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1.
通过应变等效假设在本文提出的具有过应力特征的统一粘塑性本构模型[5]中引入了描述材料损伤的内变量。并且给出了一个基于组合功密度概念的新的损伤模型。同以往的唯象模型相比,该损伤模型具有较明确的细观物理意义,能反映应变率和应力状态对损伤演化发展的影响。 相似文献
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A new turbulent constitutive relation was directly derived from Boussinesq's hypothesis and mixing length theory, and then implemented in the standard k-ε model. The performance of this constitutive relation was validated in zero pressure gradient flat-plate boundary layer flow, fully-developed turbulent channel flow and separated flow in a plane asymmetric diffuser. The investigation demonstrated that, this new constitutive relation gave very accurate results in the former two basic cases and provided significant improvement in prediction of separated and reattachment points in the plane asymmetric diffuser. Separation and reattachment points at x/H=7.5 and 29 were calculated accurately in comparison to experimental results, and the static pressure coefficient of 0.82 was very close to large eddy simulation calculation. These results are very encouraging but further verification and extensive application of the new constitutive relation to other two-equation eddy viscosity model are needed. 相似文献
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镍基单晶合金蠕变研究:试验、机理及材料模型 总被引:1,自引:2,他引:1
在镍基单晶合金高温蠕变建模研究工作的第一部分,通过对DD6镍基单晶合金不同中断时间的高温蠕变试验及透射电镜(TEM)观察,结合单晶合金蠕变机理的研究成果阐明了单晶高温蠕变的机理,并从Orowan方程出发,在晶体塑性理论框架下建立描述晶体滑移系上位错演化规律的方程,发展了以位错密度变化表征镍基单晶高温蠕变的材料模型.该模型考虑了较宽温度与载荷范围内单晶的主要蠕变机理,可较好地建模750~1100℃范围内镍基单晶的各向异性蠕变行为. 相似文献
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Foreign Object Damage to Fan Rotor Blades of Aeroengine Part Ⅱ: Numerical Simulation of Bird Impact 总被引:1,自引:0,他引:1
Guan Yupu Zhao Zhenhua Chen Wei Gao Deping 《中国航空学报》2008,21(4):328-334
Bird impact is one of the most dangerous threats to flight safety. The consequences of bird impact can be severe and, therefore, the aircraft components have to be certified for a proven level of bird impact resistance before being put into service. The fan rotor blades of aeroengine are the components being easily impacted by birds. It is necessary to ensure that the fan rotor blades should have adequate resistance against the bird impact, to reduce the flying accidents caused by bird impacts. Using the contacting-impacting algorithm, the numerical simulation is carded out to simulate bird impact. A three-blade computational model is set up for the fan rotor blade having shrouds. The transient response curves of the points corresponding to measured points in experiments, displacements and equivalent stresses on the blades are obtained during the simulation. From the comparison of the transient response curves obtained from numerical simulation with that obtained from experiments, it can be found that the variations in measured points and the corresponding points of simulation are basically the same. The deforming process, the maximum displacements and the maximum equivalent stresses on blades are analyzed. The numerical simulation verifies and complements the experiment results. 相似文献
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采用Gleeble热模拟机进行热压缩实验,研究7150铝合金在变形温度为300~450℃、应变速率为0.01~10s-1条件下的变形行为,采用Zener-Hollomon参数法构建合金高温塑性变形本构方程,并对变形后的微观组织进行分析。研究表明:7150铝合金的流变应力随应变速率增大而增大,随变形温度增大而降低。该合金热压缩变形的流变应力行为可用双曲正弦形式的本构方程描述,其参数A为4.161×1014s-1,α为0.01956 MPa-1,n为5.14336,热变形激活能Q为229.7531k J/mol。随着温度升高和应变速率降低,动态再结晶逐渐取代动态回复成为合金的主要软化机制。 相似文献