Q235钢抗拉强度测量不确定度评定

根据GB/T 228.1—2010对Q235钢抗拉强度的测量不确定度进行分析与计算。结果表明:该Q235钢的抗拉强度为580MPa,取置信度为95%,包含因子k=2,其相对扩展不确定度为1.6%。其测量不确定度报告可表示为R_m=580×(1±1.6%)=(580±9)MPa,k=2。     

电子探针波谱仪定量测定硅钢中硅含量结果的不确定度评定

依据GB/T 15616—2008《金属及合金的电子探针定量分析方法》,采用电子探针波谱仪对某W600硅钢中的硅含量进行了定量测定,对影响其定量测定结果的不确定度分量进行了分析,并对不确定度的各个分量进行了计算和合成,最后给出了硅钢中硅含量测定结果的不确定度报告:该硅钢中的硅含量(质量分数)为1.50%,扩展不确定度U=0.20%,取包含因子k=2。     

气相色谱法测定汽油中苯含量的不确定度评定

采用石化行业标准SH/T 0693-2000中的方法,以2-己酮作内标,用气相色谱对汽油中苯含量进行检测。并对该测定过程中可能引入不确定度的来源进行了分析,建立数学模型,通过计算各不确定度分量,给出苯含量测定的扩展不确定度。结果表明,该方法不确定度的主要来源为标准曲线拟合,其次是重复性测定,而样品称量对不确定度影响较小。取置信概率为95%,包含因子k=2,则汽油中苯的测定结果(ω)为0.64%±0.06%或0.54%±0. 05%(v)。     

圆形拉伸试样断后伸长率不确定度的评定

根据GB/T 228.1-2010测定低合金高强度结构钢加工成的圆形拉伸试样的断后伸长率,然后对断后伸长率的测定结果的不确定度进行了分析评定。结果表明:该圆形试样的断后伸长率为25.0%时,测定结果的相对扩展不确定度为4.8%,包含因子k=2。     

HPLC法测定头孢拉定胶囊含量的不确定度评定

对高效液相色谱法测定头孢拉定含量的不确定度进行评定。量化了各分量的相对标准不确定度,并计算出合成标准不确定度,取k=2（近似置信概率95%）得出扩展不确定度1.46%。在现有条件下使测定结果受控,并可通过分析各分量的相对标准不确定度的大小来优化实验,使测定结果更加可靠。     

软质泡沫聚合材料拉伸强度测定结果的不确定度评定

依据GB／T6344--2008测定了聚氨酯软泡的拉伸强度,并对拉伸强度测定结果的不确定度进行了分析评定。结果表明：该聚氨酯软泡的拉伸强度为142kPa时,测定结果的扩展不确定度为2kPa,包含因子k=2。     

涂料密度测定的不确定度评定

根据JJF 1059--1999,以铝粉沥青船底漆密度的测定为例,对涂料密度测定的不确定度进行了评定。结果表明:该涂料的密度ρ_23℃=1.227 6 g·mL^-1,相对扩展不确定度U_rel=0.05%,扩展不确定度U=0.000 7 g·mL^-1,包含因子k=2;该结果比GB/T 6750-2007《色漆和清漆密度的测定比重瓶法》给出的不确定度低一个数量级。     

高效液相色谱法测定中间馏分中芳烃含量的不确定度评定

本文根据SH/T 0806-2008对柴油多环芳烃量及总芳烃含量测量不确定度进行评定,及检测过程中引入的不确定度来源进行分类和量化,并通过计算各分量的不确定度评定多环芳烃和总芳烃测定结果的合成不确定度,为检测结果可靠性提供参考。结果表明,不确定度主要来源为曲线拟合、数值修约和测量重复性。取置信区间为95%,包含因子k=2,总芳烃含量(质量分数)测定结果为：27.8%±5.8%,多环芳烃含量测定结果为：3.0%±0.6%。     

电缆橡胶绝缘层热延伸试验的测量不确定度评定

依据GB/T 2951.21-2008对电缆橡胶绝缘层进行了热延伸试验,并对其试验结果的不确定度进行了评定。结果表明:影响橡胶绝缘层热延伸试验结果的主要因素为橡胶绝缘层伸长量的测量,试验拉应力、烘箱温度以及试验室环境温度等对试验结果也有一定的影响。试验橡胶绝缘层的热延伸试验结果为:高温负载下伸长率y=15%,其扩展不确定度U=4.2%(包含因子k=2);卸载冷却后永久伸长率y'=5%,其扩展不确定度U=4.4%(k=2)。     

蔬菜中吡虫啉残留量的不确定度分析

依据NY/T 761—2008农药残留分析方法的第三部分,采用高效液相色谱法测定蔬菜中吡虫啉的残留量,对测定结果的不确定度进行了分析,并对各不确定度分量进行了评定和量化,计算了合成标准不确定度和扩展不确定度.结果表明,定量重复性误差及同一样品的重复性误差所引入的不确定度是影响残留量测定不确定度的较大因素;蔬菜中吡虫啉残留量结果表示为(C±U)mg/kg,k=2.     

Effect of 1.5 wt% tin addition on the properties of AZ31 magnesium alloy

In this paper, 1.5 wt%Sn was added to the AZ31 magnesium alloy aiming at improving the mechanical properties by using a low cost alloying element. Both alloys were prepared in the cast/heat treated (HT), rolled at 350 °C, rolled/heat treated at 400 °C and extruded at 350 °C. The results indicate that with addition of tin an improvement was obtained in both tensile strength and ductility of the AZ31 alloy in the cast/heat treated and in the extruded conditions. The yield and ultimate tensile strengths reached 98 MPa and 224 MPa respectively with 14 % elongation in the cast/heat treated condition while in the extruded condition these values were 212 MPa and 286 MPa with 20 % elongation. The tensile strength was even higher after rolling reaching 315 MPa for AZ31 with tin addition; however, as the material temperature during the last passes has decreased to relatively low values, the % elongation decreased to 1 %. After heat treatment at 400 °C for 2 hours the % elongation was restored and reached 12 %; this was accompanied by a decrease in tensile strength which reached 276 MPa. The results are discussed in relation to the microstructure evolution including grain size, phase identification, and volume fraction of phases.     

Manufacturing large 2A14 aluminium alloy cylinders by a warm rolling technology

This paper aims at the problem of high performance manufacturing of large 2A14 Al-alloy cylindrical components for aerospace applications. A warm rolling process was put forward to substantially refine the grains and secondary phases of 2A14 Al alloys. The results indicated that compared with hot rolling, warm rolling was easier to implement to form abundant subgrains and fully crushed the coarse particles. Coarse second phases dissolved and the precipitated T phases (AlCuMn) hindered the migration of grain boundaries and restrained grain growth during the heat treatment.The tensile strength, yield strength and elongation of the 2A14 aluminium alloy were significantly increased by 59?MPa (an increase of 14%), 71?MPa (an increase of 21%), 4% (an increase of 67%), respectively.     

塑料弯曲强度测量的不确定度评估

对塑料弯曲强度进行评定,对引起不确定性的各个因素进行逐项评估,最后得到塑料弯曲强度的扩展不确定度为：可以期望在（14．27-0．38）～（14．27＋0．38）MPa的区间包含了弯曲强度测量结果可能值的95％。     

Using response surface methodology for modeling and optimizing tensile and impact strength properties of fiber orientated quaternary hybrid nano composite

In current study, weight percentage of nano silica and nano clay and also fiber orientation have been chosen as independent variables and the affect of these variables on tensile and izod impact strength of epoxy/glass fiber/SiO₂/clay hybrid laminate composite has been investigated. Central composite design (CCD) which is subset of response surface methodology has been employed to present mathematical models as function of physical factors to predict tensile and impact behavior of new mentioned hybrid nano composite and also optimizing mentioned mechanical properties. Totally 20 experiments were designed with 6 replicates at center point. The maximum and minimum value of tensile strength were 450.90 MPa and 158.16 MPa which occurred in design levels 1 and 14 respectively, also the maximum and minimum of izod impact strength were 10.47 kJ/m² and 2.56 kJ/m² which occurred in design levels 13 and 14 respectively. The optimization results using optimization part of Minitab software showed that the best tensile strength was obtained 488.53 MPa and occurred in 3.5 wt% of nano silica, 1.1 wt% of nano clay and 9° of fiber orientation and after preparing and testing five samples average value of tensile strength was obtained about 480 MPa. Also the results showed that the best impact strength obtained from software was 11.35 kJ/m² and occurred in 4.03 wt% of nano clay, 5 wt% of nano silica and 0° of fiber orientation. The optimization results also showed that tensile and impact strength at optimum values improved up to 6.4% and 203.5% compared to level 1 and 14 and 6.02% and 303.6% compared to level 13 and 14 respectively. In addition, the fracture surface morphologies of the quaternary nano composites were investigated by scanning electron microscopy (SEM).     

SPS制备TiNi增强镁合金复合材料的微观结构及力学性能

以AZ31镁合金为基体,TiNi形状记忆合金丝为增强体,利用放电等离子烧结法（SPS）制备了TiNi/Mg复合材料,用OM、SEM、EDS对其微观形貌进行表征,并用XRD及DSC研究TiNi丝的相变,同时对该复合材料进行准静态拉伸实验,对其室温及高温力学性能进行研究。结果表明,所制备的TiNi/Mg复合材料中界面处存在Mg、Ti、Ni元素的互扩散现象,并形成宽度约为2 μm的互扩散层;所制备的TiNi/Mg复合材料的高温力学性能高于室温,其中其屈服强度、抗拉强度及弹性模量在100℃时（分别为157 MPa,292 MPa,22 GPa）较室温分别提高了12%、33%和29%,150℃时（分别为143 MPa,251 MPa,20 GPa）较室温分别提高了2%、14%和18%。     

Z-pin/缝合对复合材料T型接头剪切承载能力的影响

利用三维有限元模型对Z-pin/缝合增强试验件进行有限元分析,采用内聚力模型模拟界面的破坏情况,通过在分层的上下界面加入非线性弹簧元来模拟Z-pin/缝合的增强机制,非线性弹簧元的力学性能（桥联律）由细观力学方法获得。通过与试验结果的对比发现,由于未进行界面增强的T型结构的剪切承载能力已较高,Z-pin/缝合增强较难提高T型接头的剪切承载能力。从少数几种可提高T型接头的剪切承载能力的增强方案中可看到,应选择拉伸强度较高而拉伸模量较低的缝线来进行T型接头剪切界面增强设计。     

Effects of aluminum additions on the microstructure and mechanical properties of alumina-forming austenitic stainless steels

The mechanical properties, including tensile and impact properties at different testing temperatures of alumina-forming austenitic steels (25 % nickel, 20 % chromium) with different aluminum contents (0, 2.5 %, 5 % and 8 %) were investigated. Scanning and transmission electron microscopy together with tensile and impact properties tests were conducted. The results showed that the tensile strength of steels at 298 K increased obviously along with aluminum contents increasing, while plasticity decreased at the same, which attributed to the higher volume fraction and number density of spherical NiAl precipitation together with main ferrite in matrix. In addition, spherical NiAl particles dispersed easily in ferrite. In particular, the ultimate tensile strength of the sample with 8 % aluminum could reach 1398 MPa, with the elongation of 14 % at 298 K. However, NiAl precipitations would lose strengthening effects at high temperatures, but the plasticity could be improved. In addition, the sample with 5 % aluminum showed better comprehensive properties by comparison to other samples, and the ultimate tensile strength was 1018 MPa and 491 MPa at 298 K and 973 K with the elongation of 26 % and 43 %, respectively, enabling it to be promising material for industrial application in advanced nuclear systems.     

拉伸状态下碳纤维复合材料T型接头的断裂行为

建立了碳纤维复合材料T型接头数值模型,模拟了其在拉伸载荷下的损伤产生、扩展及失效过程,并对碳纤维复合材料T型接头试件进行了静态拉伸试验。结果表明,接头的初始损伤载荷为9.8~12.0 kN,损伤发生后接头的载荷值发生突降（降低约27%~38%）,此时接头仍具有一定承载能力;试件完全脱胶载荷较初始损伤载荷略有降低（载荷范围为8.0~8.6 kN）。数值计算和试验结果吻合,结果均显示填料区是碳纤维复合材料T型接头最薄弱的部位,易发生破坏;填料区破坏后裂纹迅速向填料区周围的胶层扩展,导致胶层的剥离,这是导致碳纤维复合材料T型接头失效的最主要原因。     

PAN/CA共混复合膜的气体分离与力学性能

聚丙烯腈（PAN）具有较高的气体渗透性,但拉伸强度低,不适宜直接制膜。为达到气体分离膜在力学强度方面的使用要求,利用PAN与乙酸纤维素（CA）共混改善其拉伸性能。结果表明,采用相转化法制备的PAN/CA共混基膜,随着CA与PAN共混比的增加,拉伸强度有明显的上升趋势,由1.74MPa增加到2.08MPa。当共混比为0....