基于分段密集采点法的圆形材料半径非接触测量

对瓦状圆形材料的半径利用分段密集采点法进行测量,分析了分段密集采点法的数学模型及算法原理,并对算法的测量误差进行了讨论。在测量中首先利用图像采集卡获取材料的图像,利用图像处理技术提取材料边缘,扫描材料最尖端边界点的坐标,然后在边缘上选取间隔较大的三点做采样点,借助计算机软件编程算法求出圆心坐标,测得瓦状圆形材料半径的像素值。通过对测量的像素值进行数据的标定处理,最终得到瓦状材料半径的实际数值。从对测量结果的误差分析,最大偏差没有偏离出不确定度,误差较小。

圆形径向梯度表面能材料表面的凝结换热系数

在均质表面上的单个球缺形液滴换热模型和液滴通用尺度分布规律的基础上,结合梯度表面能材料表面上的液滴分布和凝结换热特性,得到了圆形径向梯度表面能材料表面上的滴状凝结换热计算式.在此基础上,研究了壁面过冷度、接触角梯度、工质物性等参数对梯度表面能材料表面滴状凝结换热性能的影响.

简析圆形断面材料在矫直过程中的弹塑性弯曲变形

圆形断面材料 ,尤其是薄壁管 ,在矫直过程中经常出现压扁和压纹现象。本文将矫直过程中的圆形断面材料看成一个连续弯曲的梁 ,精确给出了反弯矫直过程中试件的曲率、弯矩、变形能、挠度以及压扁率与塑性层深度系数的关系 ,说明试件在矫直机上进行弹塑性弯曲矫直时 ,塑性层深度系数的选取是矫直得以顺利进行、并最终实现矫直的关键 ,为矫直机的改造与发展指明了方向。

Python语言在复合材料教学中的应用

为了激发学生的学习兴趣、提高学生的学习效率,进而提高复合材料教学质量,文章首先论述了Python语言在复合材料教学中应用面临的挑战,然后阐述了Python语言在复合材料教学中应用的思路,最后提出了Python语言在复合材料教学中应用的实例,包括二维随机圆形骨料复合材料建模、螺旋结构建模、三维短纤维增强复合材料建模。

内置GFRP管钢管混凝土柱延性非线性分析

利用ABAQUS有限元软件建立内套圆形GFRP(玻璃纤维增强复合材料)管圆钢管混凝土组合柱轴心受压和单向偏心受压模型,研究内套GFRP管厚度、纤维缠绕角度、外层钢管厚度和构件长径比4个因素对构件的位移延性系数的影响,从而得到对构件的延性影响。结果表明:轴压工况下,此组合柱的位移延性系数随着内套圆形GFRP管厚度、长径比的增加而变小,随着外层钢管厚度递增而变大,GFRP管纤维缠绕角度在75°~90°对构件位移延性系数提升效果最好;偏压工况下,内套GFRP管厚度对组合柱的位移延性系数影响规律不明显,外层钢管厚度对构件的位移延性系数前期影响不大,但对后期影响显著,随着构件的长径比增大,构件的位移延性系数呈非线性下降。

Development,modeling and application of piezoelectric fiber composites

Piezoelectric materials are capable of actuation and sensing and have been used in a wide variety of smart devices and structures.Active fiber composite and macro fiber composite are newly developed types of piezoelectric composites,and show superior properties to monolithic piezoelectric wafer due to their distinctive structures.Numerous work has focused on the performance prediction of the composites by evaluation of structural parameters and properties of the constituent materials with analytical and numerical methods.Various applications have been explored for the piezoelectric fiber composites,including vibration and noise control,health monitoring,morphing of structures and energy harvesting,in which the composites play key role and demonstrate the necessity for further development.

Acoustic multipolar local effects of metamaterial with annular columnar structures

Research of the acoustic local effect of metamaterial is widely used in the fields of environmental science,military industry and biomedicine.In this paper,the metamaterial is designed by annular columnar structures.The acoustic local effect in slender columnar structure with two layers of rings in air is investigated.Results prove that when the plane acoustic wave is incident into the model,complex interference and diffraction occur.And at different frequencies,multipolar acoustic local effect existes and cycle distribution phenomenon is observed.It is noteworthy that this phenomenon has very weak relatedness with the materials and acoustic parameters of the model.The research of this metamaterial design in this paper has definite reference significance in the acoustic communication and amplification of the acoustic signal detection.

Research on vibration and near-field sound radiation of ring-ribbed cylindrical shell coated deadening and decoupling materials

The research on structural vibration and sound radiation of underwater ring-ribbed cylindrical shell, which is coated with a kind of deadening and decoupling materials, becomes a focus in recent years. This paper analyzes the problem on two aspects: model experiment and numerical calculation. The model experiment is carried out including three cases firstly, in which the structural vibration response and radiating acoustic field are measured respectively, and the results gained in these three cases are analyzed to discuss the effect of reducing structural vibration and radiating noise of the deadening and decoupling materials. The coupling FEM/BEM and the SEA methods are both used in numerical calculation, i.e. the arithmetic of the coupling FEM/BEM method is adopted to calculate the low frequency characteristics and the SEA method is adopted to calculate the medium-high frequencies characteristics of the model. By comparing experimental results with numerical calculation results, it is proved that the algorithm adopted in this paper is reasonable.

Propagation of elastic wave in nanoporous material with distributed cylindrical nanoholes

The effective propagation constants of plane longitudinal and shear waves in nanoporous material with random distributed parallel cylindrical nanoholes are studied. The surface elastic theory is used to consider the surface stress effects and to derive the nontraditional boundary condition on the surface of nanoholes. The plane wave expansion method is used to obtain the scattering waves from the single nanohole. The multiple scattering effects are taken into consideration by summing the scat- tered waves from all scatterers and performing the configuration averaging of random distributed scatterers. The effective propagation constants of coherent waves along with the associated dynamic effective elastic modulus are numerically evaluat- ed. The influences of surface stress are discussed based on the numerical results.