【摘要】 当风载作用于门座起重机矩形拉杆时,旋涡脱落频率将会接近于其本身固有频率,此时拉杆会发生涡激共振,剧烈的振动会引起拉杆的疲劳开裂。为了改善振动情况,通常在拉杆顺风向上开孔,使拉杆的脱落频率远离固有频率,以破坏涡激共振形成的条件。为了研究拉杆上孔的尺寸和分布对改善拉杆振动的影响,对不同拉杆模型进行了研究,得出孔的最优尺寸和分布。更多还原

【Abstract】 When a wind load applies on the rectangular pull rod of a portal crane,the vortex-triggered shedding frequency will approximate to the pull rod’s inherent frequency,in which case vortex-triggered resonance will occur on the pull rod,thereby generating violent vibration on the pull rod and leading to fatigue cracks.In order to improve the vibration condition,it is a normal practice to drill holes in the downwind direction so that the shedding frequency of the pull rod is far apart from the inherent frequency and thereby eliminate conditions that may cause vertex-triggered resonance.In order to study how the dimensions of the holes on the pull rod and their distribution thereon affect the vibration in the pull rod,this essay studies multiple pull rod models and by doing this obtains the optimum dimensions and distribution of such holes.更多还原