Impact Compressive Failure of a Unidirectional Carbon/Epoxy Laminated Composite in Three Principal Material Directions

2012 ◽  
Vol 706-709 ◽  
pp. 799-804 ◽  
Author(s):  
Takashi Yokoyama
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Laminated Composite ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Failure Behavior ◽  
Strain Rates ◽  
Compressive Failure ◽  
The Impact

The impact compressive failure behavior of a unidirectional T700/2521 carbon/epoxy laminated composite in three principal material directions or fiber (1-), in-plane transverse (2-) and through-thickness (3-) directions is investigated on the conventional split Hopkinson pressure bar (SHPB). Cubic and rectangular block specimens with identical square cross section are machined from an about 10 mm thick composite laminate. The uniaxial compressive stress-strain curves up to failure at quasi-static and intermediate strain rates are measured on an Instron testing machine. It is shown that the ultimate compressive strength and strain exhibit no strain-rate effect in the 1-direction, but a slight strain-rate effect in the 2-and 3-direction over a range of strain rates from10-3to 103/s.

Dynamic Mechanical Response of Renal Cortex Under Compression: Strain-Rate Effect

2009 ◽  
Author(s):  
Farhana Pervin ◽  
Weinong W. Chen ◽  
Tusit Weerasooriya
Keyword(s):  
Strain Rate ◽  
Input Data ◽  
Kidney Tissue ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
The Body ◽  
Blunt Injury ◽  
Strain Rates ◽  
Dynamic Mechanical ◽  
The Impact

The body armor can protect the soldiers from penetrating and blunt injury during the war, but its prevention standard lacks the biomedical validity. To improve the protection gear and prevention strategies, we need valid input data in mathematical modeling at different impact loading conditions. Our aim is to provide the valid data for the computer modeling and simulation based on the injury levels. Dynamic mechanical behaviors of kidney tissues are needed as input data for the impact modeling of penetrating injury. Moreover, the knowledge of mechanical responses of kidney tissues is important for diagnosis, surgical simulation and training purposes. This work investigates the impact of strain rate effect of kidney tissue under compression. The dynamic response of kidney tissues is studied using Split Hopkinson pressure bar (SHPB) technique. We have modified the classical SHPB technique to characterize the mechanical behavior of kidney tissues at high strain-rate ranging from 1000 s−1 to 3000 s−1 by incorporating quratz-crystal technique and hollow transmission bar. We have also studied the quasi-static response of kidney tissues at three different strain-rates of 0.01 s−1, 0.1 s−1 and 1 s−1 as well as the intermediate strain rate at two different strain rates of 10 s−1 and 100s−1. The experiment results indicate the non-linear stress-strain response of materials. The kidney tissue stiffens evidently with increasing strain-rate.

scholarly journals Impact Compressive Failure of a Unidirectional Carbon/Epoxy Composite: Effect of Loading Directions

2008 ◽  
Vol 13-14 ◽  
pp. 195-201 ◽  
Author(s):  
Takashi Yokoyama ◽  
Kenji Nakai
Keyword(s):  
Strain Rate ◽  
Cross Sections ◽  
Split Hopkinson Pressure Bar ◽  
Epoxy Composite ◽  
Compressive Strain ◽  
Testing Machine ◽  
Compressive Failure ◽  
Hopkinson Pressure Bar ◽  
Composite Effect ◽  
The Impact

The impact compressive failure behaviour of a unidirectional T700/2521 carbon/epoxy composite in three principal material directions is investigated in the conventional split Hopkinson pressure bar. Two different types of specimens with square cross sections are machined from the composite in the plane of the laminate. The uniaxial compressive stress-strain curves up to failure at quasi-static and intermediate strain rates are measured on an Instron testing machine. It is demonstrated that the ultimate compressive strength (or maximum stress) increases slightly, while the ultimate compressive strain (or failure strain) decreases marginally with strain rate in the range of 10-3 to 103/s in all three directions. Dominant failure mechanisms are found to significantly vary with strain rate and loading directions along three principal material axes.

Dynamic out-of-plane compressive failure mechanism of C/C composite: Strain rate effect on the defect propagation and microstructure failure

2021 ◽  
pp. 1-31
Author(s):  
Fei Guo ◽  
Qingguo Fei ◽  
Yanbin Li ◽  
Nikhil Gupta
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Failure Mechanism ◽  
Maximum Stress ◽  
Testing Machine ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Compressive Failure ◽  
Macro Scale ◽  
Out Of Plane

Abstract Out-of-plane compression experiments with the strain rate from 0.0001/s to 1000/s are performed on 3D fine weave pierced Carbon/Carbon (C/C) composite using a universal testing machine, a high-speed testing machine, and a split Hopkinson pressure bar (SHPB). The compressive failure mechanism of the composite is analyzed by multi-scale analysis method, which ranges from micro-scale defect propagation, through meso-scale microstructure failure, to macro-scale material failure. In order to predict the out-of-plane compressive properties of 3D fine weave pierced C/C composite at different strain rates, a strain-rate-dependent compressive constitutive model is proposed. The results show that the out-of-plane compressive behavior of the 3D fine weave pierced C/C composite is sensitive to strain rate. With increasing the strain rate, the initial compressive modulus, the maximum stress and the strain at the maximum stress increase. The difference in mechanical behavior between quasi-static and high strain rate compression is owing to the strain rate effect on the defect propagation of the 3D fine weave pierced C/C composite. The proposed constitutive model matches well with the experimental data.

Strain Rate Effect on Shear Behavior of Open-Graded Aggregates

2017 ◽  
Vol 2655 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Thomas Gebrenegus ◽  
Jennifer E. Nicks ◽  
Michael T. Adams
Keyword(s):  
Strain Rate ◽  
Axial Strain ◽  
Shear Behavior ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Strength Parameter ◽  
Strain Rates ◽  
Rate Dependency ◽  
Confining Stress ◽  
Dilation Angle

Despite their wide application as construction materials in various earthworks built by state and local transportation agencies, the role of physical and mechanical factors in the strength and deformation behavior of crushed, manufactured open-graded aggregates (OGAs) is not well studied. In this investigation, the strain rate dependency of strength–deformation behaviors of two commonly employed crushed aggregates with small (12.7 mm) and large (38.1 mm) sizes is investigated. A 150-mm diameter triaxial testing device was used to conduct a drained compression test at five strain rates, ranging from 0.000083%/s to 0.0083%/s. To evaluate the significance of confining stress and density on the effect of strain rates, the shear tests were conducted at 34 kPa and 207 kPa effective confining stress levels, with the samples compacted at loose (30%) and dense (95%) relative densities. The peak friction angle, maximum dilation angle, secant modulus, and axial strain at which the aggregates started to dilate were determined to evaluate the strain rate effect on the shear behavior of OGAs. The results demonstrate that within the imposed quasistatic strain rate ranges, only the dilation angle showed an increasing trend with the increase in strain rate, whereas other extracted strength parameters were less sensitive to strain rate for both OGAs tested. Hence, the selection of strain rates according to ASTM specifications is appropriate for conducting strength parameter tests, used by practitioners for the design of geotechnical structures, on OGAs under quasistatic conditions.

scholarly journals Fracture Initiation in Notched Specimens Subjected to Compression: Strain Rate Effect

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2613
Author(s):  
Elżbieta Bura ◽  
Andrzej Seweryn
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Fracture Process ◽  
Fracture Initiation ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Specimen Thickness ◽  
Strain Rates ◽  
Notched Specimens ◽  
Compression Strain

This paper shows the results of an experimental investigation on fracture in polymethyl methacrylate (PMMA) notched specimens subjected to compression (with unloading) including different strain rates. Three types of notches were used. Flat specimens were weakened by two types of V-notches and U-notches. Additionally, two specimen thicknesses were used (9.7 and 14.5 mm). The load was carried out at the strain rate of 8 × 10−4, 4 × 10−3, and 2 × 10−2 s−1 and the unloading stage was conducted ten times faster, i.e., 8 × 10−3, 4 × 10−2, and 2 × 10−1 s−1, respectively. By using a PHANTOM high-speed camera, fracture initiation moments and locations were indicated. Two types of crack were observed and distinguished as A-type and B-type. The first was formed by the contact stress of the closing notch surfaces, while the latter was formed by the residual stresses during the unloading stage. The type of notch, specimen thickness, and the strain rate have a significant influence on the fracture process. The strain rate has a large impact on the critical load value, which determines the fracture initiation, but does not affect the location and shape of the crack. The strain rate effect usually disappears with increasing specimen thickness.

Tensile Behavior of Unidirectional Carbon Reinforced Composites for Aerospace Structures under Varying Strain Rates

2015 ◽  
Vol 798 ◽  
pp. 357-361 ◽  
Author(s):  
Haris A. Khan ◽  
Mehr Nigar ◽  
Imran Ali Chaudhry
Keyword(s):  
Strain Rate ◽  
Volume Fraction ◽  
Testing Machine ◽  
Tensile Modulus ◽  
Failure Behavior ◽  
Strain Rates ◽  
Loading Rates ◽  
Matrix Volume ◽  
Versus Strain ◽  
Fiber Reinforced Laminates

This paper focuses on progressive damage investigation and failure analysis of carbon fiber reinforced laminates under varying strain rates in tensile mode. Samples specimen prepared for experiments were made from unidirectional ply with 70/30 fiber-matrix volume fraction and cross-ply (0°-90°) balanced stacking. These laminates were subjected to uniaxial longitudinal tensile loading in a Universal Testing Machine (UTM) with varying strain rates. Results acquired from the experiments were used to plot stress versus strain curves for different strain rates. These plots were subsequently analyzed to investigate the effect of varying loading rates on the mechanical properties and failure behavior of these composites. Experimental data revealed a considerable increase in the tensile strength with increasing strain rate. The tensile modulus and strain to failure were also found to exhibit slight increase with the increasing strain rate.

Effect of Foam Structure on Impact Compressive Properties in Foamed Polyethylene Film

2016 ◽  
Vol 715 ◽  
pp. 159-164 ◽  
Author(s):  
Kohei Tateyama ◽  
Hiroyuki Yamada ◽  
Nagahisa Ogasawara
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Polyethylene Film ◽  
Elastic Response ◽  
Hopkinson Pressure Bar ◽  
Compressive Properties ◽  
Foam Structure ◽  
The Impact

The purpose of this study is to elucidate the effect of foam structure on the impact compressive properties of foamed polyethylene film. Three types of foamed PE film were prepared, which have different foam structure: base type, spheral type and dense type. A quasi-static test was performed using a universal testing machine at the strain rate of 10-3~10-1s-1. Impact tests were carried out using a drop-weight testing machine at the strain rate of 101~102s-1 and using a split Hopkinson pressure bar method at the strain rate of approximately 103s-1. It was confirmed that the foamed PE film shows an increase of the flow stress with increasing of the strain rate, regardless of the specimen type. In the spheral type specimen, the elastic response is observed immediately after compression because the cell shape of this specimen has high bending resistance in comparison with the other two specimens. In addition, it is confirmed that the relative density and cell size affects the flow stress in the foamed PE film.

scholarly journals Mechanical characterization and numerical modeling of TPMS lattice structures subjected to impact loading

2021 ◽  
Vol 250 ◽  
pp. 02005
Author(s):  
Rafael Santiago ◽  
Sarah Almahri ◽  
Dong-Wook Lee ◽  
Haleimah Alabdouli ◽  
Omar Banabila ◽  
...  
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
High Energy ◽  
Image Correlation ◽  
Dynamic Strain ◽  
Correlation Technique ◽  
Fe Model ◽  
Strain Rates ◽  
The Impact ◽  
Constitutive Parameters

The advent of Powder Bed Fusion (PBF) techniques allows the additive manufacturing of complex structures, as Triply Periodic Minimal Surfaces (TPMS) lattices, which exhibit promising characteristics for impact applications, such as lightweight and high-energy absorption. Thus, this work aims to develop a numerical model of TPMS structures to investigate the mechanical response of such structures when subjected to impact loadings. To fulfill this task, stainless steel samples made by PBF technique were mechanically characterized at different strain rates using a universal testing machine and Split Hopkinson Pressure Bar. The testing campaign also explored the compressive and tensile material response, with the strain field being monitored by Digital Image Correlation technique. It was noted that the material exhibits a similar elasto-plastic response on both tension and compression and an evident strain rate hardening when the material is loaded from static (0.001 s-1) to dynamic strain rates (4000 s-1). Constitutive parameters were then obtained and implemented in an explicit finite element model developed through Abaqus CAE. Samples of TMPS lattices were manufactured and tested at different loading velocities, which showed that the FE model developed can be used to predict the impact response of TMPS lattices.

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