Comparison of Mode Shapes of Carbon-Fiber-Reinforced Plastic Material Considering Carbon Fiber Direction

Chan-Jung Kim

doi:10.3390/cryst11030311

Abstract

Previous studies have demonstrated the sensitivity of the dynamic behavior of carbon-fiber-reinforced plastic (CFRP) material over the carbon fiber direction by performing uniaxial excitation tests on a simple specimen. However, the variations in modal parameters (damping coefficient and resonance frequency) over the direction of carbon fiber have been partially explained in previous studies because all modal parameters have only been calculated using the representative summed frequency response function without modal analysis. In this study, the dynamic behavior of CFRP specimens was identified from experimental modal analysis and compared five CFRP specimens (carbon fiber direction: 0°, 30°, 45°, 60°, and 90°) and an isotropic SCS13A specimen using the modal assurance criterion. The first four modes were derived from the SCS13A specimen; they were used as reference modes after verifying with the analysis results from a finite element model. Most of the four mode shapes were found in all CFRP specimens, and the similarity increased when the carbon fiber direction was more than 45°. The anisotropic nature was dominant in three cases of carbon fiber, from 0° to 45°, and the most sensitive case was found in Specimen #3.

Highlights

Carbon-fiber-reinforced plastic (CFRP) material plays an important role in the transportation industry owing to its superior specific strength-to-weight ratio, and its manufacturing cost is approaching to make a profit in mass production
Considering their anisotropic properties, various previous studies have focused on the application of CFRP materials, including embedding fiber Bragg grating sensors [1], machine tools [2], crack identification [3], and guide-wave excitation by angle-beam wedge piezoelectric transducers [4]
If the modal analysis method is applied to CFRP structures with different directions of carbon fiber, all other interesting parameters can be eliminated from Equation (2), except θ, as follows: rie

Summary

Introduction

Carbon-fiber-reinforced plastic (CFRP) material plays an important role in the transportation industry owing to its superior specific strength-to-weight ratio, and its manufacturing cost is approaching to make a profit in mass production. Several chemical companies have produced raw materials such as carbon fiber and polymer matrix; pre-impregnated composite materials have recently been used in several applications Considering their anisotropic properties, various previous studies have focused on the application of CFRP materials, including embedding fiber Bragg grating sensors [1], machine tools [2], crack identification [3], and guide-wave excitation by angle-beam wedge piezoelectric transducers [4]. The effect of the damping coefficient of CFRP material has been efficiently evaluated by considering interesting parameters, the direction of carbon fiber, temperature, and the spectral loading pattern [13,14,15]. The modal parameters of CFRP simple specimens were determined for five different directions of carbon fiber (0◦ , 30◦ , 45◦ , 60◦ , and 90◦ ) through experimental modal testing using an impact hammer. The variations in the first four modal parameters are discussed using the summarized results according to the direction of the carbon fiber

Theoretical Background for Modal Analysis

Comparison of Mode

Variations in resonance frequencies according to the carbon fiber direction:

Variations in damping coefficients according to the to carbon fiber direction:

Findings

Conclusions