Thin-Walled Structures

Advances in Research, Design and Manufacturing Technology

J. Loughlan

• Editorial: CRC Press
• Año: 2018
• ISBN:
  9781351094207
• Edición: 1
• Categoría: Physical Sciences
• Categoría: Physics

This volume contains the papers presented at the Fourth International Conference of Thin-Walled Structures (ICTWS4), and contains 110 papers which, collectively, provide a comprehensive state-of-the-art review of the progress made in research, development and manufacture in recent years in thin-walled structures.The presentations at the conference had representation form 35 different countries and their topical areas of interest included aeroelastic response, structural-acoustic coupling, aerospace structures, analysis, design, manufacture, cold-formed structures, cyclic loading, dynamic loading, crushing, energy absorption, fatigue, fracture, damage tolerance, plates, stiffened panels, plated structures, polymer matrix composite members, sandwich structures, shell structures, thin-walled beams, columns and vibrational response. The range of applications of thin-walled structures has become increasingly diverse with a considerable deployment of thin-walled structural elements and systems being found in a wide range of areas within Aeronautical, Automotive, Civil, Mechanical, Chemical and Offshore Engineering fields. This volume is an extremely useful reference volume for researchers and designers working within a wide range of engineering disciplines towards the design, development and manufacture of efficient thin-walled structural systems.

Section XII

SHELL STRUCTURES

EXACT VIBRATION FREQUENCIES OF SEGMENTED AXISYMMETRIC SHELLS

E. Efraim and M. Eisenberger

Faculty of Civil and Environmental Engineering, Technion – Israel Institute of Technology, Technion City, Haifa 32000, Israel

ABSTRACT

Axisymmetric shells are commonly used in all fields of engineering and their dynamic characteristics are of great importance in their overall performance. Segmented shells are shells that are built of several pieces that form together an axisymmetric shell with a joint axis. These can be cylindrical, conical or plate segments that are connected to form a complete shell. In this research the exact dynamic stiffness matrices for each segment are derived and used in assembly of the complete structure dynamic stiffness matrix. Then the natural frequencies of vibrations are found as the frequencies that cause this matrix to become singular. Examples are given for the frequencies and modes of segmented shells made of conical and cylindrical segments.

KEYWORDS

Axisymmetric Shells, Vibrations, Dynamic Stiffness, Natural Frequencies, Modes

INTRODUCTION

Axisymmetric shells are commonly used in all fields of engineering and their dynamic characteristics are of great importance in their overall performance. Such shell can by cylindrical, conical, spherical, and in general with curved generators. The exact vibration frequencies for complete sections built of these four types are known for several combinations of boundary conditions. Segmented shells are shells that are built of several pieces that form together an axisymmetric shell with a joint axis as can be seen in Figure 1. In the Figure five segments are shown: Segments 1 and 4 are conical, and segments 2,3 and 5 are cylindrical. The exact values of frequency for segmented shells are not known in general.

Hu and Raney (1967) presented a comparison between analytical and experimental results for a combined conical-cylindrical shell. The analytical results were obtained by imposing continuity constraints on the segments of the shell. Lashkari and Weingarten (1973) compared finite element numerical solutions with experimental results for conical-cylindrical joined shell. Irie et. al. (1984) used the transfer matrix method to solve conical-cylindrical and annular plate-cylindrical shell systems. Wilkenand Soedel (1976) used the receptance method to solve the vibrations of ring stiffened cylindrical shell and discussed the of the location of the stiffener, inner, symmetrically located, or outer ring, on the results. Yuan and Dickinson (1994) solved combined cylinder-plate shell using the Rayligh-Ritz method. The compatibility between the segments was imposed by springs with high stiffness.

Figure 1: Segme...