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1.
The correlations between the structures, fracture behavior and dynamic shear property were investigated for 7050 to 7N01 layer of 7N01/7A01/7050 multilayer plate with different thickness ratio fabricated by hot rolling bonding. is The results showed that when thickness ratio of 7050 to 7N01 layer was 1 and 7050 layer was backplane, the absorbed energy of the multilayer plate was 39% higher than that of 7050 alloy. The excellent energy absorbing ability of 7N01/7A01/7050 multilayer plate is attributed to the blunted cracks in 7A01 interlayer, the enhanced 7050 layer by decreasing of secondary cracks and the delaying dynamic failure of 7050 layer.  相似文献   
2.
FGH96 is a powder metallurgy nickel based superally used for turbine disk of aero-engines. In the present study FGH96 alloy with four different γ' precipitate microstructures were produced via solution heat-treatment with different cooling rates, and the maximum cooling rate reached 400°C/min which was a super cooling rate for Nickel-based superalloy. The creep tests were conducted for PM FGH96 alloy under the testing condition of 704°C and 690 MPa. The relationship between the creep properties and the distribution of γ' precipitate was established. The creep mechanism was analyzed by using TEM and ACTEM, and the dislocation movement was studied at the atomic scale. The creep strain rate was calculated through a physically based crystal slip model established based on crystal plasticity. The calculated results were consistent with the test ones, illustrating the validity of the model. The fracture mechanism was also investigated, and the results showed that the creep cracks generated on the surface due to the oxidation. It was observed that the cracks propagated in different ways depending on the different average diameters of γ' precipitate. With the decrease of the average γ' precipitate size,the critical shearing stress increased and the resistance of the dislocation slipping increased. The fracture mechanism for the primary stage transformed from intragranular to intergranular due to the change of dislocation slipping.  相似文献   
3.
黔北地区牛蹄塘组页岩储层裂缝特征   总被引:1,自引:0,他引:1  
以黔北地区下寒武统牛蹄塘组页岩储层为研究对象,通过岩心、薄片、场发射扫描电镜和测试分析等手段,对牛蹄塘组页岩储层裂缝发育特征和主控因素进行了分析.结果表明:研究区牛蹄塘组页岩岩心裂缝以构造裂缝为主,包括高角度剪性裂缝、高角度张性裂缝、低角度滑脱缝,岩心裂缝充填程度较高,以方解石充填为主;镜下微观裂缝以非构造缝为主,包括层间缝、粒内缝和粒间缝.微裂缝的发育对页岩气藏丰度、页岩气井单井产能都有积极贡献.同时,对裂缝发育的主控因素研究发现,构造因素是裂缝发育最主要的控制因素.此外,同一构造背景下受不同岩性、岩石力学性质、矿物组成、有机质含量等因素影响,裂缝发育程度和性质也存在差异.其中总有机碳(total organic carbon,TOC)含量与裂缝发育程度并非单一的线性关系,当TOC过高时(6%~8%),裂缝发育程度明显降低;具有高弹性模量、低抗拉强度的碳质页岩,在区域应力作用下更易形成构造裂缝.  相似文献   
4.
为了提高裂隙岩体的力学性能,保证工程的质量和安全,采用水玻璃-水泥混合注浆液对裂隙岩体进行加固。通过直剪试验、显微镜实时观测试验,研究注浆结石体的强度与变形特性,以此评价水玻璃-水泥混合液作为注浆材料的可行性。试验结果表明,水玻璃-水泥混合注浆液有效的提高了裂隙岩体的力学性能。水玻璃-水泥注浆溶液不但改变了裂隙岩体的微结构、裂隙率和岩体的物质组成成分,使岩体的致密度和强度增加;而且注浆溶液在岩体结构面中凝固后对结构面进行填充加固,有效的提高了注浆结石体的黏聚力c,增强了注浆结石体抵抗外力破坏的能力。裂隙率对注浆结石体的强度影响显著,随裂隙岩体裂隙率的增加,注浆结石体(裂隙岩体与注浆材料经过物理化学变化后形成的结合体)的抗剪强度减小;在裂隙率相差不大时,裂隙岩体的裂隙条数对注浆结石体的抗剪强度有重大影响,随着裂隙条数的增加,注浆结石体的抗剪强度减小。在注浆结石体抗剪强度减少过程中,注浆结石体的黏聚力c不断减小,内摩擦角φ基本保持不变。注浆结石体在第12 d时达到最佳抗剪强度,而水玻璃-水泥质量比为1.3∶1注浆液工程性能最为理想,期最佳抗剪强度为6.243 MPa。  相似文献   
5.
A small amount of cerium (below 1.0 wt%) addition to AZ91 alloy have been investigated on the hot tearing susceptibility (HTS) at a cooling rate of 1.5Ks?1. The HTS increased to a maximum value with a cerium addition of 0.6 wt% and then decreased to a stable status as cerium was gradually added. Due to high chemical activity, cerium into the melts can react with aluminum to form an Al11Ce3 intermetallic compound. X–ray diffraction results also confirmed the existence of Al11Ce3. The Al11Ce3 increased with the presence of the needle-like and block morphology. As cerium levels increased, the amount of Mg17Al12 decreased. The variations between Mg17Al12 and Al11Ce3 resulted in a similar normal distribution of the HTS in AZ91 alloy. The findings were further verified through the microstructure evolution and the surface morphology of fracture.  相似文献   
6.
Accurate characterization and visualization of the complex inner structure and stress distribution of rocks are of vital significance to solve a variety of underground engineering problems. In this paper, we incorporate several advanced technologies, such as CT scan, three-dimensional(3D) reconstruction, and 3D printing, to produce a physical model representing the natural coal rock that inherently contains complex fractures or joints. We employ 3D frozen stress and photoelastic technologies to characterize and visualize the stress distribution within the fractured rock under uniaxial compression. The 3D printed model presents the fracture structures identical to those of the natural prototype. The mechanical properties of the printed model,including uniaxial compression strength, elastic modulus,and Poisson’s ratio, are testified to be similar to those of the prototype coal rock. The frozen stress and photoelastic tests show that the location of stress concentration and the stress gradient around the discontinuous fractures are in good agreement with the numerical predictions of the real coalsample. The proposed method appears to be capable of visually quantifying the influences of discontinuous,irregular fractures on the strength, deformation, and stress concentration of coal rock. The method of incorporating3 D printing and frozen stress technologies shows a promising way to quantify and visualize the complex fracture structures and their influences on 3D stress distribution of underground rocks, which can also be used to verify numerical simulations.  相似文献   
7.
弓网系统中,各种类型的受电弓滑板承担着传输电能的重要功能,其严酷的工作条件对受电弓滑板材料的性能提出了非常苛刻的要求。目前最主要的受电弓滑板有:粉末冶金滑板,纯碳滑板和浸金属碳滑板。其中碳滑板材料性能较好但价格昂贵,粉末冶金滑板材料价格便宜,但性能明显逊于前者。Ti3SiC2/TiC是一种兼具陶瓷与金属性质的新型材料,与碳滑板材料相比,其电阻率低,且具有良好的抗氧化性和自润滑减摩性,因此Ti3SiC2/TiC将可能成为一种工艺简单、成本更低、而性能则更高的新型受电弓滑板材料。本研究以Si、Ti和C为原料,利用熔渗反应烧结技术制备出Ti3SiC2/TiC复合材料,研究结果表明,制备样品的弯曲强度与硬度分别达到 423MPa~564MPa 和169~249HB。同时,本文对Ti3SiC2/TiC复合材料的断裂机理进行了研究。  相似文献   
8.
为了进一步明确混杂纤维混凝土物理特性优势,首先对其组合结构中应用与承载力进行了计算分析,接着对受弯承载力的计算完成了修正提议,在混杂纤维混凝土梁承载力的计算中,建立了纤维布直线关系的材料力学模型,得出高性能纤维补强混凝土板不仅可以增强复合梁的承载力,且有利于减缓裂缝和提高组合梁的延性,在对混杂纤维混凝土的极限应变分析中得出其应变能达到1 500以上,可以有效提高组合梁的截面延性,综合分析可得纤维混凝土同普通混凝土相比其抗折强度明显提高40%左右,抗冲击韧性明显提高50%左右,韧性得到了大幅度的提高。通过与多种其他混凝土的实验特性比较,充分验证了上述特性优势。这一研究对纤维混凝土的推广应用具有显著的实际价值。  相似文献   
9.
Carbon nanotube yarns (CNTY) possess good specific strength and specific conductivity. As such, their potential for commercial applications is significant. Fatigue performance is a significant consideration in yarn/wire applications. In this study, the flexural fatigue performance of CNTY spun from super-aligned carbon nanotube arrays was investigated using a reversed bending test. The results showed that CNTY exhibited excellent resistance to pure flexural fatigue, significantly outperforming stainless steel wire; CNTY failed where a combination of flexural fatigue and tension-tension fatigue had special hollow fracture morphology, and CNTY resistance remained fundamentally unchanged in the combination fatigue process.  相似文献   
10.
目的:研究中国蒙医整骨术的骨折分型两种判据及其因果关系.方法:基于中国蒙医整骨术对骨折类型的10种分类及其大量临床应用实践,用现代生物力学原理及方法分析验证骨折类型线性与力性分类的科学合理性及其因果关系.结果:中国蒙医整骨术的骨折分型线性判据与力性判据,二者互为因果、完美统一.结论:中国蒙医整骨术骨折分型两种判据是骨折及其类型诊断的根本依据.  相似文献   
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