题目:Effect of bending-twisting coupling on the compression and shear buckling strength of infinitely long plates
报告人:Christopher Bronn York(英国格拉斯哥大学)
时间:2017年8月30日(周三)10:00-11:00
地点:明故宫校区A18-526
主办单位:国际合作交流处、科协、航空宇航学院、航空航天交叉研究院
报告摘要:
This article describes the development of closed form polynomial equations for compression and shear buckling to assess the effect of Bending-Twisting coupling on infinitely long laminated plates with simply supported edges. The equations are used to generate contour maps, representing non-dimensional buckling factors, which are superimposed on the lamination parameter design spaces for laminates with standard ply orientations. The contour maps are applicable to two recently developed databases containing symmetric and non-symmetric laminates with either Bending-Twisting or Extension-Shearing Bending-Twisting coupling. The contour maps provide new insights into buckling performance improvements that are non-intuitive and facilitate comparison between hypothetical and practical designs. The databases are illustrated through point clouds of lamination parameter coordinates, which demonstrate the effect of applying common design heuristics, including ply angle, ply percentage and ply contiguity constraints.
报告人简介:
Dr. Christopher Bronn York is Associate Professor at the School of Engineering, University of Glasgow, UK. His current research activities are focused on the development of a unified approach to the characterisation of coupled laminated composites involving: algorithm development for identification and characterisation of coupled laminate stacking sequence configurations, the vast majority possessing unique forms of mechanical coupling behaviour not previously identified; critical assessments of the benefits, or otherwise, to a wide range of functional and/or structural material applications and; development of laminate benchmark configurations, with properties exhibiting behaviour similar to conventional (metallic) materials, and against which all unique forms of laminate behaviour, arising from isolated and combined mechanical coupling effects, are being characterised.
Recent discoveries include twenty-four unique classes of mechanically coupled laminate. One new laminate class possesses in-plane coupling behaviour only, i.e. extension-shearing coupling. Such laminates can be configured to produce bending-twisting coupling in wing-box type structures, which can be exploited to great effect in the design for passive load alleviation in wind-turbine blades, or for aero-elastic compliance in helicopter rotor-blades. Similar behaviour can also be achieved by using less sophisticated designs, such as applying off-axis material alignment to otherwise balanced and symmetric laminates, but additional forms of coupling behaviour arise in these cases, leading to detrimental effects on both stiffness and strength. Other exotic forms of mechanical coupling have also been newly discovered, and contrary to long held misconceptions, a surprisingly broad range of these designs can be manufactured without the undesirable warping distortions that generally result from the high temperature curing process. Such laminate designs may be described as Hygro-Thermally Curvature-Stable (HTCS) or warp-free and are likely to become an import enabling technology in future ‘smart’ structures.