基于子模型法的大型固定管板换热器有限元分析
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摘要
大型固定管板换热器由于管子数量大,无法在有限元模型中建出所有换热管与管板的详细连接结构,得不到相关区域的真实应力分布,无法有效地进行应力强度评定。对某大型固定管板换热器,利用粗模型确定了管板布管区换热管与管板连接区的最大应力强度位置,进而建立了该位置换热管与管板详细连接结构的子模型。子模型中考虑了换热管与管板的焊接结构及其相互接触,分别对此区域进行基于应力分类法和极限载荷法的分析计算。结果表明:虽然基于应力分类法的焊缝及换热管应力强度评定不合格,但考虑到应力分布的非轴对称特性,基于极限载荷分析的直接法评定应更为合理。对子模型结构进行了极限分析并利用零曲率法确定了极限载荷,按相关标准进行了评定,表明结构满足强度要求。
As enormous number of tubes in large fixed tubesheet heat exchangers, it is difficult to model all the tubes and tubesheet connections in detail for FEA. Therefore, it fails to yield an accurate stress field around the connecting region of tubes and tubesheet, which is essential for the effective stress intensity evaluation. Taking a large fixed tubesheet heat exchanger as example, the maximum stress intensity location is found for the tube layout region of the tubesheet according to the coarse model. Then the sub model is utilized in the predetermined maximum stress location. In the sub model, detailed connecting structure of the tube and the tubesheet are included, such as the weld metal and contact condition between the tube and tubesheet hole. Both stress classification and limit load analysis are preformed for the sub model structure. Although both the weld and the tube fail the evaluation based on stress classification, it is more reasonable to evaluate the connecting region with the direct route based on limit load analysis for the structure with non axisymmetric stress distribution. Limit analysis is carried out and limit load is determined by zero-curvature method. It is shown that the structure meets the strength requirement based on the relevant standards.
As enormous number of tubes in large fixed tubesheet heat exchangers, it is difficult to model all the tubes and tubesheet connections in detail for FEA. Therefore, it fails to yield an accurate stress field around the connecting region of tubes and tubesheet, which is essential for the effective stress intensity evaluation. Taking a large fixed tubesheet heat exchanger as example, the maximum stress intensity location is found for the tube layout region of the tubesheet according to the coarse model. Then the sub model is utilized in the predetermined maximum stress location. In the sub model, detailed connecting structure of the tube and the tubesheet are included, such as the weld metal and contact condition between the tube and tubesheet hole. Both stress classification and limit load analysis are preformed for the sub model structure. Although both the weld and the tube fail the evaluation based on stress classification, it is more reasonable to evaluate the connecting region with the direct route based on limit load analysis for the structure with non axisymmetric stress distribution. Limit analysis is carried out and limit load is determined by zero-curvature method. It is shown that the structure meets the strength requirement based on the relevant standards.
引文
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[10] 谢全利,陈仓社,樊新宇. 一种高效便捷的换热器管板有限元分析新方法[J]. 石油化工设备技术, 2015, 01: 6-11.XIE QuanLi, CHEN CangShe, FAN XinYu. A new efficient finite element analysis method for heat exchanger tubesheet[J]. Petro-Chemical Equipment Technology, 2015, 01: 6-11 (In Chinese).
[11] 陆明万,徐 鸿. 分析设计中若干重要问题的讨论(一)[J]. 压力容器, 2006, (01): 15-19.LU MingWan, XU Hong. Discussion on some important problems of design by analysis(1)[J]. Pressure Vessel Technology, 2006, (01): 15-19(In Chinese).
[12] 周 军,董俊华,高炳军. 基于应变强化特性的不锈钢筒体极限载荷分析及其轻量化设计[J]. 机械强度, 2013, (04): 472-476.ZHOU Jun, DONG JunHua, GAO BingJun. Limit load analysis and light-weight design of stainless steel cylinder based on strain-hardening[J]. Journal of Mechanical Strength, 2013, (04): 472-476(In Chinese).
[13] 章为民,陆明万,张如一. 确定实际极限载荷的零曲率准则[J]. 固体力学学报, 1982, (2): 152-159.Zhang WeiMin, Lu MingWan, Zhang RuYi. A zero-curvature criterion to determine the practical collapse load[J]. Acta Mechanica Solida Sinica, 1982, (2): 152-159 (In Chinese).
[2] 周 宇, 万朝燕, 谢素明. 基于子模型的铁路车辆结构强度精细计算[J]. 铁道机车车辆, 2009, 01:16-18.ZHOU Yu, WAN ChaoYan, XIE SuMing. Structural intensity refined calculation of railroad vehicle based on sub-model[J]. Railway Locomotive Vehicle, 2009, 01: 16-18 (In Chinese).
[3] Lucht T. Finite element analysis of three dimensional crack growth by the use of a boundary element sub model[J]. Engineering Fracture Mechanics, 2009, 76: 2148-2162.
[4] Testoni P, Fanni A, Sonato P. A sub-modeling approach for the electromechanical disruption analysis of the ITER ICH antenna[J]. Fusion Engineering and Design, 2008, 83: 695-701.
[5] Giglio M. FEM submodelling fatigue analysis of a complex helicopter component[J]. International Journal of Fatigue, 1999, 21: 445-455.
[6] Mandal N K, Dhanasekar M. Sub-modelling for the ratchetting failure of insulated rail joints[J]. International Journal of Mechanical Sciences, 2013, 75: 110-122.
[7] 高艳红, 董俊华, 高炳军. 子模型技术在大型球罐支撑区应力分析及结构优化中的应用[J]. 机械强度, 2010, 32(5): 735-739.GAO YanHong, DONG JunHua, GAO BingJun. Application of sub-model technique in stress analysis and structure optimization of the supporting region of large spherical tank[J]. Journal of Mechanical Strength, 2010, 32(5): 735-739(In Chinese).
[8] 国宏斌, 张 景. ANSYS子模型技术在LPG球罐设计检验中的应用[J]. 化工机械, 2009, 06: 582-584.GUO HongBin, ZHANG Jing. Applications of ANSYS sub-model technique in the design and inspection of LPG spherical tanks[J]. Chemical Engineering and Machinery, 2009, 06: 582-584 (In Chinese).
[9] JB4732-1995,钢制压力容器—分析设计标准[S]. 北京: 中国标准出版社, 1995: 15-17.JB4732-1995,Steel pressure vessel—analysis design standard[S]. Beijing: China Standard Press, 1995: 15-17 (In Chinese).
[10] 谢全利,陈仓社,樊新宇. 一种高效便捷的换热器管板有限元分析新方法[J]. 石油化工设备技术, 2015, 01: 6-11.XIE QuanLi, CHEN CangShe, FAN XinYu. A new efficient finite element analysis method for heat exchanger tubesheet[J]. Petro-Chemical Equipment Technology, 2015, 01: 6-11 (In Chinese).
[11] 陆明万,徐 鸿. 分析设计中若干重要问题的讨论(一)[J]. 压力容器, 2006, (01): 15-19.LU MingWan, XU Hong. Discussion on some important problems of design by analysis(1)[J]. Pressure Vessel Technology, 2006, (01): 15-19(In Chinese).
[12] 周 军,董俊华,高炳军. 基于应变强化特性的不锈钢筒体极限载荷分析及其轻量化设计[J]. 机械强度, 2013, (04): 472-476.ZHOU Jun, DONG JunHua, GAO BingJun. Limit load analysis and light-weight design of stainless steel cylinder based on strain-hardening[J]. Journal of Mechanical Strength, 2013, (04): 472-476(In Chinese).
[13] 章为民,陆明万,张如一. 确定实际极限载荷的零曲率准则[J]. 固体力学学报, 1982, (2): 152-159.Zhang WeiMin, Lu MingWan, Zhang RuYi. A zero-curvature criterion to determine the practical collapse load[J]. Acta Mechanica Solida Sinica, 1982, (2): 152-159 (In Chinese).