Dynamic Mechanical Properties of Polyvinyl Alcohol Hydrogels Measured by Double-Striker Electromagnetic Driving SHPB System

2019 ◽  
Vol 11 (02) ◽  
pp. 1950018 ◽  
Author(s):  
Beixin Xie ◽  
Peidong Xu ◽  
Liqun Tang ◽  
Yongrou Zhang ◽  
Kejia Xu ◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Soft Materials ◽  
Strain Rates ◽  
Mechanical Behaviors ◽  
Hopkinson Pressure Bar ◽  
Sensitive Material ◽  
Stress Strain ◽  
Strain Rate Effects

As an ultra-soft material (elastic modulus in magnitude of kPa), polyvinyl alcohol (PVA) hydrogels have the potential to substitute articular cartilage, but the measurement of the dynamic stress–strain relations of ultra-soft materials is still challenging. In this paper, a double-striker electromagnetic driving split-Hopkinson pressure bar (SHPB) system was developed, in which all the bars were made of polycarbonate, and the polycarbonate striker was pushed by a metal striker driven electromagnetically to ensure the precise control of impact velocity. With the new SHPB system, well design of the size of hydrogel specimen and rational processing of the signal data, the stress–strain relations of hydrogels with varied PVA contents at different strain rates were measured successfully. Experimental results indicate that PVA hydrogels are a positive strain rate sensitive material with different strain-rate effects at low and high strain rates. Finally, based on the latest quasi-static constitution of the PVA hydrogel, a rate-dependent constitutive equation was recommended, which may well depict the mechanical behaviors of hydrogels with different fiber contents at varied strain rates. It also derives that the contributions of strain rate and fiber content on the mechanical behaviors of the hydrogel are relatively independent.

scholarly journals Dynamic Constitutive Model of Ultra-High Molecular Weight Polyethylene (UHMWPE): Considering the Temperature and Strain Rate Effects

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1561 ◽  
Author(s):  
Kebin Zhang ◽  
Wenbin Li ◽  
Yu Zheng ◽  
Wenjin Yao ◽  
Changfang Zhao
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Plastic Material ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Ballistic Performance ◽  
Stress Strain ◽  
Different Temperatures

The temperature and strain rate significantly affect the ballistic performance of UHMWPE, but the deformation of UHMWPE under thermo-mechanical coupling has been rarely studied. To investigate the influences of the temperature and the strain rate on the mechanical properties of UHMWPE, a Split Hopkinson Pressure Bar (SHPB) apparatus was used to conduct uniaxial compression experiments on UHMWPE. The stress–strain curves of UHMWPE were obtained at temperatures of 20–100 °C and strain rates of 1300–4300 s−1. Based on the experimental results, the UHMWPE belongs to viscoelastic–plastic material, and a hardening effect occurs once UHMWPE enters the plastic zone. By comparing the stress–strain curves at different temperatures and strain rates, it was found that UHMWPE exhibits strain rate strengthening and temperature softening effects. By modifying the Sherwood–Frost model, a constitutive model was established to describe the dynamic mechanical properties of UHMWPE at different temperatures. The results calculated using the constitutive model were in good agreement with the experimental data. This study provides a reference for the design of UHMWPE as a ballistic-resistant material.

One-Dimensional Dynamic Compressive Behavior of EPDM Rubber

2003 ◽  
Vol 125 (3) ◽  
pp. 294-301 ◽  
Author(s):  
B. Song ◽  
W. Chen
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Dynamic Stress ◽  
Split Hopkinson Pressure Bar ◽  
Constant Strain Rate ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Epdm Rubber ◽  
One Dimensional

Dynamic compressive stress-strain curves at various strain rates of an Ethylene-Propylene-Diene Monomer Copolymer (EPDM) rubber have been determined with a modified split Hopkinson pressure bar (SHPB). The use of a pulse-shaping technique ensures that the specimen deforms at a nearly constant strain rate under dynamically equilibrated stress. The validity of the experiments was monitored by a high-speed digital camera for specimen edge deformation, and by piezoelectric force transducers for dynamic stress equilibrium. The resulting dynamic stress-strain curves for the EPDM indicate that the material is sensitive to strain rates and that the strain-rate sensitivity depends on the value of strain. Based on a strain energy function theory, a one-dimensional dynamic constitutive equation for this rubber was modified to describe the high strain-rate experimental results within the ranges of strain and strain rates presented in this paper.

Measurement of Mechanical Properties of St 37 Material at High Strain Rates Using a Split Hopkinson Pressure Bar

2014 ◽  
Vol 660 ◽  
pp. 562-566 ◽  
Author(s):  
Akbar Afdhal ◽  
Leonardo Gunawan ◽  
Sigit P. Santosa ◽  
Ichsan Setya Putra ◽  
Hoon Huh
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Test Specimen ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Split Hopkinson ◽  
Pressure Bar

The dynamic mechanical properties of a material are important keys to investigate the impact characteristic of a structure such as a crash box. For some materials, the stress-strain relationships at high strain rate loadings are different than that at the static condition. These mechanical properties depend on the strain rate of the loadings, and hence an appropriate testing technique is required to measure them. To measure the mechanical properties of a material at high strain rates, ranging from 500 s-1 to 10000 s-1, a Split Hopkinson Pressure Bar is commonly used. In the measurements, strain pulses are generated in the bars system, and pulses being reflected and transmitted by a test specimen in the bar system are measured. The stress-strain curves as the material properties of the test specimen are obtained by processing the measured reflected and transmitted pulses. This paper presents the measurements of the mechanical properties of St 37 mild steel at several strain rates using a Split Hopkinson Pressure Bar. The stress-strain curves obtained in the measurement were curve fitted using the Power Law. The results show that the strength of St 37 material increases as the strain rate increases.

Dynamic Stress-Strain Behavior of AZ91 Alloy at High-Strain Rate

2007 ◽  
Vol 546-549 ◽  
pp. 89-92 ◽  
Author(s):  
Gui Ying Sha ◽  
En Hou Han ◽  
Yong Bo Xu ◽  
Lu Liu
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Dynamic Stress ◽  
Split Hopkinson Pressure Bar ◽  
Az91 Alloy ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Strain Rate Effects ◽  
Strain Behavior ◽  
Pressure Bar

The dynamic stress-strain behavior of the AZ91 alloys in different treatment conditions (as-cast, T4 and T6) was investigated by means of split Hopkinson pressure bar. It was found that the flow stress increased at first, and then declined with the strain rate increasing at the range of 102~103s-1 for the alloys in these three conditions. And the alloys exhibited both positive and negative strain rate effects. The former was caused by strain rate strengthening and the latter was caused by strain rate weakening. However the flow stress for the alloy in aged condition at the same strain rate was higher than both of the alloys in as-cast and solution conditions. The study also showed that the maximum strains of the alloys in different conditions increased with the strain rate increasing, and the strain rate to fracture for the alloy in solution condition was higher than those of other two alloys. The work-hardening of α–Mg matrix and the reinforcement of β-Mg17Al12 phases led to the strengthening of the alloy, while thermal softening of matrix, the fracture of β phases and initiation and propagation of the cracks were responsible for the weakening of the alloy.

scholarly journals Determination of High Strain-Rate Compressive Stress-Strain Loops of Selected Polymers

2010 ◽  
Vol 24-25 ◽  
pp. 349-355 ◽  
Author(s):  
Takashi Yokoyama ◽  
Kenji Nakai
Keyword(s):  
Strain Rate ◽  
Compressive Stress ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Viscoelastic Behavior ◽  
Strain Range ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Dissipation Energy

Compressive stress-strain loops of selected polymers at strain rates up to nearly 800/s are determined in a strain range of nearly 8% on the standard split Hopkinson pressure bar. Four different commercially available extruded polymers are tested at room temperature. The compressive stress-strain loops at low and intermediate strain rates are measured on an Instron testing machine. The effects of strain rate on the Young's modulus, flow stress and dissipation energy are discussed. It is shown that the area included within the stress-strain loop increases with increasing strain rate as well as a given strain, that is, all four extruded polymers tested exhibit intrinsic strain-rate dependent viscoelastic behavior and a high elastic aftereffect following complete unloading.

STRAIN RATE EFFECTS ON COMPRESSIVE PROPERTIES OF A BIODEGRADABLE PLASTIC

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1177-1182 ◽  
Author(s):  
MASAHIRO NISHIDA ◽  
KOICHI TANAKA ◽  
NORIOMI ITO
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Biodegradable Plastic ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Compressive Properties ◽  
Strain Rate Effects ◽  
Wide Range ◽  
Pressure Bar

The compressive properties of a biodegradable plastic were measured over a wide range of strain rates from 10−5 to 104 s −1, using a universal testing machine and a split Hopkinson pressure bar method. The yield stress of the biodegradable plastic increased with increasing strain rate and decreased with temperature and water absorption. Empirical equations for the yield stresses were derived for the strain rates from 10−5 to 103 s −1 and from 103 to 104 s −1, respectively.

An Experimental Investigation of the Dynamic Mechanical Behaviors of Hollow Spheres Filled Syntactic Foam

2012 ◽  
Vol 268-270 ◽  
pp. 67-73
Author(s):  
Ming Yu ◽  
Ping Zhu
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Failure Mechanisms ◽  
Hollow Spheres ◽  
Syntactic Foam ◽  
Mechanical Behaviors ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Dynamic Mechanical ◽  
Split Hopkinson

Dynamic mechanical behaviors are critical to the engineering applications of hollow spheres filled syntactic foams. The potential of such composites cannot be fully realized unless the effects of strain rate on their mechanical properties are fully understood. In this study, both the compressive and the tensile behaviors of an epoxy syntactic foam filled by ceramic microspheres were experimentally investigated over the strain rate range from 0.001 to 2000 s-1. The compressive and tensile tests at high strain rates were carried out by means of split Hopkinson pressure bar (SHPB) and split Hopkinson tensile bar (SHTB), respectively. The stress-strain responses and failure mechanisms were examined quantitatively and qualitatively. The experimental results indicate that both the compressive and the tensile behaviors of syntactic foam are highly sensitive to strain rate. Moreover, a comparison of the stress-strain curves suggests that the compressive and tensile behaviors are dominated by different failure mechanisms, which consequently lead to distinct effects of strain rate on the compressive and tensile behaviors of syntactic foam.

Dynamic Compressive Behavior of EPDM Rubber Under Nearly Uniaxial Strain Conditions

2004 ◽  
Vol 126 (2) ◽  
pp. 213-217 ◽  
Author(s):  
B. Song ◽  
W. Chen
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Good Description ◽  
Axial Stress ◽  
Strain Energy Function ◽  
Uniaxial Strain ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Epdm Rubber

Dynamic compressive stress-strain curves for ethylene-propylene-diene monomer (EPDM) rubber at various strain rates under nearly uniaxial strain conditions have been determined with a pulse-shaped split Hopkinson pressure bar (SHPB). The resultant stress-strain curves exhibited significantly nonlinear behavior, with strong sensitivities to strain rates. The dynamic stresses in the EPDM rubber at certain strains under uniaxial strain conditions increased significantly as compared to those under uniaxial stress conditions. A strain-rate-dependent material model, including a strain-rate-sensitive term, has been developed through a strain-energy function for compressible Mooney-Rivlin hyperelastic solids. The model provided a good description of the compressive axial stress-strain response of the EPDM rubber at various strain rates under uniaxial strain conditions.

scholarly journals Study on the dynamic properties of AM-SLM AlSi10Mg alloy using the Split Hopkinson Pressure Bar (SHPB) technique

2018 ◽  
Vol 183 ◽  
pp. 04005 ◽  
Author(s):  
Bar Nurel ◽  
Moshe Nahmany ◽  
Adin Stern ◽  
Nahum Frage ◽  
Oren Sadot
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Properties ◽  
Rate Sensitivity ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Static Mechanical ◽  
Split Hopkinson ◽  
Pressure Bar

Additive manufacturing by Selective Laser Melting of metals is attracting substantial attention, due to its advantages, such as short-time production of customized structures. This technique is useful for building complex components using a metallic pre-alloyed powder. One of the most used materials in AMSLM is AlSi10Mg powder. Additively manufactured AlSi10Mg may be used as a structural material and it static mechanical properties were widely investigated. Properties in the strain rates of 5×102–1.6×103 s-1 and at higher strain rates of 5×103 –105 s-1 have been also reported. The aim of this study is investigation of dynamic properties in the 7×102–8×103 s-1 strain rate range, using the split Hopkinson pressure bar technique. It was found that the dynamic properties at strain-rates of 1×103–3×103 s-1 depend on a build direction and affected by heat treatment. At higher and lower strain-rates the effect of build direction is limited. The anisotropic nature of the material was determined by the ellipticity of samples after the SHPB test. No strain rate sensitivity was observed.

scholarly journals Dynamic properties of stainless steel under direct tension loading using a simple gas gun

2018 ◽  
Vol 183 ◽  
pp. 02035 ◽  
Author(s):  
Anatoly Bragov ◽  
Alexander Konstantinov ◽  
Leopold Kruszka ◽  
Andrey Lomunov ◽  
Andrey Filippov
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Properties ◽  
Tensile Load ◽  
Hopkinson Pressure Bar ◽  
Direct Tension ◽  
Stress Strain ◽  
Gas Gun

The combined experimental and theoretical approach was applied to the study of high-speed deformation and fracture of the 1810 stainless steel. The material tests were performed using a split Hopkinson pressure bar to determine dynamic stress-strain curves, strain rate histories, plastic properties and fracture in the strain rate range of 102 ÷ 104 s-1. A scheme has been realized for obtaining a direct tensile load in the SHPB, using a tubular striker and a gas gun of a simple design. The parameters of the Johnson-Cook material model were identified using the experimental results obtained. Using a series of verification experiments under various types of stress-strain state, the degree of reliability of the identified mathematical model of the behavior of the material studied was determined.

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