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在新课程理论指导下,我们的课堂教学打破了传统教学中老师主宰一切的局面,形成了可变的师生多向互动的关系,形成了开放的课堂教学.在这个过程中,会促使课堂数学中多向、多种类型信息得到交流,学生的个性得到充分的发展,学生的认知、情感等得到有效的发展.…… 相似文献
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飞机复合材料层压板结构中的广义强度准则 总被引:1,自引:0,他引:1
通过对经典复合材料结构强度理论和准则在层压板上的适用性计算和试验对比研究,指出了在层压板上采用经典强度理论所得计算结果与试验结果的差异。并分析了产生这种差异的原因,主要是经典强度准则表达武中采用的无拉剪耦合假设和层与层之间理想粘接假设,只适用于单层板或正交各向异性板。本文提出了一种广义强度准则的思想,其核心是放松正交各向异性约束条件和通过试验测定强度参数,而在实际飞机结构中的准正交各向异性层压板结构设计上仍可使用经典层压板强度准则。 相似文献
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一种考虑决策者偏向的综合模糊聚类方法 总被引:2,自引:0,他引:2
在分析传统模糊聚类分析方法的基础上,提出了一种建立模糊相似矩阵R的新方法,以及能够充分体现决策者偏好和经验的多向综合模糊聚类方法。该方法简单、实用、能够全面反映事物的特征,具有一定的实用价值。 相似文献
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In the symplectic space composed of the original variables, displacements, and their dual variables, stresses, the symplectic
solution for the composite laminates based on the Pipes-Pagano model is established in this paper. In contrast to the traditional
technique using only one kind of variables, the symplectic dual variables include displacement components as well as stress
components. Therefore, the compatibility conditions of displacement and stress at interfaces can be formulated simultaneously.
After being introduced into the symplectic dual system, the uniform schemes, such as the separation of variables and symplectic
eigenfunction expansion method, can be implemented conveniently to analyze composite laminate problems. An analytical solution
for the free edge effect of composite laminates is obtained, showing the effectiveness of the symplectic dual method in analyzing
composite laminates. 相似文献
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纤维复合材料极低温力学性能的试验研究国内尚处于空白阶段。利用国际间的多国合作计划,采用三点弯曲和层间剪切两种试验方法,对G-10CR玻璃布/环氧层压板的低温剪切性能进行了对比研究。试验结果发现该材料低温下的剪切强度较室温有明显增加,且低温下表现出了和室温不同的破坏机制。 相似文献
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We propose a new laser preparation technique to solder Sn-Ag3.5-Cu0.7 on a copper clad laminate (CCL). The experiment is conducted by selective laser heating and melting the thin solder layer and then preprinting it on CCL in order to form the matrix with solder pads. Through the analysis of macro morphology of the matrix with solder pads and microstructure of single pads, this technique is proved to be suitable for preparing solder pads and that the solder pads are of good mechanical properties. The results also reveal that high frequency laser pulse is beneficial to the formation of better solder pad, and that the 12-W fiber laser with a beam diameter of 0.030 mm can solder Sn-Ag3.5-Cu0.7 successfully on CCL at 500-kHz pulse frequency. The optimized parameters of laser soldering on CCL are as follows: the laser power is 12 W, the scanning speed is 1.0 mm/s, the beam diameter is 0.030 ram, the lead-free solder is Sn-Ag3.5-Cu0.7, and the laser pulse frequency is 500 kHz. 相似文献
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