A Microstructural Model for the Tensile Constitutive and Failure Behavior of Soft Skeletal Connective Tissues

1998 ◽  
Vol 120 (1) ◽  
pp. 55-61 ◽  
Author(s):  
T. A. L. Wren ◽  
D. R. Carter
Keyword(s):  
Volume Fraction ◽  
Strain Curve ◽  
Ground Substance ◽  
Uniaxial Tensile ◽  
Failure Behavior ◽  
Connective Tissues ◽  
Fiber Volume ◽  
Two Phase ◽  
Wide Range ◽  
Microstructural Model

We propose a microstructural model for the uniaxial tensile constitutive and failure behavior of soft skeletal connective tissues. The model characterizes the tissues as two-phase composites consisting of collagen fibers embedded in ground substance. Nonlinear toe region behavior in the stress versus strain curve results from the straightening of crimped fibers and from fiber reorientation. Subsequent linear behavior results from fiber stretching affected by fiber volume fraction, collagen type, crosslink density, and fiber orientation. Finally, the tissue fails when fibers successively rupture at their ultimate tensile strain. We apply the model to tendon, meniscus, and articular cartilage. The model provides a consistent approach to modeling the tensile behavior of a wide range of soft skeletal connective tissues.

Semianalytical compressive strength criteria for unidirectional composites

2017 ◽  
Vol 37 (4) ◽  
pp. 238-246
Author(s):  
Uri Breiman ◽  
Jacob Aboudi ◽  
Rami Haj-Ali
Keyword(s):  
Experimental Data ◽  
Compressive Strength ◽  
Volume Fraction ◽  
Unidirectional Composite ◽  
Fiber Volume ◽  
Unidirectional Composites ◽  
Analysis And Design ◽  
Composite Systems ◽  
Wide Range ◽  
Laminated Structures

The compressive strength of unidirectional composites is strongly influenced by the elastic and strength properties of the fiber and matrix phases, as well as by the local geometrical properties, such as fiber volume fraction, misalignment, and waviness. In the present investigation, two microbuckling criteria are proposed and examined against a large volume of measured data of unidirectional composites taken from the literature. The first criterion is based on the compressive strength formulation using the buckling of Timoshenko’s beam. It contains a single parameter that can be determined according to the best fit to experimental data for various types of polymeric matrix composites. The second criterion is based on buckling-wave propagation analogy using the solution of an eigenvalue problem. Both criteria provide closed-form expressions for the compressive strength of unidirectional composites. We propose modifications of the two criteria by a fitting approach, for a wide range of fiber volume fractions, applied to four classes of unidirectional composite systems. Furthermore, a normalized form of the two models is presented after calibration in order to compare their prediction against experimental data for each of the material systems. The new modified criteria are shown to give a good match to a wide range of unidirectional composite systems. They can be employed as practical compression failure criteria in the analysis and design of laminated structures.

An Analytical and Experimental Study of Strength and Failure Behavior of Plain Weave Composites

1998 ◽  
Vol 32 (1) ◽  
pp. 2-30 ◽  
Author(s):  
Makoto Ito ◽  
Tsu-Wei Chou
Keyword(s):  
Volume Fraction ◽  
Random Phase ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Packing Fraction ◽  
Failure Behavior ◽  
Fiber Volume ◽  
Laminate Composites ◽  
Plain Weave ◽  
Geometrical Characteristics

This paper analyzes the strengxth and failure behavior of plain weave composites. First, the geometrical characteristics of yarn shape, laminate stacking configuration, fiber volume fraction, and yarn packing fraction are investigated using three-dimensional geometrical models. Based on the geometrical characteristics, iso-strain approach is developed to predict elastic properties, stress distributions, and strengths under tensile loading. The laminate stacking configuration and fabric waviness ratio have significant influence on the composite failure behavior. Specimens of iso-phase, out-of-phase and random-phase laminate composites are prepared. The mathematical models developed are evaluated by microscopic observation and tensile tests.

scholarly journals Influence of Fiber Volume Fraction and Fiber Orientation on the Uniaxial Tensile Behavior of Rebar-Reinforced Ultra-High Performance Concrete

Fibers ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 67 ◽  
Author(s):  
Manish Roy ◽  
Corey Hollmann ◽  
Kay Wille
Keyword(s):  
Fiber Orientation ◽  
High Performance ◽  
Fiber Volume Fraction ◽  
High Performance Concrete ◽  
Volume Fraction ◽  
Tensile Behavior ◽  
Uniaxial Tensile ◽  
Ultra High Performance Concrete ◽  
Load Direction ◽  
Fiber Volume

This paper studied the influence of fiber volume fraction ( V f ), fiber orientation, and type of reinforcement bar (rebar) on the uniaxial tensile behavior of rebar-reinforced strain-hardening ultra-high performance concrete (UHPC). It was observed that the tensile strength increased with the increase in V f . When V f was kept constant at 1%, rebar-reinforced UHPC with fibers aligned with the load direction registered the highest strength and that with fibers oriented perpendicular to the load direction recorded the lowest strength. The strength of the composite with random fibers laid in between. Moreover, the strength, as well as the ductility, increased when the normal strength grade 60 rebars embedded in UHPC were replaced with high strength grade 100 rebars with all other conditions remaining unchanged. In addition, this paper discusses the potential of sudden failure of rebar-reinforced strain hardening UHPC and it is suggested that the composite attains a minimum strain of 1% at the peak stress to enable the members to have sufficient ductility.

Mechanical properties and mechanical behavior of (SiO2)f/SiO2 composites with 3D six-directional braided quartz fiber preform

2012 ◽  
Vol 19 (2) ◽  
pp. 113-117 ◽  
Author(s):  
Yong Liu ◽  
Zhaofeng Chen ◽  
Jianxun Zhu ◽  
Yun Jiang ◽  
Binbin Li
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Thermal Structure ◽  
Three Dimensional ◽  
Shear Loading ◽  
Failure Behavior ◽  
Fiber Volume ◽  
Strain Behavior ◽  
Highly Nonlinear ◽  
Nonlinear Stress

Abstract(SiO2)f/SiO2 composites reinforced with three-dimensional (3D) six-directional preform were fabricated by the silicasol-infiltration-sintering method. The nominal fiber volume fraction was 47%. To characterize the mechanical properties of the composites, mechanical testing was carried out under various loading conditions, including tensile, flexural, and shear loading. The composite exhibited highly nonlinear stress-strain behavior under all the three types of loading. The results indicated that the 3D six-directional braided (SiO2)f/SiO2 composites exhibited superior flexural properties and good shear resistant as compared with other types of preform (2.5D and 3D four-directional)-reinforced (SiO2)f/SiO2 composites. 3D six-directional braided (SiO2)f/SiO2 composite exhibited graceful failure behavior under loading. The addition of 5th and 6th yarns resulted in controlled fracture and hence these 3D six-directional braided composites could possibly be suitable for thermal structure components.

scholarly journals Experimental Analysis of Tensile Mechanical Properties of Sprayed FRP

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Zhao Yang ◽  
Kun Wu
Keyword(s):  
Mechanical Properties ◽  
Fiber Length ◽  
Fiber Type ◽  
Volume Ratio ◽  
Strain Curve ◽  
Uniaxial Tensile ◽  
Stress Strain Curve ◽  
Fiber Volume ◽  
Tensile Performance ◽  
Type Fiber

To study the tensile mechanical properties of sprayed FRP, 13 groups of specimens were tested through uniaxial tensile experiments, being analyzed about stress-strain curve, tensile strength, elastic modulus, breaking elongation, and other mechanical properties. Influencing factors on tensile mechanical properties of sprayed FRP such as fiber type, resin type, fiber volume ratio, fiber length, and composite thickness were studied in the paper too. The results show that both fiber type and resin type have an obvious influence on tensile mechanical properties of sprayed FRP. There will be a specific fiber volume ratio for sprayed FRP to obtain the best tensile mechanical property. The increase of fiber length can lead to better tensile performance, while that of composite thickness results in property degradation. The study can provide reference to popularization and application of sprayed FRP material used in structure reinforcement.

Influence of Short Polypropylene Fibers on the Toughness of High Performance Cement Slurries

2014 ◽  
Author(s):  
Thayane Martins Barghigiani ◽  
Romildo Dias Toledo Filho ◽  
Vivian K. C. B. L. M. Balthar ◽  
Cristiane R. Miranda ◽  
Reila V. Velasco
Keyword(s):  
High Performance ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Peak Load ◽  
Strain Curve ◽  
Free Fluid ◽  
Polypropylene Fibers ◽  
Fluid Density ◽  
Fiber Volume ◽  
Cracking Behavior

In oil wells, one of the goals of the cement sheath is the hydraulic seal. Generally, cement pastes, which are adopted in cementing operations, exhibit brittle fracture when subjected to tensile stresses. This behavior can compromise the hydraulic seal promoted through the sheath. One way to mitigate this problem is the use of slurries with more deformability. In this context, this work aims the determination of the toughness of high performance cement slurries reinforced by different volume fractions (0.50% and 0.75%) of short polypropylene fibers (6mm long). The influence of fiber addition in the rheological behavior, free fluid, density, stability and unconfined compression of the slurries was also determined. The obtained results indicated an increase in the yield strength and a reduction in the spreading of the reference mix with the increase of the fiber volume fraction. The free fluid, density and stability behavior of the reinforced slurries were similar to that of the control mix. An expressive change in the fracture behavior of the brittle matrix was observed in both mechanical tests carried out. Under uniaxial compression loads, although the ascending branch of the stress-strain curve did not show expressive differences with the fiber reinforcement (only minor modifications in the peak load), the descending branches were significantly modified with the reinforced mixes presenting a smooth post-cracking behavior. The greatest benefit provided by the fibers was observed, however, in the bending tests. Both, the maximum post-cracking strength and bending toughness, were significantly augmented with the increase of the fiber volume fraction.

In Situ Matrix Shear Response Using Torsional Test Data of Fiber Reinforced Unidirectional Polymer Composites

2002 ◽  
Vol 124 (2) ◽  
pp. 152-159 ◽  
Author(s):  
Chandra S. Yerramalli ◽  
Anthony M. Waas
Keyword(s):  
Shear Modulus ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Polymer Matrix Composites ◽  
Strain Curve ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Shear Response ◽  
Matrix Shear

The in situ shear response of the matrix in polymer matrix composites (PMC) has been studied. Torsion tests were performed on solid cylinders of unidirectional glass fiber reinforced/vinylester and unidirectional carbon fiber reinforced/vinylester composites. The composite specimens were subjected to a uniform rate of twist. From the composite stress-strain curve, a plot of tangent shear modulus vs shear strain was derived. Then, using the Halpin-Tsai equations, the in situ matrix shear modulus was determined. The in situ matrix properties obtained from glass/vinylester and carbon/vinylester composites were found to be different. In addition, the properties of the in situ matrix were found to be a function of fiber volume fraction and the elastic properties of the reinforcing fiber. The behavior of the in situ matrix as a function of the fiber volume fraction was explained by using a three cylinder interphase model. The validity of the interphase model in predicting the composite shear modulus was studied by comparison of results against a conventional 2 cylinder model.

scholarly journals CFD for Subcooled Flow Boiling: Parametric Variations

2013 ◽  
Vol 2013 ◽  
pp. 1-22 ◽  
Author(s):  
Roland Rzehak ◽  
Eckhard Krepper
Keyword(s):  
Heat Flux ◽  
Power Systems ◽  
Nuclear Power ◽  
Volume Fraction ◽  
Flow Boiling ◽  
Working Fluid ◽  
Model Parameters ◽  
Two Phase ◽  
Radial Profiles ◽  
Wide Range

We investigate the present capabilities of CFD for wall boiling. The computational model used combines the Euler/Euler two-phase flow description with heat flux partitioning. Very similar modeling was previously applied to boiling water under high pressure conditions relevant to nuclear power systems. Similar conditions in terms of the relevant nondimensional numbers have been realized in the DEBORA tests using dichlorodifluoromethane (R12) as the working fluid. This facilitated measurements of radial profiles for gas volume fraction, gas velocity, liquid temperature, and bubble size. Robust predictive capabilities of the modeling require that it is validated for a wide range of parameters. It is known that a careful calibration of correlations used in the wall boiling model is necessary to obtain agreement with the measured data. We here consider tests under a variety of conditions concerning liquid subcooling, flow rate, and heat flux. It is investigated to which extent a set of calibrated model parameters suffices to cover at least a certain parameter range.

scholarly journals Modal Performance of Two-Fiber Orthogonal Gradient Composite Laminates Embedded with SMA

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1102 ◽  
Author(s):  
Yizhe Huang ◽  
Zhifu Zhang ◽  
Chaopeng Li ◽  
Kuanmin Mao ◽  
Qibai Huang
Keyword(s):  
Composite Laminates ◽  
Volume Fraction ◽  
Plate Theory ◽  
Single Layer ◽  
Composite Plates ◽  
Distribution Model ◽  
Fiber Volume ◽  
Two Phase ◽  
Gradient Distribution ◽  
Component Content

A gradient composite laminate that was composed of two-phase fibers, a shape memory alloy (SMA), and graphite was prepared to investigate modal performance and improve vibration behavior. The stress-strain relation of the single-layer composite plates was derived from Kirchhoff thin plate theory and the material constitutive of the SMA. A gradient distribution model and the eigenvalue equations of gradient composite laminates were developed. The influence of the fiber component content gradient distribution, pre-strain, the two-phase fiber volume fraction, and geometric parameters on the modal performance was analyzed. This study provides a method to avoid the structural resonance of composite laminates that are embedded with an SMA through the gradient distribution of two-phase fiber content that leads to the interaction of the material properties.

Modelling Cavitation and Flash Atomization

2014 ◽  
Author(s):  
Nai-Xian Lu ◽  
Julien Reveillon ◽  
Yann Meslem ◽  
François-Xavier Demoulin
Keyword(s):  
Vapour Pressure ◽  
Phase Inversion ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Pressure Effects ◽  
Superheated Liquid ◽  
Phase Flow ◽  
Two Phase ◽  
Model Based ◽  
Wide Range

Cavitation occurs in many engineering configurations such as marine propellers, liquid turbines, injectors and even flash atomization can be considered related to cavitation. Cavitation occurs when the pressure of liquid falls below the vapour pressure. As the vapour pressure depends on temperature, boiling can happen on superheated liquid. Indeed, homogeneous boiling and cavitation are similar phenomena that can be viewed either based on heat transfer or based on pressure changes, which is more linked to dynamics of the flow. Depending on the amount of produced vapour thermal effect can be considered to be negligible or preponderant to characterize the final two-phase flow. To be applicable for atomization, models of cavitation have to be considered both from pressure and thermal point of view. This is because vapour volume fraction can range from few percent to nearly hundred percent in case of phase inversion. For high level of vapour concentration the structure of two-phase flow changes drastically. Models based on isolated spherical bubbles do not represent the interaction that appears around the surface when a phase inversion occurs. The topic of this paper is therefore to discuss a model based on dense liquid-gas turbulent flows where cavitation modelling has been included in an attempt to capture both thermal and pressure effects. This model is derived from ELSA (Eulerian Lagrangian Spray Atomization) model for atomization. The whole mixture is considered globally with two species: the liquid and the gas. An equation of the amount of surface per unit volume helps to represent momentum transfer at the surface in the ELSA model. Based on this approach, modelling proposals will be presented to represent heat and mass transfer in a wide range of conditions to allow a complete description of cavitation in the context of atomization.

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