scholarly journals Mechanical Response of Porcine Liver Tissue under High Strain Rate Compression

2019 ◽  
Vol 6 (2) ◽  
pp. 49 ◽  
Author(s):  
Joseph Chen ◽  
Sourav S. Patnaik ◽  
R. K. Prabhu ◽  
Lauren B. Priddy ◽  
Jean-Luc Bouvard ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Liver Tissue ◽  
High Strain ◽  
Material Behavior ◽  
Stress Profile ◽  
Strain Rates ◽  
High Strain Rates ◽  
Porcine Liver ◽  
Strain Rate Compression

In automobile accidents, abdominal injuries are often life-threatening yet not apparent at the time of initial injury. The liver is the most commonly injured abdominal organ from this type of trauma. In contrast to current safety tests involving crash dummies, a more detailed, efficient approach to predict the risk of human injuries is computational modelling and simulations. Further, the development of accurate computational human models requires knowledge of the mechanical properties of tissues in various stress states, especially in high-impact scenarios. In this study, a polymeric split-Hopkinson pressure bar (PSHPB) was utilized to apply various high strain rates to porcine liver tissue to investigate its material behavior during high strain rate compression. Liver tissues were subjected to high strain rate impacts at 350, 550, 1000, and 1550 s−1. Tissue directional dependency was also explored by PSHPB testing along three orthogonal directions of liver at a strain rate of 350 s−1. Histology of samples from each of the three directions was performed to examine the structural properties of porcine liver. Porcine liver tissue showed an inelastic and strain rate-sensitive response at high strain rates. The liver tissue was found lacking directional dependency, which could be explained by the isotropic microstructure observed after staining and imaging. Furthermore, finite element analysis (FEA) of the PSHPB tests revealed the stress profile inside liver tissue and served as a validation of PSHPB methodology. The present findings can assist in the development of more accurate computational models of liver tissue at high-rate impact conditions allowing for understanding of subfailure and failure mechanisms.

High Strain Rate Compression Behavior and Constitutive Relation of As-Extruded Mg-Gd-Y Magnesium Alloy

2011 ◽  
Vol 686 ◽  
pp. 162-167 ◽  
Author(s):  
Zheng Liu ◽  
Ping Li Mao ◽  
Chang Yi Wang
Keyword(s):  
Magnesium Alloy ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Strain Rates ◽  
High Strain Rates ◽  
Stress Strain ◽  
Compression Behavior ◽  
Calculated Stress ◽  
Strain Rate Compression

The high strain rate compression behavior of extruded Mg-Gd-Y magnesium alloy was tested by split Hopkinson pressure bar (SHPB) under the strain rates of 465s-1，2140s-1and 3767s-1. As comparison the quasi-static compression behavior was tested in the meanwhile. The results show that the quasi-static yield stress is equivalent to that of high strain rates, but the flow stress at high strain rates are higher than that of quasi-static stain rate at the same strain. When the strain rate is increase from quasi-static to high strain rates the deformation stresses increase obviously but within the present testing high strain rates, increasing the strain rate the stress has a slight increasing, indicating that at high strain rate the stress of Mg-Gd-Y magnesium alloy is not sensitive to the strain rate. The constitutive equation between deformation stress, strain and strain rate was build based on the tested compression stress strain curves. The calculated stress strain data were compared with tested stress strain curves. The results demonstrate that when the strain rates are 0.001s-1，465s-1，2140s-1respectively the calculated and experimental data are fit very well. The calculated stress is higher than that of tested stress if the strain rate is increase to 3767s-1and the strain is more than 0.15. The discrepancy was explained through the physical soundness of Johnson-Cook model.

scholarly journals Effect of Stress-Relieving Heat Treatment on the High Strain Rate Dynamic Compressive Properties of Additively Manufactured Ti6Al4V (ELI)

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 653
Author(s):  
Amos Muiruri ◽  
Maina Maringa ◽  
Willie du Preez ◽  
Leonard Masu
Keyword(s):  
Plastic Strain ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Deformation Behaviour ◽  
Test System ◽  
Strain Rates ◽  
Stress Relieving ◽  
Strain Rate Compression

A study was undertaken on the compressive high strain rate properties and deformation behaviour of Direct Metal Laser-Sintered (DMLS) Ti6Al4V (ELI) parts in two separate forms: as-built (AB) and stress relieved (SR). The high strain rate compression tests were carried out using a Split Hopkinson Pressure Bar test system at ambient temperature. The average plastic strain rates attained by the system were 400 s−1 and 700 s−1. Comparative analyses of the performance (flow stresses and fracture strains) of AB and SR specimens were carried out based on the results obtained at these two plastic strain rates. Microstructural analyses were performed to study the failure mechanisms of the deformed specimens and fracture surfaces. Vickers microhardness test values were obtained before and after high strain rate compression testing. The results obtained in both cases showed the strain rate sensitivity of the stress-relieved samples to be higher in comparison to those of as-built ones, at the same value of true strain.

scholarly journals An Image-Based Impact Test for the High Strain Rate Tensile Properties of Brittle Materials

2018 ◽  
Vol 183 ◽  
pp. 02042
Author(s):  
Lloyd Fletcher ◽  
Fabrice Pierron
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
High Strain Rate ◽  
Strain Rate ◽  
Stress Wave ◽  
High Strain ◽  
Brittle Materials ◽  
Test Method ◽  
Strain Rates ◽  
High Strain Rates

Testing ceramics at high strain rates presents many experimental diffsiculties due to the brittle nature of the material being tested. When using a split Hopkinson pressure bar (SHPB) for high strain rate testing, adequate time is required for stress wave effects to dampen out. For brittle materials, with small strains to failure, it is difficult to satisfy this constraint. Because of this limitation, there are minimal data (if any) available on the stiffness and tensile strength of ceramics at high strain rates. Recently, a new image-based inertial impact (IBII) test method has shown promise for analysing the high strain rate behaviour of brittle materials. This test method uses a reflected compressive stress wave to generate tensile stress and failure in an impacted specimen. Throughout the propagation of the stress wave, full-field displacement measurements are taken, from which strain and acceleration fields are derived. The acceleration fields are then used to reconstruct stress information and identify the material properties. The aim of this study is to apply the IBII test methodology to analyse the stiffness and strength of ceramics at high strain rates. The results show that it is possible to identify the elastic modulus and tensile strength of tungsten carbide at strain rates on the order of 1000 s-1. For a tungsten carbide with 13% cobalt binder the elastic modulus was identified as 516 GPa and the strength was 1400 MPa. Future applications concern boron carbide and sapphire, for which limited data exist in high rate tension.

Compressive Behavior of Plain and Fiber-Reinforced High-Strength Concrete Subjected to High Strain Rate Loading

2011 ◽  
Vol 82 ◽  
pp. 57-62 ◽  
Author(s):  
Sha Sha Wang ◽  
Min Hong Zhang ◽  
Ser Tong Quek
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strength Concrete ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
High Strength ◽  
Strain Rates ◽  
Compressive Behavior ◽  
High Strain Rates ◽  
Strength Concrete

This paper presents a laboratory experimental study on the effect of high strain rate on compressive behavior of plain and fiber-reinforce high-strength concrete (FRHSC) with similar strength of 80-90 MPa. Steel fibers, polyethylene fibers, and a combination of these were used in the FRHSC. A split Hopkinson pressure bar equipment was used to determine the concrete behavior at strain rates from about 30 to 300 s-1. The ratio of the strength at high strain rates to that at static loading condition, namely dynamic increase factor (DIF), of the concretes was determined and compared with that recommended by CEB-FIP code. Fracture patterns of the specimens at high strain rates are described and discussed as well. Results indicate that the CEB-FIP equation is applicable to the plain high strength concrete, but overestimates the DIF of the FRHSC at strain rates beyond a transition strain rate of 30 s-1. Based on the experimental results, a modified equation on DIF is proposed for the FRHSC.

A Study on the Evolution of the High Strain Rate Mechanical Properties of SAC105 Leadfree Alloy at High Operating Temperatures

2015 ◽  
Author(s):  
Pradeep Lall ◽  
Vikas Yadav ◽  
Jeff Suhling ◽  
David Locker
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Lead Free ◽  
Electronic Systems ◽  
Strain Rates ◽  
High Strain Rates ◽  
Solder Interconnects

Electronics products may often be exposed to high temperature during storage, operation and handling in addition to high strain rate transient dynamic loads during drop-impact. Electronics subjected to drop-impact, shock and vibration may experience strain rates of 1–100 per sec. There are no material properties available in published literature at high strain rate at elevated temperature. High temperature and vibrations can contribute to the failures of electronic system. The reliability of electronic products can be improved through a thorough understanding of the weakest link in the electronic systems which is the solder interconnects. The solder interconnects accrue damage much faster when subjected to Shock and vibration at elevated temperatures. There is lack of fundamental understanding of reliability of electronic systems subjected to thermal loads. Previous studies have showed the effect of high strain rates and thermal aging on the mechanical properties of leadfree alloys including elastic modulus and the ultimate tensile strength. Extended period of thermal aging has been shown to affect the mechanical properties of lead free alloys including elastic modulus and the ultimate tensile strength at low strain rates representative of thermal fatigue [Lee 2012, Motalab 2012]. Previously, the microstructure, mechanical response and failure behavior of leadfree solder alloys when subjected to elevated isothermal aging and/or thermal cycling [Darveaux 2005, Ding 2007, Pang 2004] have been measured. Pang [1998] has showed that young’s modulus and yield stress of Sn-Pb are highly depending on strain rate and temperature. The ANAND viscoplastic constitutive model has been widely used to describe the inelastic deformation behavior of solders in electronic components. Previously, Mechanical properties of lead-free alloys, at different high strain rates (10, 35, 50, 75 /sec) and elevated temperature (25 C-125 C) for pristine samples have been studied [Lall 2012 and Lall 2014]. Previous researchers [Suh 2007 and Jenq 2009] have determined the mechanical properties of SAC105 at very high strain rate (Above 1000 per sec) using compression testing. But there is no data available in published literature at high strain rate and at elevated temperature for aged conditions. In this study, mechanical properties of lead free SAC105 has been determined for high strain rate at elevated temperature for aged samples. Effect of aging on mechanical properties of SAC105 alloy a high strain rates has been studied. Stress-Strain curves have been plotted over a wide range of strain rates and temperatures for aged specimen. Experimental data for the aged specimen has been fit to the ANAND’s viscoplastic model. SAC105 leadfree alloys have been tested at strain rates of 10, 35, 50 and 75 per sec at various operating temperatures of 50°C, 75°C, 100°C and 125°C. The test samples were exposed to isothermal aging conditions at 50°C for different aging time (30, 60, and 120 Days) before testing. Full-field strain in the specimen have been measured using high speed imaging at frame rates up to 75,000 fps in combination with digital image correlation. The cross-head velocity has been measured prior-to, during, and after deformation to ensure the constancy of cross-head velocity.

Random Aggregate Generation and Mesoscale Modeling of Concrete under High Strain Rate Compression

2011 ◽  
Vol 71-78 ◽  
pp. 733-736 ◽  
Author(s):  
Xiao Qing Zhou ◽  
Yong Xia
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Coarse Aggregate ◽  
High Strain ◽  
Concrete Specimen ◽  
Material Behavior ◽  
Mesoscale Modeling ◽  
Aggregate Distribution ◽  
Random Aggregate ◽  
Strain Rate Compression

In the mesoscale modeling, concrete is assumed consisting of three components, i.e., coarse aggregates, mortar matrix, and the interfacial transition zone (ITZ), each with different material behavior. The shape and the percentage of the coarse aggregate are the key factors in the mesoscale numerical simulation. The present paper investigates the effect of the coarse aggregate shape on the concrete behavior under high strain rate compression. Simplified methods are adopted to construct the aggregate distribution. Three different aggregate shapes, i.e., circular, oval and polygons, are generated to model the gravel and crushed stone aggregates, respectively. Using these different aggregate shapes, concrete specimens under high strain rate compression are modeled. Numerical results show that the aggregate shapes have a significant effect on the crack path, whereas little effect on the overall responses of the concrete specimen.

High Strain Rate Behavior of Metals

1990 ◽  
Vol 43 (5S) ◽  
pp. S9-S22 ◽  
Author(s):  
R. J. Clifton
Keyword(s):  
Flow Stress ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Rate Sensitivity ◽  
Strong Increase ◽  
Strain Rates ◽  
Shear Strain Rate ◽  
High Strain Rates ◽  
Strain Rate Change

Experimental results on the high strain rate response of polycrystalline metals are reviewed, with emphasis on the behavior of pure metals. A strong increase in flow stress with increasing strain rate is reported for strain rates of approximately 105s−1 and higher. This increase is observed in pressure-shear plate impact experiments at nominally constant strain rates from 105s−1 to 106s−1. To improve understanding of the increased rate sensitivity at high strain rates, pressure-shear, strain-rate-change experiments have been conducted on OFHC copper specimens. These experiments have been analyzed using a conventional viscoplasticity formulation and an internal variable formulation in which the hardening rate depends on the rate of deformation. Only the latter formulation is successful in describing the observed response to the change in strain rate. This observation is discussed in terms of its implications for interpreting other dynamic plasticity experiments and for improved understanding of the underlying dislocation mechanisms. The enhanced rate sensitivity at high strain rates is concluded to be related primarily to the rate sensitivity of strain hardening, not the rate sensitivity of the flow stress at constant structure.

Strain rate effects of tensile behaviors of 3-D orthogonal woven fabric: Experimental and finite element analyses

2012 ◽  
Vol 83 (4) ◽  
pp. 337-354 ◽  
Author(s):  
Yangqing Hou ◽  
Lili Jiang ◽  
Baozhong Sun ◽  
Bohong Gu
Keyword(s):  
Finite Element ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Woven Fabric ◽  
Strain Rates ◽  
High Strain Rates ◽  
Stress Strain ◽  
Two Phase ◽  
Tensile Stiffness

The tensile behaviors of 3-D woven fabric under high strain-rate states, i.e. tensile impact behaviors, are important for the design of the fabrics and the reinforced composites under impulsive loading. This paper reports the testing and the numerical simulation of the impact tension behaviors of 3-D woven fabric under high strain rates compared with those under quasi-static tension. The tensile behaviors of 3-D orthogonal woven fabric (3DOWF) were investigated using a MTS 810.23 material testing system and a self-designed split Hopkinson tension bar apparatus, under a wide range of strain rates (0.003–2308/s). The tensile stress–strain curves obtained from the quasi-static and high strain rates were used to analyze the rate-sensitivity of 3DOWF tensile behaviors. It was found that both the tensile strength and the failure strain increased with increases in the strain rate. The two-phase tensile stiffness phenomenon of 3DOWF under high strain rates has been observed experimentally. A microstructure model combined with finite element analysis was established to explain the tensile failure mechanisms of 3DOWF under high strain rates. It was found that the fabric architecture influences the stress wave propagation, thus leading to the two-phase tensile stiffness phenomenon in the stress–strain curve under high strain-rate tensions.

scholarly journals Plane strain tension fracture at high strain rate

2021 ◽  
Vol 250 ◽  
pp. 01020
Author(s):  
Morwan Adlafi ◽  
Bertrand Galpin ◽  
Laurent Mahéo ◽  
Christian C. Roth ◽  
Dirk Mohr ◽  
...  
Keyword(s):  
Stress State ◽  
High Strain Rate ◽  
Strain Rate ◽  
Plane Strain ◽  
High Strain ◽  
Tension Stress ◽  
Outer Diameter ◽  
Strain Rates ◽  
High Strain Rates ◽  
Plane Strain Tension

Under plane stress conditions, most micromechanical and phenomenological models predict a minimum in ductility for plane strain tension stress state. Therefore, the stress state of plane strain tension plays a crucial role in many forming and crash applications and the reliable measurement of the strain to fracture for plane strain tension is particularly crucial when calibrating modern fracture initiation models. Recently, a new experimental technique has been proposed for measuring the strain to fracture for sheet metal after proportional loading under plane strain conditions. The basic configuration of the new setup includes a dihedral punch which applies out-of-plane loading onto a Nakazima-type of discshaped specimen with two symmetric holes and an outer diameter of 60 mm. In the present work, the applicability of the test is extended to high strain rates. High strain rates of about 100/s to 200/s are obtained using a drop weight tower device with an original sensor for load measurements. Quasi static tests are also performed for comparison, keeping the same specimen geometry, image recording parameters and set-up. The effective strains at fracture are compared from quasi-static to high strain rate loading for three different materials, i.e one aluminium alloy and two steels.

scholarly journals Mechanical Behavior of Titanium Based Metal Matrix Composites Reinforced with TiC or TiB Particles under Quasi-Static and High Strain-Rate Compression

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6837
Author(s):  
Pavlo E. Markovsky ◽  
Jacek Janiszewski ◽  
Oleksandr O. Stasyuk ◽  
Vadim I. Bondarchuk ◽  
Dmytro G. Savvakin ◽  
...  
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
High Strain ◽  
Strain Rates ◽  
Matrix Composites ◽  
Strain Rate Compression ◽  
Static Conditions

The mechanical behavior of titanium alloys has been mostly studied in quasi-static conditions when the strain rate does not exceed 10 s−1, while the studies performed in dynamic settings specifically for Ti-based composites are limited. Such data are critical to prevent the “strength margin” approach, which is used to assure the part performance under dynamic conditions in the absence of relevant data. The purpose of this study was to obtain data on the mechanical behavior of Ti-based composites under dynamic condition. The Metal Matrix Composites (MMC) on the base of the alloy Ti-6Al-4V (wt.%) were made using Blended Elemental Powder Metallurgy with different amounts of reinforcing particles: 5, 10, and 20% of TiC or 5, 10% (vol.) of TiB. Composites were studied at high strain rate compression ~1–3·103·s−1 using the split Hopkinson pressure bar. Mechanical behavior was analyzed considering strain rate, phase composition, microstructure, and strain energy (SE). It is shown that for the strain rates up to 1920 s−1, the strength and SE of MMC with 5% TiC are substantially higher compared to particles free alloy. The particles TiC localize the plastic deformation at the micro level, and fracturing occurs mainly by crushing particles and their aggregates. TiB MMCs have a finer grain structure and different mechanical behavior. MMC with 5 and 10% TiB do not break down at strain rates up to almost 3000 s−1; and 10% MMC surpasses other materials in the SE at strain rates exceeding 2200 s−1. The deformation mechanism of MMCs was evaluated.

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