出了典型位置的位移随时间的变化曲线,理论模型分析结果和数值模拟结果与实验结果进行了对比,吻合很好。说明理论分析模型的正确性和数值模拟结果的可靠性,可以为复合靶板的设计提供有利依据。     

Effects of a hypervelocity jet on a layered target

We present a new approach to the numerical simulations of jet target interactions. We represent the jet by sources of mass, momentum and energy moving with a prescribed velocity. This velocity is related to local flow parameters through the incompressible theory of jet penetration. A Lagrangian, 2-dimensional elastic plastic code is used to model the flow in the target. The interaction between the jet and the target is obtained by appropriate deposition of the jet material with its momentum and energy in the computational mesh of the target. To prevent large grid distortions the grid is continuously rezoned. For normal jet impingement the calculations are carried out with axial symmetry. Oblique incidence is treated approximately considering a “sheet jet” and a two dimensional plane strain flow. Results for normal and 45° oblique jet impacts on a 25.4mm thick homogeneous armor plate are presented. The computed and experimental distributions of behind-the-armor debris are compared. An additional case of a 45° oblique jet penetration into a multi-layered plate is carried out. The flow in the target and its influence on the penetration process is discussed.     

Analysis of hybrid beams composed of GFRP profiles and polymer concrete

In this paper, a numerical approach for the analysis of a new type of hybrid composite beams is presented. Such beams are composed of composite materials that resist shear and tensile stresses, and polymer concrete acommodating compression stresses.The beams offer an optimized configuration in terms of stiffness and strength, with much potential for mechanical and civil engineering structures.The current numerical model is based on a finite element formulation for layered shell-like structures. The model accounts for a polymer concrete material model, orthotropic material model, and considers the analysis of geometric and material nonlinearities. The first-order shear deformation theory is used in order to describe the shell deformation under a total Lagrangian formulation. The model is validated experimentally and a close agreement with experimental results makes this model an attractive solution method for this type of composite hybrid beams.     

A micromechanical analysis to predict the cord-rubber composite properties

Both three- and two-dimensional generalized plane strain finite element analyses based on a micromechanics approach were carried out to investigate the linear and nonlinear effective composite properties as well as the stress fields. A unit cell model of cord-rubber composite subjected to different loadings was studied to predict the effective composite properties. The numerical results of effective composite properties obtained from 2D and 3D finite element analyses were compared with experimental data and other finite element results available in the literature. The effects of rubber material nonlinearity and large deformation on the effective composite properties and interface stress distributions are presented and discussed.     

Hole drilling in ceramics/Kevlar fiber reinforced plastics double-plate composite armor using diamond core drill

Both engineering ceramics and Kevlar fiber reinforced plastics (KFRPs) are difficult to cut, so is the ceramics/KFRP double-plate composite armor. In this work, an experimental study of drilling the ceramics/KFRP double-plate composite armor by using a special sintering diamond core drill has been carried out on a general-purpose drilling machine. Machining mode, drilling sequence, and machining efficiency have been discussed based on drilling experiments. According to the discussed experimental results, machining using manual step feed, drilling the KFRP backboard firstly, and selecting the reasonable technical parameters could greatly facilitate the hole drilling in the ceramics/KFRP double-plate composite armor. The results achieved show that the machining method presented in this work is applicable for small order production.     

复合双药型罩结构冲击ERA及其后效作用研究

为了研究复合双药型罩结构在冲击爆炸反应装甲(ERA)后剩余射流的性能,以及对主装甲的后效毁伤作用,运用ANSYS/LS-DYNA有限元分析软件,分别研究射流以垂直和倾斜两种状态冲击引爆ERA。其中,侵彻斜置ERA对射流性能影响较大,而垂直侵彻时射流未断裂,且长度几乎没有变化。在相同炸高处,与普通偏心亚半球单罩结构对主装甲的毁伤情况进行对比,结果表明:当在主装甲前未添加ERA时,复合双药型罩结构对主装甲的侵彻性能优于偏心亚半球单罩结构;而在主装甲前添加ERA后,复合双药型罩结构穿过ERA后依然可以有效地对主装甲进行侵彻,但偏心亚半球单罩结构在侵彻ERA后射流形态变化巨大,离散为射流粒子,几乎丧失了继续侵彻的能力,即复合双药型罩结构不仅可以更加有效地摧毁ERA,且对主装甲的后效毁伤效能明显提升,与单罩结构相比,扩孔孔径增加27.5%,侵彻深度提升了112.2%。     

Ballistic resistance of high hardness armor steels against 7.62 mm armor piercing ammunition

Although advanced lightweight composite based armors are available, high hardness steels in military vehicles are often used to provide ballistic protection at a relatively low cost and is an interesting material due to its widespread usage in vehicle structure. In this study, ballistic limit of 500 HB armor steel was determined against 7.62 mm 54R B32 API hardened steel core ammunition. Lagrange and smoothed particle hydrodynamics (SPH) simulations were carried out using 3D model of bullet and high hardness armor target. Perforation tests on 9 and 20 mm thickness armor were performed to validate simulation methodology. Also material tests were performed for armor steel and ammunition hardened steel core to develop Johnson–Cook constitutive relations for both strength and failure models. Finally, results from 3D numerical simulations with detailed models of bullet and target were compared with experiments. The study indicates that the ballistic limit can be quantitatively well predicted independent of chosen simulation methodology, but qualitatively some differences are seen during perforation and fragmentation. As shown in results, good agreement between Ls-Dyna simulations and experimental data was achieved by Lagrange formulation with the full bullet model.