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承载型60°斜十字全熔透焊接接头疲劳寿命评估

Fatigue life assessment of load-carrying 60° oblique cruciform full penetration welded joints

  • 摘要: 为研究承载型60°斜十字全熔透焊接接头 (oblique cruciform full-penetration welded joints,OCFWJs)局部应力分布及疲劳性能,设计3个试验模型完成3种名义应力幅水平下的疲劳试验,得到试件疲劳破坏时的循环次数. 利用ABAQUS软件建立60° OCFWJs有限元模型,计算得到焊趾处热点正应力、热点剪应力及等效热点应力. 基于规范中的名义应力S-N曲线和热点应力S-N曲线,分别采用名义主应力法、等效热点应力法和相互作用方程方法对拉-剪联合作用下60° OCFWJs疲劳寿命进行了评估. 结果表明,采用名义应力幅、名义拉应力幅或名义剪应力幅均无法对60° OCFWJs疲劳寿命进行可靠评估. 依据国际焊接学会(International Institute of Welding,IIW)规范无论采用热点拉应力幅或热点剪应力幅也无法对60° OCFWJs疲劳寿命进行可靠评估. 按欧洲钢结构设计规范Eurocode3相互作用方程方法预测的疲劳寿命远低于试验值,按等效热点应力方法预测的疲劳寿命与试验值符合良好.

     

    Abstract: To study the local stress distributions and fatigue performance of load-carrying 60° oblique cruciform full-penetration welded joints (OCFWJs), three test specimens were designed for fatigue tests under three nominal stress amplitude levels, and the numbers of loading cycles until fatigue failure of the specimens were obtained. Using ABAQUS finite element software, the finite element models of 60°OCFWJs were established, and the hot spot normal stress, hot spot shear stress, and equivalent hot spot stress at the weld toe were calculated. Based on the nominal stress S-N curves and the hot spot stress S-N curves defined in the specifications, the fatigue life of 60° OCWJs under the combined action of tensile and shear stress were evaluated by using the nominal principal stress method, the equivalent hot spot stress method, and the interaction equation method, respectively. The results showed that whether the nominal stress range, the nominal tensile stress range, or the nominal shear stress range are used, the fatigue life of 60° OCWJs cannot be reliably evaluated. According to the International Institute of Welding specification, whether the hot spot tensile stress ranges or the hot spot shear stress ranges cannot be used to evaluate the fatigue life of 60° OCFWJs reliably. The fatigue lives predicted by the interaction equation method in Eurocode 3:Design of Steel Structures are much lower than the experimental values , and the fatigue lives predicted by the equivalent hot spot stress method are in good agreement with the experimental values .

     

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