Thermal and volumetric property analysis of polymer networks and composites using elevated temperature digital image correlation

Knowles, Kyler R.; Tu, Jianwei; Wiggins, Jeffrey S.

doi:10.1016/j.polymertesting.2016.12.013

Cited by 6 publications

(6 citation statements)

References 24 publications

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“…DIC systems use image analysis to observe the development of strain in a material. In the past, this technique had been used to study resin flow, crack development, and stress development in composite materials [9][10][11][12][13][14][15]. The use of a non-contact measurement technique in this study allowed the strain development of a prepreg sample through the complete process cycle to be captured.…”

Section: Digital Image Correlation (Dic)mentioning

confidence: 99%

The Effect of Material Variability on the Pre-Gelation Behaviour of Prepreg Composites

Poursartip¹,

Zobeiry²,

Duffner³

2020

SAMPE 2020 | Virtual Series

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Processes such as forming and AFP have become increasingly popular, and these manufacturing techniques require manipulation of the uncured pre-impregnated thermoset matrix composite material (prepreg). Interest in the initial state or pre-gelation behaviour of prepregs has grown due to these manufacturing trends as well as the increasing recent research connecting this regime to processing defects such as wrinkling and porosity. Historically, the pre-gelation behaviour of prepreg has been relatively unexplored due to the challenges that traditional testing methods have in handling the soft raw prepreg. It is shown here that Digital Image Correlation (DIC) can capture the prepreg behaviour through the entirety of a cure cycle on both a local and global level. This work presents the global response of the prepreg, showing the true pre-gelation response, which differs markedly from what has traditionally been presented as the expected behaviour.Additionally, the variability in local prepreg response can be linked back to local strain variations observed using DIC. With the insight into the variability of a ply and the pre-gelation strain response, the findings in this work emphasize the importance of understanding and accurately capturing the initial prepreg condition.

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Section: Digital Image Correlation (Dic)mentioning

confidence: 99%

The Effect of Material Variability on the Pre-Gelation Behaviour of Prepreg Composites

Poursartip¹,

Zobeiry²,

Duffner³

2020

SAMPE 2020 | Virtual Series

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“…[21] Analysis of the thermal strain data is not limited to CLTE calculation, [13] but also includes quantification of strain field heterogeneity [21] and residual strain of composite laminates. [20] Recently, the bias error in DIC displacement measurements was reported to be less than 0.005 pixels, which for a gauge length of 400 pixels estimates a strain error of 12.5 microstrain. [22] When applied to (T-DIC) over a temperature delta of 50 C, the CLTE error is 0:25 Â 10 À6 = C: [12] To overcome the differential thermal expansion that exists between steel, aluminum, and carbon fiber reinforced composites, a mixed material composite structure comprised of a higher stiffness (E > 120 GPa), lower CLTE (α $ 0 ppm/ C) reinforcement (carbon fiber reinforced composite) embedded within a lower stiffness (E $ 72 GPa), higher CLTE (α $ 24 ppm/ C) "matrix" material (aluminum) is studied.…”

Section: Introductionmentioning

confidence: 99%

“…[18] Interferometry is highly suited for measuring small displacements (10 À3 m) with Fizeau interferometers commonly used for CLTE measurements of samples smaller than those typically used in quartz rod dilatometry (10 Â 10 À3 m). [10] Digital image correlation [19] is an effective method for full-field strain measurement, and has been utilized to measure the thermal strains in metals, [12] films, [13,14] composites, [12,20] and polymers. [21] Analysis of the thermal strain data is not limited to CLTE calculation, [13] but also includes quantification of strain field heterogeneity [21] and residual strain of composite laminates.…”

Section: Introductionmentioning

confidence: 99%

“…Digital image correlation [ 19 ] is an effective method for full‐field strain measurement, and has been utilized to measure the thermal strains in metals, [ 12 ] films, [ 13,14 ] composites, [ 12,20 ] and polymers. [ 21 ] Analysis of the thermal strain data is not limited to CLTE calculation, [ 13 ] but also includes quantification of strain field heterogeneity [ 21 ] and residual strain of composite laminates.…”

Section: Introductionmentioning

confidence: 99%

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Tailoring thermal expansion of mechanically interlocked carbon fiber composite reinforced metal

Newcomb

2022

Polymer Composites

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A method of controlling the thermal expansion of lightweight metals through the insightful incorporation of unidirectional carbon fiber reinforced polymer (CFRP) is demonstrated. The local and directional coefficients of linear thermal expansion (CLTE) of a carbon fiber composite reinforced aluminum (CFRP/Al) specimen can be controlled by tailoring the CFRP volume fraction and CFRP layup orientation, with a 36% reduction in CLTE achieved as compared to the baseline 7075 aluminum at a CFRP volume fraction of 0.26. When a unidirectional CFRP reinforcement is considered, the CLTE as predicted by the modulus modified rule of mixtures is within 1.3% of experimentally obtained values for CFRP volume fractions of 0.10, 0.16, and 0.26. Thermal digital image correlation (T-DIC) was performed to obtain local and directional CLTE values for the anisotropic CFRP/Al specimens which indicated CLTE is heterogeneous across the specimen length and width, which is otherwise undetected using standard quartz rod dilatometry to measure the CLTE of the macroscopic sample. Evidence for a minimum critical CFRP reinforcement length is also considered based upon the local thermal strain data collected by T-DIC. Using the mixed material approach presented here, it is possible to minimize or eliminate the thermal expansion mismatch effects that occur in mixed material structures, such as an automotive body structure (i.e., body in white).

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“…Curing also causes shrinkage that can influence the surface quality of the component. Depending on the geometry of the part, thermal and curing shrinkage can also create internal stresses that can weaken the part or lead to cracking [6][7][8][9][10][11][12]. Further, the heat generated during the cure in an exothermic reaction needs to be controlled.…”

Section: Introductionmentioning

confidence: 99%

A Practical Approach for Data Gathering for Polymer Cure Simulations

Heinze

Echtermeyer

2018

Applied Sciences

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Producing precision parts requires good control of the production parameters. When casting thermoset polymers an understanding of the curing process, with its heat release and associated temperature changes, is important. This paper describes how the cure of a polymer of unknown detailed chemical composition in a large part can be predicted and how the necessary material properties required for the predictions can be obtained. The approach given is a relatively simple method that a part manufacturer can perform. It will not characterize chemical reactions in detail, but it gives sufficient accuracy to describe the process. The procedures will be explained for an example of casting a large block of a filled two-component thermoset polyurethane. The prediction of the degree of cure, the associated heat and temperature increase during the curing of a polymer was successfully done using a standard finite element program with the input parameters reaction energy, the Arrhenius pre-factor and the kinetic function, which describes the chemical reaction. The three parameters could be obtained with standard Differential Scanning Calorimetry (DSC) equipment. The data were analyzed with the model-free isoconversional method combined with the compensation effect. The same set of parameters allowed the prediction of experimental cure behavior over two orders of magnitude of time and at a curing temperature range from room temperature up to 420 K.

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Thermal and volumetric property analysis of polymer networks and composites using elevated temperature digital image correlation

Cited by 6 publications

References 24 publications

The Effect of Material Variability on the Pre-Gelation Behaviour of Prepreg Composites

The Effect of Material Variability on the Pre-Gelation Behaviour of Prepreg Composites

Tailoring thermal expansion of mechanically interlocked carbon fiber composite reinforced metal

A Practical Approach for Data Gathering for Polymer Cure Simulations

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