Mechanical Behavior and Failure Mode of Unidirectional Fiber Composites at Low Strain Rate Level

Sun, Lei; Jia, Yuxi; Ma, Fengde; Sun, Sheng; Han, Charles C.

doi:10.1177/0021998309345355

Cited by 5 publications

(3 citation statements)

References 26 publications

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“…For the unidirectional fiber composites, at the low strain rate level (2e À5 À 2e À2 s À1 ), the elastic modulus is insensitive to loading rate, but the ultimate tensile stress increases as strain rate increases. 33 Therefore, the finite element model ignores the effect of velocity on the…”

Section: Modeling Processmentioning

confidence: 99%

A novel model of Z-pin insertion in prepreg based on fracture mechanics

Cheng

Fei

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part B:

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Through-thickness reinforcement is a promising solution to the problem of delamination susceptibility in laminated composites. Modeling Z-pin–prepreg interaction is essential for accurate robotics-assisted Z-pin insertion. In this paper, a novel Z-pin insertion force model combining the classical cohesive finite element (FE) method with a dynamic analytical fracture mechanics model is proposed. The velocity-dependent cohesive elements, in which the fracture toughness is provided by the analytical model, are implemented in Z-pin insertion FE model to predict the crack initiation and propagation. Then Z-pin insertion experiments are performed on prepreg sample with metallic Z-pins at different velocities to identify the analytical model parameters and validate the simulation predictions offered by the model. Dynamics of Z-pin interaction with inhomogeneous prepreg is described and the effects of insertion velocity on prepreg contact force are studied. Results show that the force model agrees well with experiments and the fracture toughness rises with the increasing Z-pin insertion velocity.

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Section: Modeling Processmentioning

confidence: 99%

A novel model of Z-pin insertion in prepreg based on fracture mechanics

Cheng

Fei

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…[2][3][4][5][6][7] Such resin-blends have been used as a matrix in composites to study the their properties at cryogenic temperatures, 8 thermal and electrical properties, 9 damping properties, 10,11 mechanical behavior, and fracture toughness. 12,13 One such blend of epoxy made of DGEBF (commercial designation -Ciba Geigy GY282) cross-linked with slow-reacting anhydride hardener methyltetrahydrophthalic anhydride (MTHPA; commercial designation -Ciba Geigy HY 918) is being considered as a candidate for the insulation impregnation material as a woven glass/epoxy composite for the central solenoid (CS) coil modules of the International Thermonuclear Experimental Reactor (ITER). 1,14 The CS is a system of six large electromagnet coil modules, each module having an outer radius of 2.1 m, inner radius of 1.2 m, height of 2.2 m, and weighing about 112 tons each.…”

Section: Introductionmentioning

confidence: 99%

DGEBF epoxy blends for use in the resin impregnation of extremely large composite parts

Madhukar

Martovetsky

2015

Journal of Composite Materials

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Large superconducting electromagnets used in fusion reactors utilize a large amount of glass/epoxy composite for electrical insulation and mechanical and thermal strengths. The manufacture of these magnets involves wrapping each superconducting cable bundle with dry glass cloth followed by the vacuum-assisted resin transfer molding of the entire magnet. Due to their enormous size (more than 100 tons), it requires more than 40 h for resin impregnation and the subsequent pressure cycles to ensure complete impregnation and removal of any trapped air pockets. Diglycidyl ether of bisphenol F epoxy resin cross-linked with methyltetrahydrophthalic anhydride with an accelerator has been shown to be a good candidate for use in composite parts requiring long impregnation cycles. Viscosity, gel time, and glass transition temperature of four resin-blends of diglycidyl ether of bisphenol F resin system were monitored as a function of time and temperature with an objective to find the blend that provides a working window longer than 40 h at low viscosity without lowering its glass transition temperature. Based on the results, a resin-blend in the weight ratios of resin:hardener:accelerator = 100:82:0.125 is shown to provide more than 60 h at low resin viscosity while maintaining the same glass transition temperature as obtained with previously used resin-blends.

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“…However, the existing difference between the prediction results of these models and the test data for the mechanical properties in the transversal direction can't be ignored [3] . And then, the finite element method is increasingly used to predict the strength performance of unidirectional composites [4][5][6][7][8] .…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis on the Influence of Interface on the Mechanical Behavior of Unidirectional Fiber Composites under Different Loads

Jia

Zhu

et al. 2013

KEM

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On the smallest structural scale in the multi-scale structure composites, namely fiber scale, a numerical model was proposed for the analysis on the mechanical properties of unidirectional composites through the representative unit cell (RUC). The progressive method was used to simulate the failure behavior of fiber and matrix, and the debonding between fiber and matrix was characterized by the cohesive zone model (CZM). The failure strength of the unidirectional composite was predicted, and the influence of the interfacial strength on the mechanical behavior of unidirectional composite was discussed. It is shown that fiber dominates the failure strength of the material under the longitudinal load, whereas under the transverse load interfacial properties play an important role in the mechanical behavior of the material. The increase of the interfacial strength can significantly improve the capability of transverse compression and shear resistance.

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Mechanical Behavior and Failure Mode of Unidirectional Fiber Composites at Low Strain Rate Level

Cited by 5 publications

References 26 publications

A novel model of Z-pin insertion in prepreg based on fracture mechanics

A novel model of Z-pin insertion in prepreg based on fracture mechanics

DGEBF epoxy blends for use in the resin impregnation of extremely large composite parts

Numerical Analysis on the Influence of Interface on the Mechanical Behavior of Unidirectional Fiber Composites under Different Loads

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