共查询到20条相似文献，搜索用时 15 毫秒
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本文建立了热残余应力分析的数学模型，采用数值方法对陶瓷涂层材料的热残余应力进行了分析，得出了金属基底的弹性性能、过渡层的厚度和陶瓷涂层的孔隙率对热残余应力的影响，为含FGM的陶瓷涂层材料的优化提供了一种理论分析方法。 相似文献
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采用有限元方法模拟了热载荷下梯度结构硬质合金的弹塑性响应．样品几何模型为二维梯度结构的轴对称圆柱体．通过引入约束因子构建了梯度材料的弹塑性本构方程．数值模拟表明：当材料温度从初始无应力的800℃下降到0℃时,在样品表面出现了压应力而在富钴区出现了拉应力;表面压应力的最大值为254MPa,富钴区拉应力的最大值为252MPa;在钴相浓度差等于或大于0．3时,钴相梯度区出现了明显的塑性流动;当温度从0℃上升到800℃时,总的塑性应变达到0．0014．塑性流动有利于降低材料内部的热应力集中． 相似文献
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为了解玻璃纤维(GFRP)布与钢筋混凝土梁界面之间的粘结性能,进行了7根GFRP布加固的钢筋混凝土梁与2根对比梁的试验研究.试验的变化参数为GFRP布层数、粘结长度及配筋率.试验结果表明,GFRP布加固的钢筋混凝土梁极限荷载显著提高,但是发生剥离破坏的试验梁极限荷载有所降低,粘结长度是影响加固梁剥离破坏的主要因素.根据试验结果提出了GFRP布与钢筋混凝土梁界面粘结剪应力的试验分析方法并分析了界面间粘结剪应力的分布.同时,提出了GFRP布加固的钢筋混凝土梁剥离正应力与粘结剪应力的理论分析方法.最后,给出了GFRP布加固钢筋混凝土梁剥离荷载的计算方法.为验证理论分析方法的正确性,计算了试验梁界面间的粘结剪应力、剥离正应力及剥离荷载.计算结果表明,所提出的理论分析方法与试验值吻合较好. 相似文献
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以一金属-梯度材料-陶瓷的复合圆简为研究对象，研究了功能梯度材料组份连续变化论况下的温度分布和热应力分布规律；并根据强度理论，就ZrO2Ti－6AI－4V梯度材料的热应力分布进行了组份分布的统和特性设计．计算结果表明：金属-陶瓷梯度材料具有较好的热应力缓和性，且其模型具有较广的适用性． 相似文献
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Analytical solution for functionally graded anisotropic cantilever beam under thermal and uniformly distributed load 总被引：1，自引：0，他引：1
HUANG De-jin DING Hao-jiang CHEN Wei-qiu 《浙江大学学报(A卷英文版)》2007,8(9):1351-1355
The bending problem of a functionally graded anisotropic cantilever beam subjected to thermal and uniformly dis-tributed load is investigated,with material parameters being arbitrary functions of the thickness coordinate. The heat conduction problem is treated as a 1D problem through the thickness. Based on the elementary formulations for plane stress problem,the stress function is assumed to be in the form of polynomial of the longitudinal coordinate variable,from which the stresses can be derived. The stress function is then determined completely with the compatibility equation and boundary conditions. A practical example is presented to show the application of the method. 相似文献
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Pure bending of simply supported circular plate of transversely isotropic functionally graded material 总被引：3，自引：0，他引：3
LI Xiang-yu DING Hao-jiang CHEN Wei-qiu 《浙江大学学报(A卷英文版)》2006,7(8):1324-1328
INTRODUCTION In recent years, functionally graded materials (FGMs) have attracted more and more attention. Due to their continuously varying material properties in space on the macroscopic scale, FGMs, therefore, are usually superior to conventional fiber-matrix materi-als in mechanical behavior, especially for perform-ance under thermal loading. Now FGMs have been widely used in various fields including electronics, chemistry, optics, biomedicine, etc. Heretofore, volumes of literatu… 相似文献
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建立了模拟涂层残余应力的数学模型,对等离子喷涂不同厚度NiCrAl/Cr2O3-8%TiO2涂层的残余应力进行了模拟,模拟结果表明:由于涂层与基体的热膨胀系数不匹配等原因,在界面等区域存在严重的应力集中,涂层内部的残余应力水平,随涂层厚度增加而增加,涂层中的径向、轴向、切向应力均为压应力,径向应力是最主要的应力。 相似文献
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Scratch test and friction test were performed to evaluate the internal and external interface behaviors of TiAlSiN coating, respectively. The critical compressive and shearing stress of coating failure during scratch test were calculated and the values are 30.84 MPa and 4.98 MPa respectively. The average friction coefficients of TiAlSiN coating against 2Cr12Ni4Mo3VNbN steel are 0.70 (sliding speed 50 m/min), 0.63 (sliding speed 100 m/min), and 0.81 (sliding speed 150 m/min). The elements diffusion was analyzed by EDS. Al and Si element of coating material diffuse to the steel disc, except Ti element. The oxidation decreases with the increase of sliding speed, but the adhesion increases with the increase of sliding speed. More Al element diffuses to the steel disc at the high sliding speed, but the diffusion of Si element keeps almost constant at different sliding speeds. 相似文献
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用阳离子型的聚二茂铁硅烷(PFS Cl-)与阴离子型的聚苯乙烯磺酸钠(PSS-Na )在石英、金材料表面上制备了PFS -PSS-多层自组装膜.多层自组装膜的逐层UV-Vis光谱表明,多层膜具有均匀有序的结构.多层自组装膜的电化学研究表明,膜的电化学性质与膜的层数和膜外表面聚电解质性质有关.当自组装膜层数较少时,膜电极过程表现出表面定域的单层膜性质;当膜层数较多时,膜内电活性物质的扩散成为控制步骤.而且,随着膜层数增加,膜内传质阻力增大,膜内扩散速率减小,膜的CV峰的可逆性降低. 相似文献
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MA Gai-ling XU Hong CUI Wen-yong 《浙江大学学报(A卷英文版)》2007,8(5):778-785
Applying the results of stress and strain calculated by 3D finite element model of truck radial tire 11.00R20, a MATLAB program used to compute rolling resistance of the tire caused by hysteresis rolling resistance (HRR) is worked out. The HRR distribution on different part of tire section, and the effects of speed, load, internal pressure and the width of the rim on HRR are analyzed. The analysis results showed that energy loss produced by tread rubber contributes the most part to HRR of the whole tire, and that to decrease the HRR, the hysteresis factor of the tread rubber should be reduced, and the distribution of the stress and strain on the section be optimized. 相似文献
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High-Temperature Corrosion of Protective Coatings for Boiler Tubes in Thermal Power Plants 总被引：4，自引：0，他引：4
High-temperature corrosion is a serious problem for the water-wall tubes of boilers used in thermal power plants. Oxidation, sulfidation and molten salt corrosion are main corrosion ways.Thereinto, the most severe corrosion occurs in molten salt corrosion environment. Materials rich in oxides formers, such as chromium and aluminum, are needed to resist corrosion in high-temperature and corrosive environment, but processability of such bulk alloys is very limited. High velocity electric arc spraying (HVAS) technology is adopted to produce coatings with high corrosion resistance. By comparison, NiCr (Ni-45Cr-4Ti) is recommended as a promising alloy coating for the water-wall tubes, which can even resist molten salt corrosion attack. In the study of corrosion mechanism, the modern material analysis methods, such as scanning electron microscopy ( SEM ), X-ray diffractometry (XRD) and energy dispersive spectrometry (EDS), are used. It is found that the corrosion resistances of NiCr and FeCrAl coatings are much better than that of 20g steel, that the NiCr coatings have the best anti-corrosion properties, and that the NiCr coatings have slightly lower pores than FeCrAI coatings. It is testified that corrosion resistance of coatings is mainly determined by chromium content, and the microstructure of a coating is as important as the chemical composition of the material. In addition, the fracture mechanisms of coatings in the cycle of heating and cooling are put forward. The difference of the thermal physical properties between coatings and base metals results in the thermal stress inside the coatings. Consequently, the coatings spall from the base metal. 相似文献
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以应用于CRH380A型动车组上的SKMB-200型动力转向架构架为研究对象,基于UIC615-4标准计算4种模拟运营工况载荷及一种超常载荷,继而确定仿真分析所需的边界条件。静强度仿真结果表明:模拟运营工况下,构架的最大应力分别为225.7、209.0、250.3和196.2MPa,超常载荷工况下构架的最大应力为307.6MPa,均小于构架主材料SMA490BW型耐候钢的许用应力。在超常载荷工况下进行结构优化分析,分别设定侧梁上下盖板和内外侧板的厚度为设计变量、最大等效应力为约束条件、构架最小质量为目标函数。优化结果表明:优化后构架总质量减少109 kg,较优化前降低6.8%;构架最大等效应力为329.98 MPa,仍满足其强度要求。对构架结构参数的优化可有效降低SKMB-200型转向架的簧下质量,进而提升其动力学性能,可为动车组转向架结构优化提供参考。 相似文献
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We present novel vector permutation and branch reduction methods to minimize the number of execution cycles for bit reversal algorithms. The new methods are applied to single instruction multiple data （SIMD） parallel implementation of complex data floating-point fast Fourier transform （FFT）. The number of operational clock cycles can be reduced by an average factor of 3.5 by using our vector permutation methods and by 1.1 by using our branch reduction methods, compared with conventional implementations. Experiments on MPC7448 （a well-known SIMD reduced instruction set computing processor） demonstrate that our optimal bit-reversal algorithm consistently takes fewer than two cycles per element in complex array operations. 相似文献
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The thermal behavior of a thick transversely isotropic FGM rectangular plate was investigated within the scope of three-dimensional
elasticity. Noticing many FGMs may have temperature-dependent properties, the material constants were further considered as
functions of temperature. A solution method based on state-space formulations with a laminate approximate model was proposed.
For a thin plate, the method was clarified by comparison with the thin plate theory. The influences of material inhomogeneity
and temperature-dependent characteristics were finally discussed, through numerical examples.
Project (No. 10002016) supported by National Natural Science Foundation of China 相似文献
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The key in the force transmission between the tower and the foundation for offshore wind turbines is to transfer the large moment and horizontal loads.The finite element model of a large-scale prestres... 相似文献
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由于引脚、印制电路板和焊接剂的热-机材料属性不同,在受到热载荷或机械载荷时,引脚焊接界面端会产生奇异性应力,有可能产生界面开裂。为了基于界面端奇异场来评价QFP结构引脚界面端力学行为,采用数值方法求解引脚焊缝任意角度尖劈界面端的应力强度系数。具体步骤为:首先,基于高次内插有限元特征分析法确定两相任意角度尖劈界面端的奇异性指数和应力角分布函数,并引入常数热应力项,获得热-机耦合奇异性应力场表达式;采用有限元分析技术和最小二乘拟合法来获得应力强度系数的数值解。考察了热-机材料属性对热载荷下焊接剂/印制电路板界面端应力强度系数的影响。结果表明:弹性模量、泊松比和材料热膨胀系数等均对应力强度系数有影响,适当的做出调整可以使界面端呈现良好的热应力状态。 相似文献
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A novel UV-curable prepolymer neopentyl glycol diglycidyl ether diacrylate(NPGGEA)was synthesized by using neopentyl glycol diglycidyl ether(NPGGE)and acrylic acid(AA)as starting materials, N, N-dimethylbenzylamine as catalyst and p-hydroxyanisole as inhibitor. The optimum synthetic conditions were taken as follows: The concentration of N,N-dimethylbenzylamine, 0.80% of reactants; the concentration of p-hydroxyanisole, 0.3% of reactants; the reaction temperature, 90-110℃; the molar ratio of NPGGE to AA, 1:2.2. Meanwhile, 1-hydroxycyclohexyl phenyl ketone of a UV-cured initiator was added to the synthesized NPGGEA to prepare a kind of UV-cured coating. Mechanical properties of the UV-cured films were determined, giving 28.75 MPa of tensile strength, 923.82 MPa of Young‘s modulus and 5.51% of elongation at tear. 相似文献
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ＩＮＴＲＯＤＵＣＴＩＯＮＡｓｋｎｏｗｎ ,ｔｈｅｒｍａｌｂｅｈａｖｉｏｒｓｏｆｓｔｒｕｃｔｕｒｅｓｍｕｓｔｂｅｃｏｎｓｉｄｅｒｅｄｉｎｍａｎｙｓｉｔｕａｔｉｏｎｓ.Ｓｔｕｄｙｏｆｔｈｅｒｍａｌｅｆｆｅｃｔｏｎｄｅｆｏｒｍａｔｉｏｎｓａｎｄｓｔｒｅｓｓｅｓｏｆ 相似文献