【作者】 张云鹤；

【导师】 郑耀； 张继发；

【作者基本信息】 浙江大学 ， 固体力学， 2008， 硕士

【摘要】 本文主要讨论加筋板壳结构的振动问题。通过比较加筋平板采用不同类型单元和不同结点数单元时的计算结果与实验数据的误差,发现不同的单元类型适合于不同的振动模型;另一方面,单元的结点数也会通过影响结构刚度来改变固有频率。梁单元是模拟加强筋振动状况的最理想单元类型,但由于采用梁单元时忽略了加强筋的几何特征,因此需要通过考虑平板壳单元结点上转动自由度对相应的梁单元结点位移自由度的影响来改善计算精度。通过对基于不同参数的模型的相互比较,来进一步研究加强筋的添置对原平板振动特性的影响。对于加强筋横截面尺寸的影响,当固定横截面的宽度或厚度而单独改变另一横截面参数时,对于不同模态振型会产生两种不同的结果。而当横截面宽度和厚度同比增长时,各阶模态振型变化规律一致。更多地,当在平板上采用不同数量的加强筋,或将加强筋安放在不同的位置时,固有频率都会产生相应的变化。在对圆柱壳的研究中,通过对比基于不同类型单元,不同自由度单元和不同网格密度模型时的计算结果与简单圆柱壳固有频率实验结果,得到了较为合理的有限元模型,并基于此建立了加筋的圆柱壳模型以分析加强筋对圆柱壳固有频率的影响。进一步地,在引入几何非线性的影响后,还分析了在不同内压,不同纵向加速度,不同绕轴心的角速度的情况下,圆柱壳固有频率的变化规律。更多还原

【Abstract】 This thesis is focused on the study of vibration behaviors of stiffened shell and plane structure. By referring to an experimental data of a stiffened plane, models in the same conditions have been built to study the numerical errors while changed the types of elements or counts of nodes. According to the results, it is better to choose them with attributes of various models. For optimizing the stiffened plane models with beam-element stiffeners, the effect between rotational freedom of shell elements and motional freedom of beam elements has been considered.The models with different parameters have been investigated for discovering the further effects of stiffeners. There are two distinguished results while fixing the width or thickness of stiffener but changing the lengths of other edges. However, it shows the same tendency while keeping a constant ratio of width over thickness. Moreover, the counts or positions of stiffeners on a plane change, the natural frequencies change accordingly.In the study of a cylindrical shell, a relative precise model has been built by analyzing the effect of element types, freedoms on nodes and mesh densities. Furthermore, by considering the effect of nonlinear geometry, the cylindrical shell model, in different internal pressures, accelerations and rotational speeds, have been analyzed.更多还原