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In this investigation, hybrid laser/arc welding (HLAW) was employed to join 8-mm-thick high-strength quenched and tempered steel (HSQTS) plates in the butt-and T-joint configurations. The influences of welding parameters, such as laser power, welding speed, stand-off distance (SD) between the arc of gas metal arc welding, and the laser heat source on the weld quality and mechanical properties of joints, were studied to obtain non-porous and crack-free fully-penetrated welds. The weld microstructure, crosssection, and mechanical properties were evaluated by an optical microscope, and microhardness and tensile tests. In addition, a finite element model was developed to investigate the thermal history and molten pool geometry of the HLAW process to join the HSQTS. The numerical study demonstrated that the SD had a paramount role in good synergy between the heat sources and the stability of the keyhole. For the butt-joint configuration, the results showed that, at a higher welding speed (35 mm/s) and optimum SD between the arc and laser, a fully-penetrated sound weld could be achieved. A non-porous weld in the T-joint configuration was obtained at a lower welding speed (10 mm/s). Microstructural evaluations indicated that the formation of residual austenite and the continuous network of martensitic structure along the grain boundary through the heat affected zone were the primary reasons of the softening behavior of this area. This was confirmed by the sharp hardness reduction and failure behavior of the tensile coupons in this area.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-017-0193-6 相似文献
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为研究开孔钢板连接件(PBL)加劲型矩形钢管混凝土T型节点的疲劳性能,进行了T型节点支管受拉、面内受弯及面外受弯的应力集中系数分析。基于矩形钢管混凝土T型节点受拉试验,设计了主管为矩形钢管、矩形钢管混凝土和PBL加劲型矩形钢管混凝土,支管为方钢管的T型节点受拉试件,并采用ABAQUS软件对其进行非线性有限元分析,其中主管钢管宽厚比为27,支主管宽度比为0.4。通过非线性有限元数值模拟,分析热点可能出现位置,并采用二次外推法计算得到支主管的应力集中系数。结果表明:PBL加劲型矩形钢管混凝土节点热点出现位置与矩形钢管节点和矩形钢管混凝土节点一致;与矩形钢管混凝土节点相比,PBL加劲型矩形钢管混凝土节点的应力集中系数显著降低,抗疲劳性能明显提高。 相似文献
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The dual laser beam bilateral synchronous welding (DLBSW) for T-joint is limited to develop for the porosity defect in joint. In order to investigate the effect of porosity in T-joint, the DLBSW experiment of 2219 Aluminum Alloy T-joint is carried out. While, the distribution of porosity is scanned by X-ray non-destructive testing (NDT) and the size of porosity is measured by particle size analysis software Nano measurer 1.2. The morphology of pore in fracture and the elemental concentration around the pore are investigated by scanning electron microscopy (SEM) and energy spectrometer (EDS). Furthermore, the analysis results of porosity distribution show that the optimal parameter is 3700?W of laser power and 2.5?m/min of welding rate, under which the number of porosities reaches the minimum. The main factor, caused the fracture of weld seam, is the concentrated porosities in T-joint. In addition, technical porosity is mainly found in the center of the weld seam or at the bottom of the weld seam, and it can be eliminated by improving welding parameters. Metallurgical porosity mainly exists at the edge and the top of the weld seam, including hydrogen porosity and metal vapor porosity which formed by the burning of metal elements. 相似文献
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钛合金带筋壁板类T形结构常见于航空制造领域,其激光焊接工艺已经比较成熟. 但是即便在激光高速焊接过程热输入已经很低,仍然会存在一定的焊后角变形. 由于航空制造的高精度要求,需要施加额外的主动控制以最大限度减小此类角变形. 文中提出并验证了基于可编程多点柔性支撑的主动变形控制方法. 针对传统刚性装夹、预置应力不适应于弱刚性带筋壁板结构的问题,设计了一套以STM32单片机为主控,直线电动推杆为执行机构的多点柔性支撑装置. 结果表明,可在焊接过程实时监测当前支撑位置的受力状态,并进行动态调节,从而达到有效抑制焊接角变形的效果. 相似文献
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在关于拉脱载荷下Z-pin增强T型接头的有限元模拟方法基础上,通过对2组蒙皮厚度分别为7.2 mm和4.0 mm的试验件的试验结果进行分析,研究了T型接头蒙皮厚度对Z-pin增强效果的影响。结果表明:Z-pin增强效果随着蒙皮厚度的减小而增大。蒙皮厚度大于5 mm,Z-pin不能提高结构的最大承载能力,但可显著提高结构首次掉载后的承载性能,使T型接头在较大的加载位移下仍保持较高的承载能力;无论蒙皮厚薄,结构首次掉载后,各Z-pin增强T型接头可达到的载荷平台是相当的,且该载荷平台随蒙皮的变厚有降低的趋势。 相似文献