scholarly journals Rate-Dependent Scaling of Dynamic Tensile Strength of Quasibrittle Structures

2017 ◽  
Vol 85 (2) ◽  
Author(s):  
Jia-Liang Le ◽  
Jan Eliáš ◽  
Anna Gorgogianni ◽  
Joshua Vievering ◽  
Josef Květoň
Keyword(s):  
Tensile Strength ◽  
Standard Deviation ◽  
Strain Rate ◽  
Size Effects ◽  
Dynamic Tensile Strength ◽  
Rate Dependent ◽  
Weakest Link ◽  
Nominal Tensile Strength ◽  
The Mean ◽  
Link Model

This paper investigates the effect of strain rate on the scaling behavior of dynamic tensile strength of quasibrittle structures. The theoretical framework is anchored by a rate-dependent finite weakest link model. The model involves a rate-dependent length scale, which captures the transition from localized damage to diffused damage with an increasing strain rate. As a result, the model predicts a rate- and size-dependent probability distribution function of the nominal tensile strength. The transitional behavior of the strength distribution directly leads to the rate and size effects on the mean and standard deviation of the tensile strength. The model is verified by a series of stochastic discrete element simulations of dynamic fracture of aluminum nitride specimens. The simulations involve a set of geometrically similar specimens of various sizes subjected to a number of different strain rates. Both random microstructure geometry and fracture properties are considered in these simulations. The simulated damage pattern indicates that an increase in the strain rate results in a more diffusive cracking pattern, which supports the theoretical formulation. The simulated rate and size effects on the mean and standard deviation of the nominal tensile strength agree well with the predictions by the rate-dependent finite weakest link model.

scholarly journals CORRELATIONS OF THE MEAN TIME AND MEAN MAGNITUDE OF ACCELERATING PRESHOCKS WITH THE ORIGIN TIME AND MAGNITUDE OF MAINSHOCK

2017 ◽  
Vol 43 (4) ◽  
pp. 2154
Author(s):  
E. M. Scordilis
Keyword(s):  
Standard Deviation ◽  
South America ◽  
Strain Rate ◽  
Central Asia ◽  
Earthquake Prediction ◽  
Critical Region ◽  
Origin Time ◽  
The Mean ◽  
Benioff Strain ◽  
Mean Time

Forty-five preshock sequences preceding corresponding strong (M≥6.4) mainshocks which occurred recently (since 1980) in a variety of seismotectonic regimes (W. Mediterranean, Aegean, Anatolia, California, Japan, Central Asia, South America) have been examined to identify new predictive properties. It has been observed that the mean origin time, , and the mean magnitude, of the accelerating preshocks of each sequence are correlated with the origin time, tc, and the magnitude, M, of the mainshock, respectively. The following relations have been derived: where sa (in Joule ½ /yr.104 Km2 ) is the Benioff strain rate in each preshock (critical) region and σ is the corresponding standard deviation. The possibility for using these relations as constraints in attempts for intermediate term earthquake prediction is discussed.

Comparative study of tensile tests based on Hopkinson bar for recycled aggregate concrete

2018 ◽  
Vol 10 (1) ◽  
pp. 26-53
Author(s):  
Junzhou Duan ◽  
Yubin Lu ◽  
Shu Zhang ◽  
Xiquan Jiang
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Coarse Aggregate ◽  
Tensile Tests ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Dynamic Tensile Strength ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Direct Tensile

To comparatively study the tensile properties and fracture patterns of recycled aggregate concrete with various replacement percentages (i.e. 0%, 25%, 50%, 75%, and 100%) of recycled coarse aggregate, the dynamic direct tensile tests, splitting tests, and spalling tests of recycled aggregate concrete in the strain-rate range of 100–102 s−1 were carried out using large diameter (75 mm) split Hopkinson tensile bar and pressure bar. Test results show that for recycled aggregate concrete, the quasi-static direct tensile strength is more marvelous than its quasi-static splitting strength. When recycled coarse aggregate replacement percentage is 0%–75%, the replacement percentage impact minimally on the quasi-static tensile strength of recycled aggregate concrete. In dynamic tensile tests, there exists apparent difference between the dynamic direct tensile strength and dynamic splitting. The dynamic tensile strength of recycled aggregate concrete increases with the increase of average strain-rate in all three kinds of tests. The average strain-rate affects the damage form of recycled aggregate concrete, which indicates that the recycled aggregate concrete has obvious rate sensitivity. There shows no obvious regularity between the dynamic tensile strength and the recycled coarse aggregate replacement percentage. And the indirect tensile strength calculation method used in this article offers the theoretical basis for the engineering application of recycled aggregate concrete.

Effect of the Strain Rate and Water Saturation for the Dynamic Tensile Strength of Rocks

2004 ◽  
Vol 465-466 ◽  
pp. 361-366 ◽  
Author(s):  
Yuji Ogata ◽  
Woo-jin Jung ◽  
Shiro Kubota ◽  
Yuji Wada
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Water Saturation ◽  
Dynamic Tensile Strength

scholarly journals Experimental and Numerical Study on Tensile Strength of Concrete under Different Strain Rates

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Fanlu Min ◽  
Zhanhu Yao ◽  
Teng Jiang
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Numerical Study ◽  
Material Behavior ◽  
Constitutive Law ◽  
Test Machine ◽  
Strain Rates ◽  
Dynamic Tensile Strength ◽  
Dynamic Increase Factor ◽  
Versus Strain

The dynamic characterization of concrete is fundamental to understand the material behavior in case of heavy earthquakes and dynamic events. The implementation of material constitutive law is of capital importance for the numerical simulation of the dynamic processes as those caused by earthquakes. Splitting tensile concrete specimens were tested at strain rates of 10−7 s−1to 10−4 s−1in an MTS material test machine. Results of tensile strength versus strain rate are presented and compared with compressive strength and existing models at similar strain rates. Dynamic increase factor versus strain rate curves for tensile strength were also evaluated and discussed. The same tensile data are compared with strength data using a thermodynamic model. Results of the tests show a significant strain rate sensitive behavior, exhibiting dynamic tensile strength increasing with strain rate. In the quasistatic strain rate regime, the existing models often underestimate the experimental results. The thermodynamic theory for the splitting tensile strength of concrete satisfactorily describes the experimental findings of strength as effect of strain rates.

The Behavior of Carbon Black-Filled Natural Rubber under High Strain Rates3

2006 ◽  
Vol 34 (2) ◽  
pp. 119-134 ◽  
Author(s):  
Syeda A. Hussain ◽  
Michelle S. Hoo Fatt
Keyword(s):  
Tensile Strength ◽  
Carbon Black ◽  
Natural Rubber ◽  
Strain Rate ◽  
Characteristic Relaxation Time ◽  
Dynamic Tensile Strength ◽  
Extension Ratio ◽  
Strain Induced Crystallization ◽  
Quasistatic Loading ◽  
Induced Crystallization

Abstract Tensile tests were conducted to obtain the deformation and failure characteristics of unfilled natural rubber (NR) and natural rubber with 25, 50, and 75 phr of N550 carbon black filler under quasistatic and dynamic loading conditions. The quasistatic tests were performed on an electromechanical INSTRON machine, while the dynamic test data were obtained from tensile impact experiments using a Charpy impact apparatus. In general, the modulus of the stress-extension ratio curves increases with increasing strain rate up to about 407, 367, 346, and 360 s−1 for unfilled, and 25, 50, and 75 phr for filled NR, respectively. Above these strain rates, the unfilled and filled natural rubber stress-extension ratio curves remained unchanged. The modulus increased with increasing strain rate because there was little time for stress relaxation. Above a critical strain rate, no change in modulus was observed because the time of the experiment was short compared to the lowest characteristic relaxation time of the material. Dynamic stress-extension ratio curves did not have the very sharp upturn at break, which is observed from strain-induced crystallization in natural rubber under quasistatic loading. Strain-induced crystallization appeared to be suppressed at high rates of loading. In fact, the highest dynamic tensile strength for the 25- and 50-phr carbon black-filled natural rubbers was smaller than those under quasistatic loading, while the highest dynamic tensile strength of the 75-phr carbon black-filled NR was greater than that in the static test. This indicated that high amounts of carbon black fillers will impede strain-induced crystallization in natural rubber.

Variability Assessment of the Compressive and Tensile Strength of Fibred Earthen Composites

2022 ◽  
Author(s):  
Philippe Poullain ◽  
Mircea Barnaure ◽  
Stéphanie Bonnet
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Standard Deviation ◽  
Probability Density Function ◽  
Building Materials ◽  
Mean Value ◽  
Rammed Earth ◽  
The Mean ◽  
The Many

Earthen composites (rammed earth, cob, adobe, daub, CEB...) are experiencing renewed interest from builders due to the many advantages of these building materials, and in particular their eco-friendliness. Nevertheless, the widespreading of these materials, as certified materials and conforming to construction standards, comes against the lack of data concerning their mechanical properties. Indeed, the literature generally gives the average values of the properties without indicating the number of specimens tested neither the distribution of the data. Yet, the mean value of the compressive strength is not enough to assess the reliability of a given earthen composite to build a wall and it would be better to indicate the value of a defined percentile (characteristic value just like with concrete composites). The aim of this paper is to analyze the data about the mechanical properties (tensile and compressive strength) obtained on different formulations of cob including natural fibres or not. The tests performed allowed to determine the probability density function and the average values, the standard deviation and the percentiles, for the various properties.

Modeling and Testing Strain Rate-Dependent Tensile Strength of Carbon/Epoxy Composites

2007 ◽  
Vol 353-358 ◽  
pp. 1418-1421 ◽  
Author(s):  
Gui Ping Zhao ◽  
Zheng Hao Wang ◽  
Jian Xin Zhang ◽  
Qiao Ping Huang
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Strain Rate Range ◽  
Split Hopkinson Tensile Bar ◽  
Rate Dependent ◽  
Dependent Behavior ◽  
Split Hopkinson ◽  
Rate Experiment ◽  
Epoxy Matrix Composite ◽  
Dependent Model

Tensile strength is an important material property and usually can be determined experimentally. The strain rate dependent behavior of T300 carbon/epoxy matrix composite was characterized over a wide strain rate range (10×10-5 s-1to10×104s-1). The low to moderate strain rate experiments were carried out on a MTS machine, while the high strain rate experiment was conducted with a split Hopkinson tensile bar. A rate dependent model was introduced to simulate the material response. Two kinds of stacking sequence of composite specimens [(45/-45)4]s and [(0/45/90/-45)2]s were tested at different strain rates, and the results were used to determine parameters of the model. The predictions of the model showed to agree fairly well with the experimental results. The tensile strength and initial elastic modulus of the composites increase when the strain rate increases.

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