基于LabVIEW Vision的航空炮弹缺陷检测方案设计

航空炮弹在勤务保障过程中,容易受到环境和外力的破坏而造成表面的损伤,影响正常的飞行训练甚至危及载机安全。采用虚拟仪器平台提供的LabVIEW Vision视觉开发工具包,结合灰度直方图筛选、Saturation分量图像提取、灰度形态学Erode和Dilate变换以及最大熵阈值分割的图像处理等技术手段,对待测航空炮弹图像进行分析处理,精确判断炮弹锈蚀和划痕缺陷问题。试验结果表明,系统具有较高的可行性和可靠性,可以实现炮弹缺陷的快速鲁棒检测,提高了炮弹检测的效率和精度,对于提升航空弹药保障信息化、智能化水平具有重要意义。     

线膛火炮后期寿命分析

弹带削光是火炮寿命终结的标志,通过分析弹带削光的过程和机理,建立炮弹在严重磨损炮膛内的运动模型,提出了为延长火炮后期寿命,在进行弹带和身管内膛设计时应注意的一些问题。     

薄壳稳定的变分原理

按照易曲物体的形变理论来确定薄壳的内力和内矩、变形位能以及外力的功,根据虚位移原理求得临界载荷的能量准则,并导出稳定问题的平衡方程和边界条件。对公式进行了合理的分析和简化     

圆锥壳方程的二次渐近解

本文由旋转壳的一对二阶常微分方程得出圆锥壳的复变量方程,利用渐近积分法推导出方程的一次近似解和二次近似解。二次近似解达到薄壳理论所具有的精度,一次近似解也具有足够精度。对于所取算例,本文解的计算结果与已有的Kelvin函数解的结果符合良好。但本文解为有限形式的简单表达式,便于计算应用。     

水下爆炸载荷作用下受损加肋圆柱壳的剩余屈曲强度计算

研究了在水下爆炸载荷作用下受损的加肋圆柱壳的屈曲.结合DYTRAN软件和NASTRAN软件计算了水下爆炸载荷作用下受损的加肋圆柱壳的剩余屈曲强度,并且提出了一种结合上述两种软件计算加肋圆柱壳的剩余屈曲强度的方法.数值计算表明,预测结果与实验结果吻合较好.     

关于圆柱壳在水下爆炸冲击波作用下二次加载现象的数值模拟研究

运用大型商业有限元程序MSC.DYTRAN数值模拟了水下爆炸冲击波载荷作用下自由环肋圆柱壳的非线性动态响应.采用一般耦合算法(generalcoupling)模拟流体与结构的耦合效应,计算中考虑了材料的应变率强化效应,几何非线性的影响,分析了空穴现象的产生和二次加载对结构响应的影响.仿真结果表明,相同工况和厚度下的无限自由平板和自由环肋圆柱壳,后者的空化时间比前者长,而壳体运动的最大速度后者比前者低.     

Effect of the end cap on the fragment velocity distribution of a cylindrical cased charge

The prediction of the fragment velocity distribution of a cylindrical cased charge with end caps is one of the key issues to assess the damage efficiency of the warhead. However, limited work has been con-ducted to predict the fragment velocity distributions along the axis of cylindrical cased charges with end caps. This paper presents a study of the velocity distribution of fragments caused by the explosion of a cylindrical cased charge with end caps. The fragment velocity distribution and the end cap velocity were determined by an X-ray radiography method, and the axial fragment distribution was determined by witness plates. It was found that the velocities of fragments, especially near the edge, were increased when the end caps were added, and the position of maximum velocity is closer to the non-detonation end. The fragment velocities were increased, and the fragment projection range was decreased with the increase of the thickness of the end cap. A formula for fragment velocity distributions of a cylindrical cased charge with end caps, which is based on Huang's formula, was proposed by the theoretical analysis and data fitting and validated experimentally. The results indicate that the proposed formula is accurate in predicting the fragment velocity distribution along the axis of a cylindrical cased charge with end caps detonated at one end.     

The deformation and failure mechanism of cylindrical shell and square plate with pre-formed holes under blast loading

The deformation and failure mechanism of cylindrical shells and square plate with pre-formed holes under blast loading were investigated numerically by employing the Ansys 17.0 and Ls-Dyna 971. To calibrate the numerical model, the experiments of square plates with pre-formed circle holes were modeled and the numerical results have a good agreement with the experiment data. The calibrated numerical model was used to study the deformation and failure mechanism of cylindrical shells with pre-formed circle holes subjected to blast loading. The structure response and stress field changing process has been divided into four specific stages and the deformation mechanism has been discussed systematically. The local and global deformation curves, degree of damage, change of stress status and failure modes of cylindrical shell and square plate with pre-formed circular holes are obtained, compared and analyzed, it can be concluded as: (1) The transition of tensile stress fields is due to the geometrical characteristic of pre-formed holes and cylindrical shell with arch configuration; (2) The existence of pre-formed holes not only lead to the increasing of stress concentration around the holes, but also release the stress concentration during whole response process; (3) There are three and two kinds of failure modes for square plate and cylindrical shell with pre-formed holes, respectively. and the standoff distance has a key influence on the forming location of the crack initiating point and the locus of crack propagation; (4) The square plate with pre-formed holes has a better performance than cylindrical shell on blast-resistant capability at a smaller standoff distance, while the influence of pre-formed holes on the reduction of blast-resistant capability of square plate is bigger than that of cylindrical shell.     

复合材料偏心加筋壳特性分析

用任意加筋壳单元研究了复合材料偏心加筋壳结构的特性.研究表明,在结构几何尺寸已经确定的情况下,可以调整加强肋骨的偏心量,以改变加筋壳结构内部的受力和变形;调整加强肋骨的布置方式也是改变加筋壳结构强度和刚度的有效方法.     

基于双基阵的高炮弹丸炸点被动声定位研究

被动声定位技术在许多领域中有着广泛的应用,但定位精度低一直是影响其工程应用的关键问题之一。在研究单基阵被动声定位技术的基础上,提出了基于双基阵的被动声定位基本原理和方法,并对高炮弹丸炸点的被动声定位进行了仿真实验。仿真结果表明,采用双基阵对高炮弹丸炸点进行被动声定位,其精度有较大提高,克服了单基阵定位精度低的不足。此原理和方法同样适用于对其它三维空中目标进行被动声定位。