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What is the role of tensile cracks in cohesive slopes? 预览
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作者 Liansheng Tang Zhanlun Zhao +1 位作者 Zhengui Luo Yinlei Sun 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第2期314-324,共11页
The traditional limit equilibrium method(LEM)is often used to search for the failure surface with a minimum safety factor of slope.In this method,the failure surface is considered as a shear surface,irrespective of it... The traditional limit equilibrium method(LEM)is often used to search for the failure surface with a minimum safety factor of slope.In this method,the failure surface is considered as a shear surface,irrespective of its form.However,tensile cracks are frequently found at the outcrops of landslides.In this study,three sets of tests on small-scale landslides with different inclination angles were conducted.The test results demonstrated that tensile cracks could arise in the slope sliding process and the failure surface is composed of both a shear and a tensile fracture surface.Based on the test results,we used the improved LEM,and replaced the traditional shear failure surface by a tensile-shear coupling one,thus new tensile failure modes for slope stability analysis can be established.The safety factors of slope in different failure modes were compared,which show that when considering soil tensile failure and tensile strength less than a certain value(e.g.15 kPa,44 kPa and 55 kPa for linear,circular and logarithmic spiral failure surfaces,respectively),the safety factors of slope with three different failure surfaces are less than the one that did not consider the tensile failure.The most critical failure surfaces of the slope may be composed of shear and tensile damages because the tensile strength of the soil cannot be generally greater than its cohesion. 展开更多
关键词 TENSILE cracks LANDSLIDE Stability analysis Tensile-shear coupling failure surface Limit EQUILIBRIUM method(LEM)
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影响阀门高温上阀盖焊接质量的研究和分析 预览
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作者 刘兰 谢远奉 +1 位作者 段大军 尚洪宝 《仪器仪表用户》 2019年第8期22-25,38共5页
在石油化工领域选择铬钼钢作为阀门高温上阀盖的重要材质,其焊接质量直接影响生产运行的安全,合理的焊接工艺和焊接坡口设计有利于保证焊缝的使用性能。针对某石化现场运行的阀门高温上阀盖出现的问题进行了研究分析,根据试验数据探讨... 在石油化工领域选择铬钼钢作为阀门高温上阀盖的重要材质,其焊接质量直接影响生产运行的安全,合理的焊接工艺和焊接坡口设计有利于保证焊缝的使用性能。针对某石化现场运行的阀门高温上阀盖出现的问题进行了研究分析,根据试验数据探讨了合理的焊接工艺要求和坡口设计方案,对行业中此类材质的焊接方式具有重要的指导作用。 展开更多
关键词 上阀盖 V型 坡口 焊接 焊缝 失效 对比试验 间隙 裂纹 拉伸
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Delamination strength of HTS tape under transverse tensile stress and its enhancement by using different Ag layer depositing temperatures 预览
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作者 Jun Wang Ce Sun +2 位作者 Liu Cong Xingyi Zhang Youhe Zhou 《力学快报:英文版》 CAS CSCD 2019年第3期147-151,共5页
For the application of second generation high temperature superconducting coated conductors (CCs) with layered structures, thermal mismatch between different components and electromagnetic force exerted in superconduc... For the application of second generation high temperature superconducting coated conductors (CCs) with layered structures, thermal mismatch between different components and electromagnetic force exerted in superconducting layer in a working magnet can cause transverse tensile stress, which would result in delamination behavior. Therefore many research groups have designed experiments to measure the delamination strength and dedicate to improving that. However, the reason of the discrete distribution of measured data has still not get quantitatively studied, besides, there are lack of investigations on the method of changing depositing conditions to improve the delamination strength except by adding an additional metal layer. In this work, we adopt an anvil test device and obtain delamination strengths as 29.6 MPa of YBa2Cu3O7-x (YBCO)/buffer and 114.6 MPa of buffer/substrate by combing energy disperse spectroscopy (EDS) detection. The reason of discretized measurement data on the delamination strength is explained. Moreover, we find that different temperatures during Ag deposition determine the bonding force of Ag and YBCO layer. The Delamination strength between Ag and YBCO layer increases from 4.4 MPa to larger than 114.6 MPa with temperature elevated from 30℃ to 100℃. Hence we present a novel method for improving the delamination strength of YBCO CCs by setting an optimal temperature of Ag deposition. 展开更多
关键词 YBCO coated conductor TRANSVERSE TENSILE stress DELAMINATION STRENGTH Depositing temperature Energy disperse SPECTROSCOPY
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辐照用小尺寸样品力学性能表征技术研究进展 预览
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作者 钟巍华 佟振峰 +3 位作者 宁广胜 周子扬 鱼滨涛 杨文 《原子能科学技术》 EI CAS CSCD 北大核心 2019年第10期1894-1905,共12页
由于辐照空间尺寸限制、降低样品放射性和提高辐照参数精度等原因,小尺寸样品被广泛应用于核反应堆材料的辐照后力学性能表征。本文就国内外小尺寸拉伸、冲击、断裂韧性、疲劳、蠕变和小冲杆等测试表征技术的研究现状进行了综合论述,分... 由于辐照空间尺寸限制、降低样品放射性和提高辐照参数精度等原因,小尺寸样品被广泛应用于核反应堆材料的辐照后力学性能表征。本文就国内外小尺寸拉伸、冲击、断裂韧性、疲劳、蠕变和小冲杆等测试表征技术的研究现状进行了综合论述,分析了小尺寸样品测试中的关键影响因素以及数据归一化方法,总结了小尺寸样品存在的问题,并结合我国需求对小尺寸样品技术的发展进行了分析和展望,以期为小尺寸样品技术及测试分析数据进一步规范化和工程应用发展提供参考。 展开更多
关键词 小尺寸样品 辐照性能 拉伸 冲击 断裂韧性 疲劳 蠕变 小冲杆
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Discussion on“Effects of lime addition on geotechnical properties of sedimentary soil in Curitiba,Brazil”[J Rock Mech Geotech Eng 10(2018)188e194] 预览
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作者 Amin Soltani Mehdi Mirzababaei 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第1期214-218,共5页
The present discussion aims at complementing the original work published by Baldovino et al.(2018)by outlining a novel point of view.In light of the inherent limitations associated with the empirical model suggested i... The present discussion aims at complementing the original work published by Baldovino et al.(2018)by outlining a novel point of view.In light of the inherent limitations associated with the empirical model suggested in the original article,the dimensional analysis technique was introduced to the soil-lime strength problem,thereby leading to the development of simple and physically meaningful dimensional models capable of predicting the unconfined compressive and splitting tensile strengths of compacted soil-lime mixtures as a function of the mixture’s index properties,i.e.lime content,initial placement(or compaction)condition,initial specific surface area and curing time.The predictive capacity of the proposed dimensional models was examined and validated by statistical techniques.The proposed dimensional models contain a limited number of fitting parameters,which can be calibrated by minimal experimental effort and hence implemented for predictive purposes. 展开更多
关键词 Dimensional analysis LIME content CURING time Specific surface area Unconfined compressive STRENGTH SPLITTING tensile STRENGTH
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基于碳纳米纸传感器的复合材料结构低速冲击损伤监测 预览
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作者 卢少微 杜凯 王晓强 《载人航天》 CSCD 北大核心 2019年第3期355-361,共7页
针对复合材料对冲击载荷比较敏感、内部损伤不易发现的问题,提出一种利用碳纳米纸薄膜作应变传感器的复合材料结构件低速冲击损伤监测方法。在拉伸条件下,对圆形和矩形碳纳米纸薄膜进行不同方向的传感系数测试,发现圆形碳纳米纸传感器... 针对复合材料对冲击载荷比较敏感、内部损伤不易发现的问题,提出一种利用碳纳米纸薄膜作应变传感器的复合材料结构件低速冲击损伤监测方法。在拉伸条件下,对圆形和矩形碳纳米纸薄膜进行不同方向的传感系数测试,发现圆形碳纳米纸传感器具有较高且稳定的传感系数155.63,可以作为全向传感器监测冲击损伤。复合材料结构的冲击损伤由传感器的电阻变化率和超声C扫描结果同步表征。研究结果表明,传感器的电阻随着冲击能量的增加而增加,基于全向碳纳米纸传感器的结构健康监测不仅可以灵敏感知低速冲击损伤,为损伤程度评估提供客观数据,而且通过分析不同方向BP传感器的电阻变化可以判断损伤位置。进一步与传统C扫描结果相比较表明,全向碳纳米纸传感器可以有效预判低速冲击损伤,用于航空航天复合材料结构件的实时在线健康监测。 展开更多
关键词 材料结构 拉伸 低速冲击 全向碳纳米纸传感器 传感系数 损伤监测
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Microstructural Characterization and Tensile Behavior of Rutile(TiO2)-Reinforced AA6063 Aluminum Matrix Composites Prepared by Friction Stir Processing
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作者 Sahayam Joyson Abraham Isaac Dinaharan +1 位作者 Jebaraj David Raja Selvam Esther Titilayo Akinlabi 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第1期52-62,共11页
Rutile(TiO2) particle-reinforced aluminum matrix composites were prepared by friction stir processing. The microstructure was studied using conventional and advanced characterization techniques. TiO2 particles were fo... Rutile(TiO2) particle-reinforced aluminum matrix composites were prepared by friction stir processing. The microstructure was studied using conventional and advanced characterization techniques. TiO2 particles were found to be dispersed uniformly in the composite. Clusters of TiO2 particles were observed at a higher particle content of 18 vol%. The interface between the TiO2 particle and the aluminum matrix was characterized by the absence of pores and reactive layer.Sub-grain boundaries, ultra-fine grains and dislocation density were observed in the composites. TiO2 particles improved the mechanical properties of the composites. However, a drop in tensile strength was observed at a higher particle content due to cluster formation. All the prepared composites exhibited ductile mode of fracture. 展开更多
关键词 ALUMINUM matrix composites FRICTION STIR processing RUTILE Microstructure TENSILE strength
Influence of temperature cycling and pore fluid on tensile strength of chalk 预览
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作者 T.Voake A.Nermoen +2 位作者 C.Ravnas R.I.Korsnes I.L.Fabricius 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第2期277-288,共12页
Calcite has a highly anisotropic thermal expansion coefficient,and repeated heating and cooling cycles can potentially destabilize chalks by breaking cement bonds between neighboring particles.Based on tensile strengt... Calcite has a highly anisotropic thermal expansion coefficient,and repeated heating and cooling cycles can potentially destabilize chalks by breaking cement bonds between neighboring particles.Based on tensile strength measurements,we investigated how temperature cycles induce weakening of chalk.Tensile strength tests were performed on chalk specimens sampled from Kansas(USA)and Mons(Belgium),each with differing amounts of contact cement.Samples of the two chalk types were tested in dry and water-saturated states,and then exposed to 0,15,and 30 temperature cycles in order to find out under what circumstances thermally induced tensile strength reduction occurs.The testing results show that the dry samples were not influenced by temperature cycling in either of the chalk types.However,in the water-saturated state,tensile strength is increasingly reduced with progressive numbers of temperature cycles for both chalk samples,especially for the more cemented Kansas chalk.The Kansas chalk demonstrated higher initial tensile strength compared to the less cemented Mons chalk,but the strength of both chalks was reduced by the same relative proportion when undergoing thermal cycles in the water-saturated state. 展开更多
关键词 TENSILE strength WEAKENING by heating and COOLING cycles ANISOTROPIC thermal EXPANSION
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Rolling texture and its effect on tensile property of a near-α titanium alloy Ti60 plate
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作者 Wenyuan Li Zhiyong Chen +3 位作者 Jianrong Liu Shaoxiang Zhu Guoxin Sui Qingjiang Wang 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第5期790-798,共9页
Rolling texture and its effect on tensile properties of Ti60 alloy plates were investigated in the present study. The plates were β-rolled at 1070℃ and(α+β)-rolled at 980℃, using uni-directionally rolling(UDR) an... Rolling texture and its effect on tensile properties of Ti60 alloy plates were investigated in the present study. The plates were β-rolled at 1070℃ and(α+β)-rolled at 980℃, using uni-directionally rolling(UDR) and cross-directionally rolling(CDR) processes, respectively.β-rolled plates exhibited weak textures, which were attributed to the dispersive orientations of secondary α during the β→α phase transformation. Strong deformation textures formed in(α+β)-rolled plates as a result of slipping mechanisms: the strong T-type texture in UDR plate was related to {10 1 0}[11 2 0] slipping, while the B-type texture in CDR plate was relevant with {0001}[11 2 0] slip. Strong T-type textures led to anisotropic tensile properties. B-type textures would decrease such an anisotropy. The(α+β)-CDR process was found to be a candidate process for reducing anisotropy of Ti60 alloy plates. 展开更多
关键词 TI60 alloy plates ROLLING TEXTURE ANISOTROPY TENSILE properties
缝合打结过程中手术缝合线力学性能研究
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作者 张力 戴安 +1 位作者 李炜 周仲荣 《生物医学工程学杂志》 EI CAS CSCD 北大核心 2019年第3期386-392,400共8页
在临床操作中,手术缝合线的断裂、结的滑脱和缝合线对组织的撕裂是造成伤口缝合失效的主要原因。基于此,本文在生物材料试验机上模拟缝合打结过程,研究了丝线、聚乳糖酸910缝合线和聚丙烯缝合线打结前后的拉伸、松弛和线-线界面的摩擦... 在临床操作中,手术缝合线的断裂、结的滑脱和缝合线对组织的撕裂是造成伤口缝合失效的主要原因。基于此,本文在生物材料试验机上模拟缝合打结过程,研究了丝线、聚乳糖酸910缝合线和聚丙烯缝合线打结前后的拉伸、松弛和线-线界面的摩擦性能。结果表明,打结使缝合线的拉伸性能降低。其中聚乳糖酸910缝合线拉伸强度最大,聚丙烯缝合线延伸率最大;在松弛过程中,缝合线在初始2h松弛量最大,松弛量从小到大为:聚乳糖酸910缝合线、丝线、聚丙烯缝合线。涂层和单丝结构均能有效降低缝合线表面粗糙度,从而减小线-线界面的摩擦力;线-线界面的摩擦力随载荷增加而增加,而与摩擦速度无关。研究结果为优化缝合线设计和缝合打结操作提供了重要的理论基础。 展开更多
关键词 手术缝合线 表面形貌 拉伸 松弛 摩擦特性
The combined effects of grain and sample sizes on the mechanical properties and fracture modes of gold microwires
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作者 H.K.Yang K.Cao +5 位作者 Y.Han M.Wen J.M.Guo Z.L.Tan J.Lu Y.Lu 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第1期76-83,共8页
Hall-Petch relation was widely applied to evaluate the grain size effect on mechanical properties of metallic material. However, the sample size effect on the Hall-Petch relation was always ignored. In the present stu... Hall-Petch relation was widely applied to evaluate the grain size effect on mechanical properties of metallic material. However, the sample size effect on the Hall-Petch relation was always ignored. In the present study, the mechanical test and microstructure observation were performed to investigate the combined effects of grain and sample sizes on the deformation behaviors of gold microwires. The polycrystalline gold microwires with diameter of 16 ?m were annealed at temperatures from 100°C to 600°C, leading to different ratios(t/d) of wire diameter(t) to grain size(d) from 0.9 to 16.7. When the t/d was lower than 10, the yield stress dropped fast and deviated from the Hall-Petch relation. The free-surface grains played key role in the yield stress softening, and the volume fraction of free-surface grains increased with the t/d decreasing. Furthermore, the effects of t/d on work-hardening behaviors and fracture modes were also studied. With t/d value decreasing from 17 to 3.4, the samples exhibited necking fracture and the dislocation pile-ups induced work-hardening stage was gradually activated.With the t/d value further decreasing(t/d < 3.4), the fracture mode turned into shear failure, and the work-hardening capability lost. As the gold microwire for wire bonding is commonly applied in the packaging of integrated circuit chips, and the fabrication of microwire suffers multi-pass cold-drawing and annealing treatments to control the grain size. The present study could provide instructive suggestion for gold microwire fabrication and bonding processes. 展开更多
关键词 GOLD MICROWIRE Wire BONDING Tensile testing GRAIN size HALL-PETCH relationship
Promotional effects of exogenous stimulation with pulsed electromagnetic fields on skin wound healing in diabetic rats
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作者 Yan Han Ze-Dong Yan Shu-Hua Ge 《海南医科大学学报(英文版)》 2019年第5期1-5,共5页
Objective:The current study aims to identify the effects of exogenous application of pulsed electromagnetic fields on skin wound healing in diabetic rats, and thus provides experimental evidence for its more scientifi... Objective:The current study aims to identify the effects of exogenous application of pulsed electromagnetic fields on skin wound healing in diabetic rats, and thus provides experimental evidence for its more scientific clinical application in the future.Methods: The diabetic animal models were established via intraperitoneal injection of streptozotocin in 4-month-old male rats. Fourth eight rats were randomly assigned into the diabetes group (DM) and diabetes coupled with pulsed electromagnetic fields (DM+PEMF) group. Another 24 normal rats were used as the blank control group (Control). Then, all the rats in the three groups were subjected to dorsal surgery for the establishment of soft tissue wound model (circular wound with the diameter of 2 cm). Then, the rats in the DM+PEMF group were subjected to pulsed electromagnetic fields stimulation. Then, 6 rats in each group were sacrificed at Day 5, 12 and 19 post surgery. The glucose levels, wound closure, wound healing time and tissue tensile strength were examined and analyzed.Results: Pulsed electromagnetic fields significantly increased the wound closure rate in diabetic rats at Day 5, 12 and 19 post surgery, decreased overall wound healing period in diabetic rats, and also enhanced tissue tensile strength in diabetic rats at Day 5, 12 and 19 post surgery.Conclusion: Low-intensity pulsed electromagnetic fields can significantly accelerate diabetic wound healing process, and also improve diabetic tissue repair capacity. This study may be helpful for providing more scientific and reasonable experimental evidence for the treatment of pulsed electromagnetic fields on diabetic wound healing in clinics. 展开更多
关键词 PULSED electromagnetic FIELDS Diabetes Sskin WOUND Tissue tensile strength GLUCOSE
Enhanced tensile properties in a Mg-6Gd-3Y-0.5Zr alloy due to hot isostatic pressing (HIP)
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作者 B. Zhoua D.Wu +1 位作者 R.S.Chen En-hou Han 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第9期1860-1868,共9页
Hot isostatic pressing (HIP) was applied to Mg-6Gd-3Y-0.5Zr (GW63) alloy to reduce shrinkage porosity, thus, to enhance the integrity and reliability of castings. During HIP process, shrinkage porosity was closed by g... Hot isostatic pressing (HIP) was applied to Mg-6Gd-3Y-0.5Zr (GW63) alloy to reduce shrinkage porosity, thus, to enhance the integrity and reliability of castings. During HIP process, shrinkage porosity was closed by grain compatible deformation and subsequent diffusion across the bonding interface. The amount of initial shrinkage porosity was the key factor for shrinkage porosity closure. HIP was testified to be effective on shrinkage porosity reduction in GW63 alloy due to its relatively narrow solidification range and resultant low content of initial shrinkage porosity in most sections, leading to higher tensile properties both in as-cast and cast-T6 condition. The improvement in tensile properties was mainly because of shrinkage porosity reduction and resultant effective rare-earth (RE) elements homogenization and precipitation strengthening. 展开更多
关键词 Hot isostatic PRESSING MG-GD-Y-ZR SHRINKAGE POROSITY reduction TENSILE properties
Reliability-based design in rock engineering:Application of Bayesian regression methods to rock strength data 预览
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作者 Nezam Bozorgzadeh John P.Harrison 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第3期612-627,共16页
Reliability-based design (RBD) is being adopted by geotechnical design codes worldwide, and it is therefore necessary that rock engineering practice evolves to embrace RBD. This paper examines the Hoek-Brown (H-B) str... Reliability-based design (RBD) is being adopted by geotechnical design codes worldwide, and it is therefore necessary that rock engineering practice evolves to embrace RBD. This paper examines the Hoek-Brown (H-B) strength criterion within the RBD framework, and presents three distinct analyses using a Bayesian approach. Firstly, a compilation of intact compressive strength test data for six rock types is used to examine uncertainty and variability in the estimated H-B parameters m and σc, and corresponding predicted axial strength. The results suggest that within- and between-rock type variabilities are so large that these parameters need to be determined from rock testing campaigns, rather than reference values being used. The second analysis uses an extensive set of compressive and tensile (both direct and indirect) strength data for a granodiorite, together with a new Bayesian regression model, to develop joint probability distributions of m and σc suitable for use in RBD. This analysis also shows how compressive and indirect tensile strength data may be robustly used to fit an H-B criterion. The third analysis uses the granodiorite data to investigate the important matter of developing characteristic strength criteria. Using definitions from Eurocode 7, a formal Bayesian interpretation of characteristic strength is proposed and used to analyse strength data to generate a characteristic criterion. These criteria are presented in terms of characteristic parameters mk and σck, the values of which are shown to depend on the testing regime used to obtain the strength data. The paper confirms that careful use of appropriate Bayesian statistical analysis allows the H-B criterion to be brought within the framework of RBD. It also reveals that testing guidelines such as the International Society for Rock Mechanics and Rock Engineering (ISRM) suggested methods will require modification in order to support RBD. Importantly, the need to fully understand the implications of uncertainty in nonlinear strength criteria i 展开更多
关键词 Reliability-based design(RBD) Hoek-Brown(HeB)criterion BAYESIAN regression Indirect TENSILE STRENGTH Characteristic STRENGTH CRITERION
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Modeling of the Tensile Strength of Immiscible Binary Polymer Blends Considering the Effects of Polymer/Polymer Interface and Morphological Variation
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作者 Esmail Sharifzadeh 《高分子科学:英文版》 SCIE CAS CSCD 2019年第11期1176-1182,共7页
In this work, a unique model is proposed for predicting the tensile strength of binary polymer blends considering the effects of polymer/polymer interface and the morphological variation of the system. The modeling wa... In this work, a unique model is proposed for predicting the tensile strength of binary polymer blends considering the effects of polymer/polymer interface and the morphological variation of the system. The modeling was performed based on the combination of analytical and artificial neural network (ANN) modeling methods. For the analytical part, Kolarik's model was developed in accordance with the system requirements and ANN was simultaneously involved in order to interpret some effective model parameters using the tensile test result of an actual sample (e.g. the yield strength and thickness of the interface, etc.). Furthermore, the model accuracy was evaluated by comparing the tensile test results of differently prepared /PP/PA and PS/PMMA blend samples and also some other data from literature with the model predictions. It was revealed that the designed ANN perfectly elevates the capability of the analytical section in order to predict the tensile strength of binary polymer blends with different compositions (prediction error < 10%). 展开更多
关键词 POLYMER BLENDS TENSILE strength Analytical modeling Artificial neural networks Polymer/polymer INTERFACE
1860级钢绞线静力弹塑性精细化模拟 预览
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作者 钱海敏 宗周红 +2 位作者 谢冠宇 廖聿宸 杜孟林 《东南大学学报:自然科学版》 EI CAS CSCD 北大核心 2019年第4期624-630,共7页
为研究不同接触状态对钢绞线截面塑性发展的影响,以及捻角对钢绞线轴向刚度和整体受力性能的影响,基于钢绞线的空间几何理论在Solidworks中建立1860级7丝钢绞线的三维几何模型.在Hypermesh中建立了有限元模型,并与已有文献的试验结果进... 为研究不同接触状态对钢绞线截面塑性发展的影响,以及捻角对钢绞线轴向刚度和整体受力性能的影响,基于钢绞线的空间几何理论在Solidworks中建立1860级7丝钢绞线的三维几何模型.在Hypermesh中建立了有限元模型,并与已有文献的试验结果进行对比,验证了有限元模型的有效性,并基于ABAQUS进行了静力弹塑性的精细化参数分析.研究结果表明,钢丝截面的初始接触状态对钢绞线截面应力分布和截面塑性发展有较大影响;弹性阶段的钢绞线截面应力分布较为不均,当延伸率达到2%后,截面应力分布较为均匀;钢绞线的轴向刚度随捻角的增大而减小;进入塑性受力阶段后,在相同延伸率下,钢绞线产生的轴向力随捻角的增大呈线性减小.. 展开更多
关键词 钢绞线 精细化模拟 拉伸 截面应力分布
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Dissimilar Al/Mg alloys friction stir lap welding with Zn foil assisted by ultrasonic
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作者 Shude Ji Shiyu Niu Jianguang Liu 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第8期1712-1718,共7页
The Zn-added ultrasonic assisted friction stir lap welding(UaFSLW) was carried out to improve the quality of dissimilar Al/Mg alloys joint. The effects of ultrasonic power on the joint quality were also investigated.T... The Zn-added ultrasonic assisted friction stir lap welding(UaFSLW) was carried out to improve the quality of dissimilar Al/Mg alloys joint. The effects of ultrasonic power on the joint quality were also investigated.The results indicated that the larger effective lap width and mixing region between Mg and Al(Mg/Al MR) were attained by Zn foil addition and external ultrasonic assistance. Compared with the conventional joint, the finer and better-distributed Mg-Zn IMCs placing the continuous Al-Mg IMCs were formed in the Mg/Al MR of the Zn-added UaFSLW joint. The Zn foil addition and external ultrasonic assistance significantly improved the tensile shear load of the joint, and the load was increased with the increase of the ultrasonic power. The maximum tensile shear load of 7.95 kN was attained, which was 52.6% larger than that of the conventional joint. 展开更多
关键词 Dissimilar Al/Mg alloys FRICTION STIR lap welding ZN FOIL ULTRASONIC power Microstructures Tensile shear load
钢材的几种化学与机械除鳞方法探索
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作者 徐言东 顾洋 +3 位作者 谢宝盛 马树森 李建强 袁华朋 《塑性工程学报》 CAS CSCD 北大核心 2019年第3期280-285,共6页
以氧化铁皮形貌、成分和应力状态为切入点,利用SEM、EDS和XRD等手段探究酸洗、拉伸、冷轧方式对钢材表面除鳞效果的影响。结果显示:氧化铁皮由最外层红色Fe2O3,中间层磁性Fe3O4,以及最内层的FeO组成。盐酸酸洗4 min后表面出现基体钢板斑... 以氧化铁皮形貌、成分和应力状态为切入点,利用SEM、EDS和XRD等手段探究酸洗、拉伸、冷轧方式对钢材表面除鳞效果的影响。结果显示:氧化铁皮由最外层红色Fe2O3,中间层磁性Fe3O4,以及最内层的FeO组成。盐酸酸洗4 min后表面出现基体钢板斑点,6 min后表面氧化铁皮基本去除,裂纹对酸洗的速度影响较大。相比于盐酸,以磷酸为基底的复合多元酸GF2&GF1具有可重复使用、无排放等优点,同时不存在产生裂纹的问题。在变形相同的前提下,压应力的除鳞效果显著好于拉应力,为了达到破鳞效果,必须迫使钢材产生较大变形。 展开更多
关键词 酸洗 除鳞 拉伸 冷轧
An experimental study of ultra-high temperature ceramics under tension subject to an environment with elevated temperature,mechanical stress and oxygen
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作者 HAN XinXing XU ChengHai +2 位作者 JIN Hua XIE WeiHua MENG SongHe 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2019年第8期1349-1356,共8页
Ultra-high temperature ceramic(UHTC) composites are widely used in high-temperature environments in aerospace applications. They experience extremely complex environmental conditions during service, including thermal,... Ultra-high temperature ceramic(UHTC) composites are widely used in high-temperature environments in aerospace applications. They experience extremely complex environmental conditions during service, including thermal, mechanical and chemical loading. Therefore, it is critical to evaluate the mechanical properties of UHTCs subject to an environment with elevated temperature, mechanical stress and oxygen. In this paper, an experimental investigation of the uniaxial tensile properties of a ZrB_2-SiC-graphite subject to an environment with a simultaneously elevated temperature, mechanical stress and oxygen is conducted based on a high-temperature mechanical testing system. To improve efficiency, an orthogonal experimental design is used. It is suggested that the temperature has the most important effect on the properties, and the oxidation time and stress have an almost equal effect. Finally, the fracture morphology is characterized using scanning electron microscopy(SEM), and the mechanism is investigated. It was concluded that the main fracture mode involved graphite flakes pulling out of the matrix and crystalline fracture, which indicates the presence of a weak interface in the composites. 展开更多
关键词 ultra-high TEMPERATURE ceramics ENVIRONMENT with elevated TEMPERATURE mechanical stress and OXYGEN UNIAXIAL tensile strength orthogonal experimental design
Distribution of Phosphorus and Its Effects on Precipitation Behaviors and Tensile Properties of IN718C Cast Superalloy
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作者 An-Wen Zhang Yan Yang +7 位作者 Sha Zhang Dong Zhang Wei-Hong Zhang Da-Wei Han Feng Qi Yuan-Guo Tan Xin Xin Wen-Ru Sun 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第7期887-899,共13页
The effect of phosphorus on the precipitations of γ″,γ' and 8 phases and associated tensile properties in IN718C alloy are investigated in this study. It is revealed that P atoms are dissolved in the grain inte... The effect of phosphorus on the precipitations of γ″,γ' and 8 phases and associated tensile properties in IN718C alloy are investigated in this study. It is revealed that P atoms are dissolved in the grain interior to a relatively high degree and hence influence the precipitation behaviors in the grain interior and improve the tensile strength of IN718C alloy.γ″ and γ' phases did not precipitate in the alloy without P addition during air cooling, while γ″ and phases precipitated in the grain interior during air cooling in the alloys with P addition, and the amounts of γ″ and γ' phases increased with increasing P content. Therefore, the Vickers micro-hardness in the as-cast state increased gradually with increasing P content. In double-aging state, the sizes of γ″ and γ' phases in the alloys with P addition were larger than that in the alloy without P addition, while the sizes were invariable when the P content (wt%) was higher than 0.015. Therefore, the micro-hardness and tensile strength of IN718C alloy treated by double aging increased first and then kept invariable with increasing P content. The precipitations of 8 phases both in the grain interior and on grain boundaries were inhibited by P markedly. The inhibitory effect of P on 8 phase enhanced gradually with increasing content of P, but the plasticity increased first and then decreased. What is more, the crack tended to propagate into the matrix around the particles (Laves phases and NbC carbides) in the alloys without P addition at the beginning of the tensile fracture, while it tended to propagate along the interfaces between the matrix and those particles in the alloys with P addition, which resulted from the synthetical effect of P on γ″,γ' and 8 phases. 展开更多
关键词 IN718C ALLOY PHOSPHORUS γ″ and γ' PHASES 8 PHASE TENSILE properties
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