Compressive Failure of Fiber Composites: The Roles of Multiaxial Loading and Creep

1993 ◽  
Vol 115 (3) ◽  
pp. 308-313 ◽  
Author(s):  
W. S. Slaughter ◽  
N. A. Fleck ◽  
B. Budiansky
Keyword(s):  
Strain Hardening ◽  
Failure Surface ◽  
Kink Band ◽  
Fiber Composites ◽  
Analytical Models ◽  
Fiber Direction ◽  
Multiaxial Loading ◽  
Compressive Failure ◽  
Perfectly Plastic ◽  
Remote Stress

The roles of multiaxial loading and creep in compressive failure of aligned fiber composites are considered. Analytical models are developed based on the model given by Budiansky and Fleck (1992). The critical microbuckling stress in multiaxial loading is calculated for a rigid-perfectly plastic solid and an elastic-plastic strain hardening solid. The rigid-perfectly plastic results predict a plane compressive failure surface in stress space. The rigid-perfectly plastic results are sufficiently accurate, when compared to the strain hardening results, so long as the remote shear stress and stress normal to the fiber direction are not too large relative to the remote stress in the fiber direction. The model given for creep microbuckling is suitable for power law viscous composite behavior. Deformation within a localized kink band is computed as a function of time. A creep life is predicted, based on a critical strain failure criterion.

scholarly journals Preliminary observations of brittle compressive failure of columnar saline ice under triaxial loading

1994 ◽  
Vol 19 ◽  
pp. 33-38 ◽  
Author(s):  
E. T. Gratz ◽  
E. M. Schulson
Keyword(s):  
Principal Stress ◽  
Failure Mechanisms ◽  
Failure Surface ◽  
Maximum Principal Stress ◽  
Failure Stress ◽  
Multiaxial Loading ◽  
Compressive Failure ◽  
Confining Stress ◽  
Loading System ◽  
Columnar Grains

Experiments were performed on columnar saline ice prepared in the laboratory. Specifically, using a true multiaxial loading system, relatively large cubes (159 mm on edge) were proportionally loaded along three orthogonal directions; viz. perpendicular to (σ13and σ22) and parallel to (σ33), the long axis of the columnar grains. The ice was strained at 10−2s at −10°C where it behaved in a brittle mariner. Four sets of experiments were performed by setting the ratio σ22/σ11to 0, 0.25, 0.5 or 1, and varying the ratio σ22/σ11and σ22/σ11. Sections through the failure surface were then constructed. For loading along σ22= 0, the confining stress did not significantly affect the maximum principal stress at failure. For loading along σ22=0.25σ11, σ22 = 0.5 σ11and σ22 = 0.5 σ11, the application of a moderate confining stress resulted in a large increase in failure stress. However, further increase in the level of the confining stress did not have a significant effect on the failure stress. The observations are presented in terms of a failure surface and are discussed in terms of the possible failure mechanisms.

scholarly journals Preliminary observations of brittle compressive failure of columnar saline ice under triaxial loading

1994 ◽  
Vol 19 ◽  
pp. 33-38
Author(s):  
E. T. Gratz ◽  
E. M. Schulson
Keyword(s):  
Principal Stress ◽  
Failure Mechanisms ◽  
Failure Surface ◽  
Maximum Principal Stress ◽  
Failure Stress ◽  
Multiaxial Loading ◽  
Compressive Failure ◽  
Confining Stress ◽  
Loading System ◽  
Columnar Grains

Experiments were performed on columnar saline ice prepared in the laboratory. Specifically, using a true multiaxial loading system, relatively large cubes (159 mm on edge) were proportionally loaded along three orthogonal directions; viz. perpendicular to (σ13 and σ22) and parallel to (σ33), the long axis of the columnar grains. The ice was strained at 10−2 s at −10°C where it behaved in a brittle mariner. Four sets of experiments were performed by setting the ratio σ22/σ11 to 0, 0.25, 0.5 or 1, and varying the ratio σ22/σ11 and σ22/σ11. Sections through the failure surface were then constructed. For loading along σ22 = 0, the confining stress did not significantly affect the maximum principal stress at failure. For loading along σ22 =0.25σ11, σ22 = 0.5 σ11 and σ22 = 0.5 σ11, the application of a moderate confining stress resulted in a large increase in failure stress. However, further increase in the level of the confining stress did not have a significant effect on the failure stress. The observations are presented in terms of a failure surface and are discussed in terms of the possible failure mechanisms.

Dynamic Behavior of Fiber Reinforced Composites Under Multiaxial Compression

1999 ◽  
Author(s):  
Kenji Oguni ◽  
G. Ravichandran
Keyword(s):  
Failure Mode ◽  
Kink Band ◽  
Fiber Reinforced Composites ◽  
Fiber Direction ◽  
Strain Rates ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Band Formation ◽  
Multiaxial Compression ◽  
Axial Splitting

Abstract Results from an experimental investigation on the mechanical behavior of a unidirectional reinforced polymer composite with 50% volume fraction E-glass/vinylester under uniaxial and proportional multiaxial compression are presented. Specimens are loaded in the fiber direction using a servo-hydraulic material testing system for low strain rates and a Kolsky (split Hopkinson) pressure bar for high strain rates, up to 3000 s−1. The results indicate that the compressive strength of the composite increases with increasing levels of confinement and increasing strain rates. Post-test optical and scanning electron microscopy is used to identify the failure modes. The failure mode that is observed in unconfined specimen is axial splitting followed by fiber kink band formation. At high levels of confinement, the failure mode transitions from axial splitting to kink band formation and fiber failure. Also, a new energy based analytic model for studying axial splitting phenomenon in unidirectional fiber-reinforced composites is presented.

Evaluation of Creep Constitutive Equations for Type 304 Stainless Steel Under Repeated Multiaxial Loading

1982 ◽  
Vol 104 (3) ◽  
pp. 159-164 ◽  
Author(s):  
Y. Ohashi ◽  
N. Ohno ◽  
M. Kawai
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
Strain Hardening ◽  
Deviatoric Stress ◽  
304 Stainless Steel ◽  
Multiaxial Loading ◽  
Mixed Hardening ◽  
Principal Axes ◽  
Type 304 ◽  
Type 304 Stainless Steel

Four kinds of creep constitutive models, i.e., strain-hardening, modified strain-hardening, kinematic-hardening, and mixed-hardening theory, are evaluated on the basis of creep-test results on type 304 stainless steel at 650°C under repeated multiaxial loading. The predictions of the four models are compared with the experimental results. It is shown that substantial differences appear among these predictions under large rotations of the principal axes of the deviatoric stress tensor, and that none of them can describe with sufficient accuracy the transient increase of strain-rate and the noncollinearity between the deviatoric stress and creep strain-rate vectors which are observed just after the stress-rotations.

Investigation of the axial compressive behavior of Kevlar fibers using the dynamic loop test

2019 ◽  
Vol 89 (18) ◽  
pp. 3825-3838
Author(s):  
Ahmad Abuobaid ◽  
Raja Ganesh ◽  
John W Gillespie
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Failure Strain ◽  
Kink Band ◽  
Test Method ◽  
Strain Rates ◽  
Compressive Failure ◽  
Band Formation ◽  
Rate Dependent ◽  
Strain And Strain Rate

A dynamic loop test method for measuring strain rate-dependent fiber properties was developed. During dynamic loop testing, the fiber ends are accelerated at constant levels of 20.8, 50 and 343 m/s2. The test method is used to study Kevlar® KM2-600, which fails in axial compression due to kink band formation. The compressive failure strain and strain rate at the onset of kink band formation is calculated from the critical loop diameter ( D C), which is monitored throughout the test using a high-speed camera. The results showed that compressive failure strain increases with strain rates from quasi-static to a maximum strain rate of 116 s−1 by a factor of ∼3. Kink angles (φ) and kink band spacing ( D S) were 60 ° ± 2 ° and 16 ± 3 μm, respectively, over the strain rates tested. Rate-dependent mechanisms of compressive failure by kink band formation were discussed.

Subsurface Deformation in Surface Mechanical Attrition Processes

2015 ◽  
Author(s):  
Zhiyu Wang ◽  
Saurabh Basu ◽  
Christopher Saldana
Keyword(s):  
Strain Hardening ◽  
Model Material ◽  
Process Models ◽  
Image Correlation ◽  
Analytical Models ◽  
Subsurface Deformation ◽  
Multi Stage ◽  
Mechanical Attrition ◽  
Dead Metal Zone ◽  
Plane Strain Deformation

A modified expanding cavity model (M-ECM) is developed to describe subsurface deformation for strain-hardening materials loaded in unit deformation configurations occurring in surface mechanical attrition. The predictive results of this model are validated by comparison with unit deformation experiments in a model material, oxygen free high conductivity copper, using a custom designed plane strain deformation setup. Subsurface displacement and strain fields are characterized using in-situ digital image correlation. It is shown that conventional analytical models used to describe plastic response in strain-hardening metals are not able to predict important characteristics of the morphology of the plastic zone, including evolution of the dead metal zone (DMZ), especially at large plastic depths. The M-ECM developed in the present study provides an accurate prediction of the strain distribution obtained in experiment and is of utility as a component in multi-stage process models of the final surface state in surface mechanical attrition.

Shear in Flexure of Fiber Composites with Different End Supports

2003 ◽  
Vol 82 (4) ◽  
pp. 262-266 ◽  
Author(s):  
K.A. Eckrote ◽  
C.J. Burstone ◽  
M.A. Freilich ◽  
G.E. Messer ◽  
A.J. Goldberg
Keyword(s):  
Flexural Rigidity ◽  
Fiber Composites ◽  
Experimental Results ◽  
Analytical Models ◽  
Beam Deflection ◽  
Fiber Reinforced Composite ◽  
Simply Supported ◽  
Aspect Ratios ◽  
Reinforced Composite ◽  
D Values

The integrity of fiber-reinforced composite (FRC) prostheses is dependent, in part, on flexural rigidity. The object of this study was to determine if the flexure behavior of uniform FRC beams with restrained or simply supported ends and various length/depth (L/d) aspect ratios could be more accurately modeled by correcting for shear. Experimental results were compared with three analytical models. All models were accurate at high L/d ratios, but the shear-corrected model was accurate to the lowest, more clinically relevant, L/d values. In this range, more than 40% of the beam deflection was due to shear.

Effects of Strain Hardening on Rock / Bit-Tooth Interaction

1979 ◽  
Vol 101 (1) ◽  
pp. 53-58
Author(s):  
R. B. Pan ◽  
J. B. Cheatham
Keyword(s):  
Pressure Distribution ◽  
Strain Hardening ◽  
Slip Line ◽  
Confining Pressure ◽  
Line Field ◽  
Slip Line Field ◽  
Perfectly Plastic ◽  
High Confining Pressure ◽  
Rock Bit ◽  
Interaction Problem

The rock/bit-tooth interaction problem has been approximated previously by plasticity analysis of a wedge indenting a half-space. In the previous work the rock, under high confining pressure, was assumed to be perfectly plastic. In the present paper, an approximate method is presented for including the effects of strain hardening of the rock on the pressure distribution at the rock bit-tooth interface. The slip-line field for the perfectly plastic solution is used as a basis for applying corrections for the strain-hardening effect.

A General Autofrettage Model of a Thick-Walled Cylinder Based on Tensile-Compressive Stress-Strain Curve of a Material

2005 ◽  
Vol 40 (6) ◽  
pp. 599-607 ◽  
Author(s):  
X. P Huang
Keyword(s):  
Strain Hardening ◽  
Compressive Stress ◽  
Bauschinger Effect ◽  
Strain Curve ◽  
Accurate Prediction ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Perfectly Plastic ◽  
Hardening Models ◽  
Elastic Perfectly Plastic

The basic autofrettage theory assumes elastic-perfectly plastic behaviour. Because of the Bauschinger effect and strain-hardening, most materials do not display elastic-perfectly plastic properties and consequently various autofrettage models are based on different simplified material strain-hardening models, which assume linear strain-hardening or power strain-hardening or a combination of these strain-hardening models. This approach gives a more accurate prediction than the elastic-perfectly plastic model and is suitable for different strain-hardening materials. In this paper, a general autofrettage model that incorporates the material strain-hardening relationship and the Bauschinger effect, based upon the actual tensile-compressive stress-strain curve of a material is proposed. The model incorporates the von Mises yield criterion, an incompressible material, and the plane strain condition. Analytic expressions for the residual stress distribution have been derived. Experimental results show that the present model has a stronger curve-fitting ability and gives a more accurate prediction. Several other models are shown to be special cases of the general model presented in this paper. The parameters needed in the model are determined by fitting the actual tensile-compressive curve of the material, and the maximum strain of this curve should closely represent the maximum equivalent strain at the inner surface of the cylinder under maximum autofrettage pressure.

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