波系在液体中的弹性管梁上的反射和辐射

本文研究入射波系在液体中的半无限弹性管梁的开口端的反射和辐射问题,此波系由管梁上的挠曲波和管内、管外液体中相应的表面波(声波)所组成.利用Fourier变换,将这个半无限问题严格地归结为求解Wiener-Hopf型方程.然后将液体和管梁的密度比作为小参数,用摄动法求近似解.文章着重研究了反射系数的计算,还给出了远场的辐射型式曲线.     

Reflection and radiation of a wave system at the open end of a submerged elastic pipe

The reflection and radiation of a wave system at the open end of a submerged semi-infinite elastic pipe are studied. This wave system consists of a flexural wave in the pipe, an acoustic surface wave in the fluid exterior to the pipe and an acoustic wave in the pipe’s interior. Fourier transform techniques are used to formulate this semi-infinite geometry problem rigorously as a Wiener-Hopf type equation. An approximate solution is obtained by using a perturbation method in which the ratio of the massdensities of the fluid and the pipe material is regarded as a small parameter. The calculation of the reflection coefficient is emphasized, and the polar plots of the radiation coefficient are also presented.     

任意形状薄板的振动

本文改进了Nagaya提出的Fourier展开配置法,省弃了Nagaya假设和分段的做法,并用来研究任意形状薄板的微振动,计算了圆板、椭圆板、三角形板等数值例子,在与现有文献的比较中显示了本方法的优越性.     

REFLECTION AND RADIATION OF A WAVE SYSTEM AT THE OPEN END OF A SUBMERGED ELASTIC PIPE

The reflection and radiation of a wave system at the open end of a submerged.semi-infinite elastic pipe are studicd.This wave system consists of a flexural wave in the pipe,anacoustic surface wave in the fluid exterior to the pipe and an acoustit wave in the pipe’sinterior.Fourier transfrom techniques are used to formulate this semi-infinite geometryproblem rigorously as a Wiener-Hopf type equation.An approximate solution is obtainedby using a perturbation method in which the ratio of the massdensities of the fluid and thepipe material is regarded as a small parameter.The calculation of the reflection coefficientis emphasized,and the polar plots of the radiation coefficient are also presented.     

桩-土系统的振动分析

桩基工程正在现代建筑(高层建筑、巨型桥梁、海洋石油平台等等)中发挥越来越大的作用。现代钢筋混凝土桩的长度可达100m左右,直径2m以上。桩体质量的检测自然成为人们关注的问题。最近通过交通部鉴定的水电效应法,利用水中瞬间高压放电产生作用于桩顶的强大的冲击载荷,使桩体实现纵向瞬态振动;分析检测到的桩顶振动     

径流式涡轮叶片的振动分析

本文将[1]中计算转动叶片动频和离心应力的方法推广应用于径流式增压器涡轮叶片的振动分析。对方法和程序作了一些改进,以适应径流式涡轮叶片的结构特点。文章给出了较完整的理论分析和程序框图,并列出了某些实物的计算结果和测试结果,两者相当符合。