PREDICTION OF DAMAGE DETECTION AND EFFECT OF NATURAL FREQUENCY ON COMPOSITE BEAM
- Paper number
IAC-08.C2.5.5
- Author
Prof. Sylvanus Wosu, University of Pittsburgh, United States
- Coauthor
Prof. Leo Daniel, Massachusetts Institute of Technology, United States
- Year
2008
- Abstract
This paper describes the analysis and experimental effort undertaken to determine damage detection and the changes in the natural frequencies of composite beams. Finite element analysis of delamination in composites and its effect on the natural frequencies of the composite beam is determined using cohesive zone elements and material model present in the commercial finite element software, ANSYS. Numerical simulations are carried out to analyze typical cases of a delaminated composite beam with different boundary conditions. The changes in the natural frequencies of the beam due to the propagation of delamination are studied. It is found that an increase in the delaminated region ratio increases the percent deviation in the system natural frequencies. The amount of deviation was different for variable delamination types. The frequency charts of the present study may be useful for engineering design and non-destructive testing analysis. It can be used as a tool for diagnosis, detection and identification of delaminations in engineering applications by monitoring the high frequency response and change. Keywords: Composite, delamination, cohesive zone, fracture, finite element method, damage detection, modal analysis I. INTRODUCTION The use of advanced composite materials has increased considerably in the fabrication of mechanical and structural components. Their excellent stiffness to weight and strength to weight ratio provide greater advantages in certain applications as compared to traditional materials such as steel and aluminum. This has led to wide spread theoretical and experimental research to provide a better understanding of the behavior of composite material. One of the major focuses is on the detection of degradation of composite material as a result of mechanical fatigue. In laminated composite materials the failure process usually involves fiber breaking, fiber buckling, transversal matrix cracks, debond between fiber and matrix and delamination of two adjacent piles of the laminate. Delamination represents an interlaminar crack that can propagate under the effect of mechanical, thermal and hygrometric loads. This mechanism has the most detrimental effect as it reduces the material stiffness and fatigue life of the component, causes excessive vibration and is difficult to detect under service conditions. The growth of delamination is laminated composites is mainly limited to lie between the strong fiber reinforced layers. Thus the propagation of interlaminar crack may occur in mode I (opening), mode II (shearing), mode III (tearing) and in mixed mode (any combination of I, II & III).
- Abstract document
- Manuscript document
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