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.

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.

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.

Shear Lag Model for Regularly Staggered Short Fuzzy Fiber Reinforced Composite

2014 ◽  
Vol 81 (9) ◽  
Author(s):  
S. I. Kundalwal ◽  
M. C. Ray ◽  
S. A. Meguid
Keyword(s):  
Polymer Matrix ◽  
Interfacial Shear Stress ◽  
Stress Transfer ◽  
Fiber Reinforced ◽  
Shear Lag ◽  
Fiber Reinforced Composite ◽  
Shear Lag Model ◽  
Transfer Characteristics ◽  
Reinforced Composite ◽  
Lag Model

In this article, we investigate the stress transfer characteristics of a novel hybrid hierarchical nanocomposite in which the regularly staggered short fuzzy fibers are interlaced in the polymer matrix. The advanced fiber augmented with carbon nanotubes (CNTs) on its circumferential surface is known as “fuzzy fiber.” A three-phase shear lag model is developed to analyze the stress transfer characteristics of the short fuzzy fiber reinforced composite (SFFRC) incorporating the staggering effect of the adjacent representative volume elements (RVEs). The effect of the variation of the axial and lateral spacing between the adjacent staggered RVEs in the polymer matrix on the load transfer characteristics of the SFFRC is investigated. The present shear lag model also accounts for the application of the radial loads on the RVE and the radial as well as the axial deformations of the different orthotropic constituent phases of the SFFRC. Our study reveals that the existence of the non-negligible shear tractions along the length of the RVE of the SFFRC plays a significant role in the stress transfer characteristics and cannot be neglected. Reductions in the maximum values of the axial stress in the carbon fiber and the interfacial shear stress along its length become more pronounced in the presence of the externally applied radial loads on the RVE. The results from the newly developed analytical shear lag model are validated with the finite element (FE) shear lag simulations and found to be in good agreement.

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 Determining the contribution of glycosaminoglycans to tendon mechanical properties with a modified shear-lag model

2013 ◽  
Vol 46 (14) ◽  
pp. 2497-2503 ◽  
Author(s):  
Hossein Ahmadzadeh ◽  
Brianne K. Connizzo ◽  
Benjamin R. Freedman ◽  
Louis J. Soslowsky ◽  
Vivek B. Shenoy
Keyword(s):  
Mechanical Properties ◽  
Shear Lag ◽  
Shear Lag Model ◽  
Lag Model

Continuous Powder Extrusion for Fabrication of Carbon Fibre Reinforced Aluminium

2017 ◽  
Vol 742 ◽  
pp. 158-164 ◽  
Author(s):  
Martin Saefkow ◽  
Matthias List ◽  
Andreas Schubert ◽  
Andreas Lohmüller ◽  
Robert F. Singer
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Short Fibre ◽  
Carbon Fibres ◽  
Shear Lag ◽  
Resonance Frequency Analysis ◽  
Shear Lag Model ◽  
Lag Model ◽  
Continuous Extrusion

Short fibre reinforced aluminium was produced using the Temconex® process which is a continuous extrusion using a mixture of metal powder and ceramic short fibre as feedstock. The Temconex® process was derived and further developed from the ConformTM process which uses metal rod rather than powder as feedstock. In the present paper the effect of the prechamber length on the mechanical properties was examined. As material Al99.7 powder with different volume fractions of milled carbon fibres was used. Distribution, orientation and geometry of the embedded fibres were examined using light microscopy. The mechanical properties were determined via tensile testing and resonance frequency analysis. An important increase of the Young’s modulus is observed because of the introduction of fibres. It can be rationalized based on Clyne’s Shear Lag model. Results show that an extension of the prechamber enhances the Young’s modulus and the elongation of fracture due to reduced fibre fracture and better fibre alignment.

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.

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 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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