Characterization of the Effect of Material Configuration and Impact Parameters on Damage Tolerance of Sandwich Composites

Samarah, Issam K.; Weheba, Gamal; Lacy, Thomas E.

doi:10.4271/2006-01-2443

Cited by 3 publications

(4 citation statements)

References 21 publications

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“…Statistical design of experiment techniques may be used to identify and model complex relationships between input design factors and output responses in material systems. With polymer composites, these statistical techniques have previously been used for dynamic mechanical analysis, Izod impact testing of VGCNF/VE nanocomposites, and damage characterization of sandwich composites by isolating and examining the effects of multiple input design factors. The relationships between these factors can be statistically explored by developing response surface models (RSMs) to determine the estimated responses within the design boundaries.…”

Section: Introductionmentioning

confidence: 99%

Creep characterization of vapor‐grown carbon nanofiber/vinyl ester nanocomposites using a response surface methodology

Drake

Sullivan

Lacy

et al. 2015

J of Applied Polymer Sci

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The effects of selected factors such as vapor-grown carbon nanofiber (VGCNF) weight fraction, applied stress, and temperature on the viscoelastic responses (creep strain and creep compliance) of VGCNF/vinyl ester (VE) nanocomposites were studied using a central composite design (CCD). Nanocomposite test articles were fabricated by high-shear mixing, casting, curing, and post curing in an open-face mold under a nitrogen environment. Short-term creep/creep recovery experiments were conducted at prescribed combinations of temperature (23.8-69.2 C), applied stress (30.2-49.8 MPa), and VGCNF weight fraction (0.00-1.00 parts of VGCNF per hundred parts of resin) determined from the CCD. Response surface models (RSMs) for predicting these viscoelastic responses were developed using the least squares method and an analysis of variance procedure. The response surface estimates indicate that increasing the VGCNF weight fraction marginally increases the creep resistance of the VGCNF/VE nanocomposite at low temperatures (i.e., 23.8-46.5 C). However, increasing the VGCNF weight fraction decreased the creep resistance of these nanocomposites for temperatures greater than 50 C. The latter response may be due to a decrease in the nanofiber-to-matrix adhesion as the temperature is increased. The RSMs for creep strain and creep compliance revealed the interactions between the VGCNF weight fraction, stress, and temperature on the creep behavior of thermoset polymer nanocomposites. The design of experiments approach is useful in revealing interactions between selected factors, and thus can facilitate the development of more physics-based models.

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Section: Introductionmentioning

confidence: 99%

Creep characterization of vapor‐grown carbon nanofiber/vinyl ester nanocomposites using a response surface methodology

Drake

Sullivan

Lacy

et al. 2015

J of Applied Polymer Sci

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“…A response surface methodology22 was employed in a central composite design (CCD)23, 24 in order to isolate and examine the effects of multiple factors (i.e., VGCNF weight fraction, high‐shear mixing time, and ultrasonication time) on nanocomposite impact strengths using the minimum number of runs. In the context of polymer composites, such powerful statistical techniques have previously been used for dynamic mechanical analysis of VGCNF/VE nanocomposites,10 damage characterization of sandwich composites,25–28 epoxy nanocomposites,29 thermoplastic starch/clay nanocomposites,30 polyurethane/clay nanocomposites,31 polystyrene/montmorillonite nanocomposites,32 and so forth. High‐shear mixing and ultrasonication were chosen as the mixing techniques due to their prevalent use in previous studies 10, 12, 15–17.…”

Section: Introductionmentioning

confidence: 99%

Statistical characterization of the impact strengths of vapor‐grown carbon nanofiber/vinyl ester nanocomposites using a central composite design

Torres¹,

Nouranian²,

Lacy³

et al. 2012

J of Applied Polymer Sci

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The effects of vapor-grown carbon nanofiber (VGCNF) weight fraction, high-shear mixing time, and ultrasonication time on the Izod impact strengths of VGCNF/vinyl ester (VE) nanocomposites were studied using a central composite design. A response surface model (RSM) for predicting impact strengths was developed using regression analysis. RSM predictions suggested that an 18% increase in impact strength was possible for nanocomposites containing only 0.170 parts per hundred parts resin (phr) of VGCNFs ($0.1 v%) that were high-shear mixed for 100 min when compared to that of neat VE. In general, the predicted impact strengths increased for high-shear mixing times above 55 min and VGCNF weight fractions below 0.400 phr. The predicted strengths decreased as the VGCNF weight fraction was further increased. Scanning electron micrographs of the nanocomposite fracture surfaces showed that increased impact strength could be directly correlated to better nanofiber dispersion in the matrix.

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“…These five configurations represent a subset of a 20-configuration, three-factor central composite face-centered (CCF) circumscribed design of experiments test matrix that spans the limits of each of the three independent variables. Similarly to the Box-Behnken design [44], the CCF design fits a statistical response surface through a sphere that is circumscribed within a cube representing the design domain http://carbonlett.org post-tested specimens. The quasi-static uniaxial compressive response of each material configuration was characterized at an applied engineering strain rate of 10 -3 s -1 in order to ensure an isothermal state of pure mechanical loading with no influences from temperature effects that manifest themselves at higher loading rates through the conversion of a percentage of the plastic work into internal heat generation within the sample.…”

Section: Experimental Design Spacementioning

confidence: 99%

“…the length scale of the nano-reinforcements of interest [48]. A typical sample of each material configuration was broken into manually to expose a fracture surface for cross-sectional imaging.…”

Section: Sem Imaging and Quantitative Characterization Of The Bulk Namentioning

confidence: 99%

Carbon nanofiber-reinforced polymeric nanocomposites

Jang¹,

Hutchins²,

Yu³

2013

Carbon letters

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Five vapor-grown carbon nanofiber (VGCNF) reinforced vinyl ester (VE) nanocomposite configurations were fabricated, imaged, and mechanically tested in order to obtain information on the influence and the interactions of the role of the microstructure at lower length scales on the observed continuum level properties/response. Three independent variables (the nanofiber weight fraction and two types of nanofiber mixing techniques) were chosen to be varied from low, middle, and high values at equally spaced intervals. Multiple mixing techniques were studied to gain insight into the effect of mixing on the VGCNF dispersion within the VE matrix. The point count method was used for both lower length-scale imaging techniques to provide quantitative approximations of the magnitude and the distribution of such lower length-scale features. Finally, an inverse relationship was shown to exist between the stiffness and strength properties of the resulting nanocomposites under uniaxial quasistatic compression loading.

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Characterization of the Effect of Material Configuration and Impact Parameters on Damage Tolerance of Sandwich Composites

Cited by 3 publications

References 21 publications

Creep characterization of vapor‐grown carbon nanofiber/vinyl ester nanocomposites using a response surface methodology

Creep characterization of vapor‐grown carbon nanofiber/vinyl ester nanocomposites using a response surface methodology

Statistical characterization of the impact strengths of vapor‐grown carbon nanofiber/vinyl ester nanocomposites using a central composite design

Carbon nanofiber-reinforced polymeric nanocomposites

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