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21.
The solution of polarization field strength in ellipsoid and a homogeneous dielectric in condition of a constant external field is obtained with strict derivation and ellipsoidal coordinate. The conclusion that some textbooks given: the direction of polarization field strength with the direction of external field holds strict anti-parallel must be supplemented with additive certain conditions, otherwise it will not be correct. By means of the latticework and the step change calculation, the angle value of polarization vector with the external field is calculated and the changing situation about the angle value with the change of three half axes of ellipsoid is analysied. 相似文献
22.
Xu Jiang Xian Xuefu Du Yungui Zhang Guangyang 《保鲜与加工》1993,(5):42-47
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A new type of inorganic anchoring material is developed as a substitution for anchoring adhesive to overcome some imperfections in the process of planting reinforcing steel bar.The mix proportion of the anchoring material is determined by experiments.The compressive strength,adhesive force to concrete,volume stability and anchoring force with steel bar are studied.The early strength of the anchoring inorganic material is quite high: for 1d up to 38.5MPa and 3d up to 60MPa.It is a good adhesive to concrete and the adhesive strength of 28d is about 2MPa.The anchoring material will have tiny volume expansion with the age,which is beneficial to enhancing the anchoring force.The essential component of the inorganic anchoring material is cement-based material,so some defects of the organic macromolecular material can be avoided,such as poor stability and requirement for vigorous construction conditions.Its characteristics in early strength,adhesive force to concrete and volume expansion can satisfy the requirement of the construction to the planting reinforcing steel bar and the loading force,thus it can be used as a substituting material for anchoring adhesive. 相似文献
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为了研究约束高强度Q460钢梁的抗火性能,在已有约束钢梁分析理论的基础上,引入残余应力,提出了约束钢梁的抗火性能分析方法,并采用普通强度约束钢梁试验数据对分析方法进行了验证。考虑高强度Q460钢材高温下力学性能参数,利用所提出的方法分析了约束高强度Q460钢梁的抗火性能,并与普通强度Q345钢梁进行了对比。对影响约束高强度Q460钢梁的抗火性能参数进行了分析,包括荷载比、残余应力、轴向约束刚度、转动约束刚度和受火方式等。研究表明:所提出的分析方法准确可靠,高强度Q460钢梁抗火性能与普通强度钢梁具有较大的区别,高强度Q460约束钢梁的抗火性能明显优于普通强度约束钢梁。荷载比、轴向约束刚度、转动约束刚度、受火方式对高强度Q460约束钢梁有较大影响。 相似文献
27.
LIU Zhongming 《保鲜与加工》2015,(1):133-139
Based on pitting strength, some approaches to enhance power density of gearboxes for wind turbines are discussed. The calculation load is greatly reduced by power division. Allowable stress numbers are effectively increased by improving property of quality materials, precision heat treatment or shot peening. Load capacities can be also obviously enhanced by improving the tooth shape of morphology optimization of tooth root, tooth correction or superfinishing of tooth surface. The center distance is effectively decreased by minishing minimum allowable safety factor or enlarging face width. The power density of gearbox can be further improved by means of structure optimization of planet carrier or uniform load of planetary gear transmission. 相似文献
28.
A theoretic model is proposed based on the mechanism of the buckling failure of the stitched composite laminates containing delaminations. The buckling strength of the stitched composite laminates under the in-plane compressive load is predicted. The critical percentage elongation of the stitching thread is taken into account as a control parameter of the buckling failure. The energy method is used to calculate the buckling strength of the stitched composite laminates, and the minimal potential energy is used to calculate that of the unstitched composite laminates. The result shows that the buckling strength of the stitched composite laminates is larger than that of the unstitched composite laminates. The effects of stitching technical parameters such as the stitch thread diameter, stitch step and stitch space on the stitched composite laminates are also analyzed. 相似文献
29.
The tensile strength of high strength bolt is affected by many factors, including prying force. The prying force can result in the increment of bolt force, for which the connection failed ahead of time. Several methods are presented for calculating the prying force. In the China's "Code for Design of Steel Structure" (GB50017), there is no formula for calculation of prying force and a factor of 0.8 is considered in formula for tensile strength of bolt for taking the prying force into account. It is proposed that the design value of tensile resistance for high strength bolt should be increased. 相似文献
30.
Some additional effects of stitching on the in-plane mechanical properties of composite laminate is introduced while it was used to improve the interlaminar of plane mechanical properties of the composite laminate. The paper investigates the effect of stitching on in-plane tensile strength of composite laminates. The results show that the effect of stitching is dependent on the stitching parameters. The in-plane tensile strength of laminates is degraded with the decreasing of stitching space and step and increasing diameter of stitching thread. It is found that the initial damage of laminate increased with increasing of stitching parameters such as stitching density. This causes the decrease in the in-plane strength of composite laminate. 相似文献