scholarly journals Sensitivity Analysis of the Frequency Response Function of Carbon-Fiber-Reinforced Plastic Specimens for Different Direction of Carbon Fiber as Well as Spectral Loading Pattern

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2983 ◽  
Author(s):  
Chan-Jung Kim
Keyword(s):  
Carbon Fiber ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Carbon Fiber Reinforced Plastic ◽  
Sensitivity Index ◽  
Fiber Reinforced ◽  
Loading Pattern ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic

Carbon-fiber-reinforced plastic (CFRP) has been used in many industries owing to its excellent specific-strength characteristics; however, the control of its mechanical properties is difficult owing to the directivity nature of carbon fiber as well as the composition of layered structures. In addition, the damping coefficient of CFRP varies with spectral loading patterns under random and harmonic excitation owing to the high values of damping characteristics compared with conventional steel materials. A scaled sensitivity index was proposed to compare the magnitude of the frequency response function over two parameters of interest: the direction of the carbon fiber and the spectral loading pattern for CFRP specimens. Three specimens with different directions (0°, 45°, and 90°) were prepared and uniaxial excitation testing was conducted for two different spectral loading cases: random and harmonic. The summation of the frequency response was used to calculate the sensitivity index to eliminate the effects of the location of measurement data, and all sensitivity indexes were calculated using the measured responses. Finally, the sensitivity of each CFRP specimen was discussed for two cases, i.e., the direction of carbon fiber and the spectral loading pattern, using the scaled sensitivity index results.

scholarly journals Temperature-Dependent Dynamic Characteristics of Carbon-Fiber-Reinforced Plastic for Different Spectral Loading Patterns

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5238
Author(s):  
Chan-Jung Kim
Keyword(s):  
Carbon Fiber ◽  
Modal Parameters ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Direction ◽  
Sensitivity Index ◽  
Fiber Reinforced ◽  
Loading Pattern ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Parameter Dependent

The dynamic properties of carbon-fiber-reinforced plastic (CFRP) can be efficiently estimated through a modal damping coefficient and a resonance frequency, and the modal parameters can be calculated using a frequency response function (FRF). The modal parameters used in an CFRP FRF are influenced by the carbon fiber direction, temperature, and spectral loading pattern, as well as the operating conditions. In this study, three parameters—temperature, spectral loading pattern, and carbon fiber direction—were selected as the influential factors for CFRP dynamics, and the sensitivity index formulation was derived from the parameter-dependent FRF of the CFRP structure. The derivatives of the parameter-dependent FRF over the three considered parameters were calculated from the measured modal parameters, and the dynamic sensitivity of the CFRP specimens was explored from the sensitivity index results for five different directional CFRP specimens. The acceleration response of a simple CFRP specimen was obtained via a uniaxial excitation test at temperatures ranging from −8 to 105 °C for the following two spectral loading cases: harmonic and random.

scholarly journals Modal Damping Coefficient Estimation of Carbon-Fiber-Reinforced Plastic Material Considering Temperature Condition

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2872 ◽  
Author(s):  
Ho-Young Kang ◽  
Chan-Jung Kim ◽  
Jaewoong Lee
Keyword(s):  
Carbon Fiber ◽  
Frequency Response ◽  
Plastic Material ◽  
Damping Coefficient ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Modal Damping ◽  
Reinforced Plastic ◽  
Carbon Fiber Reinforced

Excellent mechanical properties of carbon-fiber-reinforced plastic material (CFRP) demonstrates many possibilities in industries using lightweight materials, but unlike isotropic materials, such as iron, aluminum, and magnesium, they show direction-sensitive properties, which makes it difficult to apply for them. The sensitivity of a modal damping coefficient of a CFRP material over the direction of carbon fiber was examined on spectral input patterns in recent research, but the effect of temperature was not considered up to now. To overcome this, uniaxial vibration tests were conducted using five simple specimens with different direction of carbon fiber in a CFRP specimen, the frequency response functions were experimentally determined and the modal damping coefficients were calculated. It was revealed that the resonance point and the modal damping of the specimen changed according to the change in temperature condition. Based on the experimental results, it was demonstrated that the theoretical frequency response function of the carbon composite material is a function of temperature, and it was confirmed that the nonlinear characteristic of the modal damping was the smallest under the 0 degree of direction of carbon fiber.

scholarly journals Stressing State Analysis of Reinforced Concrete Beam Strengthened by CFRP Sheet with Anchoring Device

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 576
Author(s):  
Liang Luo ◽  
Jie Lai ◽  
Jun Shi ◽  
Guorui Sun ◽  
Jie Huang ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Strain Distribution ◽  
Carbon Fiber Reinforced Plastic ◽  
Rc Beams ◽  
Fiber Reinforced ◽  
Strain Distribution Pattern ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Cfrp Sheet ◽  
Carbon Fiber Reinforced

This paper investigates the working performance of reinforcement concrete (RC) beams strengthened by Carbon-Fiber-Reinforced Plastic (CFRP) with different anchoring under bending moment, based on the structural stressing state theory. The measured strain values of concrete and Carbon-Fiber-Reinforced Plastic (CFRP) sheet are modeled as generalized strain energy density (GSED), to characterize the RC beams’ stressing state. Then the Mann–Kendall (M–K) criterion is applied to distinguish the characteristic loads of structural stressing state from the curve, updating the definition of structural failure load. In addition, for tested specimens with middle anchorage and end anchorage, the torsion applied on the anchoring device and the deformation width of anchoring device are respectively set parameters to analyze their effects on the reinforcement performance of CFRP sheet through comparing the strain distribution pattern of CFRP. Finally, in order to further explore the strain distribution of the cross-section and analyze the stressing-state characteristics of the RC beam, the numerical shape function (NSF) method is proposed to reasonably expand the limited strain data. The research results provide a new angle of view to conduct structural analysis and a reference to the improvement of reinforcement effect of CFRP.

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

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 311
Author(s):  
Chan-Jung Kim
Keyword(s):  
Carbon Fiber ◽  
Modal Analysis ◽  
Dynamic Behavior ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic

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.

Study on the mechanism of inhomogeneous microdamage in short-pulse laser processing of carbon fiber reinforced plastic

2021 ◽  
pp. 073168442098359
Author(s):  
Luyao Xu ◽  
Jiuru Lu ◽  
Kangmei Li ◽  
Jun Hu
Keyword(s):  
Carbon Fiber ◽  
Pulse Energy ◽  
Short Pulse ◽  
Heterogeneous Material ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Reinforced ◽  
Processing Efficiency ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Carbon Fiber Reinforced

In this article, a micro-heterogeneous material simulation model with carbon fiber and resin phase about laser ablation on carbon fiber reinforced plastic (CFRP) is established by Ansys. The ablation process of CFRP by nanosecond ultraviolet laser is simulated, and the mechanism of pulse energy and spot spacing on the heat-affected zone (HAZ) is studied, then the process parameters are optimized with the goal of HAZ size and processing efficiency, and finally the validity of the model is verified by experiments. It is found that the residual gradient and the width of the radial HAZ increase with the increase of the spot spacing, and the width of the axial HAZ decreases slightly with the increase of the spot spacing, which indicates the existence of the optimal spot spacing. Second, the ablation depth increases with the increase of the pulse energy, and the carbon fiber retains a relatively complete degree of exposure when the pulse energy is low, which has a certain guiding significance for the cleaning and bonding of CFRP.

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