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三圆弧椭圆封头及其参数优化 总被引:2,自引:0,他引:2
使用有限元方法研究了标准椭圆封头以及双圆弧近似椭圆封头应力状态,对它们的应力分布进行了分析。针对双圆弧近似椭圆封头的峰值应力较标准椭圆有较大提高这一事实,提出了用优化的三段圆弧代替了两段圆弧作近似椭圆封头的母线。应力分析的结果表明,三段圆弧近似椭圆封头的峰值应力已十分接近标准椭圆封头,而且其成形工艺亦不复杂。 相似文献
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冷旋近似椭圆封头与标准椭圆封头的比较 总被引:8,自引:0,他引:8
本文对冷旋近似椭圆封头与标准椭圆封头(JB1154—73)的成型方法、几何特征及应力状态进行了分析比较。结果表明,冷旋近似椭圆封头是碟形封头。本文指出,冷旋近似椭圆封头不能直接等效地代用标准椭圆封头(JB1154—73)。本文也给出了一个两者的简单代用关系。 相似文献
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椭圆封头是压力容器的重要组成部分,其制造质量的优劣直接关系着容器质量和使用安全。有关椭圆封头制造参数的函数关系、数值的确定十分重要,也是工艺人员非常关注的技术问题。本文就有关问题加以简要说明。一、椭圆封头的结构与参数椭圆封头的中心剖面及参数如图1所示。图1椭圆封头示意图椭圆封头的内表面是由半个椭圆及直边组成。a——椭圆的长半轮(工程上称为椭圆封头的半径,为叙述的一致,此处仍以a表示)1。———椭圆的短半轴h——一直进高’一板厚D.———椭圆的内径按文献「1]推荐:::b一2:1。这种应用最为广泛的椭圆封头… 相似文献
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运用ANSYS的APDL语言进行参数化有限元建模,对椭圆封头大开孔接管整体补强结构的重量进行优化设计。 相似文献
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旋压碟形封头的应用和几何尺寸的选择 总被引:1,自引:0,他引:1
1 前言碟形封头采用旋压加工效益明显,目前,国内设计的压力容器多采用椭圆封头,其中以标准椭圆封头(h_i=0.25D_j)最多。根据旋压成形原理,不可能旋压椭圆封头,而实际是旋压碟形封头。碟形封头的推广应用涉及两个方面:一是采用碟形封头代替椭圆封头使用,另一是选定较优的碟形封头几何尺寸参数,并尽快建立旋压碟形封头标准,规定尺寸系列,供设计者直接选用。 相似文献
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本文从标准椭圆封头在内压P作用下的受力分析出发 ,对GB150 - 1998《钢制压力容器》中关于椭圆封头开孔补强的有关条款的合理性进行了探讨 ,并提出了作者的建议。 相似文献
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旋压封头残余应力的试验研究 总被引:3,自引:2,他引:1
本文采用钻小盲孔法对旋压椭圆封头进行了残余应力的试验研究,结果表明:旋压封头产生的冷加工残余应力存在于整个封头。本文还对旋压封头在内压作用下的应力水平及分布状况进行了实测研究。 相似文献
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《压力容器》2019,(11):25-33
采用有限元弹塑性屈曲分析,考虑椭圆封头的最大形状偏差并在过渡区施加局部厚度减薄缺陷,针对不同材料和厚径比δ_e/D_i,较为系统地讨论了内压标准椭圆封头结构屈曲载荷P_(cr)与极限载荷P_L的变化规律。研究结果表明,厚径比小于某临界值时,屈曲载荷低于极限载荷,分析模型发生屈曲破坏;厚径比大于某临界值时,屈曲载荷高于极限载荷,分析模型发生强度破坏。不同材料分析模型厚径比临界值存在一定差异,对高强钢13MnNiMoR材料而言,GB 150—2011标准防止标准椭圆封头内压弹性屈曲失效的厚径比规定偏于冒进。本文结果可为内压薄壁标准椭圆封头设计准则提供指导。 相似文献
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介绍了切削SiC非连续增强铝基复合材料时第一切削变形区的材料变形情况,推导了SiC增强相的转角公式,并用试验结果验证了SiC增强相的重定向现象。结果表明,第一切削变形区中的SiC增强相发生了重新定向运动,转向了铝基体的纤维化方向,转角大小会因SiC增强相在第一切削变形区中的具体位置和原位向的不同而存在差异。SiC增强相重定向后并不与剪切面重合,而是成一定角度。第一切削变形区的宽度与切削铝基体材料相比要大。 相似文献
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Zhang Wenge Li Jianrong Yu JilinKey Laboratory of Mechanical Behavior Design of Materials University of Science Technology of China CAS Hefei ChinaChen Xuedong Zhang Haibo Wang Bing Hefei General Machinery Research Institute 《机械工程学报(英文版)》2002,15(2):189-192
A numerical model on stress assessment of a defective elliptic gathering tube used in the heat recovery boiler of a pyrolyzer is built up. The effect of local defects on the carrying capacity of the tube is analyzed by using the MSC/NASTRAN finite element code, and the critical size of defects is obtained. Then, two numerical models of damaged tube with local and integral reinforcements, respectively, are also calculated. Stress classification and assessments are provided by applying the ASME and JB4732-1995 standard. Some guidance and suggestions about the tube reinforcements and the prediction of the remaining life of the structure for engineering practice are discussed. 相似文献
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Young-Tae Cho 《Journal of Mechanical Science and Technology》2002,16(2):192-202
In particle or short-fiber reinforced composites, cracking of the reinforcements is a significant damage mode because the
cracked reinforcements lose load carrying capacity. This paper deals with an incremental damage theory of particle or short-fiber
reinforced composites. The composite undergoing damage process contains intact and broken reinforcements in a matrix. To describe
the load carrying capacity of cracked reinforcement, the average stress of cracked ellipsoidal inhomogeneity in an infinite
body as proposed in the previous paper is introduced. An incremental constitutive relation on particle or short-fiber reinforced
composites including progressive cracking of the reinforcements is developed based on Eshelby’s (1957) equivalent inclusion
method and Mon and Tanaka’s (1973) mean field concept. Influence of the cracking damage on the stress-strain response of composites
is demonstrated. 相似文献
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Two new steel-reinforced, metal-matrix composites (MMCs), Kirksite+1080 and Kirksite+M2 are developed by adding 25 wt% of AISI 1080/AISI M2 steel machining chips to a zinc-based alloy, Kirksite (4% Al and 3% Cu). The sliding wear resistance of the Zn alloy and the two MMCs, against AISI 52100 steel, is determined under increasing normal load (1–10 N) and temperature (25–150 °C), using a pin-on-disc configuration. The MMCs are found to exhibit superior wear performance under all test conditions. At room temperature, a maximum wear reduction in excess of 70% is obtained for the composites relative to the Zn-alloy at the highest load of 10 N. This reduction is as much as 86% at 150 °C and 1 N for the Kirksite+M2. The wear-reducing ability of the steel reinforcements is generally greater at the more severe contact conditions. The stability of the MMC matrices and recommended limits to the MMC operating temperatures are established using deformation measurements made via dynamic mechanical analysis. The principal wear mechanisms are analysed based on the sliding wear measurements, complemented by optical microscopy and SEM observations, and EDX microanalysis. The results show that the steel chip reinforcements are effective in improving the wear resistance of Zn alloys under severe conditions. Implications for use of low-cost machining chips as reinforcements to create MMCs for improved wear performance, and for recycling/reuse of these chips in advanced structural material systems are discussed. 相似文献
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为实现汽车车身轻量化,尝试将镁合金应用在国内某桥车的车门防撞杆上。根据镁合金变形特点,把原来的一段式钢结构车门防撞杆更换为两段式镁合金防撞杆。利用有限元仿真软件,对镁合金防撞杆的动态碰撞性能进行了仿真。 相似文献
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在316L不锈钢粉中分别添加10%的TiC、WC、NbC、Al2O3、Si3N4五种增强体,研究了各种增强体与不锈钢基体的反应性及对烧结过程的影响。结果表明:TiC、WC、NbC与不锈钢基体有良好的相容性,能均匀分布到不锈钢基体中,可以有效提高其强度,添加TiC的不锈钢还表现出优越的耐腐蚀性;由于Al2O3与基体不锈钢相容性过差,不能发挥增强体的作用,使材料的强度和耐蚀性不良;添加Si3N4的不锈钢在烧结过程中Si3N4发生分解,弥散强化了基体,硅有促进烧结的作用,而氮均匀渗透到不锈钢中,有利于形成高强度的高氮钢,从而使其相对密度、硬度及耐蚀性都高于其他材料。 相似文献
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Dry sliding wear of an AA 6061 alloy reinforced with both modified SiC particles and metal coated carbon fibres has been studied. SiC particles were used to increase the hardness of the composite while short carbon fibres are supposed to act as a solid lubricant. SiC particles were coated with a silica layer deposited through a sol–gel procedure to increase the processability of the composite and to enhance the particle–matrix interfacial resistance. The metallic coatings on carbon fibres were made of copper or nickel phosphorus which was deposited through an electroless process. The metallic coatings favoured the wetting of the fibres during processing and then dissolved in the aluminium matrix forming intermetallic compounds that increased its hardness. Wear behaviour of AA 6061–20%SiC and AA 6061–20%SiC–2%C was compared with that of the composites with the same reinforcement content but using coated particles and fibres. The influence that the modification of the matrix because of the incorporation of coatings on the reinforcements had on the mild wear behaviour was investigated. The wear resistance of the composites increased when carbon fibres were added as secondary reinforcement and when coated reinforcements were used. 相似文献