Nondestructive and noncontact evaluation on FRP composite laminates using a terahertz ray

2012 ◽  
Author(s):  
Je-Woong Park ◽  
Kwang-Hee Im ◽  
David K. Hsu ◽  
Chien-Ping Chiou ◽  
Dan Barnard ◽  
...  
Keyword(s):  
Composite Laminates ◽  
Frp Composite ◽  
Terahertz Ray

Terahertz Ray Nondestructive Characterizations in FRP Composites

2010 ◽  
Vol 123-125 ◽  
pp. 839-842 ◽  
Author(s):  
Je Woong Park ◽  
Kwang Hee Im ◽  
David K. Hsu ◽  
Chien Ping Chiou ◽  
Daniel J. Barnard
Keyword(s):  
Composite Laminates ◽  
Electromagnetic Properties ◽  
Reflection Mode ◽  
Frp Composites ◽  
Frp Composite ◽  
Application Systems ◽  
Spectroscopy System ◽  
Terahertz Ray ◽  
Characterization Procedure ◽  
Good Agreement

Recently, terahertz ray imaging has emerged as one of the most promising new powerful nondestructive evaluation (NDE) techniques, and new application systems are under processing development for the area applications. In this study, a new time-domain spectroscopy system was utilized for detecting and evaluating layup effect and flaw in FRP composite laminates. Extensive experimental measurements in reflection mode were made to map out the T-ray images. Especially in this characterization procedure, we estimated the electromagnetic properties such as the refractive index. Estimates of properties are in good agreement with known data. Furthermore layup effect and flaw of FRP composite laminates were observed in reflection mode and limitations will be discussed in the T-ray processing.

T-Ray NDE Inspections on the Fiber Direction of Thermoplastic PPS-Based CFRP Composites

2013 ◽  
Vol 650 ◽  
pp. 253-257 ◽  
Author(s):  
Kwang Hee Im ◽  
David K. Hsu ◽  
Chien Ping Chiou ◽  
Daniel J. Barnard
Keyword(s):  
Time Domain ◽  
Composite Laminates ◽  
Index Of Refraction ◽  
Fiber Direction ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
Frp Composite ◽  
Application Systems ◽  
Conducting Materials ◽  
Terahertz Ray

Terahertz ray (T-ray) imaging has been emerged as one of the most promising new powerful nondestructive evaluation (NDE) techniques, and new application systems are under processing development for the area applications. The terahertz time domain spectroscopy (THz TDS) can be considered as a useful tool using general non-conducting materials; however it is quite limited to conducting materials. In this study, a new time-domain spectroscopy system was utilized for detecting and evaluating layup effect and flaw in FRP composite laminates. In order to solve various material properties, the index of refraction (n) and the absorption coefficient (α) are derived in reflective and transmission configuration using the terahertz time domain spectroscopy. However, the T-ray is limited in order to penetrate a conducting material to some degree. So, investigation of terahertz time domain spectroscopy (THz TDS) was made and reflection and transmission configurations were studied for a 48-ply thermoplastic PPS (poly-phenylene sulfide)-based CFRP solid laminate.

scholarly journals Microtomographic Analysis of Impact Damage in FRP Composite Laminates: A Comparative Study

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
M. Alemi-Ardakani ◽  
A. S. Milani ◽  
S. Yannacopoulos ◽  
L. Bichler ◽  
D. Trudel-Boucher ◽  
...  
Keyword(s):  
Composite Laminates ◽  
Impact Damage ◽  
Glass Fibers ◽  
Impact Testing ◽  
Frp Composites ◽  
Frp Composite ◽  
Flexural Testing ◽  
Close Relationship ◽  
High Level ◽  
Tomographic Analysis

With the advancement of testing tools, the ability to characterize mechanical properties of fiber reinforced polymer (FRP) composites under extreme loading scenarios has allowed designers to use these materials in high-level applications more confidently. Conventionally, impact characterization of composite materials is studied via nondestructive techniques such as ultrasonic C-scanning, infrared thermography, X-ray, and acoustography. None of these techniques, however, enable 3D microscale visualization of the damage at different layers of composite laminates. In this paper, a 3D microtomographic technique has been employed to visualize and compare impact damage modes in a set of thermoplastic laminates. The test samples were made of commingled polypropylene (PP) and glass fibers with two different architectures, including the plain woven and unidirectional. Impact testing using a drop-weight tower, followed by postimpact four-point flexural testing and nondestructive tomographic analysis demonstrated a close relationship between the type of fibre architecture and the induced impact damage mechanisms and their extensions.

Mechanics of FRP Composite Laminates

2021 ◽  
pp. 99-148
Author(s):  
Hota V. S. GangaRao ◽  
Woraphot Prachasaree
Keyword(s):  
Composite Laminates ◽  
Frp Composite

Coating Thickness Characterization of Composite Materials Using Terahertz Waves

2016 ◽  
Vol 878 ◽  
pp. 70-73 ◽  
Author(s):  
Kwang Hee Im ◽  
Sun Kyu Kim ◽  
David K. Hsu ◽  
Jong An Jung
Keyword(s):  
Refractive Index ◽  
Coating Thickness ◽  
Composite Laminates ◽  
Electromagnetic Properties ◽  
Terahertz Waves ◽  
Reflection Mode ◽  
Cfrp Composite ◽  
Spectroscopy System ◽  
Terahertz Ray

Recently, terahertz ray imaging has emerged as one of the most promising new powerful nondestructive evaluation (NDE) techniques for the area applications. In this study, a new time-domain spectroscopy system was utilized for measuring the coating thickness on CFRP composite laminates. Extensive experimental measurements in reflection mode were made to map out the T-ray images. Also, the refractive index was estimated based on the electromagnetic properties. The CFRP composite laminates were observed in reflection mode and limitations will be discussed in the T-ray processing. By using these characterized material properties, the characteristics was successfully demonstrated for T-ray behavior propagating through the Shim Stock films for acquiring the refractive index. The T-ray technique has been developed for the measurement of the thickness of the Shim Stock films and the coating thickness on CFRP composites. Good results have been obtained in tests made on the thickness of the standard film samples with the coating thickness ranging from around hundreds of μm.

scholarly journals The effect of temperature on fatigue strength and damage of FRP composite laminates

2021 ◽  
Author(s):  
Hossein Mivehchi
Keyword(s):  
Tensile Strength ◽  
Fatigue Strength ◽  
Ultimate Tensile Strength ◽  
Fatigue Damage ◽  
Composite Laminates ◽  
Damage Model ◽  
Effect Of Temperature ◽  
Temperature Dependent ◽  
Frp Composites ◽  
Frp Composite

The present study intends to investigate the effect of temperature on cumulative fatigue damage of laminated fibre-reinforced polymer (FRP) composites. The effect of temperature on fatigue damage is formulated based on a previously proposed residual stiffness fatigue damage model. The fatigue strength of FRP composite laminates is also formulated to have temperature dependent parameters. The research work is divided into three main parts; the first part reviews the fatigue damage mechanism is fibre-reinforced composites based on stiffness degradation. The recent residual stiffness of Varvani-Shirazi was used as the backbone structure of damage analysis in this thesis. This model is capable of damage assessment while the effects of maximum stress, stress ratio and fibre orientation of FRP composites were recognized. The Varvani-Shirazi damage model was further developed to assess fatigue damage of FRP composites at various temperatures (T). Inputs of the damage model are temperature dependent parameters including Young's modulus (E), ultimate tensile strength(ðult) and fatigue life (Nf). As the next part of the proposed analysis, the temperature dependency of each parameter is formulated, and the relations of E-T and ðult-T are substituted in the Varvani-Shirazi fatigue model. Finally, all terms and equations are evaluated with the experimental data available in the literature. Six sets fatigue data were used in this thesis to evaluate fatigue of FRP specimens. The predicted results were found to be in good agreement with the experimentally obtained data. The proposed fatigue damage model was found promising to predict the fatigue damage of unidirectional (UD) and women FRP composites at different temperatures. Temperature dependant parameters of Young's modulus, ultimate tensile strength, and S-N diagram were also found to be responsive when used of UD, cross-ply, and quasi-isotropic FRP laminates.

FAILURE PREDICTION OF COMPOSITE MATERIALS USING DEEP NEURAL NETWORKS

2021 ◽  
Author(s):  
ALLYSON FONTES ◽  
FARJAD SHADMEHRI
Keyword(s):  
Experimental Data ◽  
Neural Networks ◽  
Composite Materials ◽  
Composite Laminates ◽  
Deep Neural Networks ◽  
Mean Squared Error ◽  
Failure Criteria ◽  
Failure Strength ◽  
Failure Data ◽  
Frp Composite

Fiber-reinforced polymer (FRP) composite materials are increasingly used in engineering applications. However, an investigation into the precision of conventional failure criteria, known as the World-Wide Failure Exercise (WWFEI), revealed that current theories remain unable to predict failure within an acceptable degree of accuracy. Deep Neural Networks (DNN) are emerging as an alternate and time-efficient technique for predicting the failure strength of FRP composite materials. The present study examined the applicability of DNNs as a tool for creating a data-driven failure model for composite materials. The experimental failure data presented in the WWFE-I were used to develop the datadriven model. A fully connected DNN with 23 input units and 1 output unit trained with a constant learning rate (α=0.0001). The network’s inputs described the laminates and the loading conditions applied to the test specimen, whereas the output was the length of the failure vector (L=(σx+σy+τxy)0.5). The DNN’s performance was evaluated using the mean squared error on a subset of the experimental data unseen during training. Network configurations with a varying number of hidden layers and units per layer were evaluated. The DNN with 3 hidden layers and 20 units per hidden layer performed the best. In fact, the network’s predictions show good agreement with the experimental results. The failure boundaries generated by the DNN were compared to three conventional theories: the Tsai-Wu, Cuntze, and Puck theory. The DNN’s failure envelopes were found to fit the experimental data more closely than the above-mentioned theories. In sum, the DNN’s ability to fit higher-order polynomials to data separates it from conventional failure criteria. This characteristic makes DNNs an effective method for predicting the failure strength of composite laminates.

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