Shrinkage defects in thermosets: plate model

Chekanov, Yu. A.; Коротков, В. Н.

doi:10.1007/bf00241158

Cited by 1 publication

(2 citation statements)

References 5 publications

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“…Quite a different geometry of the model, which also leads to curing under three-dimensionally constrained conditions and to the origination of damage, is realized when the system is cured between two plates separated by rigid spacers used to keep the plates apart in the transverse direction under the action of the shrinkage stresses (plate model) [9]. The introduced parameters make it possible to characterize quantitatively the intensity of damage formation.…”

Section: Results Of Modeling the Formation Of Shrinkage Damagementioning

confidence: 99%

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Experimental and theoretical modeling of shrinkage damage formation in fiber composites

Коротков¹,

Розенберг²

1998

Mech Compos Mater

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The cure of a thermoset matrix in the formation of composites is always accompanied by chemical shrinkage that generates internal stresses. In composites with high fiber content, the matrix is cured under three-dimensionally constrained conditions. The results of the preuiou~ experimental and theoretical modeling of formation of shrinkage damage under these conditions in epoxy-amine system~ are briefly discu~ed. The effect of the model geometry (tube and plate models), scale factor, cure schedule, and chemical structure of composites is analyzed. A theoretical model for predicting the possibility of formation of shrinkage damage in fiber composites is proposed. A regular square structure wa~ considered. Analysis showed that the ma:dmum level of shrinkage stress in the matrix at the ultimate fiber fraction ~+ was close to the stress level ~ in an experimental long tube model, where the formation of shrinkage damage took place. The experimental results for the short tube model showed that the shrinkage damage in epoxy-amine systems occurred up to approximately a*/3. The damage development took place within the whole range of fiber content from ~+ to ~* (where the shrinkage stress level u~ about o+/3). In the long tube model, cohesive defects always nucleated inside the matrix. The damage grew, reached the inner surface of the tube, and then extended as adhesive debondings. A similar situation is expected in composites with a high fiber content. The damage considered is local, and the total monolithic character of a composite product is conserved.Polymer composite materials (PCM) contain two components with different physical-mechanical properties that during formation of the material inevitably lead to the appearance of internal (technological) stresses. The reasons for their origin on the micro-and macrolevel, the role of various factors in their formation, as well as their control methods are considered, for example, in [1][2][3].On the microlevel, the temperature stresses caused by the noniaothermal process of forming a polymer composite, as a rule, make the basic contribution to internal residual stresses. The influence of the stresses generated by chemical shrinkage of the polymeric matrix during synthesis is usually neglected, since at this stage the elastic characteristics of the matrix are very low. However, under certain conditions considered further on, the role of the chemical shrinkage stresses can considerably increase, and these stresses can evidently lead to the appearance of shrinkage damage in the composite on the microlevel.

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Section: Results Of Modeling the Formation Of Shrinkage Damagementioning

confidence: 99%

“…Despite the marked distinction in shape of the shrinkage damage nucleated upon curing the system in tube and plate models, some general features and the identity of mechanisms of damage formation in each relaxation state can be clearly traced [9].…”

Section: Results Of Modeling the Formation Of Shrinkage Damagementioning

confidence: 99%

Experimental and theoretical modeling of shrinkage damage formation in fiber composites

Коротков¹,

Розенберг²

1998

Mech Compos Mater

View full text Add to dashboard Cite

show abstract

Shrinkage defects in thermosets: plate model

Cited by 1 publication

References 5 publications

Experimental and theoretical modeling of shrinkage damage formation in fiber composites

Experimental and theoretical modeling of shrinkage damage formation in fiber composites

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