Comparing non-destructive 3D X-ray computed tomography with destructive optical microscopy for microstructural characterization of fiber reinforced composites

Hanhan, Imad; Agyei, Ronald F.; Xiao, Xianghui; Sangid, Michael D.

doi:10.1016/j.compscitech.2019.107843

Cited by 30 publications

(19 citation statements)

References 37 publications

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“…Typically, engineers are not interested in fragments of fibers with aspect ratios close to one because they contribute almost no load bearing capability when compared to their longer cylindrical neighbors present in the microstructure [28][29][30] . Therefore, techniques and algorithms to detect and characterize fibers are typically not suitable for ≤ l d / 1, which can be easily confused with noise 30,31 . In this work, the fragment of glass was manually observed in the in-situ tomography images, detected as a fragment of a fiber, included in the microstructural simulation, and proved to be a region of high hydrostatic stress and a region of corresponding microvoid nucleation, as was seen in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The material used in this work was a polypropylene thermoplastic reinforced with 30% by weight E-glass fibers which were approximately 10 m µ in diameter and were pre-treated with a tailored silane solution to promote fiber-matrix adhesion. The composite material was injection molded into a cylindrical rod measuring 1.27 cm in diameter and 45.72 cm in length where the flow direction was in the length direction of the rod, and the rod was then machined into a dog-bone shaped specimen with a gauge section diameter of 2.4 mm and length of 5 mm containing fibers that were, on average, approximately 300 µm long 31 . The specimen was studied in-situ by applying tensile load (at a quasi-static strain rate of approximately 0.001 − s 1 ) using a custom motorized screw driven miniature load frame, interrupting the tensile load by holding the cross-head displacement, and acquiring an in-situ X-ray µ-CT scan.…”

Section: Methods Experimental Detailsmentioning

confidence: 99%

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Predicting Microstructural Void Nucleation in Discontinuous Fiber Composites through Coupled in-situ X-ray Tomography Experiments and Simulations

Hanhan

Agyei

Xiao

et al. 2020

Sci Rep

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composite materials have become widely used in engineering applications, in order to reduce the overall weight of structures while retaining their required strength. in this work, a composite material consisting of discontinuous glass fibers in a polypropylene matrix is studied at the microstructural level through coupled experiments and simulations, in order to uncover the mechanisms that cause damage to initiate in the microstructure under macroscopic tension. Specifically, we show how hydrostatic stresses in the matrix can be used as a metric to explain and predict the exact location of microvoid nucleation that occurs during damage initiation within the composite's microstructure. furthermore, this work provides evidence that hydrostatic stresses in the matrix can lead to coupled microvoid nucleation and early fiber breakage, and that small fragments of fibers can play an important role in the process of microvoid nucleation. These results significantly improve our understanding of the mechanics that drive the initiation of damage in the complex microstructures of discontinuous fiber reinforced thermoplastics, while also allowing scientists and engineers to predict the microstructural damage behavior of these composites at sub-fiber resolution and with high accuracy. Composite materials have gained attention in many engineering applications, especially in the aerospace and automotive industries due to their low weight and high strength. Specifically, polymer matrix composites have allowed for major weight savings and higher performance aircraft and vehicles. Despite their high rate of implementation, scientists and engineers have faced challenges in predicting their mechanical behavior and performance, especially past the small strain regime and into the damage initiation and damage propagation regimes, because there exist a number of damage mechanisms which are often coupled and are active throughout the life of a component. Compared to continuous fiber composites, discontinuous fiber reinforced polymers exhibit vastly heterogeneous microstructures that can vary significantly depending on the component geometry, making mechanical behavior predictions even more complicated 1-3. Until recently, most efforts in predicting the mechanical performance of discontinuous fiber composites have been focused on the elastic loading regime during which damage has not yet initiated and progressed 4,5. Efforts in understanding and predicting the behavior of fiber composites past the elastic regime have typically focused on attempting to replicate the macroscopic bulk stress-strain behavior of a specimen through phenomenological damage parameters 6. In recent years, some microstructural approaches have been used to explore the damage mechanisms in certain composites using homogenization approaches 7 as well as unit cell methods 8. Experimentally, one in-situ study of a thermoset polymer, reinforced with discontinuous carbon fibers, showed that fiber tips play an important role in microvoid nucleation due to high shear stress...

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Section: Discussionmentioning

confidence: 99%

Section: Methods Experimental Detailsmentioning

confidence: 99%

Predicting Microstructural Void Nucleation in Discontinuous Fiber Composites through Coupled in-situ X-ray Tomography Experiments and Simulations

Hanhan

Agyei

Xiao

et al. 2020

Sci Rep

Self Cite

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“…The MoE implies the sectioning and polishing of the samples, i.e., it is a destructive technique, followed by optical microscopy or scanning electron microscopy (SEM) in order to determine the in-plane and out-of-plane angles of the projected fibers from the surface characterization. This method has certain limitations, such as the ambiguity in determining the 3D fiber orientation and the difficulty in achieving a proper FOD characterization over a representative area/volume of the material (McGee and McCullough, 1984;Vélez-Garcia, 2012;Sharma et al, 2018;Hanhan et al, 2019). Alternatively, in recent years the application of three-dimensional techniques, such as micro-CT scanning, have become really appealing for non-destructively characterizing composites' microstructural features (Salaberger et al, 2011;Emerson et al, 2017;Hanhan et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…This method has certain limitations, such as the ambiguity in determining the 3D fiber orientation and the difficulty in achieving a proper FOD characterization over a representative area/volume of the material (McGee and McCullough, 1984;Vélez-Garcia, 2012;Sharma et al, 2018;Hanhan et al, 2019). Alternatively, in recent years the application of three-dimensional techniques, such as micro-CT scanning, have become really appealing for non-destructively characterizing composites' microstructural features (Salaberger et al, 2011;Emerson et al, 2017;Hanhan et al, 2019). However, there are few studies using these techniques to validate predictions given by simulation (Kleindel et al, 2015;Tseng et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Fiber Orientation Distribution Predictions for an Injection Molded Venturi-Shaped Part Validated Against Experimental Micro-Computed Tomography Characterization

et al. 2020

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“…Before going to take microstructure, the weld samples were cut into transverse directions and the cross-sectional surface was carried out for the standard metallographic procedure. Polishing with emery sheets of SiC with grit size varying from 220 to 2000 followed by disc polishing using alumina and velvet cloth were employed on the specimen to obtain a mirror finish the weldments [17]. Metallurgical characterization was performed with the use of an optical microscope and inverted microscope on the weldment, compromising of base metal and fusion zone.…”

Section: Optical Microscopy and Tensile Strength Testmentioning

confidence: 99%

Optimization of ultimate tensile strength of welded Inconel 625 and duplex 2205

Madhankumar¹,

Manonmani²,

Karthickeyan³

et al. 2021

JMES

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The ultimate strength is an important property of any material for the manufacturing of components. This paper utilized the laser beam welding (LBW), due to its smaller dimension, which produces lesser distortion and process velocity is higher. Inconel 625 alloy and duplex 2205 stainless steel is having higher strength and corrosive resistance properties. Due to the above-mentioned properties, it could be used in oil and gas storage containers, marine and geothermal applications. This research work presents an investigation of various input variable effects on the output variable (ultimate tensile strength) in LBW for dissimilar materials namely, Inconel 625 alloy and duplex 2205 stainless steel. The input variables for this research are the power of a laser, welding speed, and focal position. The experimental runs are developed with the help of design of experiment (DOE) and utilized statistical design expert software. The ultimate tensile strength on different runs is measured using a universal tensile testing machine. Then from a response surface methodology and ANOVA, the optimum value of ultimate tensile strength was determined to maximize the weld joint and bead geometry. Finally, the confirmation test was carried out, it reveals the maximum error of 0.912% with the predicted value. In addition, the microstructure of the weld beads was examined using optical microscopy.

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Comparing non-destructive 3D X-ray computed tomography with destructive optical microscopy for microstructural characterization of fiber reinforced composites

Cited by 30 publications

References 37 publications

Predicting Microstructural Void Nucleation in Discontinuous Fiber Composites through Coupled in-situ X-ray Tomography Experiments and Simulations

Predicting Microstructural Void Nucleation in Discontinuous Fiber Composites through Coupled in-situ X-ray Tomography Experiments and Simulations

Fiber Orientation Distribution Predictions for an Injection Molded Venturi-Shaped Part Validated Against Experimental Micro-Computed Tomography Characterization

Optimization of ultimate tensile strength of welded Inconel 625 and duplex 2205

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