Effect of Initial Static Load on the Rate-Sensitive Behavior of Concrete in Compression

2006 ◽  
Vol 326-328 ◽  
pp. 1109-1112
Author(s):  
Dong Ming Yan ◽  
Gao Lin
Keyword(s):  
Strain Rate ◽  
Static Load ◽  
Dynamic Properties ◽  
Concrete Structures ◽  
Dynamic Strength ◽  
Rate Sensitivity ◽  
Static Loads ◽  
Dynamic Loadings ◽  
Strength And Deformation ◽  
The Relationship

Before concrete structures are subjected to dynamic loadings such as earthquake, usually they have already withstood static loads. Accordingly, the study on the strain-rate sensitivity of concrete should also be closely related to the initial static loads that concrete structures experience. But majority of the available documents concerning the dynamic properties of concrete do not take initial static load into consideration. In this study, experiments were carried out to investigate the effect of initial static load on the dynamic strength and deformation characteristics of concrete in compression. A load was initially applied on the specimen at a very low speed to a specified value and then the dynamic load was applied at a high strain rate up to the failure of the specimen. From the test results it was revealed that the initial static load had significant influence on the dynamic strength. The dynamic strength tended to decrease as initial static load increased. An exponential function was proposed to formulate the relationship between the initial static load and the dynamic strength.

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 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.

The strain-rate sensitivity of the hardness in indentation creep

2007 ◽  
Vol 22 (4) ◽  
pp. 926-936 ◽  
Author(s):  
A.A. Elmustafa ◽  
S. Kose ◽  
D.S. Stone
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Hertzian Contact ◽  
Indentation Creep ◽  
Proportionality Factor ◽  
Element Analysis ◽  
Elastic Deformations ◽  
The Relationship

Finite element analysis is used to simulate indentation creep experiments with a cone-shaped indenter. The purpose of the work is to help identify the relationship between the strain-rate sensitivity of the hardness, νH, and that of the flow stress, νσ in materials for which elastic deformations are significant. In general, νH differs from νσ, but the ratio νH/νσ is found to be a unique function of H/E* where H is the hardness and E* is the modulus relevant to Hertzian contact. νH/νσ approaches 1 for small H/E*, 0 for large H/E*, and is insensitive to work hardening. The trend in νH/νσ as a function of H/E* can be explained based on a generalized analysis of Tabor’s relation in which hardness is proportional to the flow stress H = k × σeff and in which the proportionality factor k is a function of σeff/E*.

Quasi-Static and Dynamic Compressive Properties of AZ31 Magnesium Alloy Processed by Equal Channel Angular Pressing

2014 ◽  
Vol 566 ◽  
pp. 86-91
Author(s):  
Xia Yu ◽  
Tao Suo ◽  
Feng Zhao ◽  
Yu Long Li
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
Equal Channel Angular Pressing ◽  
Rate Sensitivity ◽  
Compressive Properties ◽  
Compression Properties ◽  
Angular Pressing ◽  
Strength Failure ◽  
Dynamic Loadings ◽  
Az31b Alloy

Equal channel angular pressing (ECAP) was applied to control the microstructure of AZ31B magnesium alloy. Compression properties of both as-received and grain refined AZ31B alloy were investigated under quasi-static and dynamic loadings. The yield strength, ultimate strength, failure strain and flow stress under compression loading were studied. Both the as-received alloy and ECAPed alloy show strong strain rate sensitivity. Grain size, texture and strain rate jointly affect the deformation mechanisms. Through fractography analysis, the fracture mechanism was analyzed.

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.

An Experimental Evaluation on Change in Impedance of TRIP Steel Subjected to Plastic Deformation at Various Strain Rates

2013 ◽  
Vol 535-536 ◽  
pp. 445-448 ◽  
Author(s):  
Daiki Inoshita ◽  
Shiro Yamanaka ◽  
Takeshi Iwamoto
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Martensitic Transformation ◽  
Strain Rate ◽  
Trip Steel ◽  
Rate Sensitivity ◽  
Volume Resistivity ◽  
Strain Rates ◽  
Trip Steels ◽  
The Relationship

For automotive industries, weight of an automobile can be reduced if TRIP steel which has excellent mechanical properties dominated by strain-induced martensitic transformation (SIMT) can be applied to shock absorption members. However, strain rate sensitivity of TRIP steels has not been fully understood because a relationship between a strain rate and an amount of martensite produced by SIMT is still unclear. In previous studies, volume resistivity and impedance have been measured to obtain information on the amount of produced martensite, however, these studies have not been succeeded to clarify the relationship. Here, by focusing a property that martensite shows ferromagnetism, it is attempted that impedance of TRIP steel is measured at various strain rates during the deformation by using prototype coil and circuits.

Dynamic Response of Magnesium Alloy AZ31B under High Strain Rate Compressive Loading

2011 ◽  
Vol 83 ◽  
pp. 60-65 ◽  
Author(s):  
Iram Raza Ahmad ◽  
Dong Wei Shu
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
High Speed ◽  
Dynamic Properties ◽  
Weight Ratio ◽  
Rate Sensitivity ◽  
Consumer Electronics ◽  
Magnesium Alloy Az31b ◽  
Wide Range ◽  
Structural Applications

Magnesium alloys have been increasingly used in automobile, aerospace, consumer electronics and communication industries due to their low density, high strength to weight ratio, good impact resistance and castability. Impact situations in vehicles and airplanes and high speed metal working are characterized with the high rates of loading. The dynamic properties of materials are critical to evaluate the materials’ response in impact situations. They are also useful to design various automotive and aerospace components that are subjected to high rates of loadings. In current study, the compressive behaviour of magnesium alloy AZ31B has been examined over a wide range of strain rate between 103 and 3x103 s-1 in order to evaluate its potential in structural applications. Higher stresses are observed at higher strain rates. The peak stress increases about 10% for an increase in the strain rate from 980 s-1 to 2450 s-1. The hardening exponent n increases from 0.65 to 0.72 with increasing strain rate from 980 s-1 to 2450 s-1 indicating that the alloy is rate sensitive. However, the rate sensitivity of the alloy is negligible at lower strains and is significantly higher at higher strains. Energy absorption during deformation in general is increased with the strain rate.

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.

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