Postbuckling of Marine Stifened Composite Plates with Initial Geometric Imperfections Using Progressive Failure Analysis

This work explores the postbuckling behavior of a marine stifened composite plate in the presence of initial imperfections.The imperfection shapes are derived from buckling mode shapes and their combinations.Thereafter,these imperfection shapes are applied to the model,and nonlinear large defection fnite element and progressive failure analyses are performed in ANSYS 18.2 software.The Hashin failure criterion is employed to model the progressive failure in the stifened composite plate.The efect of the initial geometric imperfection on the stifened composite plate is investigated by considering various imperfection patterns and magnitudes.Results show that when the magnitude of the imperfection is 20 mm,the ultimate strength of the stifened composite plate decreases by 31%.Moreover,global imperfection shapes are found to be fundamental in determining the ultimate strength of stifened composite plates and their postbuckling.

Stability analysis of ellipse- like suspen-dome structures with low rise-span ratio

To investigate the effects of initial geometric imperfection and material nonlinearity on the stability analysis of the suspen-dome, the steel roof of Jiangsu Culture Sports Center Gymnasium was utilized as a numerical model, and modal analyses were performed. Then, linear buckling analysis,geometric nonlinear stability analysis, geometric nonlinear stability analysis with initial imperfection, and double nonlinear analysis considering material nonlinearity and geometric nonlinearity were discussed in detail to compare the stability performance of the ellipse-like suspen-dome and the single-layer reticulated shell. The results showthat the cable-strut system increases the integrity of the suspen-dome, and moderates the sensibility of the single-layer reticulated shell to initial geometric imperfection. However, it has little influence on integral rigidity, fundamental vibration frequencies, linear ultimate live loads, and geometric nonlinear ultimate live loads without initial imperfection. When considering the material nonlinearity and initial imperfection, a significant reduction occurs in the ultimate stability capacities of these two structures. In this case, the suspen-dome with a lowrise-span ratio is sensitive to the initial imperfection and material nonlinearity. In addition, the distribution pattern of live loads significantly influences the instability modes of the structure, and the uniform live load with full span is not always the most dangerous case.

Stress concentration coefficients of optimized cope-hole welded detail

The fatigue performance of optimized welded detail has been investigated by fatigue experiments of three welded specimens under different loadings.In addition,local finite element models of this welded detail were established using finite element software ANSYS.The influences of different factors such as plate thickness,plate gap and initial geometric imperfections on the stress concentration coefficient(SCC) were discussed.The experimental results indicate that the fatigue life of three specimens for this welded detail is 736,000,1,044,200 and 1,920,300 times,respectively.The web thickness,the filler plate thickness and the initial geometric imperfection have relatively less effect on the SCCs of this welded detail.However,cope-hole radius is influential on the SCCs of the web and the weld.The SCC of weld is significantly affected by the weld size and plate gap,but the SCCs of other parts of the welded detail are hardly affected by the plate gap.

预应力下具有初始几何缺陷的石墨烯增强多孔复合材料双曲率壳结构的非线性主共振分析

本文研究了石墨烯增强多孔复合材料(GPLRMFs)双曲率壳结构的非线性主共振行为.考虑初始几何缺陷和预应力,并基于Reddy高阶剪切变形壳理论和冯卡门几何非线性,推导出GPLRMFs双曲率壳的非线性运动方程.接着,考虑简支边界条件,利用伽辽金法进行离散得到了非线性常微分方程,随后,利用改进的Lindstedt-Poincare(MLP)法求解,便可以得到GPLRMFs双曲率壳结构的主共振幅频响应关系.在数值分析中,通过与现有文献进行比较,从而验证了本研究的正确性.最后,分析了各个参数(包括壳体类型、石墨烯片(GPLs)分布模式、孔隙率分布类型、初始几何缺陷、GPLs重量分数、孔隙率系数和预应力)对非线性主共振幅频响应曲线的影响.