Finite element free vibration analysis of beams/columns subjected to progressive compressive load

• Main Author: Lim, Rebecca
• Other Authors: Sellakkutti Rajendran
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Mechanical engineering; Engineering::General
• Online Access: https://hdl.handle.net/10356/149201
• Institution: Nanyang Technological University

Beams are commonly used in many practical engineering applications such as buildings, bridges, aircraft, or automobile structures. In most applications, beams are subjected to bending and shear loads. A few may also be subjected to axial (tensile/compressive) loads. A beam subjected to axial compressive load is often known as a column. It is recognized that the axial load can significantly affect the natural frequencies of a system, resulting in early resonance for compressive loads. In this final year project (FYP), the effect of compressive load on the natural frequencies of flexural (bending) vibration of beams is studied. ANSYS Mechanical APDL is employed for the determination of natural frequencies. The solution procedure (in ANSYS) used to determine the natural frequencies under compressive load involves two steps: linear static analysis and modal analysis. A 2D column with a rectangular cross-section subjected to compressive load is analyzed in this project. Two boundary conditions, viz., fixed-free ends and fixed-pinned ends are considered. The natural frequencies and mode shapes of the column are calculated for each load by varying the compressive load in steps. Natural frequencies are determined in the column’s pre-buckling and post-buckling configurations. The natural frequencies are found to decrease as the buckling load is increased. In addition, the first natural frequency is found to be the more sensitive to the compressive load than the other set of natural frequencies.