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本文采用大面积(540×250mm)光弹性贴片的方法,对模拟焊接吊车工型梁端部区段的试件进行了腹板剪应力分布的研究。结果表明,当荷载作用位置靠近支点时,靠近支座载面处的腹板仅承受理论计算剪力的40％-70％,与文献[1]的论述相符;且作用力离支点愈近,腹板所承受的剪力将愈小。剪应力的分布规律也不是以往设计焊接吊车梁时所取用的典型抛物线。本文还对荷载作用点下面的剪应力和竖向正应力沿水平方向的分布作了测定,并观察了腹板初始屈曲的位置与失稳破坏的现象。文中还对大面积光弹性贴片的制作与应用进行了初步的研究。研究表明,采用“浇片”的方法可以解决通常制作大面积贴片时所遇到的反应热大,无大面积模板、不易脱模,以及粘贴时夹生气泡、厚度不匀、粘贴不牢等问题,从而得到较理想的大面积光弹性贴片。
In this paper, a large-area (540×250mm) photoelastic patch method was used to study the distribution of shear stress in the webs of the specimens that simulate the end sections of the crane beam. The results show that when the loading position is close to the fulcrum, the web near the bearing surface of the bearing bears only 40%-70% of the theoretically calculated shear force, which is consistent with the discussion in [1]; and the closer the force is to the fulcrum, The smaller the shear force the web will experience. The distribution law of shear stress is also not a typical parabola used when designing welded crane beams in the past. In this paper, the distribution of shear stress and vertical normal stress along the horizontal direction under the load point is measured, and the position of the initial buckling of the web and the phenomenon of instability failure are observed. The paper also made a preliminary study on the production and application of large-area photoelastic patches. Studies have shown that the method of “pulling the sheet” can solve the large reaction heat encountered when making large-area patches. There is no large-area template, and it is not easy to release, and bubbles, uneven thickness, and poor adhesion are not allowed in the paste. The problem is that the ideal large-area photoelastic patch is obtained.