首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3篇
  完全免费   6篇
  物理学   9篇
  2020年   1篇
  2018年   1篇
  2016年   1篇
  2014年   1篇
  2008年   1篇
  2003年   2篇
  1995年   1篇
  1991年   1篇
排序方式: 共有9条查询结果,搜索用时 250 毫秒
1
1.
光弹法测量超声换能器声场   总被引:3,自引:3,他引:0       下载免费PDF全文
超声换能器声场的测试对于超声检测具有基础性作用,而传统的超声换能器声场测试方法具有一些局限性。本文介绍了搭建的动态激光光弹实验平台,并利用动态光弹法测量了纵波换能器和横波换能器辐射声场的特征,由瞬态声场图像获得了传声介质的声波速度及超声换能器的中心频率;由稳态声场图像获得了声场的近场长度、指向性和扩散角等参数;分析了光弹实验系统和测量方法可能引起测量误差。本文结果表明动态光弹法是一种有效的定量测量超声换能器声场的方法。  相似文献
2.
为了研究变壁厚结构中兰姆波的传播特性,以K9玻璃制成的台阶板为波导,运用动态光弹法实现了兰姆波在阶梯板中传播过程的可视化。使用MATLAB对兰姆波的理论应力分布进行了仿真,将仿真结果与光弹图像相对比以进行模式识别。此外,根据兰姆波的动态光弹图像计算了特定模式的相速度,并与相速度频散曲线相对比,以支持模式识别的结果。对4mm-3mm和4mm-2mm厚度差台阶板进行了对比分析。研究发现在激励目标模式的兰姆波时,可能会出现非目标模式,并且兰姆波的模态转换与频散程度与台阶处的厚度差有关。本文的结果可对具有相同性质类似结构材料的无损检测提供参考。  相似文献
3.
为了研究超声表面脉冲波在钢、铁等不透明曲面材料中的传播规律,我们采用和金属材料声速比较接近的光学玻璃作样品,利用研制的数字化动态光弹系统,分析了表面波和次表面波沿玻璃圆棒侧面传播时的行为,记录了不同时刻的横截面上的脉冲声场传播图像,求出了表面波和次表面波沿曲面爬行的传播速度。  相似文献
4.
回顾了基于动态光弹技术的超声应力测量方法,分析了各方法的优缺点。优化了现有光弹系统的前端光路,提出了电控旋转偏振和自动判读技术,研制了高稳定性的动态光弹实验系统。利用Senarmont补偿法实现了高精度的应力测量。多次重复测量结果表明,该系统测量结果的相对标准偏差小于1%。光弹测量数据与电测结果相比,其相似系数为99.95%,显著性水平小于0.001,证明了测量结果的可靠性。  相似文献
5.
The generation and the subsequent evolution of dynamic failure events in homogeneous layered materials that occur within microseconds after impact were investigated experimentally. Tested configurations include three-layer and two-layer, bonded Homalite specimens featuring different bonding strengths. High-speed photography and dynamic photoelasticity were utilized to study the nature, sequence and interaction of failure modes. A series of complex failure modes was observed. In most cases, and at the early stages of the impact event, intra-layer failure (or bulk matrix failure) appeared in the form of cracks radiating from the impact point. These cracks were opening-dominated and their speeds were less than the crack branching speed of the Homalite. Subsequent crack branching in several forms was also observed. Mixed-mode inter-layer cracking (or interfacial debonding) was initiated when the intra-layer cracks approached the interface with a large incident angle. The dynamic interaction between inter-layer crack formation and intra-layer crack growth (or the so-called “Cook–Gordon Mechanism”) was visualized for the first time. Interfacial bonding played a significant role in impact damage spreading. Cracks arrested at weak bonds and the stress wave intensity was reduced dramatically by the use of a thin but ductile adhesive layer.  相似文献
6.
The Rayleigh pulse interaction with a pre-stressed, partially contacting interface between similar and dissimilar materials is investigated experimentally as well as numerically. This study is intended to obtain an improved understanding of the interface (fault) dynamics during the earthquake rupture process. Using dynamic photoelasticity in conjunction with high-speed cinematography, snapshots of time-dependent isochromatic fringe patterns associated with Rayleigh pulse–interface interaction are experimentally recorded. It is shown that interface slip (instability) can be triggered dynamically by a pulse which propagates along the interface at the Rayleigh wave speed. For the numerical investigation, the finite difference wave simulator SWIFD is used for solving the problem under different combinations of contacting materials. The effect of acoustic impedance ratio of the two contacting materials on the wave patterns is discussed. The results indicate that upon interface rupture, Mach (head) waves, which carry a relatively large amount of energy in a concentrated form, can be generated and propagated from the interface contact region (asperity) into the acoustically softer material. Such Mach waves can cause severe damage onto a particular region inside an adjacent acoustically softer area. This type of damage concentration might be a possible reason for the generation of the “damage belt” in Kobe, Japan, on the occasion of the 1995 Hyogo-ken Nanbu (Kobe) Earthquake.  相似文献
7.
动态光弹成像技术是观测固体内部超声应力场的重要手段,然而样品在制作过程中会产生残余应力,给观测带来一定干扰,特别是缺陷附近的应力集中效应,使得缺陷散射声场的研究更为困难。本文利用线性应力理论分析了超声应力与残余应力的相互关系,并推导出该叠加应力场在光弹系统中的光强表达式,通过实验验证,证明了该理论的可行性。本文结果可为应力集中区域的散射声场分析提供借鉴。  相似文献
8.
Over the years, several techniques have been developed to record dynamic fringe patterns in photoelasticity. Due to the whole field recording capability, the photoelastic technique continues to be of interest to the experimental mechanics community. A low-cost dynamic recording system employing an out-dated fax scanner is presented in this article. Details of the optical and electronic functions are discussed. The feasibility of the system is demonstrated by recording dynamic fringe patterns off a simply supported beam subjected to impact loading. Further modifications to the set-up to improve the quality of the fringe patterns are discussed briefly.  相似文献
9.
黄福 《光子学报》1991,20(4):418-422
高速动光弹仪是动态光弹性研究的有效诊断工具,主要用于记录各种结构在动载荷作用下,不同瞬间的应力条纹图像。研究应力波的传播规律,裂纹扩展过程,固体高速变形等。通常的动光弹仪为多火花式动光弹仪。国外也有采用静态光弹仪与转镜式高速分幅相机结合的系统。我们研究调试的动光弹系统,是在高速纹影系统中加入偏振光场,即静态光弹系统、纹影系统与转镜式高速分幅相机结合。在雷管动载荷作用下,应用高压脉冲氙灯光源,单色圆偏振光亮场,获得了不同光弹模型的清晰应力条纹图像。给出应力波的传播过程和孔附近产生的应力集中现象。该系统具有摄影频率高、曝光时间短、测试灵敏度高、适于强载荷、远距离研究大尺寸光弹模型,同时具有透射式和反射式光学系统等特点。从而为动态光。弹性研究提供了有效的测试技术和诊断系统。  相似文献
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号