Inertial Effects on Void Growth in Porous Viscoplastic Materials

The present work examines the inertial effects on void growth in viscoplastic materials which have been largely neglected in analyses of dynamic crack growth and spallation phenomena using existing continuum porous material models. The dynamic void growth in porous materials is investigated by analyzing the finite deformation of an elastic/viscoplastic spherical shell under intense hydrostatic tensile loading. Under typical dynamic loading conditions, inertia is found to have a strong stabilizing effect on void growth process and consequently to delay coalescence even when the high rate-sensitivity of materials at very high strain rates is taken into account. Effects of strain hardening and thermal softening are found to be relatively small. Approximate relations are suggested to incorporate inertial effects and rate sensitivity of matrix materials into the porous viscoplastic material constitutive models for dynamic ductile fracture analyses for certain loading conditions.

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A viscoplastic model for void growth under dynamic loading conditions

AIP Advances ◽

10.1063/1.5130056 ◽

2019 ◽

Vol 9 (12) ◽

pp. 125119

Author(s):

Fu-Qi Zhao ◽

Hao Pan ◽

Feng-Guo Zhang ◽

Jing-Xing Liu

Keyword(s):

Dynamic Loading ◽

Void Growth ◽

Loading Conditions ◽

Viscoplastic Model ◽

Dynamic Loading Conditions

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Dynamic Crack Growth in a Power Hardening Viscoplastic Material

Journal of Engineering Materials and Technology ◽

10.1115/1.2904314 ◽

1994 ◽

Vol 116 (4) ◽

pp. 465-470 ◽

Cited By ~ 3

Author(s):

Vijay B. Shenoy ◽

R. Krishna Kumar

Keyword(s):

Fracture Toughness ◽

Crack Growth ◽

Plastic Material ◽

Dynamic Stress Intensity Factor ◽

High Rate ◽

Small Scale ◽

Dynamic Crack ◽

Viscoplastic Material ◽

Element Analysis ◽

Dynamic Crack Growth

In this paper a finite element analysis of steady-state dynamic crack growth under mode I plane strain small scale yielding conditions has been performed in a power law hardening rate dependent plastic material, characterized by the Perzyna over stress model. A modified version of the rate tangent modulus method has been used to update the stress. The main objective of the work is to obtain a quantitative relationship between dynamic fracture toughness ratio (K/Kss) and crack speed. A plastic strain criteria proposed by McClintock (1968) has been applied to obtain this relationship. It is found that dynamic stress intensity factor increases with velocity for all values of βˆ (a normalized viscosity parameter). At a low value of βˆ, which corresponds to high rate sensitivity, the fracture toughness ratio (K/Kss) increases with hardening. On the other hand, at a higher βˆ, the ratio increases initially and falls subsequently, with increasing hardening.

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Prediction of Crack Propagation under Dynamic Loading Conditions by Using the Enhanced Point Collocation Meshfree Method

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.324-325.1059 ◽

2006 ◽

Vol 324-325 ◽

pp. 1059-1062

Author(s):

Hyo Jin Kim ◽

Sang Ho Lee ◽

Moon Kyum Kim

Keyword(s):

Crack Propagation ◽

Dynamic Loading ◽

Meshfree Method ◽

Dynamic Loads ◽

Dynamic Crack Propagation ◽

Dynamic Crack ◽

Loading Conditions ◽

Point Collocation ◽

Dynamic Loading Conditions ◽

Numerical Program

An efficient and accurate numerical program with enhanced point collocation meshfree method is developed to simulate crack propagation under dynamic loading conditions. The enhanced meshfree method with point collocation formulation and derivative approximation in solids is presented. This study also presents the crack propagation criterion and computation of propagating direction, and the total structure of the numerical program named PCMDYC(Point Collocation Meshfree method for DYnamic Crack propagation). Several examples of crack propagation under dynamic loads are analyzed to simulate the arbitrary crack propagation under dynamic loads. The results show that PCMDYC predicts the propagating path of crack under dynamic loading conditions accurately and robustly.

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Dynamic Crack Initiation And Growth In Cellulose Nanopaper

10.21203/rs.3.rs-600089/v1 ◽

2021 ◽

Author(s):

Chengyun Miao ◽

Haishun Du ◽

Xinyu Zhang ◽

Hareesh Tippur

Keyword(s):

Crack Initiation ◽

Crack Growth ◽

Dynamic Loading ◽

Image Correlation ◽

Thin Strip ◽

Dynamic Crack ◽

Loading Conditions ◽

Structural Applications ◽

Cellulose Nanopaper ◽

Dynamic Loading Conditions

Abstract Cellulose nanopaper (CNP) made of cellulose nanofibrils (CNF) has gained extensive attention in recent years for its lightweight and superior mechanical properties alongside sustainable and green attributes. The mechanical characterization studies on CNP at the moment have generally been limited to tension tests. In fact, thus far there has not been any report on crack initiation and growth behavior, especially under dynamic loading conditions. In this work, crack initiation and growth in self-assembled CNP, made from filtration of CNF suspension, are studied using a full-field optical method. Dynamic crack initiation and growth behaviors and time-resolved fracture parameters are quantified using Digital Image Correlation (DIC) technique. The challenge associated with dynamic loading of a thin strip of CNP has been overcome by an acrylic holder with a wide pre-cut slot bridged by edge-cracked CNP. The ultrahigh-speed digital photography is implemented to map in-plane deformations during pre- and post-crack initiation regimes including dynamic crack growth. Under stress wave loading conditions, macroscale crack growth occurs at surprisingly high-speed (600-700 m/s) in this microscopically fibrous material. The measured displacement fields from dynamic loading conditions are analyzed to extract stress intensity factors (SIF) and energy release rate (G) histories. The results show that the SIF at crack initiation is in the range of 6-7 MPa(m)1/2, far superior to many engineering plastics. Furthermore, the measured values increase during crack propagation under both low- and high-strain rates, demonstrating superior fracture resistance of CNP valuable for many structural applications.

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ON A VERY HIGH RATE SENSITIVITY OF CONCRETE FAILURE AT HIGH LOADING RATES AND IMPACT

Brittle Matrix Composites 7 ◽

10.1533/9780857093103.1 ◽

2003 ◽

pp. 1-27 ◽

Cited By ~ 1

Author(s):

Janusz R. KLEPACZKO

Keyword(s):

Rate Sensitivity ◽

High Rate ◽

High Loading ◽

Loading Rates ◽

Concrete Failure ◽

Very High

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The Distinct Elemental Analysis of the Microstructural Evolution of a Methane Hydrate Specimen under Cyclic Loading Conditions

Energies ◽

10.3390/en12193694 ◽

2019 ◽

Vol 12 (19) ◽

pp. 3694 ◽

Cited By ~ 1

Author(s):

Dong Wang ◽

Bin Gong ◽

Yujing Jiang

Keyword(s):

Cyclic Loading ◽

Methane Hydrate ◽

Mechanical Response ◽

Distinct Element ◽

Constitutive Models ◽

Slope Instability ◽

Loading Conditions ◽

Shear Process ◽

Hydrate Saturation ◽

Dynamic Loading Conditions

Submarine slope instability may be triggered by earthquakes and tsunamis. Methane hydrate sediments (MHS) are commonly buried under submarine slopes. Submarine slides would probably be triggered once the MHS are damaged under cyclic loading conditions. For this reason, it is essential to research the mechanical response of MHSs under dynamic loading conditions. In this study, a series of drained cyclic biaxial compressive tests with constant stress amplitudes were numerically carried out with the distinct element method (DEM). The cyclic loading number decreased as the hydrate saturation (Sh) increased when the MHS were damaged. The failure mode of the MHS was shown to be dependent on the dynamic stress amplitude and hydrate saturation. The microstructure of MHS during the cyclic loading shear process was also analyzed. The results can help us to understand the mechanical behavior of MHS during the cyclic loading process and develop micromechanical-based constitutive models.

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Tensile and Fracture Characterization of PETI-5 and IM7/PETI-5 Graphite/Epoxy Composites Under Quasi-Static and Dynamic Loading Conditions

Journal of Engineering Materials and Technology ◽

10.1115/1.4003487 ◽

2011 ◽

Vol 133 (2) ◽

Cited By ~ 8

Author(s):

Dongyeon Lee ◽

Hareesh V. Tippur ◽

Brian J. Jensen ◽

Philip B. Bogert

Keyword(s):

Dynamic Loading ◽

Dynamic Fracture ◽

Fracture Behavior ◽

Matrix Material ◽

Image Correlation ◽

Dynamic Crack ◽

Loading Conditions ◽

Fiber Reinforced ◽

Dynamic Loading Conditions ◽

Static And Dynamic Loading

Tensile and fracture responses of the phenylethynyl terminated imide oligomer (PETI-5) are studied. Since this polymer is a candidate aerospace structural adhesive as well as a matrix material in composite systems, neat as well as fiber reinforced forms of PETI-5 are studied under static and dynamic loading conditions. A split-Hopkinson tension bar apparatus is used for performing tensile tests on dogbone specimens. The dynamic fracture tests are carried out using a drop tower in conjunction with 2D image correlation method and high-speed digital photography on edge cracked specimens in three-point bend configuration. A toughened neat epoxy system, Hexcel 3900, is also studied to provide a baseline comparison for neat PETI-5 system. The tensile stress-strain responses show PETI-5 to have excellent mechanical characteristics under quasi-static and dynamic loading conditions when compared with 3900. Fracture behavior of PETI-5 under quasi-static and impact loading conditions also shows superiority relative to 3900. The dynamic fracture behavior of a PETI-5 based graphite fiber reinforced composite, IM7/PETI-5, is also studied and the results are comparatively evaluated relative to the ones corresponding to a more common aerospace composite system, T800/3900-2 graphite/epoxy. Once again, the IM7/PETI-5 system shows excellent fracture performance in terms of dynamic crack initiation and growth behaviors.

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The Mechanics of Superplastic Forming - How to Incorporate and Model Superplastic and Superplastic-Like Conditions

Materials Science Forum ◽

10.4028/www.scientific.net/msf.838-839.468 ◽

2016 ◽

Vol 838-839 ◽

pp. 468-475 ◽

Cited By ~ 3

Author(s):

Olga I. Bylya ◽

R.A. Vasin ◽

Paul L. Blackwell

Keyword(s):

Phase Distribution ◽

Constitutive Models ◽

Grain Morphology ◽

Rate Sensitivity ◽

Superplastic Forming ◽

Point Of View ◽

High Rate ◽

Key Factor ◽

Accumulation Of Damage ◽

Deformation Modes

Much work has been carried out in understanding the mechanics of superplasticity (SP). Some of the present challenges in SP forming revolve around the use of lower forming temperatures and faster strain rates, which may involve pushing the process boundaries to incorporate “superplastic-like” forming – perhaps also in materials with non-optimized microstructures. For process optimization there is a requirement to be able to model both within the SP and superplastic-like processing window in an integrated way. From a mechanics point of view the presence of high rate sensitivity is often seen as the key factor in controlling SP response. However, changes in phase distribution and grain morphology, or the accumulation of damage (cavitation) may compromise this assumption. The paper will examine the range of validity of some SP constitutive models and how they may be adapted to take into account processing routes that may incorporate superplastic-like and more conventional SP deformation modes.

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