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.

A Study on Rate Sensitivity of Impedance in TRIP Steel during Deformation at Various Strain Rate under Two Kinds of Deformation Mode

2014 ◽  
Vol 566 ◽  
pp. 140-145
Author(s):  
Daiki Inoshita ◽  
Takeshi Iwamoto
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Trip Steel ◽  
Testing Machine ◽  
Rate Sensitivity ◽  
Deformation Mode ◽  
Tensile Tests ◽  
Material Testing ◽  
Trip Steels ◽  
Material Testing Machine

TRIP steel possesses excellent mechanical properties dominated by strain-induced martensitic transformation (SIMT). For automotive industries, if TRIP steel can be applied to shock absorption members, it can be considered that the weight of automobile can be reduced. However, the strain rate sensitivity of TRIP steels has not been fully understood because the strain rate sensitivity and the deformation mode dependency of SIMT are still unclear. Therefore, it is important to reveal these sensitivity and dependency for confirming a reliability of TRIP steel. Therefore, in this study, it is attempted to estimate the amount of produced martensite in TRIP steel by measuring the inductance of TRIP steel. The specimen made of TRIP steel is used as a core of a prototype coil manufactured in this study. Then, the compressive and tensile tests are conducted by using a material testing machine and a drop weight testing machine using the specimen inside the coil. The inductance of the coil with the deformed specimen are measured continuously during the tests.

Strain-Rate Sensitivity of Concrete: Influence of Temperature

2011 ◽  
Vol 243-249 ◽  
pp. 453-456
Author(s):  
Dong Ming Yan ◽  
Wei Xu
Keyword(s):  
Low Temperature ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Dynamic Properties ◽  
Testing Machine ◽  
Concrete Structures ◽  
Free Water ◽  
Rate Sensitivity ◽  
Influence Of Temperature ◽  
Wide Range

Knowledge about the dynamic properties of concrete is vital to the design and safety evaluation of large-scale concrete structures subjected to seismic excitation. There are many factors affecting the dynamic properties of concrete such as moisture content and temperature. Though a lot of concrete structures have been designed to withstand low temperature, research on the strain-rate sensitivity of concrete under low temperature condition is still very limited so far. In this study, both tensile and compressive experiments were carried out to investigate the influence of temperature on the rate-dependent characteristics of concrete. Tensile experiments of dumbbell-shaped specimens were carried out on a MTS810 testing machine and compressive tests on cubic specimens were performed using a servo-hydraulic testing machine. Specimens at two types of temperature, room temperature 20oC and low temperature -30oC, were characterized. The strain rate varied over a wide range. It was concluded from the test data that the strengths of specimens at both types of temperature tended to increase as strain rate increased. Temperature had slight influence on the rate-sensitive behavior of concrete when concrete specimens were dry; however, test on saturated specimens indicated that the role of temperature on the mechanical behavior of concrete subject to dynamic loading was very significant. This phenomenon may be attributed to the state of free water in concrete.

scholarly journals Strain rate sensitivity of the aluminium-magnesium-scandium alloy - Scalmalloy®

2021 ◽  
Vol 250 ◽  
pp. 05014
Author(s):  
Puneeth Jakkula ◽  
Georg Ganzenmüller ◽  
Florian Gutmann ◽  
Stefan Hiermaier
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Testing Machine ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Image Correlation ◽  
Strain Rates ◽  
Rate Dependency ◽  
Strain Rate Dependency ◽  
Scandium Alloy

This work investigates the strain rate sensitivity of the aluminiummagnesium-scandium alloy Scalmalloy, which is used extensively for additive manufacturing of lightweight structures. This high strength aluminium alloy combines very good weldability, machinability and mechanical strength: it can be heat-treated to reach nominal ultimate tensile strengths in excess of 500 MPa. We report tensile tests at strain rates ranging from 10−3 /s to 103 /s at room temperature. It is well known that Al-Mg alloys exhibit a negative strain rate dependency in combination with serrated flow caused by the Portevin-Le Chatelier effect, which describes the interaction of Mg solutes with dislocation propagations. In contrast, in Al-Sc alloys, the flow stress increases with increasing strain rate and displays positive strain rate dependency. Additionally, the presence of Sc in the form of Al3-Sc provides a fine-grained microstructure which allows higher tensile and fatigue strength. This research shows how these combined effects interact in the case of Scalmalloy, which contains both Mg and Sc. Tests are performed at quasi-static, intermediate and high strain rates with a servohydraulic testing machine and a Split-Hopkinson tension bar. Local specimen strain was performed using 2D Digital Image Correlation.

Measurement on Strain Rate Sensitivity and Dynamic Mechanical Properties of Various Polymeric Materials

2011 ◽  
Vol 471-472 ◽  
pp. 385-390 ◽  
Author(s):  
Mohd Firdaus Omar ◽  
Md Akil Hazizan ◽  
Zainal Arifin Ahmad
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Rate Sensitivity ◽  
Polymeric Materials ◽  
Dynamic Mechanical Properties ◽  
Dynamic Mechanical ◽  
Wide Range

Strain rate sensitivity and dynamic mechanical properties of polymeric materials are affected to a certain extent especially by the rate of loading. However, there is limited number of works reported on that particular issue. Therefore, the paper presents on static and dynamic mechanical properties of various polymeric materials across strain rate from 10-2 to 10-3 s-1. The specimen were tested using universal testing machine (UTM) for static loading and a conventional split Hopkinson pressure bar (SHPB) apparatus for dynamic loading. From the results, the compression modulus and compressive strength of all tested specimen increased significantly with increasing strain rates. In addition, positive increment in terms of strain rate sensitivity was recorded for all tested polymers over a wide range of strain rate investigated. Meanwhile, the thermal activation volume has decreased as increasing strain rate. Of the three polymers, polypropylene shows the highest strain rate sensitivity at static region. On the other hand, at dynamic region, polycarbonate shows the highest strain rate sensitivity than that of polypropylene and polyethylene.

scholarly journals Low Temperature Strain Rate Sensitivity of Titanium Alloys

2016 ◽  
Vol 258 ◽  
pp. 570-573 ◽  
Author(s):  
Héloise Vigié ◽  
Thalita de Paula ◽  
Martin Surand ◽  
Bernard Viguier
Keyword(s):  
Strain Rate ◽  
Titanium Alloys ◽  
Strain Rate Sensitivity ◽  
Constant Strain Rate ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Industrial Applications ◽  
Sustained Load ◽  
Dwell Fatigue ◽  
Wide Range

Titanium alloys are widely used in many industrial applications such as in aeronautics due to their combination of good mechanical properties, excellent corrosion resistance and low density. The mechanical behaviour of titanium alloys is known to exhibit a peculiar dependence on both deformation temperature and strain rate. Titanium alloys show significant room temperature creep and they are very sensitive to dwell fatigue and sustained load cracking. This behaviour is related to the viscosity of plastic deformation in titanium alloys, which can be represented by a strain rate sensitivity (SRS) parameter. The present study aims to compare the tensile behavior of two different titanium alloys, Ti-6Al-4V and β21S, which exhibit dissimilar microstructures. Results of tensile tests, performed under constant strain rate and including strain rate changes, are reported in terms of flow stress, ductility and SRS over a wide range of temperatures.

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.

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.

Using Embossing to Create a Fiber Reinforced Honeycomb Composite

2005 ◽  
Vol 127 (2) ◽  
pp. 257-262 ◽  
Author(s):  
William Jordan
Keyword(s):  
Tensile Strength ◽  
Composite Material ◽  
Carbon Fibers ◽  
Flexural Modulus ◽  
Testing Machine ◽  
Charpy Impact ◽  
Tensile Tests ◽  
Hydraulic Testing ◽  
Charpy Impact Toughness ◽  
Bend Tests

This research project used hot embossing to create a strong and tough polymeric based composite structure. A honeycomb type structure was created by pressing small grooves into thin polycarbonate sheets. A trapezoidal die was used to create hexagonal shaped channels in the polymeric sheet. A number of these sheets were then bonded together to form a composite material. Carbon fibers were embedded into the channels in some of the laminates. The embossing process was carried out at an elevated temperature in an environmental chamber attached to an MTS servo hydraulic testing machine. The grooved structure had a 31% to 45% decrease in the apparent density compared to the ungrooved specimens. Bend tests, tensile tests, and Charpy impact tests were performed on laminates made from this material. The specific values of tensile strength, flexural modulus, and Charpy impact toughness were increased. A small percentage of fibers significantly increased both the stiffness and strength of the laminate.

Effect of Consolidation and Sintering Parameters on the Mechanical Responses of Nanocrystalline Al-Fe Alloy Processed by Mechanical Alloying

2015 ◽  
Vol 719-720 ◽  
pp. 87-90
Author(s):  
Muneer Baig ◽  
Hany Rizk Ammar ◽  
Asiful Hossain Seikh ◽  
Mohammad Asif Alam ◽  
Jabair Ali Mohammed
Keyword(s):  
Mechanical Alloying ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Compressive Loading ◽  
Rate Sensitivity ◽  
Testing Temperature ◽  
Fine Grained ◽  
Mechanical Responses ◽  
Wide Range ◽  
High Frequency Induction

In this investigation, bulk ultra-fine grained and nanocrystalline Al-2 wt.% Fe alloy was produced by mechanical alloying (MA). The powder was mechanically milled in an attritor for 3 hours and yielded an average crystal size of ~63 nm. The consolidation and sintering was performed using a high frequency induction sintering (HFIS) machine at a constant pressure of 50 MPa. The prepared bulk samples were subjected to uniaxial compressive loading over wide range of strain rates for large deformation. To evaluate the effect of sintering conditions and testing temperature on the strain rate sensitivity, strain rate jump experiments were performed at high temperature. The strain rate sensitivity of the processed alloy increased with an increase in temperature. The density of the bulk samples were found to be between 95 to 97%. The average Vickers micro hardness was found to be 132 Hv0.1.

Strain-Rate Effect on the Tensile Behaviour of High Strength Alloys

2011 ◽  
Vol 82 ◽  
pp. 124-129 ◽  
Author(s):  
Ezio Cadoni ◽  
Matteo Dotta ◽  
Daniele Forni ◽  
Stefano Bianchi
Keyword(s):  
Strain Rate ◽  
Rate Sensitivity ◽  
High Strength ◽  
Constitutive Law ◽  
Tensile Behaviour ◽  
Strain Rates ◽  
Cross Sectional ◽  
Split Hopkinson Tensile Bar ◽  
Wide Range ◽  
First Results

In this paper the first results of the mechanical characterization in tension of two high strength alloys in a wide range of strain rates are presented. Different experimental techniques were used for different strain rates: a universal machine, a Hydro-Pneumatic Machine and a JRC-Split Hopkinson Tensile Bar. The experimental research was developed in the DynaMat laboratory of the University of Applied Sciences of Southern Switzerland. An increase of the stress at a given strain increasing the strain-rate from 10-3 to 103 s-1, a moderate strain-rate sensitivity of the uniform and fracture strain, a poor reduction of the cross-sectional area at fracture with increasing the strain-rate were shown. Based on these experimental results the parameters required by the Johnson-Cook constitutive law were determined.

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