共查询到20条相似文献，搜索用时 31 毫秒
1.
提出了一种基于粒子群算法的织物组织结构识别新方法。该方法采用USB数码显微镜摄取布样图像,经直方图均衡化以增加灰图图像对比度、二值化、去除噪声等一系列图像预处理,用经线纬线的宽度法来提取织物组织结构的特征,用粒子群算法进行识别分类。实验结果表明,通过该方法对织物组织结构的识别具有较高的准确率。 相似文献
2.
以蒙皮材料Uretek3216L为对象开展了膜材的双轴循环拉伸力学性能试验研究.首先,通过一系列双轴循环试验获得了膜材的应力应变数据,并对其非线性、各向异性等性质进行了探讨分析.然后,运用应变残差最小二乘法,计算出不同应力比组合的弹性常数.最后,分析了应力比的组合方法及正交互补性质对膜材弹性常数的影响规律.结果表明,经纬向纱线卷曲形态的不均衡性是膜材正交异性特征的主要原因.膜材的弹性常数受应力比组合方法及正交互补性质的影响显著,且弹性模量随名义应力比的改变而有规律地变化.在结构设计中,需要根据具体受力状态及应力比范围来确定膜材的弹性常数,以提高设计分析的精确性;且考虑到弹性常数的多变性,采用2组界限弹性常数比仅采用1组更可取. 相似文献
3.
A continuum damage mechanics （CDM） meso-model was derived for both intraply and interply progressive failure behaviors of a 2D woven-fabric composite laminate under a transversely low velocity impact.An in-plane anisotropic damage constitutive model of a 2D woven composite ply was derived based on CDM within a thermodynamic framework,an elastic constitutive model with damage for the fibre directions and an elastic-plastic constitutive model with damage for the shear direction.The progressive failure behavior of a 2D woven composite ply is determined by the damage internal variables in different directions with appropriate damage evolution equations.The interface between two adjacent 2D woven composite plies with different ply orientations was modeled by a traction-separation law based interface element.An isotropic damage constitutive law with CDM properties was used for the interface element,and a damage surface which combines stress and fracture mechanics failure criteria was employed to derive the damage initiation and evolution for the mixed-mode delamination of the interface elements.Numerical analysis and experiments were both carried out on a 2D woven glass fibre/epoxy laminate.The simulation results are in agreement with the experimental counterparts,verifying the progressive failure model of a woven composite laminate.The proposed model will enhance the understanding of dynamic deformation and progressive failure behavior of composite laminate structures in the low velocity impact process. 相似文献
4.
Showmore Mafirakureva 《海外英语》2012,(9):276-280
If an uncut woven pile fabric is to be subjected to compressive load in use its compression resilience performance becomes very crucial.In order to optimize the extent of recovery in fabric thickness when the applied force is removed,thirteen uncut woven pile fabric samples were woven and tested on KES-G5 Hand Type Compression Tester (small compress Hammer).The results show that the above parameters influence compression resilience property of the uncut woven pile fabrics,and the structural factors have a more pronounced effect as compared to effect of fibre and yarn type. 相似文献
5.
王航罗敏峰 《福建工程学院学报》2021,(6):524-531
为探究金属工件在砂带磨削加工中的材料去除机理,对砂带磨削系统简化后建立几何模型,并设置模型参数及运动建立了砂带磨削加工的离散元动态仿真。仿真结果表明:通过单因子试验研究不同的磨削参数对材料去除深度(material removal depth, MRD)的影响规律?通过正交试验得到不同磨削参数对MRD 的影响贡献率,其中砂带转速的影响最大、其次是砂带进给量,同时得到磨削参数的最优组合为工件进给量为0.5 mm,砂带转速为1 800 r/ min,工件速度为40 mm/ s,水平夹角为40°;最后通过实验验证仿真结果与结论的正确性。 相似文献
6.
张国辉 《南通职业大学学报》2001,15(2):46-47
除纱线的刚度，经纬纱的特数和后整理过程中织物经纬向受力等因素外，织造参变数对织物结构相的影响是很大的，本就织造参变数中的经纱上机张力，后梁高度，开口时间等对织物结构相的影响进行分析。 相似文献
7.
To study the bending strength of mass concrete under dynamic loading, the pure bending zone of three-graded concrete beam is considered as a three-phase composite composed of matrix, aggregate and interface between them on meso-level. Dynamic constitutive model considering strain-rate strengthening effect and damage softening effect is adopted to describe the cocrete and meso-element's damage. The failure mechanisms of beam under impact loading, triagle wave load, dynamic load coupling with initial static loading were simulated by using displacement-controlled FEM. Furthermore, stress-strain curve of the specimens and their dynamic bending strength were obtained. The results obtained from numerical simulation agreed well with experimental data. 相似文献
8.
To predict the distortion of aerospace monolithic components, a model is established to simulate the numerical control （NC） milling process using 3D finite element method （FEM）. In this model, the cutting layer is simplified firstly. Then, the models of cutting force and cutting temperature are established to gain the cutting loads, which are applied to the mesh model of the part. Finally, a prototype of machining simulation environment is developed to simulate the milling process of a spar. Key factors influencing the distortion, such as initial residual stress, cutting loads, fixture layout, cutting sequence, and tool path are considered all together. The total distortion of the spar is predicted and an experiment is conducted to validate the numerical results. It is found that the maximum discrepancy between the simulation results and experiment values is 19.0%. 相似文献
9.
弹性针织运动胸衣的纸样处理 总被引：1，自引：0，他引：1
从运动胸衣的功能出发,在日本文化式原型的基础上,通过去除多余的松量得到其基本结构,并分析了弹性针织面料的弹性运用率,提出了纬弹和经纬加弹两种情况下的运动胸衣纸样处理方法. 相似文献
10.
To improve the machining precision of a surface grinding machine, a micropositioning workpiece table with high performance was used as auxiliary infeed mechanism to implement nanometer level positioning and dynamic compensation. To better understand the characteristics of the grinding machine modulated with micropositioning workpiece table, the dynamic model of the grinding system was established with modal synthesis and Lagrange's equation methods. The grinding system was divided into five subsystems. For each subsystem, the generalized kinematic and potential energies were obtained. Accordingly the dynamic model of the grinding system was given in the modal domain. The waviness of the grinding process was achieved based on the wheel and workpiece vibration. A nonlinear proportional integral derivative (PID) controller with differential trackers was developed to realize dynamic control. The simulation results show that the machining accuracy of the workpiece can be effectively improved by utilizing the micropositioning workpiece table to implement dynamic compensation. An experimental test was carried out to verify the proposed method, and the waviness of the workpiece can be reduced from 0.46 μm to 0.10 μm. 相似文献
11.
应用SINUMERIK 802D数控系统开发工具磨床的研究 总被引：1，自引：0，他引：1
陈兴武 《福建工程学院学报》2003,1(3):40-44
采用SINUMERIK 802D数控系统，对国产手动工具磨床进行数控改造。通过更换导轨、改进传动结构、增加计算机数控回转轴等硬件，使手动工具磨床实现数控四轴联动，加工各种复杂工具。一套简明实用的编程方法使复杂工具可以在改造后的cNc磨床上实现数控磨削加工，提高加工精度、生产效率和系统的性能／价格比。 相似文献
12.
亲属称谓是随着相应的社会关系的建立而产生的语言符号,因此,从亲属称谓的多少及变化的方式可以看出社会关系,特别是亲属关系的复杂程度及亲属之间关系的亲疏.花腰彝社会是以家族亲属关系中的本家为经,以外家为纬,交织成的一个网状结构.这个网状结构在时空中无限延伸成为一个以家族为主线,以姻亲为支线的错综复杂的社会网络.血缘关系和姻亲关系是人类社会中最为基础,也是最为稳定的一种关系,是网络状社会关系中的关键节点.本文主要从本家和外家亲属之间的互称来探讨花腰彝亲属称谓语及其特点. 相似文献
13.
针对复杂结构仿真中有限元仿真精度及效率不高的问题,提出采用高阶响应面方法进行建模及优化,并用桥梁模型来验证。选取合适参数,采用试验设计获取响应样本点,基于数理统计的逐步回归法对各自变量进行显著性分析,筛选对目标响应函数显著度高的自变量,再应用最小二乘法拟合各自变量的系数,得到三阶多项式响应面模型,用多目标优化算法进行优化。对比修正前后模态频率,结果表明应用响应面方法能得到简单而高精度的结构模型,从而验证了高阶响应面方法在建模及模型优化中的有效性。 相似文献
14.
受沿经向简单剪切的织物屈曲分析 总被引：5，自引：0，他引：5
分析了织物受沿经向简单剪切时的屈曲 ,得到确定织物屈曲方向 (屈曲波的方向 )的方程 ,该方程表明织物屈曲方向与临界剪切值有关 .还证明了织物受沿经向简单剪切时会发生离面屈曲 ,并且只存在一种屈曲模态——弯曲屈曲模态 ,得到了该屈曲模态的屈曲条件及屈曲条件曲线 . 相似文献
15.
A new method was worked out to improve the precision of springback prediction in sheet metal forming by combining the finite element method (FEM) with the data mining (DM) technique. First the genetic algorithm (GA) was adopted for recognizing the material parameters. Then according to the even design idea, the suitable calculation scheme was confirmed, and FEM was used for calculating the springback. The computation results were compared with experiment data, the difference between them was taken as source data, and a new pattern recognition method of DM called hierarchical optimal map recognition method (HOMR) is applied for summarizing the calculation regulation in FEM. At the end, the mathematics model of the springback simulation was established.Based on the model, the calculation errors of springback can be controlled within 10 % compared with the experimental results. 相似文献
16.
侯敏 《鞍山师范学院学报》2013,(5):74-76
中国新诗在现代文学30年的发展历程中,在"民族"与"现代"的双重视野下不断地走向了成熟。如果说第一个十年(1917~1927)是中华民族现代诗的形成期,那么第二个十年(1928~1937)和第三个十年(1938~1949)则分别是中华民族现代诗的发展期和成熟期。本文以时间为经,以作家、流派为纬,对现代文学三十年的中国新诗发展历程作一整体性的勾勒,并深入透析中华民族现代诗的建构问题。 相似文献
17.
In this paper, a stabilized finite element technique, actualized by streamline upwind Petrov-Galerkin (SUPG) stabilized method
and three-step finite element method (FEM), for large eddy simulation (LES) is developed to predict the wind flow with high
Reynolds numbers. Weak form of LES motion equation is combined with the SUPG stabilized term for the spatial finite element
discretization. An explicit three-step scheme is implemented for the temporal discretization. For the numerical example of
2D wind flow over a square rib at Re=4.2×105, the Smagorinsky’s subgrid-scale (SSGS) model, the DSGS model, and the DSGS model with Cabot near-wall model are applied,
and their results are analyzed and compared with experimental results. Furthermore, numerical examples of 3D wind flow around
a surface-mounted cube with different Reynolds numbers are performed using DSGS model with Cabot near-wall model based on
the present stabilized method to study the wind field and compared with experimental and numerical results. Finally, vortex
structures for wind flow around a surface-mounted cube are studied by present numerical method. Stable and satisfactory results
are obtained, which are consistent with most of the measurements even under coarse mesh. 相似文献
18.
大口径非球面磨削系统中的电源控制 总被引：1，自引：0，他引：1
大口径非球面磨削系统主要采用的是840D数控对工件进行磨削,而电源的控制在整个840D数控系统中是非常重要的.本系统采用西门子的PLC控制系统的上下电顺序,完成对整个系统的电源控制. 相似文献
19.
1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｔｈｅｔｒａｄｉｔｉｏｎａｌｍｅｔｈｏｄｔｏｓｔｕｄｙｔｈｅｐｅｒｆｏｒｍａｎｃｅｓｏｆｉｎｄｕｃｔｉｏｎｍｏｔｏｒｓｉｓｂａｓｅｄｏｎｔｈｅｃｏｎｃｅｐｔｏｆｅｑｕｉｖａｌｅｎｔｃｉｒｃｕｉｔ.Ｔｈｅｐａｒａｍｅｔｅｒｓｉｎｔｈｅｅｑｕｉｖａｌｅｎｔｃｉｒｃｕｉｔａｒｅｕｓｕａｌｌｙｏｂｔａｉｎｅｄｂｙｍａｇｎｅｔｉｃｃｉｒｃｕｉｔｃｏｍｐｕｔａｔｉｏｎ .Ｉｎｒｅ ｃｅｎｔｙｅａｒｓｉｔｈａｓｂｅｃｏｍｅｐｒａｃｔｉｃａｌｔｏｕｓｅｆｉｎｉｔｅｅｌｅｍｅｎｔｍｅｔｈ… 相似文献
20.
贺姗姗 《襄樊职业技术学院学报》2013,(5):61-63,70
作为先锋小说和新历史主义的代表作家,苏童的小说有着独特的语言魅力.细细品味苏童小说的语言,你可以在诗意与梦魇相交织的感受中体会到一种神秘诡异的力量.无论是“枫杨树”系列、“香椿树”系列,还是后来的“红粉”系列,苏童以轻盈细腻的诗意性语言为经,以诡谲怪异的梦魇式语言为纬,在家族、历史故事中穿凿,为自己织就了如蛛网般错杂斑斓的“纸上故乡”,为读者呈现出别样的南方风景. 相似文献