scholarly journals Evaluation of Strain Rate Dependent Tensile Fracture Behavior of CFRP with High-speed Imaging and DIC

2015 ◽  
Vol 35 (138) ◽  
pp. 26-31
Author(s):  
Yoshiyasu HIRANO
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Fracture Behavior ◽  
Tensile Fracture ◽  
High Speed Imaging ◽  
Rate Dependent

High-speed tensile fractures in granite and gneiss: an experimental study

2021 ◽  
Author(s):  
Beno J Jacob ◽  
Santanu Misra ◽  
Venkitanarayanan Parameswaran ◽  
Nibir Mandal
Keyword(s):  
Aspect Ratio ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Speed ◽  
High Strain ◽  
Tensile Fracture ◽  
High Speed Photography ◽  
Fracture Networks ◽  
Compression Direction ◽  
Tensile Fractures

<p>Tensile fractures are ubiquitous in impact structures formed because of high strain rate deformations of the earth’s crust. At regions far from the point of meteorite impact, intense rupturing, fragmentation, and pulverisation are an implication of pressure waves limiting at the tensile strength of the host rock with little influence of shock deformation or shear failure. The branching and anastomosing of the fractures are controlled by the local stress state and anisotropy. Thus, a network of infilled fractures or impact breccia dikes is a common feature in the subsurface of impact sites.</p><p>We have investigated the failure processes under high strain rates responsible for the formation of Mode-I breccia dikes, at the laboratory scale. The control of planar fabric structures in the development of anastomosing tensile fracture networks was studied through high-strain-rate Brazilian disc tests on gneiss (foliated) and granite (isotropic) samples. A Split Hopkinson Pressure Bar, equipped with high-speed photography (~10<sup>5</sup> fps), was employed in the study. The gneissic foliation in the gneiss samples were oriented at θ = 0, 45 and 90° to the compression direction. The strength of granite lies between 24 and 26 MPa, and the gneisses failed in the range of 29-37MPa at about 70-90 μs. The fracture network formation was seen in the time series images. There is a stark disparity in the nature of failure of granite from gneiss and the geometry of clasts formed in each rock type. While granite samples fail with pulverised clasts localised along a single fracture spanning the diameter of the sample along the compression direction, the gneisses further developed a network of secondary fractures forming large elongate clasts. Preferential orientation of secondary crack growth in relation to the foliation is strongly influenced by <em>θ</em> in gneiss samples. The aspect ratio of the pulverised clasts (size < 10mm) formed in granite was about 1:2, whereas the gneisses produced larger clasts. The clasts in gneisses had an aspect ratio of 1:4 for <em>θ</em> = 45 and 90º, and 1:5 for <em>θ</em> = 0º.</p><p>The branching and anastomosing nature of fractures is similar in fracture networks observed from the field and in the experiments, thus providing an insight into the formation of high-speed impact breccia dikes in isotropic and foliated rocks. Our experiments demonstrate that monomict breccia dikes may by formed <em>in situ</em> inclusive of clasts, rather than by infilling in previously formed tensile fractures.</p>

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.

Dynamic Mechanical Behavior of Two Fiber-Reinforced Composites

2012 ◽  
Vol 525-526 ◽  
pp. 261-264
Author(s):  
Y.Z. Guo ◽  
X. Chen ◽  
Xi Yun Wang ◽  
S.G. Tan ◽  
Z. Zeng ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Rate Dependent ◽  
Dynamic Loadings ◽  
Axial Splitting

The mechanical behavior of two composites, i.e., CF3031/QY8911 (CQ, hereafter in this paper) and EW100A/BA9916 (EB, hereafter in this paper), under dynamic loadings were carefully studied by using split Hopkinson pressure bar (SHPB) system. The results show that compressive strength of CQ increases with increasing strain-rates, while for EB the compressive strength at strain-rate 1500/s is lower then that at 800/s or 400/s. More interestingly, most of the stress strain curves of both of the two composites are not monotonous but exhibit double-peak shape. To identify this unusual phenominon, a high speed photographic system is introduced. The deformation as well as fracture characteristics of the composites under dynamic loadings were captured. The photoes indicate that two different failure mechanisms work during dynamic fracture process. The first one is axial splitting between the fiber and the matrix and the second one is overall shear. The interficial strength between the fiber and matrix, which is also strain rate dependent, determines the fracture modes and the shape of the stress/strain curves.

Response and failure of fiber metal laminates subjected to high strain rate tensile loading

2018 ◽  
Vol 53 (11) ◽  
pp. 1489-1506 ◽  
Author(s):  
Ankush P Sharma ◽  
Sanan H Khan ◽  
Venkitanarayanan Parameswaran
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Glass Fiber ◽  
High Speed ◽  
High Strain ◽  
Image Correlation ◽  
Fiber Metal Laminates ◽  
Rate Dependent ◽  
Dependent Behavior ◽  
Fiber Metal

The tensile behavior of fiber metal laminates consisting of layers of aluminum 2024-T3 alloy and glass fiber reinforced composites under high strain rate loading is investigated. Fiber metal laminates having four different layups, but all having the same total metal layer thickness, were fabricated using a combined hand lay-up cum vacuum bagging method. The fiber metal laminate specimens were loaded in high strain rate tension using a split Hopkinson tensile bar. The rate-dependent behavior of the glass fiber composite was also obtained as baseline data. The strain on the gage area of the specimen was measured directly using high-speed digital image correlation. Another high-speed camera was used to capture the sequence of damage by viewing the specimen edgewise. The results indicated that the strength of the fiber metal laminates increased at high strain rates primarily due to the rate-dependent behavior of the composite used. The response was also influenced by the distribution of the metallic layers in the fiber metal laminates. The failure in the case where the individual composite layers were separated by metallic layers was more progressive in nature.

High speed imaging for material parameters calibration at high strain rate

2015 ◽  
Vol 225 (2) ◽  
pp. 295-309 ◽  
Author(s):  
M. Sasso ◽  
M. Fardmoshiri ◽  
E. Mancini ◽  
M. Rossi ◽  
L. Cortese
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Speed ◽  
High Strain ◽  
High Speed Imaging ◽  
Material Parameters

Temperature and Strain Rate Dependent Simulation of High Speed Tensile Tests of I-PP

2005 ◽  
Vol 25 (5) ◽  
Author(s):  
M. Keuerleber ◽  
N. Woicke ◽  
S.R. Raisch ◽  
P. Eyerer
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Tensile Tests ◽  
Rate Dependent

Large Strain, High Strain Rate Testing of Copper

1980 ◽  
Vol 102 (4) ◽  
pp. 376-381 ◽  
Author(s):  
U. S. Lindholm ◽  
A. Nagy ◽  
G. R. Johnson ◽  
J. M. Hoegfeldt
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Large Strain ◽  
Shear Banding ◽  
Testing Machine ◽  
Shear Instability ◽  
Large Strains ◽  
Rate Dependent ◽  
Torsional Testing ◽  
Strain Hardening Behavior

This paper describes the development of a high-speed torsional testing machine and results obtained on the strain-rate dependent strength of copper at large shear strains. Test techniques and data obtained are intended to be useful in applications such as ballistics and machining. For copper, the results indicate positive strain hardening behavior to very large strains under low rate, isothermal conditions and the transition to adiabatic thermal softening, shear instability and localization (shear banding) at high rates.

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