DN 2 800mm氨塔平盖厚度的计算

GB 150-2011对开孔平盖厚度计算公式进行了较大的修改和补充,但最新版的SW6软件却未进行相关的修改,以至于目前的大盖厚度的计算存在材料浪费的情况。以DN 2 800mm氨塔平盖为例,运用新的修正公式计算后,使大盖计算厚度由680.7mm减少到614.9mm,重量减轻约4.6t。进一步利用Ansys软件对厚度减少后的大盖进行全面的应力强度评定,以探究是否有进一步优化的可能。     

不同支座条件下开孔球壳的有限元分析

利用ANSYS有限元分析软件对带有开孔接管的球壳容器在不同支座条件下进行了建模分析.在相同的内压静载荷条件下对各模型相应的应力、应变以及线位移值进行了精确求解,分析了其最大应力、应变等值出现的区域范围,为该类容器的设计与使用提供了哩论参考依据.     

复合材料开孔平板剪切稳定性研究

本文对复合材料开孔平板试验件进行剪切载荷下的稳定性分析。对厚度为2mm,铺层为16层的开孔平板进行剪切稳定性试验。采用工程算法对复合材料平板的临界屈曲载荷与剪切屈曲应变进行计算，该方法考虑了铺层与边界条件的影响。通过有限元仿真软件建立剪切平板模型，计算模型的屈曲模态，并将模态作为初始缺陷引入模型，通过有限元弧长法计算复合材料平板模型的非线性屈曲载荷及屈曲应变。对于平板模型，工程算法得到的剪切屈曲载荷、屈曲应变与有限元模型计算的结果基本吻合。对于带孔平板模型，利用有限元弧长法仿真得到剪切载荷作用下的应力分布及非线性屈曲载荷，与试验结果对比较好。通过有限元结果与试验、工程算法结果对比，验证了有限元模型的可靠性。基于验证过的有限元模型进行了参数化研究，评估了不同开孔直径对复合材料平板剪切屈曲稳定性的影响。研究结果表明，开孔会导致结构剪切屈曲载荷显著下降，孔边比为0.3时，为临界屈曲载荷最优的结构模型。开孔直径越大，结构的剪切屈曲载荷越小，孔边应变逐渐增大。     

换热器外导流筒应力分析与大开孔研究及试验

本文采用了工程上实用的薄壳理论和有限元两种方法以及进行实验验证相结合的方针对外导流筒进行了全面的应力应变分析研究，并同时考虑了开孔，特别是在大开孔情况。     

换热器外导流筒应力分析与大开孔研究及试验

本文采用了工程上实用的薄壳理论和有限元两种方法以及进行实验验证相结合的方针对外导流筒进行了全面的应力应变分析研究,并同时考虑了开孔,特别是大开孔情况。     

几种大开孔补强方法的分析比较

针对大开孔的补强计算方法——压力面积法、ASME压力面积应力法、俄罗斯ГОСТР52857.3-2007中的极限载荷法以及GB150-2011中的分析法,分别介绍了几种方法的适用情况。通过对大开孔结构的补强计算比较,显示出几种方法的异同之处。提出当开孔率ρ>0.9时,可借鉴极限载荷法进行补强计算。     

卷染机矩形开孔结构的应力分析

本文采用有限元法，对某移门式卷染机的矩形开孔部位进行了应力计算和强度分析，对矩形孔边应力分布和开孔补强设计进行了讨论。     

医用氧舱壳体封头矩形大开孔有限元分析计算

医用氧舱封头矩形大开孔的尺寸超出GB150－1998《钢制压力容器》的开孔和补强计算的适用开孔范围。本文给出了有限元计算和分析，应力和应变在允许范围之内。     

喷嘴洗涤器弯头开孔结构有限元分析及强度评定

由于弯头开孔结构无法按常规设计方法进行开孔补强计算,故对弯头接管开孔区域建立了三维有限元力学分析模型。利用三维实体模型,真实地模拟了特殊结构的形状、载荷分布、边界条件,计算出最接近真实状况的应力分布情况;根据有限元分析结果,按JB4732-1995《钢制压力容器——分析设计标准》进行了应力强度评定,为详细工程设计提供了弯头开孔补强计算方法。     

离心机转鼓强度计算规范中开孔系数的讨论

运用有限元分析软件ANSYS,对开孔后的离心机转鼓进行应力模拟计算,并与JB/T 8051-1996《离心机转鼓强度计算规范》得到的结果进行了对比分析。结果表明,规范中开孔系数的选取对转鼓应力的计算会带来一定的偏差,需要进一步的修正。     

钻井分流器壳体的有限元分析

通过SilidWorks中的Simulation软件对钻井分流器壳体进行分析,在额定工作压力和静水压试验压力下分别分析壳体受压应力区,验证壳体的设计的合理性,进而对其设计进行优化。     

Dynamics of Emerging Water Droplet Subjected to Sidewall with Different Wettabilities in a Fuel Cell Cathode Channel

On‐site experiments on low temperature fuel cells revealed that water droplets tend to emerge into the gas channel at the corner. This motivates the present investigation on the effects of the location where water emerges from and the wettability of sidewall on the dynamic behaviour of liquid water in gas channel by numerical simulations that employ the volume‐of‐fluid method. A microchannel with a square cross‐section of 0.25 mm in width and a pore of 0.05 mm in diameter is adopted. The simulation results for different pore locations and wettabilities of sidewall show that the behaviour of water droplet only depends on the wettability of bottom wall when it emerges from the centreline without attaching to the sidewall and gains the highest pressure drop. When the emergence location shifts towards the corner, the water droplet unavoidably attaches to the sidewall and thus the wettability of sidewall is found to have significant effects on its dynamics: hydrophobic sidewall results in droplet detachment and fast removal with the highest pressure drop and the minimal water saturation, whereas hydrophilic sidewall leads to a water film and accumulation with the lowest pressure drop and the minimal water coverage on the bottom wall.     

机制砂混凝土应力-应变试验研究

为研究机制砂混凝土单轴应力状态下的力学性能,通过对0%、4%、8%、12%、16%、20%(质量分数)六种石粉含量,C20、C30和C40三类强度等级的机制砂混凝土棱柱体试件进行单轴抗压试验,并与河砂混凝土进行对比,获得了其在单轴受压下的应力-应变全曲线,拟合得到了适用于机制砂混凝土单轴受压的本构方程,结果表明:机制砂混凝土应力-应变曲线变化趋势和河砂混凝土基本相似,在曲线的上升段,机制砂混凝土与河砂混凝土基本重合,但在曲线下降段,机制砂混凝土比较陡峭;随着石粉含量的增加,机制砂混凝土试件的峰值应力和峰值应变都呈现出先增加后减小的趋势,当石粉质量分数为8%时,三种不同强度等级的机制砂混凝土峰值应变均达到最大;机制砂混凝土峰值应力和弹性模量均随着混凝土设计强度等级的提高而增大;基于Sargin模型拟合得到的机制砂混凝土应力-应变全曲线与试验全曲线吻合性较好。     

K2 Transfection System Boosts the Adenoviral Transduction of Murine Mesenchymal Stromal Cells

Adenoviral vectors are important vehicles for delivering therapeutic genes into mammalian cells. However, the yield of the adenoviral transduction of murine mesenchymal stromal cells (MSC) is low. Here, we aimed to improve the adenoviral transduction efficiency of bone marrow-derived MSC. Our data showed that among all the potential transduction boosters that we tested, the K2 Transfection System (K2TS) greatly increased the transduction efficiency. After optimization of both K2TS components, the yield of the adenoviral transduction increased from 18% to 96% for non-obese diabetic (NOD)-derived MSC, from 30% to 86% for C57BL/6-derived MSC, and from 0.6% to 63% for BALB/c-derived MSC, when 250 transduction units/cell were used. We found that MSC derived from these mouse strains expressed different levels of the coxsackievirus and adenovirus receptors (MSC from C57BL/6≥NOD>>>BALB/c). K2TS did not increase the level of the receptor expression, but desensitized the cells to foreign DNA and facilitated the virus entry into the cell. The expression of Stem cells antigen-1 (Sca-1) and 5′-nucleotidase (CD73) MSC markers, the adipogenic and osteogenic differentiation potential, and the immunosuppressive capacity were preserved after the adenoviral transduction of MSC in the presence of the K2TS. In conclusion, K2TS significantly enhanced the adenoviral transduction of MSC, without interfering with their main characteristics and properties.     

A critique of master sintering curve analysis

In this work, we explore factors affecting the accuracy of the master sintering curve (MSC) approach for analyzing the complete sintering profile of ceramic powders. We show that the instantaneous anisotropic shrinkage must be accounted for to develop an accurate MSC. The MSC diverges at >90% density because of basic assumptions that oversimplify the analysis of the densification process. We also show that powder chemistry and forming techniques can affect the fitting parameter Q. Q should not be interpreted as the sintering activation energy, or used to interpret mechanistic differences since it is comprised of several mechanisms that influence densification throughout the sintering cycle. Despite these limitations, the MSC is a useful and practical tool for predicting thermal load (i.e. time and temperature) effects on the densification of a ceramic part fabricated from a singular powder that is fabricated by a singular forming process.     

600/50-22.5 IMP的设计开发

依据ETRTO标准,采用60度左右的大角度冠角控制外直径伸张,肩部采用半径115mm的大圆弧过渡,增加行驶面接地面积,提高通过性,同时减少转弯阻力;采用横向有向花纹设计,提高驱动时的抓着力,同时在用于从动轮时可降低滚动阻力;花纹沟底部采用全圆弧设计,防止花纹沟底部裂口;采用工程轮胎胎面胶配方,提高轮胎的耐刺扎、耐切割及磨耗性能;胎体采用8层1400dtex/2帘布,增加胎侧刚性,同时采用大三角胶,提高胎圈部位的支撑性能,避免超载引起胎圈部位损坏。采用模具合模处加100mm“腰带”及胎侧字体采用活络块的方式,一模两用,降低模具成本。     

子午斜交轮胎力学性能有限元分析

提出一种新型子午斜交轮胎结构,即将子午线轮胎胎侧部位的胎体帘线子午结构改为斜交结构,并利用有限元模型对子午斜交轮胎和子午线轮胎的特性进行对比分析.结果表明:与子午线轮胎相比,子午斜交轮胎的径向刚度较高;胎侧应变能密度分布较连续且相对均匀,且最大应变能较低;胎面横向接地压力分布较均匀、尤其是胎肩处的应力集中区域较小,接地印痕形状近似椭圆形;带束层边缘的剪切应变峰值较小.     

子午线轮胎充气和负荷加载数值分析

利用MSC.MARC软件对子午线轮胎的骨架材料进行三维非线性有限元计算,带束层、胎体和钢丝圈等部位采用rebar单元以及实体Herrmann单元进行模拟,橡胶材料采用Yeoh材料模型描述. 轮胎在不同充气压力、不同负荷以及滚动状态下的受力计算结果与实际情况一致.采用该方法有助于改进轮胎结构设计、提高轮胎性能.     

Simulations on structure performance of 3C thin‐wall injection‐molded parts

Manufacturing of 3C (Computer, Communication, and Consumer Electronics) products toward weight reduction, thin‐wall, and minified‐size is an inescapable trend for the future 3C industries. However, the induced damage information from drop impact, including exterior housing fracture, liquid crystal display (LCD) cracking, solder‐joint breaking, or interior component failure, is still derived experimentally and involves very complicated parametric analyses, such as a dynamic impact process, drop orientation, contact behavior, and large deformation during the impact instance. In the present study, numerical simulations for the drop test and bending strength were applied to a thin‐wall computer dictionary (Model CD‐66) housing to understand the key factors that affect the part drop test performance. The appropriate modeling that would affect simulation accuracy as well as the associated nodal degree of freedom and computer time were also investigated. A housing of CD‐66 was redesigned to be 1 mm thick and structurally verified with two different plastics: polycarbonate (PC) and acrylonitrile butadiene styrene (ABS). The simplification of the PC board and LCD backlight circuit in finite element modeling (FEM) only causes about a 10% difference, while saving many modeling costs. The numerical simulations also indicate that both its bending strength and drop‐impact strength were decreased only about 5%, whereas the product quality still met its strength requirement if only the top housing plate thickness was reduced while the remaining sidewall thickness was kept unchanged. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3064–3071, 2002     

低温冻融循环对陶粒混凝土动态力学性能的影响

为了研究冻融循环温度和循环周次对陶粒混凝土动态力学性能的影响,开展了冻融循环试验和Hopkinson束杆动态压缩试验.冻融循环温度上限取+10℃,下限取为-20～-60℃,间隔-10℃,试样尺寸150 mm×150 mm×100 mm,对冻融循环后的试样进行动态压缩试验.结果表明,增加冻融循环周次和降低冻融循环温度,均...