PREDICTION OF YIELD FUNCTIONS ON BCC POLYCRYSTALS

By the nonlinear optimization theory, we predict the yield function of single BCC crystals in Hill＇s criterion form. Then we give a formula on the macroscopic yield function of a BCC polycrystal Ω under Sachs＇ model, where the volume average of the yield functions of all BCC crystallites in Ω is taken as the macroscopic yield function of the BCC polycrystal. In constructing the formula, we try to find the relationship among the macroscopic yield function, the orientation distribution function （ODF）, and the single BCC crystal＇s plasticity. An expression for the yield stress of a uniaxial tensile problem is derived under Taylor＇s model in order to compare the expression with that of the macroscopic yield function.

Calibration of anisotropic yield function by introducing plane strain test instead of equi-biaxial tensile test

The equi-biaxial tensile test is often required for parameter identification of anisotropic yield function and it demands thespecial testing technique or device. Instead of the equi-biaxial tensile test, the plane strain test carried out with the traditional uniaxialtesting machine is suggested to provide the experimental data for calibration of anisotropic yield function. This simplified method byusing plane strain test was adopted to identify the parameters of Yld2000-2d yield function for 5xxx aluminum alloy and AlMgSialloy sheets. The predicted results of yield stresses, anisotropic coefficients and yield loci by the proposed method were very similarwith the experimental data and those by the equi-biaxial tensile test. It is validated that the plane strain test is effective to provideexperimental data instead of equi-biaxial tensile test for calibration of Yld2000-2d yield function.

Improvement of the Yield Function of Continuum Mechanics of Textured Polycrystals

The calculation procedure of the continuum mechanics of textured polycrystals (CMTP) method is reviewed to estimate calculating time with various yield functions (YFs). A so called semi quadratic YF is proposed to eliminate time consuming numerical calculation and avoid the decrease of prediction precision. The reasonability of the new YF is proved by making the comparisons between predicted R values and earing behaviour for some materials and the experimental results.

NEW NON QUADRATIC ORTHOTROPIC YIELD FUNCTION FOR TRIAXIAL STRESS STATE

A new Don-quadratic orthotropic yield function is developed in the present paper.It does not have those limitatioins which existing non-quadratic anisotropic yield functions have,such as being usable only for the plane stress problems and in-plane isotropic sheet metals,and that the directions of principal stress or the ex ponent in yield function can not be arbitrary,etc.Furthermore all of the material constants involved in this yield function can be determined by performing only uniaxial tension lest.This yield function contains three new parameters,of which each one is present for one principal plane of anisotropy.Their values can be.generally,selected to equal 3.Other methods to determine the value of these parmeters are discussed and given in this paper.From the regression estimate for the yield stress in five directions of several kinds of titanium metal sheet.it is obtained that the suitable value of exponent in yield function for titanium sheets is 6 or 8.This is confirmed from the use for several plastic deformation problems of titanium sheets.

Effect of hydrostatic stress on yield function and plastic constitutive relations

A new yield function taking effect of hydrostatic stress into account is presented through establishing and solving the functional equation satisfied by the yield function, and its characteristic is simple in form and strong in generality. In order to reveal its availability, a comparison is made between the results obtained with it and the experimental results of grey cast iron has be done, both seem to be in good agreement. At the same time, taking the yield function obtained here as a potential function, a new associative plastic constitutive equation taking effect of hydrostatic stress into account is built, and the plastic volume change ratio of plastic deformation is given.

Numerical study of influence of anisotropy on flanging earing based on Barlat six-component yield function

The anisotropy of stamped sheet metal exerts evident effects on the formability. Barlat six component yield function was introduced into the elastoplastic finite element formulation based on the principle of virtual velocity and the discrete Kirchhoff triangular element model. The flanging earing in cylindrical cup drawing process of circular sheet metal was numerically simulated. The influence of anisotropy on the forming process was studied.

A NEW ORTHOTROPIC YIELD FUNCTION DESCRIBABLE ANOMALOUS BEHAVIOR OF MATERIALS

ＡＮＥＷＯＲＴＨＯＴＲＯＰＩＣＹＩＥＬＤＦＵＮＣＴＩＯＮＤＥＳＣＲＩＢＡＢＬＥＡＮＯＭＡＬＯＵＳＢＥＨＡＶＩＯＲＯＦＭＡＴＥＲＩＡＬＳＡＮＥＷＯＲＴＨＯＴＲＯＰＩＣＹＩＥＬＤＦＵＮＣＴＩＯＮＤＥＳＣＲＩＢＡＢＬＥＡＮＯＭＡＬＯＵＳＢＥＨＡＶＩＯＲＯＦ...

氮、磷、钾配施对葛根生长及品质的影响

为探明氮、磷、钾肥配施对葛根生长及品质的影响,为葛根高效栽培提供合理的施肥技术支撑和理论依据,采用L_(9)(3~4)正交试验设计,研究氮、磷、钾配施对葛根产量和主要功能成分的影响,明确研究区葛根氮、磷、钾的最佳施用量。结果表明,不同施肥方案对葛根产量和功能成分的影响显著,其中以N_(3)P_(1)K_(2)(N 270kg/hm^(2),P_(2)O_(5)45 kg/hm^(2),K_(2)O 90 kg/hm^(2))处理的产量和总黄酮含量最高,分别为2.13 kg/株和83.10 mg/g;N_(1)P_(3)K_(2)(N 90 kg/hm^(2),P_(2)O_(5)135 kg/hm^(2),K_(2)O 90 kg/hm^(2))的葛根素含量最高,为24.85 mg/g,N_(1)P_(2)K_(3)(N 90 kg/hm^(2),P_(2)O_(5)90 kg/hm^(2),K_(2)O 135 kg/hm^(2))处理的大豆苷和大豆苷元含量均为最高,分别为22.96和2.55 mg/g。氮、磷、钾肥配施对葛根产量和葛根素含量影响的大小顺序为氮肥>钾肥>磷肥。以葛根产量为目标的最佳施肥量为N 270 kg/hm^(2)、P_(2)O_(5)135 kg/hm^(2)、K_(2)O 90 kg/hm^(2),以葛根品质提升为目标的最佳施肥量为N 180 kg/hm^(2)、P_(2)O_(5)135 kg/hm^(2)、K_(2)O 90 kg/hm^(2)。

A New Economic Assessment Index for the Impact of Climate Change on Grain Yield

The impact of climate change on agriculture has received wide attention by the scientific community. This paper studies how to assess the grain yield impact of climate change, according to the climate change over a long time period in the future as predicted by a climate system model. The application of the concept of a traditional ＂yield impact of meteorological factor （YIMF）＂ or ＂yield impact of weather factor＂ to the grain yield assessment of a decadal or even a longer timescale would be suffocated at the outset because the YIMF is for studying the phenomenon on an interannual timescale, and it is difficult to distinguish between the trend caused by climate change and the one resulting from changes in non-climatic factors. Therefore, the concept of the yield impact of climatic change （YICC）, which is defined as the difference in the per unit area yields （PUAY） of a grain crop under a changing and an envisaged invariant climate conditions, is presented in this paper to assess the impact of global climate change on grain yields. The climatic factor has been introduced into the renowned economic Cobb-Douglas model, yielding a quantitative assessment method of YICC using real data. The method has been tested using the historical data of Northeast China, and the results show that it has an encouraging application outlook.

20个青贮玉米品种在陇东南地区的生产性能和营养价值评价

为筛选出适合陇东南地区(甘肃天水)种植的优质高产青贮玉米(Zea mays)品种,本研究以20个青贮玉米品种为材料,测定并分析了各品种农艺性状、生物产量、营养物质含量及产量,并采用隶属函数法进行了综合评价。结果表明:粗蛋白含量与绿叶数、果穗数、有效果穗数、果穗长、鲜果穗重和黄叶数显著相关(P<0.05);酸性洗涤纤维和中性洗涤纤维含量与株高、穗位高、全株叶片数和黄叶数极显著相关(P<0.01);淀粉含量与穗位高、全株叶片数、单株鲜重和株高显著相关(P<0.05)。本研究中鲜草产量达到60 t·hm^(-2)以上的品种有5个,干物质产量达到15 t·hm^(-2)以上的品种有6个,‘先玉1620’的总可消化营养物产量最高。综合评价得出,在本试验条件下,青贮综合生产性能高的品种为‘先玉1620’‘文玉3号’和‘科大101’,可以大面积在陇东南地区作为全株青贮玉米品种推广种植。

IMPACT OF CLIMATE ON GRAIN YIELD PER UNIT AREA IN CHINA DURING THE YEARS OF 1949～1992

The grain yield per unit area in China has been increasing from 1949 to 1992 with annual fluctuations, which was caused by both policies and monsoon climate. The total grain yield is divided into trend yield, which reflects the influence of economic factors, and climate yield, which reflects the impact of climate factors. The results of grain and climate yield by EOF (empirical orthogonal function) method show that the grain yield in the eastern China is higher and more fluctuating than that in the western region. The spatial and temporal distributions of climate yield were divided into four patterns. Regional unanimity of climate yield variation is the first and main spatial pattern, and then there are the spatial patterns of north-south difference and east-west difference in some years. Generally, climate conditions are good for grain yield during the 1950s and 1980s all over the country.

咸水灌溉下设施番茄水盐生产函数构建及产量预测

以新疆南部地区设施番茄品种“秦岭蔬越”为研究对象开展咸水灌溉试验,设置4个咸水矿化度,分别为T1(2 g·L^(-1))、T2(4 g·L^(-1))、T3(6 g·L^(-1))和T4(8 g·L^(-1)),以淡水灌溉为对照(CK),采用修正后的Jensen模型构建咸水灌溉条件下设施番茄水盐生产函数,估算不同矿化度咸水灌溉番茄产量。结果表明,连续灌溉高矿化度咸水导致番茄减产,初始灌溉矿化度为2~4 g·L^(-1)咸水可确保番茄产量和IWUE。大于4g·L^(-1)咸水灌溉抑制作物生长且减产严重。土壤含水率和盐分随土层深度逐渐降低,40 cm深处达到含水率峰值,盐分主要聚集在浅层且盐分含量随咸水矿化度增高;番茄耐盐能力早期较弱而后期增强,番茄不同生育期盐分敏感指数σ为苗期>开花结果期>结果盛期>结果末期。开花结果期对水分敏感性最强,水分敏感指数λ依次为开花结果期>结果盛期>苗期>结果末期;基于Jensen模型构建设施番茄水盐生产函数对产量估算精度较高,R2>0.96,可用于指导新疆南部地区设施番茄咸水灌溉管理。综合考虑咸水灌溉对番茄产量及土壤水盐变化,建议新疆南部地区设施番茄微咸水滴灌最优方案为:在非连续咸水灌溉条件下,苗期、开花结果期采用淡水充分灌溉,结果盛期、结果末期采用亏缺灌溉和咸水矿化度为2~4g·L^(-1)的微咸水灌溉组合。通过构建咸水灌溉条件下设施番茄水盐生产函数,为作物水盐精准管理及咸水资源安全利用提供理论依据。

Evaluation of excitation function by TALYS code for producing ^(109)Cd with different ion beams

TALYS code was used to calculate excitation functions for proton induced onn atAg,natCd and 113In,deuteron induced onn atAg and alpha induced on natPd that lead to produce 109Cd radioisotope using low and medium energy accelerators;calculates was performed out up to 50 MeV.Recommended thickness of the targets according to SRIM code was premeditated.Theoretical integral yields for any reaction were computed.TALYS 1.0 code predicts that production of a few curries of 109Cd is feasible using a target of high isotopically enriched 110Cd,proton energy of 15 to 27 MeV,however high cost of the enriched target seems to be not a practical economic alternative to produce1 09Cd.The Ag+p and Ag+d processes can be an efficient route and economic for the production of millicurries of the radioisotope with incident beam energy less 15 MeV using low energy accelerator.

车用7075铝合金板的各向异性和拉压不对称屈服行为

对退火态7075铝合金板进行了不同加载方向(与轧制方向呈0°,15°,30°,45°,60°,75°,90°)下的单轴拉伸与单轴压缩试验以及液压胀形试验,研究了屈服行为;通过耦合静水压力项修正了Yld2004-18p各向异性屈服函数,对铝合金板的屈服强度进行预测,并与试验结果进行了对比。结果表明:不同加载方向或加载方式下,试验合金板的屈服强度不同,合金板具有显著的屈服各向异性和拉压不对称性;修正后的非对称各向异性屈服函数预测的屈服强度和试验值之间的总相对误差仅有0.0005,可以准确描述7075铝合金板各向异性和拉压不对称屈服行为。

基于分数阶黏壶元件的岩石损伤蠕变模型

目的为了建立一个能描述岩石蠕变全过程的蠕变模型。方法首先以分数阶黏壶元件描述岩石的黏弹性,采用基于Kachanov损伤率公式的损伤体描述岩石的粘塑性并串联一个胡克体建立成只有四个元件的蠕变模型。然后,将其本构方程推广到三维应力状态,考虑球应力,并引入一个屈服函数来准确判断岩石是否发生非稳定蠕变。最后,采用最小二乘法分析得到模型参数,用红砂岩和砂质泥岩的蠕变实验数据验证模型的有效性。结果新的蠕变模型理论曲线与实验数据曲线吻合较好,可以描述岩石蠕变的全过程。结论新的蠕变模型解决了经典模型在描述岩石蠕变时的模型复杂和参数较多的问题,对研究岩石蠕变特性具有一定的参考价值。

Derivation of Plastic Work Rate Done per Unit Volume for Mean Yield Criterion and Its Application

In Haigh Westergaard stress space linear combination of twin shear stress and Tresca yield functions is called the mean yield （MY） criterion. The mathematical relationship of the criterion and its plastic work rate done per unit volume were derived. A generalized worked example of slab forging was analyzed by the criterion and its corresponding plastic work rate done per unit volume. Then, the precision of the solution was compared with those by Mises and Twin shear stress yield criterions, respectively. It turned out that the calculated results by MY criterion were in good agreement with those by Mises criterion.

基于C++的金属丝线屈服曲线的设计与实现

在工业生产实践中,金属丝线折弯成型是常见的加工工艺过程.例如:弹簧机将钢丝压出弹簧,眼镜绕框机将框丝绕出眼镜框型等.该类设备都有一个送丝机构,将直的金属丝推入由动、静轮为主要部件构成的成型机构中挤压变形,从而加工出不同形状、不同大小的框型产品.以自动眼镜绕框机系统为例,说明金属框丝形变与动轮压力角度之间函数关系的建立及使用C++语言实现过程.

适宜水氮互作提升膜下滴灌瓜尔豆产量品质与水氮利用效率

瓜尔豆是一种重要的经济作物,因其种子中含有大量的瓜尔胶而具有重要的经济和工业价值。为探究适合新疆地区膜下滴灌瓜尔豆的水氮管理模式,设置4个灌水量水平(W1:1 170 m^(3)/hm^(2)、W2:1 530 m^(3)/hm^(2)、W3:1 890 m^(3)/hm^(2)、W4:2 250 m^(3)/hm^(2))和2个施氮量水平(N1:30 kg/hm^(2)、N2:50 kg/hm^(2)),研究膜下滴灌条件下水氮互作对瓜尔豆生长指标、产量、水氮利用效率及品质的影响。结果表明,新疆干旱区绿洲种植瓜尔豆具有可行性,膜下滴灌水肥一体化处理下水氮耦合效应对瓜尔豆产量、灌溉水利用效率、氮肥偏生产力及半乳甘露聚糖含量影响极显著(P <0.01)。在W1~W3灌水条件下,增施氮肥能有效提高作物单株质量及千粒质量,从而最终提高作物产量。基于主成分分析及隶属函数分析得出灌水量为1 890 m^(3)/hm^(2),施氮量为50 kg/hm^(2)(W3N2)水氮组合模式为最优处理。研究可为促进新疆干旱区绿洲膜下滴灌瓜尔豆高产、高水、氮利用效率提供理论依据。

核桃蛋白提取方法研究进展

核桃粕是核桃榨油后的副产物,富含蛋白质,核桃蛋白中必需氨基酸含量较高,成分均衡,是成人必需氨基酸的良好来源。核桃蛋白传统提取方法主要为碱溶酸沉法,随着提取设备及提取技术的进步,更多的新型方法及组合方式被开发且证实优于传统方法。然而,采用不同的方法提取核桃蛋白的提取率、纯度,以及结构和功能性质存在显著差异。因此本文重点介绍了具有潜在产业化应用价值的核桃蛋白提取方法,包括碱溶酸沉法、超声辅助、酶辅助以及反胶束法,阐述了不同提取方法对核桃蛋白质结构及功能的影响,并对其应用前景进行了展望,旨在为核桃蛋白质资源的深入研究及开发提供参考。

基于气候适宜度的吉林省烤烟产量评估

烤烟是吉林省的经济作物之一,也是农民增收的重要作物之一,掌握其产量变化对保障烟农增收十分必要。气候条件是对烤烟产量影响最大的因素,目前预测评估气象因子对吉林省烤烟产量影响方面的研究较少。因此,本文利用指数平滑法分离出1981—2018年吉林省烤烟趋势产量和气象产量,利用隶属函数法确定了旺长期(6月)降水和大田生长期可用时间是影响吉林省烤烟产量的重要气象因子,计算出每个县各个影响因子的适宜度,再通过信息熵值法计算出烤烟产量气候影响因子的权重,并计算出每个地市的综合气候适宜度,最后建立烤烟气象产量与地市综合气候适宜度的多元线性回归模型。结果表明,烟叶旺长期降水和大田生长期可用时间是吉林省烤烟产量的气象限制因素,其中烤烟旺长期降水影响权重占0.81,大田生长期可用时间影响权重占0.19。通过该方法建立的产量预报模型准确率在80%以上,该方法可以用于烤烟产量评估。