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1.
圆环面上纤维轨迹的计算机辅助设计   总被引:2,自引:0,他引:2  
曲面上的曲线造型是计算机图形领域的一个新的研究热点,而且它们在纤维织物编织,三维服装裁剪以及复合材料的纤维缠绕轨迹设计等领域有十分广泛的应用,为了解决圆环面上纤维轨迹的计算机辅助设计问题,研究了圆环面上测地线的解析解以及拟测地线数值求解的具体算法并给出了其表达式,测地线是曲面上两点之间最短距离的曲线段,在一般曲面上没有解析解,但是在圆环面上却可求出其精确的解析解,但在曲面的边沿部分,测地线因不能实现自然的折返过渡,于是拟测地线就被引进到曲面上的曲线造型设计之中,在拟测地线分析研究基础上,给出了圆环面上拟测地线的方程及数值解法,通过其在一个实例中的应用结果证明,该方法可获得织物的纺织条纹以及缠绕物体的纤维轨迹。  相似文献
2.
有初始缺陷复合材料梁在湿热状态下混沌运动   总被引:2,自引:2,他引:0       下载免费PDF全文
在考虑剪切变形的影响基础上,研究了有初始缺陷复合材料梁在湿热状态下的混沌运动,并讨论分析了剪切变形、初始缺陷、温度、湿度等因素对混沌运动区域的影响,得到了以下结论:当温度升高时,非完善复合材料粱发生混沌运动区域增大;当初始缺陷程度增加,非完善复合材料梁的混沌运动区域越来越小;湿度升高时。非完善复合材料梁发生混沌运动区域增大;当考虑剪切变形影响时非完善复合材料梁的混沌运动区域变大;在湿热状态下理想复合材料梁的混沌运动区域要比非完善复合材料梁的混沌运动区域大。  相似文献
3.
机织复合材料内部损伤的图像检测方法研究   总被引:1,自引:0,他引:1  
在机织复合材料结构预成型时织入光纤网络,并经RTM(Resintransfermoulding,树脂传递模塑)工艺成型。文中分别采用光纤网络损伤检测方法和图像增强反向照明方法,实时显示受冲击机织结构内部损伤产生和扩展的图像。实验证明了这两种方法结果的一致性。对比层合结构和机织结构冲击损伤扩展的反向照明图像,显示后者有更高的抗冲击能力。  相似文献
4.
基于瞬态动力学复合材料火箭定向器数值仿真   总被引:1,自引:1,他引:0  
随着世界军事科学的日益发展,纤维增强复合材料在武器装备上得到越来越多的应用,为了深入研究纤维增强复合材料定向器的刚强度,必然要对各种参数进行大量的实验,造成效费比很高.为解决这个问题,文中用数值仿真的方法对玻璃纤维增强复合材料火箭定向器进行了研究,计算了火箭在定向器内运行的全过程,得到了复合材料定向器的一些有价值的计算数据曲线.数值计算结果与实际数据对比,取得良好的一致性.研究表明,用该复合材料制成的火箭定向器完全能够满足工程需要.  相似文献
5.
Mapping method for sensitivity analysis of composite material property   总被引:1,自引:0,他引:1  
Composite properties are dependent on the microstructure of materials, which is depicted with a base cell. The parameters for representing the microstructure should include the shape parameters of the base cell and those used to describe the distribution of materials in the base cell. The goal of material design optimization is to find appropriate values of these parameters to make the materials have specific properties. Design optimization needs the sensitivity information of the material properties with respect to the shape parameter of the base cell and the material distribution parameters. Moreover, sensitivity calculation is often expensive. Thus, it is very important to develop an efficient sensitivity analysis method. In this paper, a mapping method is proposed for predicting the material properties and computing their sensitivities with respect to the shape parameters of the base cell. Through mapping transformation, solutions to the micro-scale homogenization problem defined on the domain of a base cell can be obtained by solving a homogenization problem defined on an initial given domain. The composite properties and their sensitivities with respect to the shape parameters of the base cell are explicitly expressed in terms of the properties and their sensitivities of a virtual material with respect to the distribution parameters. This virtual material has an initially given base cell domain. Thus re-meshing for discretizing the problem is avoided and computing cost savings are realized. Numerical examples show that the proposed method is accurate and efficient in both the prediction of material properties and sensitivity calculation.  相似文献
6.
碳纤维复合材料的超声反射波频域定征分析   总被引:1,自引:0,他引:1  
对碳纤维复合材料的孔隙率进行超声测试法研究,发现材料前后表面超声回波均值频率偏移量与材料内部孔隙率,与超声信号衰减之间存在着特定关系.提出前后表面回波均值频率偏移特性为基础的超声无损表征方法,通过最小二乘法算法对材料内部孔隙率和超声衰减进行了定量分析,实验结果证明了该方法的实用性.  相似文献
7.
The use of fiber reinforced polymers (FRP) to reinforce and retrofit reinforced concrete (RC) structures has become one of the main applications of composites in civil engineering. This paper describes a procedure, based on a finite element formulation, that can be used to perform numerical simulations of RC structures reinforced with FRP. Composites are treated using the serial/parallel mixing theory, which deduces the composite behavior from the constitutive equations of its components. A new construction-stages algorithm is developed for simulating retrofitted structures. The performance of the proposed formulation is proved comparing numerical and experimental results. Finally, the developed code is used to obtain the optimum FRP reinforcement configuration for a RC frame structure.  相似文献
8.
The Rao–Nakra model of a three layer sandwich beam is analyzed for exact boundary controllability. The damped and undamped cases are considered. The multiplier method is used to obtain required observability inequalities that imply controllability. It is shown that if the control time T is large enough, under certain other parametric restrictions, the system is exactly controllable.  相似文献
9.
A composite material of nano-sized SiO2 and poly(2-acrylamido-2-methylpropane sulfonate) (poly(AMPS)) was used to make a humidity sensor. The infrared (IR) spectra and microstructure of the material were analyzed, and the humidity sensing and electrical properties of the sensor were measured. The sensor well responded to humidity with a relative good linearity, though it depended on the applied frequency. The temperature influence between 15 and 35 °C was −0.71 and −0.15% RH/°C at 30 and 90% RH, respectively. The sensor showed a negligible hysteresis and fast response time upon humidification and desiccation. The stability of the sensor in a highly humid and alcoholic environment increased with increasing the SiO2 content. The activation energy for conduction reduced with water adsorption. The different impedance plots observed at low and high relative humidity suggested different sensing mechanisms of the SiO2/poly(AMPS) composite material.  相似文献
10.
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