scholarly journals Analytical Study of a Pin-Loaded Hole in Unidirectional Laminated Composites With Triangular and Circular Fibers

2013 ◽  
Vol 80 (2) ◽  
Author(s):  
Hossein Robati ◽  
Mohammad Mahdi Attar
Keyword(s):  
Composite Structures ◽  
Analytical Study ◽  
Glass Fibers ◽  
Stress Fields ◽  
Shear Lag ◽  
Stress Concentrations ◽  
Equilibrium Equations ◽  
Shear Lag Model ◽  
Lag Model ◽  
Good Agreement

The problem of stress concentrations in the vicinity of pin-loaded holes is of particular importance in the design of multilayered composite structures made of triangular or circular glass fibers. It is assumed that all of the fibers in the laminate lie in one direction while loaded by a force p0 at infinity, parallel to the direction of the fibers. According to the shear lag model, equilibrium equations are derived for both types of fibers. A rectangular arrangement is postulated in either case. Upon the proper use of boundary and bondness conditions, stress fields are derived within the laminate, along with the surrounding pinhole. The analytical results are compared to those of the finite element values. A very good agreement is observed between the two methods. According to the results, composite structures made of triangular glass fibers result in lower values of stress concentrations around the pin, as opposed to those of circular glass fibers.

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.

Interfacial characteristics of hybrid nanocomposite under thermomechanical loading

2017 ◽  
Vol 26 (3-4) ◽  
pp. 95-103 ◽  
Author(s):  
Vijay Choyal ◽  
Shailesh I. Kundalwal
Keyword(s):  
Axial Stress ◽  
Interfacial Shear Stress ◽  
Transversely Isotropic ◽  
Hybrid Nanocomposite ◽  
Shear Lag ◽  
Shear Lag Model ◽  
Three Phase ◽  
Lag Model ◽  
Interfacial Characteristics ◽  
Good Agreement

AbstractIn this work, an improved shear lag model was developed to investigate the interfacial characteristics of three-phase hybrid nanocomposite which is reinforced with microscale fibers augmented with carbon nanotubes on their circumferential surfaces. The shear lag model accounts for (i) radial and axial deformations of different transversely isotropic constituents, (ii) thermomechanical loads on the representative volume element (RVE), and (iii) staggering effect of adjacent RVEs. The results from the current newly developed shear lag model are validated with the finite element simulations and found to be in good agreement. This study reveals that the reduction in the maximum value of the axial stress in the fiber and the interfacial shear stress along its length become more pronounced in the presence of applied thermomechanical loads on the staggered RVEs. The existence of shear tractions along the RVE length plays a significant role in the interfacial characteristics and cannot be ignored.

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.

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.

scholarly journals On the Stress Transfer of Nanoscale Interlayer with Surface Effects

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Quan Yuan ◽  
Mengjun Wu
Keyword(s):  
Surface Effect ◽  
Surface Elasticity ◽  
Stress Transfer ◽  
Interfacial Stress ◽  
Interlayer Thickness ◽  
Shear Lag ◽  
Multilayered Structures ◽  
Residual Surface Stress ◽  
Shear Lag Model ◽  
Lag Model

An improved shear-lag model is proposed to investigate the mechanism through which the surface effect influences the stress transfer of multilayered structures. The surface effect of the interlayer is characterized in terms of interfacial stress and surface elasticity by using Gurtin–Murdoch elasticity theory. Our calculation result shows that the surface effect influences the efficiency of stress transfer. The surface effect is enhanced with decreasing interlayer thickness and elastic modulus. Nonuniform and large residual surface stress distribution amplifies the influence of the surface effect on stress concentration.

Investigation of Damage in Unidirectional Ceramic Matrix Composites Using a Cohesive-Shear-Lag Model

2001 ◽  
Author(s):  
B. Yang ◽  
S. Mall
Keyword(s):  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Interfacial Debonding ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Shear Lag ◽  
Stress Strain ◽  
Unidirectional Fiber ◽  
Shear Lag Model ◽  
Lag Model

Abstract The present study develops a cohesive-shear-lag model to analyze the cycling stress-strain behavior of unidirectional fiber-reinforced ceramic matrix composites. The model, as a modification to a classical shear-lag model, takes into account matrix cracking, partial interfacial debonding, and partial breakage of fibers. The statistical nature of partial breakage of fibers is modeled by using a cohesive force law. The validity of the model is demonstrated by investigating stress-strain hysteresis loops of a unidirectional fiber-reinforced ceramic-glass matrix composite, SiC/1723. This example demonstrates the capability of the proposed model to characterize damage and deformation mechanisms of ceramic matrix composites under tension-tension cycling loading. The dominant progressive damage mechanism with cycling in this case is shown to be accumulation of fibers breakage, accompanied by increase in interfacial debonding and smoothening of frictional debonded interface.

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