排序方式: 共有63条查询结果,搜索用时 15 毫秒
1.
2.
The geometric shapes of specimens are important in impact tensile tests because geometric shapes determine the stress states of the specimens, and precise geometric shapes can obtain proper material properties without non-material factors. The aim of this study was to investigate the 1D form of the stress by changing the length-to-diameter (L/D) ratios of specimens. The experiments were carried out on a split Hopkinson tensile bar (SHTB)-rotating disk indirect bar-bar tensile impact apparatus. The L/D ratios of the LY12CZ specimens used in the test ranged from 1 to 5. Results show that the specimens can be used to obtain exact parameters of materials under the proposed conditions when the L/D ratio is greater than 2. This is because the longer length will reduce or eliminate the effects of the interfaces. 相似文献
3.
Ca对AE42镁合金的显微组织和拉伸性能的影响 总被引:1,自引:0,他引:1
AE42的铸态组织主要包含了α镁和少量的针状Al11RE3相, 呈典型的树枝晶分布. 少量Ca的加入使合金组织细化并形成新相Al2Ca, Al2Ca主要呈现分布在晶界的层片状形貌和弥散在晶粒内部的颗粒状形貌. 随着Ca的加入量增多, Al11RE3的体积百分比降低, 相应Al2Ca含量增加. 拉伸性能方面, Ca的加入使合金的屈服强度在室温和高温下都有显著提升, 随之延伸率有少量降低. Ca的加入还使合金在室温和150 ℃下抗拉强度下降. 温度的提高使Ca对抗拉强度的影响逐渐加大, 175 ℃和200 ℃下, 随Ca含量的增加抗拉强度逐渐增大. 相似文献
4.
Koji Murofushi Shinji Sakurai Koji Umegaki Junji Takamatsu 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):301-314
Ground reaction force and wire tensile force were measured during test throws by three hammer throwers: the Asian record holder, who had a personal best of 83.47 m at the time of the investigation, and two university athletes, with personal bests of 59.95 m and 46.30 m respectively. They were filmed using three high-speed video cameras (250 Hz). The displacements of the hammer head and the athletes' centres of mass were calculated using three-dimensional analysis procedures. The Asian record holder's centre of mass and the hammer head on the final two turns exhibited approximate conjunctions of the hammer high point and the thrower's low point and vice versa about the hammer's azimuth angle. It is conjectured that the reason why the thrower's movement is asynchronous with the hammer's movement by approximately half a turn is to accelerate the hammer head in a manner similar to the way that the amplitude of a pendulum increases when it is pulled upward by a string against the downward movement of the swinging weight. 相似文献
5.
钢筋混凝土受弯构件纵向配筋率ρ的取值,现行混凝土设计规范(GB50010—2002)允许的范围是比较大的,然而在实际工程中,钢筋混凝土受弯构件内纵向配筋率ρ的大小对建筑工程质量、耐久性、经济性等方面都有很大影响。该文仅从有屈服点钢筋在钢筋混凝土梁内纵向配筋率入手,通过理论分析、经济比较,研究确定钢筋混凝土受弯构件-梁的合理纵向配筋率。 相似文献
6.
7.
选取了市场中常见的几种可再分散乳胶粉,采用低掺量配比拌制粘接砂浆,列出试验资料,分析了在较低的可再分散乳胶粉掺量下,胶粉对EPS薄抹灰系统中胶粘剂拉伸粘结强度的影响效果。 相似文献
8.
运用J-积分与终极抗拉强度评估了环氧沥青混合料在-10℃和20℃的断裂特性, 共测试了60个不同切口深度的半圆弯曲试件. 结果表明, 环氧沥青混合料的半圆弯曲试验(SCB)结果复现性好; 由非切口试件的半圆弯曲试验与标准间接拉伸试验(IDT)所测得的环氧沥青混合料的抗拉强度, 其比值在1.4~1.7之间, 且SCB抗拉强度与切缝深度指数相关; 在20℃与-10℃试验条件下, 环氧沥青混合料具有比热塑性HMA高得多的临界J-积分值; 当温度由20℃降至-10℃时, 环氧沥青混合料的响应模式由延性变为脆性, 断裂能增加30%, 而临界J-积分值下降15%. 与热塑性HMA相比, 环氧沥青混合料的常温与低温抗裂性更好; 环氧沥青混合料低温起裂需要更高的能量, 但其裂纹扩展速度比常温时更快. 相似文献
9.
不同的高等教育哲学观导致不同的高等教育发展观。深刻理解布鲁贝克的高等教育哲学观,在此基础上确立一种符合时代发展的新的高等教育发展的价值取向,既是高等教育发展的一个理论问题,也是一个现实问题。文章在深入解读《高等教育哲学》的基础上,提出了保持张力平衡的价值取向。 相似文献
10.
吉仙枝 《洛阳师范学院学报》2015,(5):44-48
选择成型效果和抗张强度为指标,分别对不同成型支撑载体、干燥温度、布料量、增稠剂配方和增塑剂用量等工艺条件进行了研究.实验结果显示,将新鲜包菜护色打桨后添加由0.40%CMC、0.40%海藻酸钠和2.5%玉米变性淀粉组成的复合增稠剂和1.5%的甘油增塑,所得包菜泥涂布在耐高温不粘烤盘表面,厚度2mm,于65℃鼓风干燥3h,所得包菜纸的抗张强度达到最大值,且成型效果最优. 相似文献