Effect of Crack Location and Crack Depth on Natural Frequencies of Fixed Beam Using Experimental Modal Analysis

Abstract

In this paper, the dynamic characteristics of fixed beam with and without crack are observed. A basic flexible aluminum fixed beam with surface crack at various locations is considered for the dynamic investigation. The crack dimensions and its location are the principle parameters to portray the well-being state of beams. Modal analysis is commonly well thought-out as an effective tool to obtain the intrinsic characteristics of structures including resonant frequencies and mode shapes. These are significant indicators for monitoring the health status of engineering beam like structures. Damage of beam deeply changes its natural frequencies and its mode shapes at various crack locations and depths are observed numerically and experimentally. Finite element modal analysis (FEMA) was performed on damaged and intact beam using ANSYS workbench. An experimental setup was developed for fixed beam with crack was excited by an impulse hammer, and the response was obtained by PCB accelerometer through data acquisition system (DAQ) using NI LabVIEW software. From frequency response functions (FRFs), natural frequencies and mode shapes are extracted and validated with FEMA results.