Dynamic Compressive Properties Research Articles

Static and dynamic compressive properties of polypropylene/zinc oxide nanocomposites

The effect of strain rate is widely recognized as an essential factor that influences the mechanical properties of polymer matrix composites. Despite its importance, no previous work has been reported on the high‐strain rate behavior of polypropylene/zinc oxide nanocomposites. Based on this, static and dynamic compression properties of polypropylene/zinc oxide nanocomposites, with particle contents of 1%, 3%, and 5% by weight, were successfully studied at different strain rates (i.e., 0.01 s−1, 0.1 s−1, 650 s−1, 900 s−1, and 1100 s−1) using a universal testing machine and a split Hopkinson pressure bar apparatus. For standardization, approximately 24 nm of zinc oxide nanoparticles were embedded into polypropylene matrix for each of the tested polypropylene/zinc oxide nanocomposites. Results show that the yield strength, the ultimate strength, and the stiffness properties, of polypropylene/zinc oxide nanocomposites, were greatly affected by both particle loading and applied strain rate. Furthermore, the rate sensitivity and the absorbed energy of all tested specimens showed a positive increment with increasing strain rate, whereas the thermal activation volume showed a contrary trend. In addition, the fractographic analysis and particle dispersion of all composite specimens were successfully obtained using a field emisission scanning electron microscopy. POLYM. ENG. SCI., 54:949–960, 2014. © 2013 Society of Plastics Engineers

The Material Behavior and Fracture Mechanism of a Frangible Bullet Composite

The quasi-static and dynamic compressive mechanical properties of a bullet composite are investigated using the scattered spot technique, an electronic universal testing machine, and a Split—Hopkinson pressure bar. The stress-strain curves under static and dynamic loading are also obtained, and the strain rate effect is analyzed. The rupture structure is observed under a scanning electron microscope, and the microscopic damage mechanism of the bullet composite is examined. Results show that the composite is sensitive to the strain rate, such that the compressive strength of the composite increases with increased strain rate. The relationship of the compressive strength and elastic modulus with the logarithmic strain rate is nonlinear.

Effect of austenitising temperature on microstructure and mechanical properties of an ultrahigh strength high alloy G33 steel

The microstructures of ultrahigh strength high alloy G33 steels quenched at different austenitising temperatures in the range of 1000–1150°C and tempered at 260°C were characterised by optical microscopy, scanning electron microscopy and transmission electron microscopy. The quasi-static tensile, dynamic compression and impact properties were evaluated from the as tempered specimens. Results showed that the prior austenite grain size was enhanced as the austenitising temperatures increased, whereas the lenticular martensite and undissolved carbides decreased. The strength at both quasi-static and dynamic impacts varied little, while the quasi-static plasticity, dynamic plasticity and impact toughness increased with elevated austenitising temperatures. The undissolved carbides had an adverse effect on toughness and plasticity. A high austenitising temperature of 1100 and 1150°C was beneficial for G33 alloy to acquire both high strength and high toughness.

Magnetic Field-Induced Compressive Property of Magnetorheological Elastomer under High Strain Rate

The dynamic compressive property of magnetorheological elastomer (MRE) under high strain rate was investigated using a modified split Hopkinson pressure bar system. Both the compressive properties in the pre-yield region and the post-yield region were studied. Experimental results show that the dynamic compressive property of MRE under high strain rate is related to the magnetic field and the strain rate. In the pre-yield region, with increasing magnetic field or strain rate, both the Young’s modulus and the yield stress increase. However, the yield strain decreases with increasing magnetic field or strain rate. A constitutive model consisting of hyperelasticity, viscoelasticity, and a magnetic part was proposed to describe the compressive property of MRE, and the model agrees well with the experimental results. In the post-yield region, the stress first decreases to a minimum value and then increases smoothly when the strain exceeds the yield strain, which is due to the change of the chainlike structures...

Experimental confirmation of some factors influencing dynamic concrete compressive strengths in high-speed impact tests

This paper reports probably the first systematic experimental investigation of the influences of lateral inertia confinement, end friction confinement and aggregates in high-speed impact tests on dynamic compressive properties of concrete. The influences of the concerned factors on the dynamic increase factor (DIF) are discussed. The proposed DIF relations in Hao and Hao [36] are verified by the experimental data in this study. The results confirm the observations made before based on numerical simulations that lateral inertia confinement effect is dependent on the specimen diameter and strain rate. The influences of aggregate size and volume to DIF are considerable, and aggregates cannot be neglected in experimental or numerical studies. It also confirms that the end friction confinement effect is sensitive to the specimen geometry and strain rate. The equation proposed in Hao et al. [40] based on numerical simulations satisfactorily removes the friction confinement effect on the DIF of concrete material strength obtained in impact test.

Dynamic tensile and compressive properties of vacuum and ordinary die-casting AT72 magnesium alloy at high strain rates

Abstract To investigate dynamic tensile and compressive properties of AT72 magnesium alloys under high strain rates, the Split Hopkinson tensile Bar (SHTB) and the Split Hopkinson Pressure Bar apparatus was used at ambient temperature. The specimens after dynamic tension and dynamic compression were analyzed by scanning electron microscope (SEM) and metallographic microscope. Dynamic mechanical properties and fracture mechanism were discussed in this paper. The results show that at approximate tensile strain rate, the dynamic tensile strength of ordinary die-casting AT72 and vacuum die-casting AT72 is very similar, but the dynamic failure strain is of great difference. AT72 magnesium alloys under dynamic compressive yield continuously, and have the slight positive strain rate effect. The dynamic compressive behaviors of ordinary die-casting AT72 and vacuum die-casting AT72 are nearly the same. The dynamic tensile fracture mechanism of both vacuum die-casting AT72 and ordinary die-casting AT72 is inter-granular fracture. The dynamic compressive fracture mechanism of both vacuum die-casting AT72 and ordinary die-casting AT72 is quasi-cleavage intra-crystalline failure. The pores have an important effect on dynamic properties of die casting magnesium alloys.

Quasi-static and dynamic compressive deformation behaviors in Zr-based amorphous alloys containing ductile dendrites

Quasi-static and dynamic compressive properties of four Zr-based amorphous alloys containing ductile dendrites, whose sizes were varied with cooling rates, were investigated. Deformation mechanisms related with property improvement were investigated by focusing on how the size of ductile dendrites affected the initiation and propagation of deformation bands. These alloys contained 47–49vol% of dendrites whose effective sizes were ranged from 15μm to 43μm, and showed excellent quasi-static compressive properties of maximum strength over 1.3GPa and total strain up to 34%. Under the dynamic compressive loading, the compressive strength increased up to 2.1GPa, whereas the total strain decreased to 9–10%. According to the observation of dynamic compressive deformation behavior, dendrites played an important role in improving the ductility by interrupting the radical propagation of shear cracks initiated at the amorphous matrix and by taking over a considerable compressive load. Particularly in the alloy containing sufficiently coarse dendrites for developing deformation bands, the deformation took place relatively homogeneously as the applied stress could be effectively dispersed even under the dynamic loading.

332 発泡高分子材料の準静的および動的圧縮特性

332 発泡高分子材料の準静的および動的圧縮特性

Experimental Research on Dynamic Mechanical Properties of 5083 Aluminum Alloy

5083 aluminum alloy was investigated with respect to its uniaxial dynamic compressive properties over a range of strain rates using the split Hopkinson pressure bar (SHPB). The dynamic stress-strain curves of this alloy were obtained for strain rates from 1000 s-1 to 6000 s-1. Effects of strain rate, the samples size and anti-impact capability were analyzed. The experimental results show that under impaction loading, 5083 aluminum alloy has a remarkable strengthening response to strain rate and size; in particular, the responded stress increases with increasing strain rate, which implies that this alloy has high strength and high anti-impact capability.

OS1922 発泡フィルムの動的圧縮特性

OS1922 発泡フィルムの動的圧縮特性

Effect of Temperature on the Dynamic Compressive Properties of Magnesium Alloy AZ91D

Lightweight materials are getting more and more attraction towards their use in automobiles, planes, protective structures, electronics and supports for numerous benefits ranging from reduction in fuel consumption in vehicles to lighter and stronger in protective structures. For efficient use of materials in applications where they are subjected to unusual higher sudden loads and varying temperatures, it is necessary to know their accurate response under such conditions. Magnesium alloys due to low density, high specific strength, high specific stiffness and damping capacity have been in use for variety of structural and non-structural applications mainly in automotive and aerospace industries along with many other applications in defense, supports and electronics. In present study, the effect of temperature variation has been investigated for magnesium alloy AZ91D at high strain rates. The temperature is varied in the range between -30oC to 200oC at a strain rate of 103 s-1. Lower stresses and larger strains to peak compressive stresses are observed with increasing temperature. At higher strain rate, the effect of temperature on the alloy’s hardening behaviour is less significant

The region-dependent dynamic properties of porcine temporomandibular joint disc under unconfined compression

In this study, the dynamic compressive properties in five different regions of the porcine temporomandibular joint (TMJ) disc are investigated over a wide range of loading frequencies. The aim was, thus far, to evaluate the regional difference and the frequency-related effect of the applied load on these properties. Eleven porcine TMJ discs were used; each disc was divided into 5 regions, anterior, central, posterior, lateral and medial. Sinusoidal compressive strain was applied with an amplitude of 1.0% and a frequency range between 0.01 and 10Hz. The dynamic storage and loss moduli increase with frequency, the highest values being attained at the posterior region, followed by the central and anterior regions. Loss tangent, tanδ, ranged from 0.20 to 0.35, which means that the disc is primarily elastic in nature and has a small but not negligible viscosity. The present results suggest that the dynamic viscoelastic compressive modulus is region-specific and depends on the loading frequency, thus having important implications for the transmission of load to the TMJ.

Particle size – Dependent on the static and dynamic compression properties of polypropylene/silica composites

The effect of particle size is widely known as an essential factor that influences the mechanical properties of particulate filled polymer composites. However, there is a limited number of works available, on the particular under dynamic perspective. Based on this, the static and dynamic compression properties of polypropylene/silica composites, with particle sizes of 3μm, 1μm, 20nm, and 11nm, were successfully studied at different levels of strain rates (i.e., 0.01s−1, 0.1s−1, 650s−1, 900s−1, and 1100s−1) using a universal testing machine and a split Hopkinson pressure bar apparatus. Results show that the yield strength, the ultimate strength, and the stiffness properties, of polypropylene/silica composites were greatly affected by both particle size and loading rates. Furthermore, particle size also influences the rate sensitivity and the thermal activation volume of polypropylene/silica composites; where, smaller particle recorded lower rate sensitivity. Meanwhile, for the thermal activation volume, the trend was reversed.

Dynamic Compressive Properties of Vulcanized Rubber Material from a Split Hopkinson Pressure Bar Experiment in Rubber Manufacturing

In this paper, an attempt has been made to study the dynamic mechanic properties of vulcanized rubber material which is used for industrial structure. A split Hopkinson pressure bar (SHPB) is utilized to obtain uniaxial compression response of the vulcanized rubber material under different strain-rate and temperatures loading conditions. The stress-strain curves under different conditions are obtained, which can be used as a basis for the data analysis procedure. It is found that the dynamic compressive strength of vulcanized rubber improves with the increase of strain-rate. And it is also significantly higher at low temperature than that at normal temperature，which is opposite from stiffness. Vulcanized rubber exhibits excellent superelasticity at temperature of -40°C that is noted as well.

Quasi-static and dynamic compressive mechanical properties of engineered cementitious composite incorporating ground granulated blast furnace slag

The ground granulated blast-furnace slag (GGBS) has been widely used as a supplementary cementitious material in concrete production due to its lower heat of hydration, ability to gain strength over a longer period, superior performance against chemical attacks, and lower environmental impact. Four Engineered Cementitious Composite (ECC) mixtures with 50%, 60%, 70% and 80% substitution amounts of GGBS were prepared and their dynamic compressive mechanical behavior had been investigated by using a split Hopkinson pressure bar (SHPB) system at strain rates ranging from 84.8 to 184.6s−1. The corresponding quasi-static compressive responses of GGBS–ECC were also studied experimentally for contrasting with their dynamic tests. The objective of using GGBS to replace fly ash in ECC was to obtain higher quasi-static compressive strength and dynamic load-carrying capacity. The dynamic compressive stress–strain curves did not show residual strength behavior as that in the quasi-static stress–strain curves. ECC incorporating GGBS exhibited strain rate dependence. The peak stress increased and the peak strain decreased with the increase of strain rates. The toughness ratio under quasi-static compression was lower than that of dynamic compression according to the proposed method in this study. The toughness ratio under dynamic compression showed a slight increase with the GGBS content increasing. The strain rate had little influence on the toughness ratio.

Analysis of Failure Patterns and Damage Mechanisms under Impact Compression of Hybrid Fiber Reinforced Concrete

In order to studying the failure patterns under impact compression of Hybrid Fiber Reinforced Concrete(HFRC), tests focused on static and dynamic compression properties according to steel fiber reinforced concrete(SFRC) and HFRC are adopted. The equipment of dynamic compression properties test is Ф74mm split Hopkinson pressure bar (SHPB). The static and dynamic compressive strength at four different strain rates of the two materials are obtained, while failure mechanism has been analyzed from specimens’ failure modes in static and dynamic compressive tests, which in turn provides theory basis for the application of HFRC.

Static and dynamic mechanical properties of concrete after high temperature exposure

Abstract The aim of this paper is to investigate the static and dynamic mechanical properties of concrete before and after high temperature exposure. Quasi-static and impact loading experiments were carried out on concrete before and after exposure to the temperature of 200–800 °C by using a servo-hydraulic testing machine and a 100-mm-diameter split Hopkinson bar (SHPB) apparatus, respectively. The results show that, mechanical properties of concrete after high temperature exposure change evidently, and the critical temperature for those changes acquiring dramatic character is 400 °C. With the rise of temperature up to 400 °C, compressive strength and critical strain change little compared with that of at room temperature. While with temperature increasing from 400 to 800 °C, the decrease in strength and the increase in critical strain become obvious. Consequentially, specific energy absorption (SEA), which is the synthetic exhibition of strength and ductility, decreases much less than those observed for strength over 400 °C. Dynamic compressive mechanical properties of concrete before and after high temperature exposure increase with the rise in strain rate rapidly, which exhibits strong strain rate dependency. Dynamic increase factor (DIF) increases approximately linearly with strain rate. In a word, concrete can be recognized as an excellent thermal-resistant and anti-impact construction material.

Measurement of Dynamic Compressive Properties of Apples using the Oscillatory Test

Purpose: This study performed the oscillatory test using the texture analyzer to characterize the viscoelastic behavior of apples such as the storage modulus (E``), the loss modulus (E````), the complex modulus (|E*|) and the energy dissipated per cycle (Wdiss). Methods: The sinusoidal deformation with the frequency of 1~10 Hz and the maximum displacement of 0.1 mm were applied to the flesh tissues of Fuji, Golden Delicious and Red Delicious apples. The Lissajous figure was used to measure the phase angle (δ) between stress and strain curve. Results: Trigger force was critical to the measurement of the phase angle. E``, E````, |E*| and Wdiss were measured using the Lissajous figure and the phase angle. The complex modulus of Golden Delicious apple was significantly lower than those of Fuji apple and Red Delicious apple. Conclusions: Apple flesh was exhibiting more elasticity at low frequency, and more viscosity at high frequency. Dynamic compressive properties of Fuji apple were similar to those of Red Delicious apple but significantly different from those of Golden Delicious apple

Dynamic Compressive Properties of Zr-based Amorphous Matrix Composites Reinforced with Tungsten Continuous Fibers or Porous Foams

In this study, amorphous matrix composites, whose matrix was a Zr-based amorphous alloy and reinforcements were tungsten continuous fibers or porous foams, were fabricated by the liquid pressing process, and their dynamic compressive properties were investigated. Approximately 65 to 69 vol pct of tungsten fibers or foams were distributed homogeneously in the amorphous matrix, whereas defects such as misinfiltration or pores were eliminated. According to the dynamic compressive test results of the tungsten-fiber-reinforced composite, tungsten fibers worked to withstand a considerable amount of applied loads, whereas the amorphous matrix sustains bent or bucked fibers, thereby leading to the maximum strength of 3328 MPa and the plastic strain of 2.6 pct. In the tungsten-foam-reinforced composite, the compressive stress continued to increase according to the work hardening after the yielding, thereby leading to the maximum strength of 3458 MPa and the plastic strain of 20.6 pct. This dramatic increase in maximum strength and plastic strain was attributed to the simultaneous and homogeneous deformation at tungsten foams and amorphous matrix because tungsten foams did not show anisotropy and tungsten/matrix interfaces were excellent. These findings suggested that tungsten-foam-reinforced composite could be applied to penetrators, in which the self-sharpening should be well promoted while keeping high specific gravity, sufficient strength, and plastic strain because cracks were formed at some heavily deformed tungsten foams by the shear fracture.

Effect of molecular structures on dynamic compression properties of polyethylene

The properties of polymers are strongly affected by their molecular structures. Therefore, three different types of polyethylene; low density, low-linear density and high density polyethylene were used in this study to experimentally investigate the dependency and attractive effect of molecular structures towards compressive properties of polyethylene over a wide range of strain rate studied. For the mechanical tests, an experimental technique based on the compression split Hopkinson pressure bar was introduced to perform high strain rate testing whereas a conventional universal testing machine was used to perform static compression testing. Additionally, two constitutive equations were employed to validate the yield behaviour of all tested polyethylene specimens under different levels of strain rates. Results indicated that the molecular structure of polyethylene did affect its mechanical properties in terms of yield behaviour, stiffness, strength, rate sensitivity, activation volume and absorbed energy, respectively. Meanwhile, the levels of strain rates also played as secondary roles that influenced the mechanical properties of the polyethylene specimens. Of the three types of polyethylene specimens, high density polyethylene recorded an excellent performance in terms of yield behaviour, absorbed energy, stiffness, and strength properties than that of other polyethylene specimens. However, low linear polyethylene showed greater rate sensitivity than that of other polyethylene specimens under both static and dynamic regions. Interestingly, both constitutive models almost agreed with the experimental results.