Dependency of observation parameters on soil dynamic parameters in unconfined impact compression tests

1992 ◽  
Vol 29 (3) ◽  
pp. 289-306 ◽  
Author(s):  
Sakae Shibusawa ◽  
Akira Oida
Keyword(s):  
Dynamic Parameters ◽  
Compression Tests ◽  
Impact Compression ◽  
Soil Dynamic

scholarly journals Lightweight Cement Conglomerates Based on End-of-Life Tire Rubber: Effect of the Grain Size, Dosage and Addition of Perlite on the Physical and Mechanical Properties

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 225
Author(s):  
Andrea Petrella ◽  
Michele Notarnicola
Keyword(s):  
Grain Size ◽  
End Of Life ◽  
Compression Tests ◽  
Tire Rubber ◽  
Impact Compression ◽  
Weight Percentage ◽  
Deep Groove ◽  
Mechanical Strengths ◽  
The Impact ◽  
Thermal Conductivities

Lightweight cement mortars containing end-of-life tire rubber (TR) as aggregate were prepared and characterized by rheological, thermal, mechanical, microstructural, and wetting tests. The mixtures were obtained after total replacement of the conventional sand aggregate with untreated TR with different grain sizes (0–2 mm and 2–4 mm) and distributions (25%, 32%, and 40% by weight). The mortars showed lower thermal conductivities (≈90%) with respect to the sand reference due to the differences in the conductivities of the two phases associated with the low density of the aggregates and, to a minor extent, to the lack of adhesion of tire to the cement paste (evidenced by microstructural detection). In this respect, a decrease of the thermal conductivities was observed with the increase of the TR weight percentage together with a decrease of fluidity of the fresh mixture and a decrease of the mechanical strengths. The addition of expanded perlite (P, 0–1 mm grain size) to the mixture allowed us to obtain mortars with an improvement of the mechanical strengths and negligible modification of the thermal properties. Moreover, in this case, a decrease of the thermal conductivities was observed with the increase of the P/TR dosage together with a decrease of fluidity and of the mechanical strengths. TR mortars showed discrete cracks after failure without separation of the two parts of the specimens, and similar results were observed in the case of the perlite/TR samples thanks to the rubber particles bridging the crack faces. The super-elastic properties of the specimens were also observed in the impact compression tests in which the best performances of the tire and P/TR composites were evidenced by a deep groove before complete failure. Moreover, these mortars showed very low water penetration through the surface and also through the bulk of the samples thanks to the hydrophobic nature of the end-of-life aggregate, which makes these environmentally sustainable materials suitable for indoor and outdoor elements.

Study on Soil Dynamic Parameters of One Site in Shijiazhuang

2012 ◽  
Vol 170-173 ◽  
pp. 1060-1063
Author(s):  
Ji Hua Chen ◽  
Hui Ge Wu ◽  
Wei Wang ◽  
Ai Hong Zhou
Keyword(s):  
Seismic Risk ◽  
Response Spectra ◽  
Dynamic Parameters ◽  
Construction Site ◽  
Peak Acceleration ◽  
Acceleration Response ◽  
Earthquake Effect ◽  
Calculation Results ◽  
Engineering Projects ◽  
Soil Dynamic

Earthquake effect of the construction site in Shijiazhuang city was studied when the artificial wave is taken as input ground motion. The dynamic parameters in the model were taken from the measured values, recommended values in 94 Code and recommended values by X.M. Yuan respectively. The ground peak acceleration and acceleration response spectra are compared and analyzed, and it shows that the calculation results from the recommended values by X.M. Yuan are more close to the results from the real measured values than 94 Code. The results can be taken as a reference of the soil dynamic value in seismic risk assessment of engineering projects.

scholarly journals Analysis of Fractal and Energy Consumption Characteristics of Concrete under Impact Loading

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yutao Li ◽  
Faning Dang ◽  
Mei Zhou ◽  
Jie Ren
Keyword(s):  
Fractal Dimension ◽  
Surface Energy ◽  
Failure Modes ◽  
Crack Surface ◽  
Split Hopkinson Pressure Bar ◽  
Utilization Rate ◽  
Compression Tests ◽  
Hopkinson Pressure Bar ◽  
Impact Compression ◽  
Aggregate Rate

In order to study the compressive deformation and energy evolution characteristics of concrete under dynamic loading, impact compression tests with impact velocities of 5, 6, and 7 m/s were carried out on concrete samples with aggregate volume ratios of 0, 32%, 37%, and 42%, respectively, using a split Hopkinson pressure bar test apparatus. The broken concrete pieces after destruction were collected and arranged. The fractal characteristics of fragmentation distribution of concrete specimens with different aggregate rates under impact were discussed, and the roughness of the fragment surface was characterized by the fractal dimension of the broken fragment and the crack surface energy was calculated. In addition, the analytical equation of the fractal dimension of the broken fragment and the crack surface energy was established. The relationship between the specimen energy absorption and the crack surface energy was compared and analyzed. The results show that the concrete specimens are mainly tensile split failure modes under different impact speeds. The fractal dimension, absorption energy, and crack surface energy all increase with the increase in impact speed and decrease with the increase in the aggregate rate. When the aggregate rate is different, the effective utilization rate of the absorbed energy is the largest when the aggregate content is 37%. The surface energy of the crack can be used to estimate the concrete dynamic intensity.

scholarly journals Dynamic Constitutive Model for Reactive Powder Concrete with Standard Curing

2018 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Steel Fiber ◽  
High Strength ◽  
Reactive Powder Concrete ◽  
Strengthening Effect ◽  
Compression Tests ◽  
Softening Effect ◽  
Impact Compression ◽  
Reactive Powder

In view of the disadvantages of steam curing of reactive powder concrete (RPC), RPC with standard curing (SCRPC) is proposed. SC-RPC is an ultra-high strength concrete material prepared with high strength cement, silica fume, and gypsum by standard curing. In this study, quasi-static and impact compression tests were performed to investigate the mechanical properties of SC-RPC. The results show that steel fiber and the strain rate significantly affect the compression performance. Nevertheless, the Holmquist–Johnson–Cook (HJC) constitutive model is mainly used to analyze the dynamic response of brittle materials, such as common concrete, under shock and impact. Therefore, based on the quasi-staticand impact compression tests and the HJC constitutive model for concrete, by analyzing the steel fiber strengthening effect under quasi-static uniaxial compression, strain rate hardening, and the damage softening effect under SHPB impact compression, the steel fiber strengthening factor Kf , dynamic increase factor DIF, and revised damage variable D are introduced, and a modified HJC constitutive model for RPC with standard curing is proposed.

High Strain-Rate Compressive Response of Friction Stir Welded AA7075-T651 Joints

2007 ◽  
Vol 7-8 ◽  
pp. 251-256 ◽  
Author(s):  
Takashi Yokoyama ◽  
Kenji Nakai
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Base Material ◽  
Compression Tests ◽  
Hopkinson Pressure Bar ◽  
Strain Rate Effects ◽  
Impact Compression ◽  
Friction Stir

High strain-rate compressive responses of AA7075-T651 and its welds as produced by the friction stir welding (or FSW) process are investigated using the conventional split Hopkinson pressure bar. Cylindrical specimens machined along the thickness direction of the base material (AA7075-T651) and the friction stir (FS) welds are used in the static and impact compression tests. The micro-hardness tests are conducted across the centerline of a FS welded AA707-T651 joint in order to examine the microstructural change. It is shown that FSW reduces the compressive flow stress of the FS weld (weld nugget) to below that of the base material, and both the base material and the FS weld exhibit almost no strain rate effects up to nearly € ε˙ =103/s.

scholarly journals Research On Water-Immersion Softening Mechanism of Coal Rock Mass Based on Split Hopkinson Pressure Bar Experiment

2021 ◽  
Author(s):  
Zhiyuan Liu ◽  
Gang Wang ◽  
Jinzhou Li ◽  
Huaixing Li ◽  
Haifeng Zhao ◽  
...  
Keyword(s):  
Moisture Content ◽  
Coal Sample ◽  
Split Hopkinson Pressure Bar ◽  
Water Immersion ◽  
Compression Tests ◽  
Hopkinson Pressure Bar ◽  
Impact Compression ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
The Impact

Abstract The coal mining process is affected by multiple sources of water such as groundwater and coal seam water injection. Understanding the dynamic mechanical parameters of water-immersed coal is helpful to the safe production of coal mines. The impact compression tests were performed on coal with different moisture contents by using the ϕ50 mm Split Hopkinson Pressure Bar (SHPB) experimental system, and the dynamic characteristics and energy loss laws of water-immersed coal with different compositions and water contents were analyzed. Through analysis and discussion, it is found that: (1) When the moisture content of the coal sample is 0%, 30%, 60%, the stress, strain rate and energy first increase and then decrease with time; (2) When the moisture content of the coal sample increases from 30% to 60%, the stress "plateau" of the coal sample disappears, resulting in an increase in the interval of the compressive stress and a decrease in the interval of the expansion stress. (3) The increase of the moisture content of the coal sample will affect its impact deformation and failure mode. When the moisture content is 60%, the incident rod end and the transmission rod end of the coal sample will have obvious compression failure, and the middle part of the coal sample will also experience expansion and deformation. (4) The coal composition ratio suitable for the impact experiment of coal immersion softening is optimized.

Identifying Soil Dynamic Parameters for Soil-Machine Systems

1972 ◽  
Vol 15 (1) ◽  
pp. 0009-0013 ◽  
Author(s):  
C. E. Johnson ◽  
Glenn Murphy ◽  
W. G. Lovely and R. L. Schafer
Keyword(s):  
Dynamic Parameters ◽  
Machine Systems ◽  
Soil Dynamic

Compression Tests of High Strength Steels

2008 ◽  
Vol 59 ◽  
pp. 293-298
Author(s):  
Vaclav Mentl ◽  
Josef Bystricky
Keyword(s):  
Mechanical Properties ◽  
Mechanical Testing ◽  
High Speed ◽  
Dynamic Compression ◽  
Testing Machine ◽  
High Strength Steels ◽  
High Strength ◽  
Strain Rates ◽  
Compression Tests ◽  
Impact Compression

Mathematical modelling and virtual testing of components and structures represent a useful and economic tool for design and safety assessment. The basic mechanical properties which can be found in material standards are not relevant in cases where the real service conditions differ from those applied during standardised testing. Thus e.g. mechanical behaviour at higher strain rates can be interesting for the car components when the simulation of crash situations is used during structure development. The dynamic compression tests are usually performed by means of drop towers, by means of high speed hydraulic testing machines or Hopkinson bar method. At the Mechanical Testing Laboratory of the SKODA Research Inst. in Pilsen, Czech Republic, an instrumentation of Charpy pendulum testing machine was realised in order that it was possible to perfom dynamic compression tests, [1], and the compatibility of obtained results in comparison with traditional impact compression tests was verified within the round–robin carried out by TC5 ESIS Sub-Committee on “Mechanical Testing at Intermediate Strain Rates“, [2]. A new striking tup and load measurement system were designed and callibrated. At the same time, a new software was developed which makes it possible to evaluate the test force-deformation record. The goal of this study was 1. to check the possibility of compression testing of high strength materilas by mens of Charpy pendulum, and 2. to study the strain rate influence on basic mechanical properties.

Sign in / Sign up

Export Citation Format

Share Document