Finite Element Modeling to Predict Cure-Induced Microcracking in Three-Dimensional Woven Composites

Tsukrov, Igor; Bayraktar, Harun H.; Giovinazzo, Michael; Goering, J.; Gross, T. S.; Fruscello, Monica; Martinsson, Lars

doi:10.1007/s10704-011-9659-x

Cited by 37 publications

(13 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These characteristics play a significant role in determining the resulting composite performance, especially during damage and failure, where they can lead to strain hardening in tension [5] and kink-band formation in compression [6]. Also, cracks frequently initiate at low strain levels in resin rich regions which form around the binder yarns [7], sometimes even in as-manufactured specimens due to thermal stresses induced from curing [8].…”

Section: Introductionmentioning

confidence: 99%

Numerical modelling of 3D woven preform deformations

Green¹,

Long²,

Said³

et al. 2014

Composite Structures

142

View full text Add to dashboard Cite

In order to accurately predict the performance of 3D woven composites, it is necessary that realistic textile geometry is considered, since failure typically initiates at regions of high deformation or resin pockets. This paper presents the development of a finite element model based on the multi-chain digital element technique, as applied to simulate weaving and compaction of an orthogonal 3D woven composite. The model was reduced to the scale of the unit cell facilitating high fidelity results combined with relatively fast analysis times. The results of these simulations are compared with micro computed tomography (CT) scans of a dry specimen of fabric subjected to in-situ compaction. The model accurately depicted all of the key features of the fabric including yarn waviness and cross-sectional shapes as well as their development with compaction. A parametric study is presented to characterise the effect of the model inputs on the analysis speed and accuracy.

show abstract

Section: Introductionmentioning

confidence: 99%

Numerical modelling of 3D woven preform deformations

Green¹,

Long²,

Said³

et al. 2014

Composite Structures

142

View full text Add to dashboard Cite

show abstract

“…The resulting temperature may locally overshoot beyond the degradation temperature of the polymer, thus yielding thermal degradation and residual stresses. The accumulation of these residual stresses in the composite can initiate microcracks, typically during cooling as the residual stresses are increasing (Khoun et al, 2011;Timmerman et al, 2003, Tsukrov et al, 2011Zhao et al, 2001). For instance, Tsukrov et al (2011) reported the formation of cure induced microcracks in a 4 mmthick, 3D woven carbon/epoxy RTM composite cured at 160 8C.…”

Section: Microcracksmentioning

confidence: 99%

“…The accumulation of these residual stresses in the composite can initiate microcracks, typically during cooling as the residual stresses are increasing (Khoun et al, 2011;Timmerman et al, 2003, Tsukrov et al, 2011Zhao et al, 2001). For instance, Tsukrov et al (2011) reported the formation of cure induced microcracks in a 4 mmthick, 3D woven carbon/epoxy RTM composite cured at 160 8C. Using micro-computed tomography, the microcracks were observed mostly in the resin pockets, but also at the interfaces and transversely through the yarns.…”

Section: Microcracksmentioning

confidence: 99%

Process Induced Defects in Liquid Molding Processes of Composites

Hamidi

Altan

2017

International Polymer Processing

View full text Add to dashboard Cite

Liquid Composite Molding (LCM) processes are cost efficient manufacturing alternatives to traditional autoclave technology for producing near-net shape structural composite parts. However, process induced defects often limit wider usage of LCM in structural applications. Thorough knowledge of these defects, as well as their formation mechanisms and prevention techniques, is essential in developing improved LCM processes. In this article, process induced defects in liquid molding processes of composites, categorized into preform, flow induced and cure induced defects, are reviewed. Preform defects are further presented as fiber misalignment and fiber undulation (waviness and wrinkling). The respective causes, detrimental effects, and possible prevention methods of these defects are presented. Thereafter, flow induced defects are classified as voids and dry spots. Dry spot formation mechanisms in LCM processes and available prevention techniques are summarized. In addition, void formation mechanisms, adverse effects on composite properties, and removal techniques are presented. Cure induced defects include microcracks, void growth and geometrical distortions (warpage and spring-in). Each of these defects are discussed along with their underlying causes as well as their control and reduction schemes.

show abstract

“…These stresses arise from the difference in coefficient of thermal expansion (CTE) between the resin and the carbon fibers (55 ppm/K vs. −0.4 ppm/K in the axial direction) as the composite cools from the curing temperature. This problem has been studied using mesoscale finite element methods and experimental methods in the following references . This article focuses on the measurement and control of hydrostatic tensile stress generated when a curing epoxy resin is constrained from contracting or expanding during curing and during cooling after curing.…”

Section: Introductionmentioning

confidence: 99%

Curing cycle modification for RTM6 to reduce hydrostatic residual tensile stress in 3D woven composites

Gross

Jafari

Tsukrov

et al. 2016

J of Applied Polymer Sci

Self Cite

View full text Add to dashboard Cite

Triaxial residual tensile stresses resulting after cooling a 3D woven composite from the curing temperature cause cracking in the resin pockets for weave architectures that have high through‐the‐thickness constraint. We show how curing cycle modifications can reduce the hydrostatic tensile stress generated by thermal mismatch during cooling of Hexcel RTM6 epoxy resin constrained in a quartz tube which simulates extreme constraint in a composite. The modified curing schedule consists of a high temperature cure to just before the glass transition, a lower temperature hold that takes the resin through the glass transition thereby freezing in the zero stress state, followed by high temperature cure to bring the resin to full conversion. We show that this process is sensitive to heating rates and can reduce the zero stress state of non‐toughened RTM6 resin to a temperature similar to a commercial rubber‐toughened resin, Cycom PR520. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43373.

show abstract

Finite Element Modeling to Predict Cure-Induced Microcracking in Three-Dimensional Woven Composites

Cited by 37 publications

References 12 publications

Numerical modelling of 3D woven preform deformations

Numerical modelling of 3D woven preform deformations

Process Induced Defects in Liquid Molding Processes of Composites

Curing cycle modification for RTM6 to reduce hydrostatic residual tensile stress in 3D woven composites

Contact Info

Product

Resources

About