动载荷作用下壳体的结构声强分析

结构声强矢量图直观地给出了壳体表面各点能量传输的分布特性。首先推导了壳体局部坐标下的结构声强计算公式,应用坐标转换得到了结构声强的全局坐标表达式,用有限元计算了筒体和板壳组合结构的结构声强,并绘制出了矢量图。结果表明用有限元法对各种壳体的结构声强进行分析是十分有效的。     

任意荷载作用下结构动力响应的并行算法

介绍计算任意荷载作用下线性结构动力响应的精细时程积分及其并行算法。离散化结构的动力响应方程通过变量变换可以转换为一阶线性常微分方程组，该方程组的解由表示初值影响的齐次方程解和反映荷载作用的积分之和构成。上述第一项用矩阵指数函数计算，第二项在本文中用数值积分计算。这种算法很适应并行计算，已在ＴＲＡＮＳＰＵＴＥＲ并行机上实现。     

Experimental Study of Concrete Subjected to Explosive Loading

The main subject of this paper is to demonstrate the response of structural concrete to different imposed strain rates. Attention is focused on the strain rate about 10^-2 s ^-1>, where some technical difficulties are experienced when an exact determination of mechanical properties for quasi-brittle materials is attempted. The design of a measurement system, which realizes computer acquisition, analysis, and graphic representation of data, is also presented.     

大载荷聚氨酯隔振器的分析

浇注型聚氨酯材料具有良好的机械性能和动态性能。文章通过聚氨酯材料试片的测试结果和隔振器数值计算及试验验证确定材料内部许用应力，并在此基础上开发出承载能力达到了300 kN的聚氨酯隔振器，其固有频率小于5 Hz。     

An Experimental Study on the Interaction of Thermal Loading and Mechanical Loading in Membrane Structures

Abstract: Maintenance of membrane structures geometry is crucial for them to be utilised in some space missions, including membrane antennae being developed at the Canadian Space Agency. In the harsh space environment, thermal loading and mechanical loading both can cause the distortion of membrane surfaces. Their effects on surface distortion will interact with each other. In order to properly design active control system, the interaction needs to be well understood. An experimental setup is designed for this purpose. A square membrane is subjected to mechanical loading provided by corner tension forces and thermal loading provided by a ceramic heater. Surface profile of the membrane is measured using the photogrammetry technique. In cases of symmetric thermal loading and asymmetric thermal loading, different mechanical loading cases are evaluated in terms of mitigating surface distortions. Some results are compared and explained using numerical results. Finally, the controllability of membrane structures is discussed using the results from these experiments.     

Minimum-Weight Sandwich Structure Optimum Design Subjected to Torsional Loading

As one of the most valued structural engineering innovations developed by the composites industry, sandwich structures are now used extensively in automotive, aerospace and civil infrastructure due to the main advantage of lightweight. This paper develops a minimum weight optimization method for sandwich structure subjected to torsion load. The design process are identified for a sandwich structure required to meet the design constraint of torsion stiffness. The optimum solutions show that at optimum design the core weight accounts for 66.7% of the whole sandwich structure. To illustrate the newly developed optimum design solutions, numerical examples are presented for sandwich structures made of either isotropic face skins or orthotropic composite face skins. Agreement between the theoretical analysis and the examples results is good.     

A Fully Discretized Nonlinear Finite Strip Formulation for Pre-Buckling and Buckling Analyses of Viscoelastic Plates Subjected to Time-Dependent Loading

A semi-analytical fully discretized finite strip method is developed to investigate the pre-buckling and local buckling of viscoelastic plates with different boundary conditions subjected to time-dependent loading. The mechanical properties of the material are considered to be linear viscoelastic by expressing the relaxation modulus in terms of Prony series. The fully discretized finite strip equations are developed using a two-point recurrence formulation, which leads to a computationally superior formulation. Time history of maximum deflection of plates with different end conditions is calculated. The effects of thickness, length of plate, and transverse loading on critical buckling load are also studied.     

复杂载荷下的枪炮减重技术

目的研究复杂载荷下的枪炮减重技术;方法分析国内外研究现状和技术水平,采用理论与实验研究相结合的方法进行枪炮减重研究结果采用复合材料对某机枪进行减重研究,并归纳出机枪结陶合理动力匹配的原则;结论利用复合材料和动态优化进行枪炮减重是有效的.     

钢筋混凝土在冲击载荷下的动态力学性能

利用一级轻气炮加载,对钢筋混凝土圆柱形靶板进行冲击压缩实验,飞片与靶板同质,由预埋的锰铜压阻传感器测量出压力-时间信号曲线.实验数据采用拉氏分析方法中的路径线法自编程序进行处理,反算出粒子速度、应变等力学参量.实验结果表明:钢筋混凝土材料的应力应变总体呈滞回特性,并具有明显的应变率相关性和波形弥散效应等动态力学性能.同时基于复合材料细观力学的方法,认为理想情况下钢筋混凝土本构关系可由混凝土材料粘弹性本构关系与一个依赖于增强钢筋材料特性的常量G的乘积确定,并假定损伤只发生在混凝土内部,给出了钢筋混凝土的损伤型动态本构关系,理论预测曲线与试验结果吻合良好.     

冲击荷载作用下纤维增强水泥砂浆模型研究

冲击荷载作用下，纤维增强水泥砂浆的冲击过程有五个阶段，即弹性压缩阶段、损伤阶段、材料内部发生大的贯穿性破坏阶段、孔洞崩塌阶段和“固体’’压缩阶段。根据此压缩过程进行模型分析，采用基于扰动态概念（DSC）模型和朱王唐（ZWT）模型建立的动态损伤模型描述材料的完整态和损伤态。本可以拟合测试波形，但与Lagrange分析结果存在一定差异。其余阶段采用状态方程进行描述。分析结果表明，此模型基这两种分析方法可以互相补充，相互检验。     

不同加载速率下CA砂浆的抗压性能试验

通过CA砂浆在不同加载速率下的单轴抗压试验,研究CA砂浆在高频荷载冲击等复杂外界条件下的抗压性能,分析了CA砂浆试件破坏模式、应力应变关系、抗压强度和弹性模量的变化规律,并根据试验结果建立了CA砂浆在不同加载速率下的应力应变关系。结果表明:CA砂浆的抗压强度和弹性模量随加载速率增大而增大;根据试验和理论曲线的对比结果,提出的应力应变模型能够合理地描述CA砂浆在不同加载速率下的应力应变关系。     

EB-PVD 热障涂层的热循环失效机理

采用电子束物理气相沉积方法(EB—PVD)在NiCrAlY粘结层上沉积Y2O3部分稳定的ZrO2陶瓷层。对样品进行了1050C的热循环实验。结果表明，沉积态陶瓷层表面比较致密．其柱状晶粒簇拥成团，晶粒簇间存在间隙。随着热循环不断进行，陶瓷层表面变得疏松，晶粒簇间距增大，相邻较大的间隙互相连接成微裂纹。并逐渐横向及纵向扩展。1050C循环200次，粘结层氧化物是均匀连续的—薄层，主要由Al2O3组成；循环300次后,出现了NiO、尖晶石等氧化物。根据显微结构观察和EDS、XRD分析结果，提出了EB—PVD热障涂层热循环的失效机理。     

Cross‐laminated Timber Plates Subjected to Concentrated Loading

Since wood products for structural elements, especially cross‐laminated timber (CLT), have gained importance in the building sector, the need for appropriate and reliable design codes for such wood products has become essential. For the improvement and development of design concepts, a profound knowledge about the mechanical behaviour of these products is necessary. For this reason, this work focuses on global failure mechanisms and the corresponding evolution of different crack modes in CLT plates, depending on geometric and/or material related properties. Therefore, plate‐bending experiments on three‐ and five‐layered CLT plates were carried out. In addition to standard evaluation methods, each specimen was cut into small cubes to identify the failure modes inside the plates. Regions with dominant shear failure, tensile failure, delamination and mixed failure modes could be captured and connected to geometry and loading situation. Based on this evaluation, well‐known but not yet in detail described effects, such as the ductile structural behaviour of CLT plates, can be explained. Moreover, the evolution of rolling shear failure modes as well as from which point the progressive failure highly affects the plate stiffness is investigated and analysed in detail.     

爆炸载荷作用下临界震塌爆距公式研究

坑道震塌破坏机制复杂,是工程中亟待解决的难题之一。为了得到便于工程应用的临界震塌爆距计算公式以及影响临界震塌爆距的主要因素,在常用经验公式的基础上,通过拟合爆距与洞跨比影响系数,将经验公式显化,推导的修正公式不需要反复迭代试算,使用方便。利用ANSYS/LS-DYNA有限元分析软件对坑道正上方装药爆炸进行数值模拟,得出临界震塌爆距,其结果与修正公式相比较,表明修正公式与模拟结果吻合较好,可用于临界震塌爆距的计算。数值模拟临界震塌爆距随洞室跨度的变化,结果表明:洞室跨度越大,临界震塌爆距越大,且趋于某一极限值;洞室跨度小于15 m时临界震塌爆距随洞跨的增大增幅较快。     

Buckling of Cracked Laminated Composite Cylindrical Shells Subjected to Combined Loading

A series of finite element analysis on the cracked composite cylindrical shells under combined loading is carried out to study the effect of loading condition, crack size and orientation on the buckling behavior of laminated composite cylindrical shells. The interaction buckling curves of cracked laminated composite cylinders subject to different combinations of axial compression, bending, internal pressure and external pressure are obtained, using the finite element method. Results show that the internal pressure increases the critical buckling load of the CFRP cylindrical shells and bending and external pressure decrease it. Numerical analysis show that axial crack has the most detrimental effect on the buckling load of a cylindrical shell and results show that for lower values of the axial compressive load and higher values of the external pressure, the buckling is usually in the global mode and for higher values of axial compressive load and lower levels of external pressure the buckling mode is mostly in the local mode.     

Dynamic Deformation of Clamped Circular Plates Subjected to Confined Blast Loading

In this paper, the dynamic deformation of thin metal circular plates subjected to confined blast loading was studied using high‐speed three‐dimensional Digital Image Correlation (3D DIC). A small‐scale confined cylinder vessel was designed for applying blast loading, in which an explosive charge was ignited to generate blast loading acting on a thin metal circular plate clamped on the end of the vessel by a cover flange. The images of the metal plates during the dynamic response were recorded by two high‐speed cameras. The 3D transient displacement fields, velocity fields, strain fields and residual deformation profiles were calculated by using 3D DIC. Some feature deformation parameters including maximum out‐of‐plane displacement, final deflection, maximum principal strain and residual principal strain were extracted, and the result was in good agreement with that simulated by AUTODYN. A dimensionless displacement was introduced to analyse the effects of plate thickness, material types and charge mass on the deflection of metal plates. DIC is also proven to be a powerful technique to measure dynamic deformation under blast loading.     

Micro-Mechanical Behavior of a Unidirectional Composite Subjected to Transverse Shear Loading

The effects of interphase between fibers and matrix on the micro-and macro-mechanical behaviors of fiber-reinforced composite lamina subjected to transverse shear load at remote distance have been studied. The interphase has been modeled by the compliant spring-layers that are linearly related to the normal and tangential tractions. Numerical analyses on composite basic cells have been carried out using the boundary element method. For undamaged composites the micro-level stresses at the matrix side of the interphase and effective shear modulus have been calculated as a function of the fiber volume fraction and the interphase stiffness. Results are presented for various interphase stiffnesses from perfect bonding to total debonding. For a square array composite results show that for a high interphase stiffness k > 10, an increase in a fiber volume fraction results in a higher effective transverse shear modulus. For a relatively low interphase stiffness k < 1, it is shown that an increase in the fiber volume fraction causes a decrease in the effective transverse shear modulus. For perfect bonding, the effective shear modulus for a hexagonal array composite is slightly larger than that for a square array composite. Also for the damaged composite with partially debonded interphase, local stress fields and effective shear moduli are calculated and a decrease in the effective shear modulus has been observed.     

地铁地下结构内爆炸防护问题研究

地铁地下结构作为重要的生命线工程,进行抗爆设计具有重要的意义,而我国在地铁地下结构应对突发性爆炸的防护技术方面研究起步晚,基础薄弱.在参考国内外地铁地下结构抗爆设计研究成果的基础上,阐述了需要亟待解决的四个问题:炸药爆炸当量估算方法和设防标准的确定,地铁地下结构内冲击波流场的研究,地铁地下结构内爆炸破坏效应模型建立及人员伤亡效应评估,地铁地下结构的抗爆设计和抗爆加固设计技术措施研究.这些问题的研究和解决将对新建地铁地下结构的抗爆没计和现有地铁结构抗爆加固技术措施提供坚实的理论基础.