波浪对弹性支撑平板结构冲击作用的实验研究

发布时间：2019-04-17 21:29

【摘要】：波浪冲击(又说砰击)是波浪与结构物之间发生的强烈冲击碰撞现象,涉及到固体、流体和气体三相介质之间的复杂耦合作用。严重的波浪冲击会造成结构物局部损坏或整体坍塌。对于弹性海洋结构物,其所受的波浪冲击作用耦合结构物的振动响应,形成一个复杂的动力过程。随着水弹性力学在海岸和近海工程中的发展,迫切需要开展系统深入的研究工作来深入研究波浪冲击过程的机理、了解结构物在波浪冲击作用下动力响应的变化特性。本文通过物理模型试验开展了波浪作用下弹性支撑平板结构所受的冲击荷载与动力响应变化特性研究。试验在大连理工大学的波浪水槽中进行,试验中设计了三种不同支撑刚度的结构物模型,并通过静位移法和瞬态激励法得到了结构物模型的动力特性。利用Crio-9074多通道同步采集系统得到了结构物底面所受的波浪冲击压力和结构物的振动加速度的同步测量数据。试验中应用概率理论分析了弹性支撑平板结构底面的波浪冲击压力,给出了波浪冲击压力峰值超值概率分布曲线及其表达式,并分析了入射波要素和结构物动力特性与超值分布曲线特征参数的变化关系。通过对平板结构所受的波浪冲击力与振动加速度的同步分析,给出了波浪冲击过程与平板结构运动过程的同步变化特性,分析了波浪冲击力与振动加速度同步历时曲线的四个特征阶段,即：波浪冲击阶段、动水作用阶段、流体脱落阶段和自由振动阶段；讨论了弹性支撑刚度、入射波高、波浪周期和相对净空对冲击作用历时的影响规律。基于波浪冲击荷载的统计分析与频谱分析结果,给出了波浪冲击压力峰值沿平板结构底面的分布规律；分析了支撑刚度和入射波波要素以及相对净空对波浪冲击压力(冲击力)峰值的影响规律；讨论了支撑刚度对波浪冲击荷载幅值谱的影响；得到了结构物所受波浪冲击荷载随支撑刚度增大而增大的结论。应用频域积分方法由加速度历时曲线得到了平板结构振动速度和位移的历时曲线,并对结构动力响应进行了频谱分析。分析了平板结构动力响应的影响因素；讨论了支撑刚度与结构动力响应幅值谱的关系；得到了结构物振动加速度随支撑刚度增大而增大,振动速度和位移随支撑刚度增大而减小等结论。
[Abstract]:Wave impact (also called slamming) is a strong impact collision phenomenon between wave and structure, which involves the complex coupling of solid, fluid and gas three-phase medium. Severe wave shocks can cause local damage to the structure or collapse of the structure as a whole. For elastic marine structures, a complex dynamic process is formed by the vibration response of the coupled structures subjected to wave impact. With the development of hydroelasticity in coastal and offshore engineering, there is an urgent need to carry out systematic and in-depth research on the mechanism of wave impact process and to understand the dynamic response of structures under the action of wave impact. In this paper, the characteristics of impact load and dynamic response of elastic braced plate structure under wave action are studied by physical model test. The experiment was carried out in the wave tank of Dalian University of Technology. Three kinds of structural models with different bracing stiffness were designed and the dynamic characteristics of the structural models were obtained by static displacement method and transient excitation method. The simultaneous measurement data of the wave impact pressure and the vibration acceleration of the structure are obtained by using the Crio-9074 multi-channel synchronous acquisition system. In this paper, the probability theory is used to analyze the wave impact pressure on the bottom of the plate structure with elastic support, and the probability distribution curve of the peak value of wave impact pressure and its expression are given. The relationship between the dynamic characteristics of the incident wave elements and structures and the characteristic parameters of the super-value distribution curve is analyzed. Based on the synchronous analysis of the wave impact force and the vibration acceleration of the flat plate structure, the synchronous variation characteristics of the wave impact process and the plate structure motion process are given. Four characteristic stages of the simultaneous duration curve of wave impact force and vibration acceleration are analyzed, that is, wave impact stage, dynamic water action stage, fluid shedding stage and free vibration stage. The effects of elastic brace stiffness, incident wave height, wave period and relative clearance on impact duration are discussed. Based on the results of statistical analysis and spectrum analysis of wave impact load, the distribution law of peak wave impact pressure along the bottom of plate structure is given. The effects of brace stiffness, incident wave elements and relative clearance on the peak value of wave impact pressure (impact force) are analyzed, and the influence of support stiffness on wave impact load amplitude spectrum is discussed. It is concluded that the wave impact load on the structure increases with the increase of the brace stiffness. The frequency domain integral method is used to obtain the duration curve of vibration velocity and displacement of the plate structure from the acceleration duration curve, and the frequency spectrum analysis of the structural dynamic response is carried out. The influence factors of dynamic response of plate structure are analyzed, and the relationship between brace stiffness and amplitude spectrum of structural dynamic response is discussed. The results show that the vibration acceleration of the structure increases with the increase of the support stiffness, and the vibration velocity and displacement decrease with the increase of the support stiffness.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TV139.2

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