Analysis of Delaminated Plates with Piezoelectric Sensors Subjected to Transverse Impact

有關探討含壓電材料之撓性結構物的動態問題,現有大多數的分析僅 考慮簡單樑模型或採用古典板理論的板模式.而同時考慮含脫層的複合材 料板,壓電材料感測器及承受拋射體撞擊等問題的研究則較缺乏. 分 析脫層的效應時,本文中所發展的有限元素模式,除了考慮板的橫向正應力 與剪應力等因素外,並包含因脫層所引起的拉伸與彎曲的耦合效應.除此之 外,脫層與壓電材料片大小與位置均可自由選擇.本文中除對邊界效應,脫 曾大小與脫層位置對板自然振動頻率影響與現有文獻驗證外,對複合材料 板受撞擊時的暫態分析亦有介紹. 分析複合材料板受一橫向外物撞擊 的暫態響應時,本文中採用Sun等人的修正碰撞法則關係式,本文中採用兩 種不同的方法分析板受撞擊時的暫態行為,其一為直接積分法;另一為模態 疊加法.本文分析結果與現存之解析解及有限元素解相比較,均相當的吻 合.Concerning the dynamic analysis of flexible structures with piezoelectricsensors, most of the papers published to date have adopted either the Bernouli-Euler beam model or the classical plate model. Furthermore, it seems there are rather few studies available that have treated the dynamic problems of the delaminated composite plates with piezoelectric sensors, which is subjected tothe impact from a foreign object. The present formulation include the effect of transverse shear deformationas well as that of the bending-extension coupling caused by the presence of delamination within the plate. The effects of boundary conditions, delamination size, and delamination location on the natural frequencies and the transient behavior of composite plates are investigated. A transient dynamic finite element analysis is presented for studying theresponse of laminated composite plates due to the transverse impact of a foreignobject. The contact force is determined using the modified Hertzian contact law of Sun''s. Two different methods are used in the teansient dynamic analysis. One is thedirect integral method where the Newmark scheme is adopted to perform time integration. The other is the model method where the physical equations of motionare transformed into a set of independent modal equations. Next, the modal displacements of the plate are computed, which are then transformed back to the physical coordinates. After that, the contact force is determined using the contactlaw. Comparisions are made between the present results and those publishedpapers. An excellent agreement is found betweem them