中低强度钢超声冲击处理焊接接头热点应力设计曲线

用ANSYS计算了对接接头、横向非承载十字接头和纵向非承载角接板的热点应力集中系数K_hs,根据Q235B和Q345B的超声冲击处理焊接接头的相关疲劳试验数据得出经过应力比、板厚和几何不平度修正后的超声冲击处理焊接接头的热点应力设计S-N曲线. 结果表明,经过超声冲击处理后,中低强钢(R_m≤355 MPa)对接接头、横向非承载十字接头和纵向非承载角接板的热点应力S-N曲线的分散性降低,与接头形式无关,可以用一条热点应力设计S-N曲线表达. 在采用热点应力法进行疲劳设计时,选取m=10.0,上述三种类型焊接接头在2×106次疲劳强度级别可统一采用FAT135来表示.

Hot spot stress design S-N curve of ultrasonic impact treated welded joints of medium and low strength steel

First, the hot spot stress concentration factor (Khs ) of butt joints, transverse non-load-carrying cruciform joints and non-load-carrying longitudinal fillet plate joints are calculated using ANSYS. Then, according to the relevant fatigue tests results of ultrasonic impact treated welded joints of Q235B and Q345B, the corrected hot spot stress design S-N curve by stress ratio, thickness and geometric irregularities of ultrasonic impact treated welded joints is obtained. Analysis shows that the dispersion of data points of the hot spot stress design S-N curve of ultrasonic impact treated butt welds, transverse non-load-carrying cruciform joints and non-load-carrying longitudinal fillet welds of medium and low strength steel reduced and can be expressed with one design S-N curve independent of the form of joint. The recommended m=10.0 is also applied for hot spot stress fatigue design and the fatigue strength level of the three types of welded joint above-mentioned can uniformly applied to FAT135 at 2×106 times.