【作者】 周楠；

【导师】 徐慧；

【作者基本信息】 天津大学 ， 船舶与海洋结构物设计制造， 2010， 硕士

【摘要】 船舶在恶劣的海况中航行时,会伴随着剧烈的升沉和纵摇运动,当船体出水后再入水时极易发生砰击现象。砰击会造成局部结构破坏,同时也能引起船体梁的弹性振动,威胁船舶的总纵强度安全。随着船舶的大型化和高速化,砰击问题变得更易发生且对船体结构的危害也愈大。砰击载荷是船舶波浪载荷的重要组成部分,各大船级社已将船体结构在砰击载荷作用下的强度安全作为衡量船舶安全的标准之一。本文以Wagner的入水砰击理论为指导,使用MSC.DYTRAN瞬态动力学分析软件模拟结构入水砰击过程。首先,对刚性楔形体的入水砰击进行仿真模拟,将斜升角为30o的楔形体落水过程中受到的砰击力和运动速度与Zhao的试验结果进行对比,两者吻合较好,从而验证了该仿真方法的可行性和计算精度;其次,改变楔形体的斜升角和入水速度,进行参数敏感性分析,得到砰击压力系数与斜升角的关系曲线,其与Wagner的理论值和Chuang的试验值具有可比性,并对砰击压力在楔形体底面的时间分布规律进行了研究;最后,建立平底加筋板的模型,模拟弹性体的入水砰击过程。通过对比弹性体和刚性体的入水砰击载荷,表明弹性效应的存在降低了砰击载荷的峰值,且入水速度越大,弹性效应越明显。改变结构的底板厚度和入水速度进行敏感性分析,得到结构响应随上述参数改变的变化规律。更多还原

【Abstract】 When the ship is navigating in adverse conditions, slamming is easily occurred when the hull reenter the water because of the severe heave and pitch motion. Slamming will result in local structural damage and the elastic vibration of hull girder which will threaten the ship’s longitudinal strength security. With the ship’s large scale and high speed, slamming is becoming more susceptible and greater harm to the ship structure. Slamming loads is an important part of wave loads, and the intensity security under slamming loads has been seen as one of the ship safety standards by major classification societies.In this paper, the Wager’s theory is seen as a guide, and the transient dynamic analysis software which called MSC.DYTRAN is used to simulate the process of slamming into the water. First, the slamming process of rigid wedge is simulated, and the slamming force and velocity of the wedge which ramp angle is 30 degrees were compared with Zhao’s experimental results, both in good agreement, which verifies the feasibility of the simulation method and precision. Second, the ramp angle and velocity were changed and parameter sensitivity was analyzed, slamming pressure coefficient was derived and compared with Wagner’s theory result and Chuang’s experiment result, and the spatial distribution of slamming pressure was studied. Finally, a flat stiffened plate model was modeled to simulate the elastic body slamming. By comparing the slamming loads of elastic and rigid body and indicated that the presence of elastic effect reduce the peak value of slamming loads, and the greater the speed, flexibility was more obvious. Change the speed and base plate thickness of the flat panel, parameter sensitivity was analyzed and the structural response with these parameters was obtained.更多还原