scholarly journals Experimental Characterization of Short Fiber-Reinforced Composites on the Mesoscale by Indentation Tests

Author(s):  
Natalie Rauter ◽  
Rolf Lammering

AbstractIndentation tests are widely used to characterize the material properties of heterogeneous materials. So far there is no explicit analysis of the spatially distributed material properties for short fiber-reinforced composites on the mesoscale as well as a determination of the effective cross-section that is characterized by the obtained measurement results. Hence, the primary objective of this study is the characterization of short fiber-reinforced composites on the mesoscale. Furthermore, it is of interest to determine the corresponding area for which the obtained material parameters are valid. For the experimental investigation of local material properties of short fiber-reinforced composites, the Young’s modulus is obtained by indentation tests. The measured values of the Young’s modulus are compared to results gained by numerical simulation. The numerical model represents an actual microstructure derived from a micrograph of the used material. The analysis of the short fiber-reinforced material by indentation tests reveals the layered structure of the specimen induced by the injection molding process and the oriented material properties of the reinforced material are observed. In addition, the experimentally obtained values for Young’s modulus meet the results of a corresponding numerical analysis. Finally, it is shown, that the area characterized by the indentation test is 25 times larger than the actual projected area of the indentation tip. This leads to the conclusion that indentation tests are an appropriate tool to characterize short fiber-reinforced material on the mesoscale.

2011 ◽  
Vol 55-57 ◽  
pp. 303-307 ◽  
Author(s):  
Bin Zhang ◽  
Bo Qin Gu

In this paper, the stress distribution of short-fiber-reinforced composites (SFRC) using representative volume element (RVE) approach based on the finite element analysis (FEA) was presented. A three-phase model was built, in which loads were applied to the matrix. The influences of interphase parameters like Young’s modulus and thickness were studied. The FEA confirms that interphase Young’s modulus and thickness control stress distribution in SFRC. The stress concentration at the fiber interface becomes greater with high interphase Young’s modulus and thin interphase thickness. The FEA results were also compared with those obtained by analytic method.


Author(s):  
Natalie Rauter

AbstractIn this study a modeling approach for short fiber-reinforced composites is presented which allows one to consider information from the microstructure of the compound while modeling on the component level. The proposed technique is based on the determination of correlation functions by the moving window method. Using these correlation functions random fields are generated by the Karhunen–Loève expansion. Linear elastic numerical simulations are conducted on the mesoscale and component level based on the probabilistic characteristics of the microstructure derived from a two-dimensional micrograph. The experimental validation by nanoindentation on the mesoscale shows good conformity with the numerical simulations. For the numerical modeling on the component level the comparison of experimentally obtained Young’s modulus by tensile tests with numerical simulations indicate that the presented approach requires three-dimensional information of the probabilistic characteristics of the microstructure. Using this information not only the overall material properties are approximated sufficiently, but also the local distribution of the material properties shows the same trend as the results of conducted tensile tests.


2007 ◽  
Vol 353-358 ◽  
pp. 1435-1438
Author(s):  
Zhi Ying Ou ◽  
Dong Xia Lei

A simplified approach for calculating the stress field of the fiber-reinforced composites is developed to improve the work of Theocaris et al. (1985) in this paper. This approach considers that the main factor affecting the stress field of composites is the existence of interphase between fiber and matrix, which possesses different Young’s modulus than those of the constituent phase. A parabolic law is adopted for the variation of Young’s modulus of graded interphase, versus the polar radius from fiber to matrix, while the Poisson’s ratio of the interphase is assumed as constant. Space axisymmetric model is applied to the Representative Volume Element (RVE) of the fiber-reinforced composites to evaluate stress field of the composites. Also, the effective longitudinal modulus of the fiber-reinforced composite can be obtained.


2011 ◽  
Vol 216 ◽  
pp. 393-396
Author(s):  
Huai Wen Wang ◽  
Le Le Gui ◽  
Hong Wei Zhou

Young’s Modulus of glass fiber reinforced composites for wind energy applications are studied using numerical method. The effect of volume content of glass fiber on the Young’s modulus of composites is investigated. Results indicate the relation between them is nearly linear. In order to explore the effect of inclined angle of fiber on the Young’s modulus of composites, different finite element models with inclined glass fiber are developed via the ABAQUS Scripting Interface. Results indicate that Young’s modulus of the composites strongly depends on the inclined angle of fiber. A U-shaped dependency of the Young’s modulus of composites on the inclined angle of fiber is found, which agree with the experimental results. The results of the investigation are expected to provide some design guideline for the microstructural optimization of the glass fiber reinforced composites.


1999 ◽  
Vol 66 (3) ◽  
pp. 709-713 ◽  
Author(s):  
R. S. Feltman ◽  
M. H. Santare

A model is presented to analyze the effect of fiber fracture on the anisotropic elastic properties of short-fiber reinforced composite materials. The effective moduli of the material are modeled using a self-consistent scheme which includes the calculated energy dissipated through the opening of a crack in an arbitrarily oriented elliptical inclusion. The model is an extension of previous works which have modeled isotropic properties of short-fiber reinforced composites with fiber breakage and anisotropic properties of monolithic materials with microcracks. Two-dimensional planar composite systems are considered. The model allows for the calculation of moduli under varying degrees of fiber alignment and damage orientation. In the results, both aligned fiber systems and randomly oriented fiber systems with damage-induced anisotropy are examined.


2017 ◽  
Vol 24 (5) ◽  
pp. 765-772 ◽  
Author(s):  
Dawei Jia ◽  
Huiji Shi ◽  
Lei Cheng

AbstractA study of the micromechanical behavior to predict the overall response of short fiber-reinforced composites under cyclic mechanical and thermal loading is presented. The instantaneous average over a “representative volume” of the material is considered. The influence of the short fiber’s aspect ratio, volume fraction, and spatial orientation has been investigated. The linear combined hardening model is used to describe the cyclic hardening effects in the case of metal matrix. A numerical procedure is used to predict the response of composites under mechanical and thermal conditions. The results of the numerical procedure have been compared to the results of three different models and to published experimental data.


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