Constitutive Model of Discontinuously-Reinforced Composites Taking Account of Reinforcement Damage and Size Effect and Its Application

2015 ◽  
pp. 489-527
Author(s):  
Keiichiro Tohgo
Keyword(s):  
Constitutive Model ◽  
Size Effect ◽  
Reinforced Composites

MODELING AND SIMULATION OF THE CURING PROCESS OF EPOXY RESINS AND FIBER COMPOSITES

2021 ◽  
Author(s):  
ANASTASIA MULIANA
Keyword(s):  
Constitutive Model ◽  
Residual Stresses ◽  
Elastic Moduli ◽  
Processing Parameters ◽  
Fiber Composites ◽  
Curing Process ◽  
Reinforced Composites ◽  
Micromechanics Model ◽  
Epoxy Curing ◽  
Exothermic Process

This study discusses simulations of the curing process in epoxy and fiberreinforced polymer composites incorporating changes in the thermal and mechanical properties of epoxy during curing at various temperatures. A coupled constitutive model that includes an exothermic process from the cross-linking, heat conduction across the specimen and deformations of the specimen from the thermal expansion and shrinkage effects is formulated. The model is used to capture the curing process in the epoxy resin. The coupled constitutive model is then integrated into a micromechanics model of fiber-reinforced composites and used to study the influence of epoxy curing on the formation of residual stresses in the composites. Furthermore, the micromechanics model is also used to predict the macroscopic properties, i.e., elastic moduli, of the cured composites. The model can then be used to understand the influence of processing parameters, i.e., temperatures and pressure, on the formation of residual stresses and their consequences on the overall properties of cured composites.

Size Effect on Microbond Testing Interfacial Shear Strength of Fiber-Reinforced Composites

2019 ◽  
Vol 86 (7) ◽  
Author(s):  
Qiyang Li ◽  
Guodong Nian ◽  
Weiming Tao ◽  
Shaoxing Qu
Keyword(s):  
Shear Strength ◽  
Carbon Fiber ◽  
Size Effect ◽  
Epoxy Matrix ◽  
Interfacial Shear Strength ◽  
Interfacial Shear ◽  
Experimental Results ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Material Systems

Microbond tests have been widely used for studying the interfacial mechanical properties of fiber-reinforced composites. However, experimental results reveal that the interfacial shear strength (IFSS) depends on the length of microdroplet-embedded fiber (le). Thus, it is essential to provide an insight into this size effect on IFSS. In this paper, microbond tests are conducted for two kinds of widely used composites, i.e., glass fiber/epoxy matrix and carbon fiber/epoxy matrix. The lengths of microdroplet-embedded glass fiber and carbon fiber are in the ranges from 114.29 µm to 557.14 µm and from 63.78 µm to 157.45 µm, respectively. We analyze the representative force–displacement curves, the processes of interfacial failure and frictional sliding, and the maximum force and the frictional force as functions of le. Experimental results show that IFSS of both material systems monotonically decreases with le and then approaches a constant value. The finite element model is used to analyze the size effect on IFSS and interfacial failure behaviors. For both material systems, IFSS predicted from simulations is consistent with that obtained from experiments. Moreover, by analyzing the shear stress distribution, a transition of interface debonding is found from more or less uniform separation to crack propagation when le increases. This study reveals the mechanism of size effect in microbond tests, serving as an effective method to evaluate the experimental results and is critical to guidelines for the design and optimization of advanced composites.

scholarly journals Analysis of Crack-Tip Field of Particulate-Reinforced Composites Taking Account of Particle Size Effect and Debonding Damage

2010 ◽  
Vol 452-453 ◽  
pp. 625-628
Author(s):  
Tomoyuki Fujii ◽  
Keiichiro Tohgo ◽  
Yu Itoh ◽  
Daisuke Kato ◽  
Yoshinobu Shimamura
Keyword(s):  
Particle Size ◽  
Size Effect ◽  
Crack Tip ◽  
Energy Criterion ◽  
Particle Size Effect ◽  
Reinforced Composites ◽  
Crack Tip Field ◽  
Damage Area ◽  
Particulate Reinforced Composites ◽  
Particulate Reinforced

This paper deals with an analysis of a crack-tip field of particulate-reinforced composites which can describe the evolution of debonding damage, matrix plasticity and particle size effect on deformation and damage. Numerical analyses were carried out on a crack-tip field in elastic-plastic matrix composites reinforced with elastic particles by using a finite element method developed based on an incremental damage theory. The particle size effect on damage is described by a critical energy criterion for particle-matrix interfacial debonding. The effect of debonding damage on a crack-tip field is discussed based on numerical results. The debonding damage initiates and progresses ahead of a crack-tip. The stress distribution shifts downward in the debonding damage area. It is concluded that a crack-tip field is strongly affected by debonding damage.

An Inelastic Biaxial Constitutive Model for Fabric-Reinforced Composites

1984 ◽  
Vol 13 (3) ◽  
pp. 144-160 ◽  
Author(s):  
Segun Thomas ◽  
Norris Stubbs
Keyword(s):  
Constitutive Model ◽  
Reinforced Composites
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