Fatigue Resistance of Sealing Joint to Shear Movement at Earthquake

为了支持剪切运动对密封接头设计的支持，通过试验和分析研究了钢珠横截面对剪切疲劳抗力的影响。结果表明：(1)在形状因子(接头深度/宽度)相同的情况下，钢珠的尺寸对疲劳抗力的影响不明显。(2)对于钢珠的形状，凹形深度越深，疲劳抗力越低。钢珠剪切运动的耐久截面被认为是矩形或略微凹陷的形状。(3)用有限元方法研究了剪切变形钢珠的应力。计算结果表明，在微凹的形状下，可以避免应力集中。(4)目前疲劳试验采用的平行式试件存在着从胎圈端部意外萌生裂纹等缺陷。为了避免剪切试验中的意外破坏，提出了一种无胎圈的环状试件，并研制了试件的疲劳试验装置。用这种新的剪切试验方法成功地获得了密封胶的剪切疲劳抗力数据，而没有出现意外破坏。

To support design of sealing joint to shear movement, the effect of cross section of a bead on shear fatigue resistance was studied experimentally and analytically. The results obtained are as follows.(1) Size of a bead does not so clearly affect their fatigue resistance when it has the same shape factor (Depth /Width of joint).(2) As for shape of a bead, the deeper the depth of concave shape is, the lower the fatigue resistance becomes. Durable cross section of a bead to shear movement is considered to be rectangular or slightly concave shapes.(3) The stresses of a bead of.being shear deformed were studied using a finite element method. The calculated result shows that stress concentration could be avoided at the slightly concave shape,(4) There was the shortcoming such as unexpected crack initiation from bead ends in a parallel type specimen used for present fatigue test. To avoid the unexpected failure during a shear test, a ring type specimen of not having bead ends was proposed and a fatigue test apparatus for the specimen was also developed. The data of shear fatigue resistance of a sealant were successfully obtained without the unexpected failure by the new shear test method.