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.

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

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.

Analysis of Stresses for Cross-Ply Laminates with a Matrix Crack under Bending

2011 ◽  
Vol 284-286 ◽  
pp. 492-495
Author(s):  
Qing Dun Zeng ◽  
Mao Hua Ouyang
Keyword(s):  
Failure Mechanism ◽  
Transverse Crack ◽  
Approximate Solutions ◽  
Matrix Crack ◽  
Stress Distributions ◽  
Shear Lag ◽  
New Approach ◽  
Shear Lag Model ◽  
Lag Model ◽  
Shear Lag Theory

On the basis of the shear-lag theory, an analysis was presented for stress redistributions of cross-ply laminates with a transverse matrix crack in the 90º ply under bending by establishing a layered shear-lag model. The present results show that approximate solutions of displacement and stress distributions for cross-ply laminates with a transverse crack under bending can be obtained by using a shear-lag method. The present paper therefore affords a new approach for studying the stress redistributions and failure mechanism for cross-ply laminates with flaw under bending.

Analysis of Stresses for Cross-Ply Laminates with Multiple Matrix Cracks under Bending

2011 ◽  
Vol 311-313 ◽  
pp. 256-259
Author(s):  
Qing Dun Zeng ◽  
Mao Hua Ouyang
Keyword(s):  
Finite Element ◽  
Approximate Solutions ◽  
Stress Distributions ◽  
Shear Lag ◽  
Transverse Cracks ◽  
Shear Lag Model ◽  
Matrix Cracks ◽  
Variational Solutions ◽  
Lag Model ◽  
Good Agreement

On the basis of the shear-lag theory, a layered shear-lag model was established to study the stress redistributions of cross-ply laminates with multiple transverse matrix cracks in the 90º ply under bending. The present results are in a good agreement with variational solutions and finite element results and show that approximate solutions of stress distributions for cross-ply laminates with transverse cracks under bending can be obtained by using a shear-lag method. The present paper therefore affords a new way or method for studying the stress redistributions and failure mechanism for cross-ply laminates with flaws under bending.

On the Mechanics of Microcracking in Fiber Composite Laminates Under Combined Stress

1989 ◽  
Vol 111 (2) ◽  
pp. 145-149 ◽  
Author(s):  
S. R. Swanson
Keyword(s):  
Composite Laminates ◽  
Fiber Composite ◽  
Tensile Modulus ◽  
Shear Loading ◽  
Shear Lag ◽  
Shear Lag Model ◽  
Fiber Tension ◽  
Approximate Relationship ◽  
Lag Model ◽  
Modulus Reduction

The formation of matrix microcracks in fiber composite laminates has been widely observed. The present paper addresses the mechanics of this microcracking by means of a shear lag model in conjunction with a Weibull failure criterion for further cracking. This shear lag model considers both shear loading as well as cross-fiber tension in the cracked ply. The reduction in inplane shear and tensile modulus of the cracked ply is computed directly from the model. The increase in applied load required to produce new cracks is computed and shows general agreement with previous experimental results. A general approximate relationship between the applied strain levels and the modulus reduction is presented.

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.

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