scholarly journals Dynamic Strength and Anisotropy of Dmls Manufactured Maraging Steel

2019 ◽  
Vol 21 (3) ◽  
pp. 35-39
Author(s):  
Eva Schmidova ◽  
Premysl Hojka ◽  
Bohumil Culek ◽  
Filip Klejch ◽  
Michal Schmid
Keyword(s):  
Strain Rate ◽  
Maraging Steel ◽  
Testing Machine ◽  
Dynamic Strength ◽  
Hydraulic Testing ◽  
Wall Structure ◽  
Thin Wall ◽  
Indentation Tests ◽  
Structural Parts ◽  
Strain Rate Loading

This paper deals with maraging steel, as a prospective material for the 3D printed lightened structural parts of transport means. Direct Metal Laser Sintering technology was tested for creation of a thin-wall structure with defined internal geometry. The referential samples prepared by the DMLS technology were examined under quasi-static and high strain rate loading using a servo-hydraulic testing machine at strain rates up to 1400 s-1. Microstructural analyses served for evaluation of structural homogeneity and metallurgy quality, including the influence of crystallization gradient. The stabile ductile fracture mode was proven by fractography analyses, even at a maximal strain rate. The post-impact tests were conducted to evaluate the local residual plasticity by indentation tests.

Strain-Rate Sensitivity of Concrete: Influence of Moisture Content

2006 ◽  
Vol 326-328 ◽  
pp. 1661-1664
Author(s):  
Gao Lin ◽  
Dong Ming Yan
Keyword(s):  
Moisture Content ◽  
Strain Rate ◽  
Earthquake Engineering ◽  
Testing Machine ◽  
Dynamic Strength ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Hydraulic Testing ◽  
Wide Range ◽  
Compressive Tests

Understanding the behavior of concrete under dynamic loading conditions is an issue of great significance in earthquake engineering. Moisture content has an important influence on the strain-rate effect of concrete. In this study, both tensile and compressive experiments were carried out to investigate the rate-dependent behavior of concrete. Tensile experiments of dumbbell-shaped specimens were conducted on a MTS810 testing machine and compressive tests of cubic specimens were performed on a servo-hydraulic testing machine designed and manufactured at Dalian University of Technology, China. The strain rate varied in a wide range. The analytical formulations between the dynamic strength and strain rate were proposed for both compressive tests and tensile tests. It was concluded from the results that with the increasing strain rate, strengths of specimens with both moisture contents tended to increase and the increase seemed to be more remarkable for the saturated specimens; based on the experimental observation, a better explanation for the dynamic behavior is presented.

scholarly journals Review of Intermediate Strain Rate Testing Devices

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 894
Author(s):  
Trunal Bhujangrao ◽  
Catherine Froustey ◽  
Edurne Iriondo ◽  
Fernando Veiga ◽  
Philippe Darnis ◽  
...  
Keyword(s):  
Strain Rate ◽  
Measurement Techniques ◽  
Testing Machine ◽  
Hydraulic Testing ◽  
Manufacturing Processes ◽  
Strain Rates ◽  
General Description ◽  
Intermediate Strain Rate ◽  
Friction Stir ◽  
Rate Testing

Materials undergo various loading conditions during different manufacturing processes, including varying strain rates and temperatures. Research has shown that the deformation of metals and alloys during manufacturing processes such as metal forming, machining, and friction stir welding (FSW), can reach a strain rate ranging from 10−1 to 106 s−1. Hence, studying the flow behavior of materials at different strain rates is important to understanding the material response during manufacturing processes. Experimental data for a low strain rate of <101 s−1 and a high strain rate of >103 s−1 are readily available by using traditional testing devices such as a servo-hydraulic testing machine and the split Hopkinson pressure bar method, respectively. However, for the intermediate strain rate (101 to 103 s−1), very few testing devices are available. Testing the intermediate strain rate requires a demanding test regime, in which researchers have expanded the use of special instruments. This review paper describes the development and evolution of the existing intermediate strain rate testing devices. They are divided based on the loading mechanism; it includes the high-speed servo-hydraulic testing machines, hybrid testing apparatus, the drop tower, and the flywheel machine. A general description of the testing device is systematically reviewed; which includes the working principles, some critical theories, technological innovation in load measurement techniques, components of the device, basic technical assumption, and measuring techniques. In addition, some research direction on future implementation and development of an intermediate strain rate apparatus is also discussed in detail.

EFFECT OF MICROSTRUCTURES ON THE DYNAMIC DEFORMATION BEHAVIOR OF Ti-6Al-4V ALLOY

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1221-1227
Author(s):  
JIN-YOUNG KIM ◽  
IN-OK SHIM ◽  
SOON-HYUNG HONG
Keyword(s):  
Strain Rate ◽  
Strain Hardening ◽  
Volume Fraction ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Deformation ◽  
Testing Machine ◽  
Hydraulic Testing ◽  
Deformation Condition ◽  
Strain Hardening Exponent ◽  
Hopkinson Pressure Bar

The effects of microstructures of Ti -6 Al -4 V alloy on the flow stresses and fracture behaviors at quasi-static and dynamic deformation conditions were investigated. Specimens of different sizes and fractions of α globules in equiaxed and bimodal structures were compressed at the strain rate of 2×10−3/ s and 3×103/ s using hydraulic testing machine and split Hopkinson pressure bar, respectively. The a globule size in equiaxed structure changed the level of flow stresses, but did not affect the strain hardening characteristics. Meanwhile, the volume fraction of α globule (or lamellar phase) in bimodal structures influenced both the flow stress and strain hardening exponent at quasi-static and dynamic deformation conditions. Bimodal structure of 50% lamellar fraction is considered to be more favorable in dynamic deformation condition at strain rate regime of 3×103/ s than equiaxed or bimodal one having higher lamellar fraction.

Mechanical Properties of High Density Polyethylene (HDPE)/Sawdust Composites under Wide Range of Strain Rate

2015 ◽  
Vol 754-755 ◽  
pp. 83-88 ◽  
Author(s):  
Mohd Firdaus Omar ◽  
Haliza Jaya ◽  
Hazizan Md. Akil ◽  
Zainal Arifin Ahmad ◽  
N.Z. Noriman
Keyword(s):  
Strain Rate ◽  
Static Loading ◽  
Experimental Approach ◽  
Testing Machine ◽  
Damage Analysis ◽  
Static Compression ◽  
Compression Properties ◽  
Wide Range ◽  
Strain Rate Loading ◽  
Low Strain Rate

An experimental approach based on the conventional universal testing machine (UTM) was employed to perform low strain rate loading (0.001/s, 0.01/s and 0.1/s) in this research, to examine the reliance of natural filler contents towards HDPE/sawdust composites. By following to the low strain rate loading, static compression properties of HDPE/sawdust composites with varies filler contents of 5 wt% SD, 10 wt% SD, 15 wt% SD, 20 wt% SD and 30 wt: % SD were successfully studied. The results show that the yields stress, ultimate compression strength and the rigidity properties of HDPE/sawdust composites were sturdily affected by both filler contents and strain rate loadings. Moreover, for the post damage analysis, the results clearly show that different static loading employed to the specimens gives significant effects towards deformation behavior of HDPE/sawdust composites. The increasing of static loading employed caused the specimens to experience severe deformation.

Dynamic Strength of Steel Welds under High Strain Rate Loading

2005 ◽  
Vol 9 ◽  
pp. 87-92 ◽  
Author(s):  
B. Wang ◽  
Guo Xing Lu
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Dynamic Strength ◽  
Rate Sensitivity ◽  
Steel Material ◽  
Base Steel ◽  
Steel Welds ◽  
Strain Rate Loading ◽  
Q Values

An experimental study was conducted to investigate the dynamic strength of steel welds under high strain rate loadings. Flow stresses of both the base steel material and the weld filament were obtained under strain rate loadings of up to 9 × 102 s-1. The data was then fitted to the Cowper-Simmons [1] relation with the D and q values given. The finding helps to understand the strain rate sensitivity of the base and welded materials.

Mechanical Behavior of Metals in Dynamic Compression

1979 ◽  
Vol 101 (3) ◽  
pp. 238-247 ◽  
Author(s):  
A. J. Holzer ◽  
R. H. Brown
Keyword(s):  
Strain Rate ◽  
Dynamic Compression ◽  
Testing Machine ◽  
Hydraulic Testing ◽  
Strain Rate Range ◽  
Load Cell ◽  
Fast Fourier Transformation ◽  
Compression Tests ◽  
Stress Strain ◽  
High Frequency Response

A technique for the measurement of force and displacement data in metal processing at high rates of deformation is described briefly. Forces are determined by fast Fourier transformation of the signal from a quartz load cell and correction in the frequency domain for dynamic response of the load cell. Displacement is measured by a high frequency response fiber-optic transducer. The force and displacement signals are processed by an on-line computer which enables stress, strain, strain-rate, and other parameters to be determined and plotted rapidly. Results from continuous dynamic compression tests are presented in the form of computer generated stress-strain and stress-strain rate curves for two steels. In the strain rate range 10−3 s−1 to 102 s−1 an hydraulic testing machine is used. In the range 102 s−1 to 104 s−1 a drop forge is used. A discussion of the effects of specimen geometry in compression testing is included.

The Combined Effect of Grain Size and Strain Rate on the Mechanical Behavior in Ultra-High Purity Aluminum

2011 ◽  
Vol 179-180 ◽  
pp. 662-667
Author(s):  
Yong Gang Wang ◽  
Chun Lei Wang ◽  
Hong Wei Liu
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Flow Stress ◽  
Strain Rate ◽  
Pure Aluminum ◽  
Testing Machine ◽  
Tensile Tests ◽  
Hydraulic Testing ◽  
Petch Relation ◽  
Split Hopkinson

The effect of grain size on the mechanical properties in ultra-high pure aluminum had been investigated as a function of strain rate. Specimens with average grain diameter sizes of 243, 678 and 1070 m were compressed and elongated at quasi-static and high strain rates by a computer controlled servo-hydraulic testing machine and a Split Hopkinson Pressure (Tension) Bar (SHPB and SHTB). The mechanical properties were found to vary significantly with grain size, and strain rate. The relationship between flow stress and grain size can be expressed by a Hall - Petch relation with the different slope for both compressive tests and tensile tests. The influence of strain rate on the slope of the Hall - Petch relation is such that in compression, the slope does not change much, but in tension, there is an increase in the slope value. The strain hardening rate was seen to increase with increasing strain rate. The strain rate dependence of flow stress is obvious, and is seen to be more significant for the smallest grain size specimens. The 3D fractographs illustrated that the numbers of the dimples decrease with the increase of the grain size.

Observation of dislocations in dynamically loaded Cu-SiO2

1986 ◽  
Vol 44 ◽  
pp. 424-425
Author(s):  
D. S. Pritchard
Keyword(s):  
Electron Microscope ◽  
Strain Rate ◽  
Single Crystal ◽  
Transmission Electron Microscope ◽  
Volume Fraction ◽  
Screw Dislocations ◽  
Spherical Inclusions ◽  
Transmission Electron ◽  
Crystal Dispersion ◽  
Strain Rate Loading

The effect of varying the strain rate loading conditions in compression on a copper single crystal dispersion-hardened with SiO2 particles has been examined. These particles appear as small spherical inclusions in the copper lattice and have a volume fraction of 0.6%. The structure of representative crystals was examined prior to any testing on a transmission electron microscope (TEM) to determine the nature of the dislocations initially present in the tested crystals. Only a few scattered edge and screw dislocations were viewed in those specimens.

HIGH STRAIN RATE LOADING OF ZIRCALOY

1985 ◽  
Vol 46 (C5) ◽  
pp. C5-511-C5-516
Author(s):  
A. Kobayashi ◽  
S. Hashimoto ◽  
Li-lih Wang ◽  
M. Toba
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Strain Rate Loading
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