微曲率壳板横向失稳临界载荷计算方法

Calculation method of critical load for lateral buckling of shell plates with micro curvature

微曲率壳板广泛存在于舰船结构中,在壳板静力学性能试验中发现了“跳跃”失稳现象。为了能够对微曲率壳板横向承载失稳的机理进行探究,本文以船体微曲率壳板结构横向承载失稳问题为工程背景,探讨壳板临界失稳载荷的预报方法。基于铁木辛柯曲梁理论与薄板大挠度弯曲理论,对单向微曲率壳板结构的横向承载问题开展理论分析,求解壳板的临界失稳载荷;基于Riks弧长法,对单向微曲率壳板的横向承载稳定性进行数值仿真,通过载荷比例因子曲线获取壳板的临界失稳载荷,并且发现仿真与理论计算结果吻合度较好。结果表明:微曲率壳板结构在承受横向载荷时会出现“跳跃”失稳现象,该现象与曲率半径相关,半径越小,发生“跳跃”失稳的临界失稳载荷的几率越高;在壳板曲率半径相同的情况下,矩形壳板的长宽比对临界失稳载荷影响不明显;针对曲率半径为4000~6000 mm的壳板,提出的临界失稳载荷预报公式具有较高准确性。

Micro curvature shell plates are widely used in ship structures.The phenomenon of‘jumping instability’was found in the static performance experiment of curved plates.In order to explore the buckling mechanism of micro curvature plates under lateral loading,the prediction method was discussed considering the engineering background in this paper.Based on Timoshenko curved beam theory and large deflection bending theory of thin plates,the transverse bearing capacity of unidirectional micro curvature plates was analyzed theoretically.The critical buckling load of plates was solved.The lateral bearing stability of unidirectional micro curvature plates was simulated with the Riks method.The critical buckling load of plates was obtained by load scale factor curve.And it was found that the simulation results were in good agreement with the theoretical calculation results.The results show that the phenomenon of‘jumping instability’occurs when the micro curvature plate structure is subjected to transverse load.And this phenomenon is related to the radius of curvature.The smaller the radius is,the higher the critical buckling load is.Under the same curvature radius of plates,the influence of length-width ratio on critical instability load is not obvious.For plates with a curvature radius of 4000-6000 mm,the prediction formula of critical buckling load has a high accuracy.