Effect of Structure on Response of a Three-Dimensional-Printed Photopolymer-Particulate Composite Under Intermediate Strain Rate Loading

2020 ◽  
Vol 87 (11) ◽  
Author(s):  
Amirreza Keyhani ◽  
Min Zhou
Keyword(s):  
Strain Rate ◽  
Mechanical Response ◽  
Local Heating ◽  
Three Dimensional ◽  
Particulate Composite ◽  
Deformation Energy ◽  
Material Behavior ◽  
Localized Deformation ◽  
Failure Initiation ◽  
Lagrangian Finite Element

Abstract The thermo-mechanical response of an additively manufactured photopolymer-particulate composite under conditions of macroscopic uniaxial compression without lateral confinement at overall strain rates of 400–2000 s−1 is studied. The material has a direct-ink-written unidirectional structure. Computations are performed to quantify the effects of microstructure attributes including anisotropy, defects, and filament size on localized deformation, energy dissipations, and temperature rises. To this effect, an experimentally informed Lagrangian finite element framework is used, accounting for finite-strain elastic–plastic deformation, strain-rate effect, failure initiation and propagation, post-failure internal contact and friction, heat generation due to friction and inelastic bulk deformation, and heat conduction. The analysis focuses on the material behavior under overall compression. Despite relatively low contribution to overall heating, friction is localized at fracture sites and plays an essential role in the development of local temperature spikes unknown as hotspots. The microstructural attributes are found to significantly affect the development of the hotspots, with local heating most pronounced when loading is transverse to the filaments or when the material has higher porosities, stronger inter-filament junctions, or smaller filament sizes. Samples with smaller filament sizes undergo more damage, exhibit higher frictional dissipation, and develop larger hotspots that occur primarily at failure sites.

scholarly journals Dynamic Behavior of Advanced Ti Alloy under Impact Loading: Experimental and Numerical Analysis

2011 ◽  
Vol 70 ◽  
pp. 207-212
Author(s):  
Murat Demiral ◽  
Anish Roy ◽  
Vadim V. Silberschmidt
Keyword(s):  
Numerical Analysis ◽  
Strain Rate ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Three Dimensional ◽  
Element Model ◽  
Industrial Applications ◽  
Material Behavior ◽  
Hopkinson Pressure Bar ◽  
Strain And Strain Rate

Industrial applications of Ti-based alloys, especially in aerospace, marine and offshore industries, have grown significantly over the years primarily due to their high strength, light weight as well as good fatigue and corrosion-resistance properties. A combination of experimental and numerical studies is necessary to predict a material behavior of such alloys under high strain-rate conditions characterized also by a high level of strains accompanied by high temperatures. A Split Hopkinson Pressure Bar (SHPB) technique is a commonly used experimental method to characterize a dynamic stress-strain response of materials at high strain rates. In a SHPB test, the striker bar is shot against the free end of the incident stress bar, which on impact generates a stress pulse propagating in the incident bar towards the specimen sandwiched between the incident and transmitted bars. An experimental study and a numerical analysis based on a three-dimensional finite element model of the SHPB experiment are performed in this study to assess various features of the underlying mechanics of deformation processes of the alloy tested at high-strain and -strain-rate regimes.

scholarly journals A Lattice Model for Elastic Particulate Composites

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1584 ◽  
Author(s):  
Darius Zabulionis ◽  
Vytautas Rimša
Keyword(s):  
Mechanical Response ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Particulate Composite ◽  
High Volume ◽  
Spherical Particles ◽  
Particulate Composites ◽  
The Finite Element Method ◽  
Network Method

In the present article, a version of the lattice or spring network method is proposed to model the mechanical response of elastic particulate composites with a high volume fraction of spherical particles and with a much weaker matrix compared to the stiffness of the particles. The main subject of the article is the determination of the axial stiffnesses of the springs of the cell. A comparison of the mechanical response of a three-dimensional particulate composite cube obtained using the finite element method and the proposed methodology showed that the efficiency of the proposed methodology increases with an increasing volume fraction of the particles.

On the Microstructural Characteristics of UFG Microalloyed Steel Influencing the Mechanical Behavior under Dynamic Loading

2018 ◽  
Vol 941 ◽  
pp. 39-45 ◽  
Author(s):  
Janusz Majta ◽  
Remigiusz Bloniarz ◽  
Marcin Kwiecień ◽  
Krzysztof Muszka
Keyword(s):  
Strain Rate ◽  
Mechanical Behavior ◽  
Dynamic Loading ◽  
Work Hardening ◽  
Mechanical Response ◽  
Thermomechanical Processing ◽  
Microalloyed Steel ◽  
Material Behavior ◽  
Second Phase ◽  
Loading Conditions

This paper presents a summary of a preliminary research aimed at producing ultrafine-grained (UFG) and heterogeneous microstructure in microalloyed steel and testing these materials under dynamic loading conditions (strain rates 800 s-1 and 1800s-1). The UFG and bimodal-structures, due to grain size, structural composition or morphology of structural components, were produced by an advanced thermomechanical processing, namely rolling in: hot, two-phase and cold-hot combined conditions. The advantage of bimodal microstructures is their maximization of mechanical behavior under extreme loading conditions due to promoted accumulation and interactions of geometrically necessary dislocations. The dynamic work-hardening behavior has been studied as a function of solute atoms and fine-scale, second-phase particles in the UFG and bimodal-structures. The substantial complexity of the phenomena, which occur through the evolution of microstructure and texture in response to dynamic loading, presents formidable challenges to theoretical model development of plastic deformation of UFG and bimodal-structures. Such an extraordinary work hardening provides an attractive strategy to develop optimal combination of mechanical properties i.e. strength/ductility ratio. A multi-scale analysis capable of including material behavior in different scales should be applied to discuss mechanical response of mentioned above microstructures and to help to analyze their influence on mechanical behavior under dynamic loading. The investigation was performed for a material of common application: high strength microalloyed steel X70. The experimental results show that strain rate sensitivity of the heterogeneous microstructures obtained by various thermomechanical rolling routes are significant, but not by a similar magnitude with the microstructure compositions and increasing strain rate.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

scholarly journals Understanding the Strain Path Effect on the Deformed Microstructure of Single Crystal Pure Aluminum

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1189
Author(s):  
Yingjue Xiong ◽  
Qinmeng Luan ◽  
Kailun Zheng ◽  
Wei Wang ◽  
Jun Jiang
Keyword(s):  
Strain Rate ◽  
Single Crystal ◽  
Strain Path ◽  
Mechanical Response ◽  
Pure Aluminum ◽  
Lattice Rotation ◽  
Softening Behavior ◽  
Theoretical Support ◽  
Commercial Applications ◽  
Electron Back Scattered Diffraction

During plastic deformation, the change of structural states is known to be complicated and indeterminate, even in single crystals. This contributes to some enduring problems like the prediction of deformed texture and the commercial applications of such material. In this work, plane strain compression (PSC) tests were designed and implemented on single crystal pure aluminum to reveal the deformation mechanism. PSC tests were performed at different strain rates under strain control in either one-directional or two-directional compression. The deformed microstructures were analyzed according to the flow curve and the electron back-scattered diffraction (EBSD) mappings. The effects of grain orientation, strain rate, and strain path on the deformation and mechanical response were analyzed. Experimental results revealed that the degree of lattice rotation of one-dimensional compression mildly dependents on cube orientation, but it is profoundly sensitive to the strain rate. For two-dimensional compression, the softening behavior is found to be more pronounced in the case that provides greater dislocations gliding freeness in the first loading. Results presented in this work give new insights into aluminum deformation, which provides theoretical support for forming and manufacturing of aluminum.

scholarly journals High-strain-rate mechanical response of HTPE propellant under SHPB impact loading

AIP Advances ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 035145
Author(s):  
Heng-ning Zhang ◽  
Hai Chang ◽  
Jun-qiang Li ◽  
Xiao-jiang Li ◽  
Han Wang
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Impact Loading ◽  
Mechanical Response ◽  
High Strain

scholarly journals Visualization of the Strain-Rate State of a Data Cloud: Analysis of the Temporal Change of an Urban Multivariate Description

2019 ◽  
Vol 9 (14) ◽  
pp. 2920
Author(s):  
Lorena Salazar-Llano ◽  
Camilo Bayona-Roa
Keyword(s):  
Strain Rate ◽  
Temporal Change ◽  
Three Dimensional ◽  
Urban System ◽  
Deformation Pattern ◽  
Analysis Methodology ◽  
Global Deformation ◽  
Temporal Rate ◽  
Cloud Of Points ◽  
Entire Dataset

One challenging problem is the representation of three-dimensional datasets that vary with time. These datasets can be thought of as a cloud of points that gradually deforms. However, point-wise variations lack information about the overall deformation pattern, and, more importantly, about the extreme deformation locations inside the cloud. This present article applies a technique in computational mechanics to derive the strain-rate state of a time-dependent and three-dimensional data distribution, by which one can characterize its main trends of shift. Indeed, the tensorial analysis methodology is able to determine the global deformation rates in the entire dataset. With the use of this technique, one can characterize the significant fluctuations in a reduced multivariate description of an urban system and identify the possible causes of those changes: calculating the strain-rate state of a PCA-based multivariate description of an urban system, we are able to describe the clustering and divergence patterns between the districts of a city and to characterize the temporal rate in which those variations happen.

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