Use of an Advanced Shear-Lag Model to Obtain the Optimum Internal Damping in Short-Fiber Composites

1989 ◽  
Vol 42 (11S) ◽  
pp. S93-S99
Author(s):  
P. Hajela ◽  
C.-J. Shih
Keyword(s):  
Stress Distribution ◽  
Matrix Material ◽  
Short Fiber ◽  
Internal Damping ◽  
Shear Lag ◽  
Shear Lag Model ◽  
Damping Characteristics ◽  
The Matrix ◽  
Lag Model ◽  
Perfect Bonding

The present paper examines a modified shear-lag model for predicting the stress distribution in short fiber reinforced composite materials. The model assumes perfect bonding between the fiber and the matrix materials, and allows for the matrix material to partially sustain axial loads. The stress distribution obtained on the basis of this model is used to predict the internal damping characteristics of the composite material. These characteristics are a function of both the material properties and the geometrical layout of the composite, and are optimized by combining the analytical model with a nonlinear programming optimization algorithm. Representative numerical results are obtained for glass–epoxy and graphite–epoxy composites

An Improved Shear-Lag Model for a Single Fiber Composite with a Ductile Matrix

2007 ◽  
Vol 334-335 ◽  
pp. 333-336
Author(s):  
Souta Kimura ◽  
Jun Koyanagi ◽  
Takayuki Hama ◽  
Hiroyuki Kawada
Keyword(s):  
Fiber Composite ◽  
Matrix Material ◽  
Single Fiber ◽  
Uniaxial Tensile ◽  
Fiber Direction ◽  
Stress Distributions ◽  
Shear Lag ◽  
Shear Lag Model ◽  
The Matrix ◽  
Lag Model

A shear-lag model is developed to predict the stress distributions in and around an isolated fiber in a single-fiber polymer matrix composite (PMC) subjected to uniaxial tensile loading and unloading along the fiber direction. The matrix is assumed to be an elasto-plastic material that deforms according to J2 flow theory. The stress distributions are obtained numerically and compared with a different shear-lag model that employs total strain theory as a constitutive equation of the matrix material. An effect of the difference between the models on the derived stress state is discussed.

scholarly journals Stress Transfer from Axially Loaded Fiber to Matrix in a Microcomposite

1994 ◽  
Vol 365 ◽  
Author(s):  
Chun-Hway Hsueh
Keyword(s):  
Analytical Solutions ◽  
Volume Fraction ◽  
Axial Stress ◽  
Stress Transfer ◽  
Radial Dependence ◽  
Shear Lag ◽  
Shear Lag Model ◽  
The Matrix ◽  
Lag Model ◽  
Loaded Fiber

ABSTRACTThe shear lag model has been used extensively to analyze the stress transfer in a singe fiberreinforced composite (i.e., a microcomposite). To achieve analytical solutions, various simplifications have been adopted in the stress analysis. Questions regarding the adequacy of those simplifications are discussed in the present study for the following two cases: bonded interfaces and frictional interfaces. Specifically, simplifications regarding (1) Poisson's effect, and (2) the radial dependences of axial stresses in the fiber and the matrix are addressed. For bonded interfaces, the former can be ignored, and the latter can generally be ignored. However, when the volume fraction of the fiber is high, the radial dependence of the axial stress in the fiber should be considered. For frictional interfaces, the latter can be ignored, but the former should be considered; however, it can be considered in an average sense to simplify the analysis. Comparisons among results obtained from analyses with various simplifications are made.

A Shear-Lag Model for Nanotube-Reinforced Composite Systems Under Transient Heat Transfer

2006 ◽  
Author(s):  
Amin Salehi-Khojin ◽  
Nader Jalili
Keyword(s):  
Heat Transfer ◽  
Mechanical Properties ◽  
Composite Structures ◽  
Transient Heat Transfer ◽  
Shear Lag ◽  
Equilibrium Equations ◽  
Shear Lag Model ◽  
Reinforced Composite ◽  
The Matrix ◽  
Lag Model

Understanding the stress transfer between nanotube reinforcements and matrix is an important factor in determining the overall mechanical properties of nanotube-reinforced composites. The classical shear-lag model in which the fiber and the matrix are equally long can not be applied to nanotube-based composite structures. Recently, a shear-lag model under mechanical loading for a concentric composite cylinder embedded with a capped nanotube has been introduced as the representative volume element (RVE). In this study, using similar approach the shear lag model is extended for a system under both mechanical and thermal loadings. The outer surface of RVE is prescribed to heating and cooling conditions, and transient heat transfer concept is used to find the temperature distribution in the matrix and on the surface of the nanotube. Using constitutive, geometrical and equilibrium equations for a given RVE, new shear-lag model for a nanotube-reinforced composite is then derived. It is demonstrated that the proposed model at room temperature could reduce to the same results obtained previously. These equations can be used to predict the mechanical properties of nanocomposite systems in real applications.

Longitudinal Relaxation of a Thermally Stressed Fiber by Prismatic Dislocation Punching

1990 ◽  
Vol 209 ◽  
Author(s):  
David C. Dunand ◽  
Andreas Mortensen
Keyword(s):  
Fiber Length ◽  
Interfacial Shear Stress ◽  
Interfacial Shear ◽  
Longitudinal Stress ◽  
Shear Lag ◽  
Shear Lag Model ◽  
Cylindrical Fiber ◽  
The Matrix ◽  
Lag Model ◽  
Critical Fiber Length

ABSTRACTA model predicting the number of prismatic loops dislocation punched at the ends of a cylindrical fiber by thermal mismatch stresses is presented and compared to another based on a mismatching ellipsoid. The longitudinal stress in the fiber and the interfacial shear stress are derived by adapting a shear-lag model to the plastic portion of the interface. In certain cases, the central part of the fiber is strained by plastic and elastic interfacial shear until it exhibits no mismatch with the matrix. This leads to a critical fiber length above which the number of punched loops is constant.

scholarly journals Analysis of creep behavior of SiC/Al metal matrix composites based on a generalized shear-lag model

2004 ◽  
Vol 19 (12) ◽  
pp. 3633-3640 ◽  
Author(s):  
Ho J. Ryu ◽  
Kyung H. Chung ◽  
Seung I. Cha ◽  
Soon H. Hong
Keyword(s):  
Effective Stress ◽  
Volume Fraction ◽  
Matrix Composites ◽  
Shear Lag ◽  
Shear Lag Model ◽  
Sic Particles ◽  
Al Composite ◽  
The Matrix ◽  
Lag Model

The creep behaviors of 20 vol% SiCw/2124Al, extruded with different ratios, and SiCp/2124Al, reinforced with 10–30 vol% SiC particles, were investigated to clarify the effects of aspect ratio, alignment, and volume fraction of reinforcement on creep deformation. The effective stresses on the matrix of SiC/Al composites are calculated based on the generalized shear-lag model. The minimum creep rates of SiCw/2124Al extruded with different ratios and SiCp/2124Al reinforced with different volume fractions of SiC particles are found to be similar under a same effective stress on matrix, which is calculated by the generalized shear-lag model. The subgrain sizes in matrices of crept SiC/Al composites are dependent on the effective stress on matrix but not on the applied stress on the composite. It is suggested that the role of SiC reinforcements is to increase the creep resistance of SiC/Al composite by reducing the effective stress on matrix.

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