scholarly journals Torsional Shear Device for Testing the Dynamic Properties of Recycled Material

2016 ◽  
Vol 38 (4) ◽  
pp. 15-24 ◽  
Author(s):  
Katarzyna Gabryś ◽  
Wojciech Sas ◽  
Emil Soból ◽  
Andrzej Głuchowski
Keyword(s):  
Dynamic Behavior ◽  
Dynamic Properties ◽  
Low Frequency ◽  
Recycled Aggregates ◽  
New Materials ◽  
Torsional Loading ◽  
Environmental Preservation ◽  
Effective Utilization ◽  
Torsional Shear ◽  
Recycled Material

Abstract From the viewpoint of environmental preservation and effective utilization of resources, it is beneficial and necessary to reuse wastes, for example, concrete, as the recycled aggregates for new materials. In this work, the dynamic behavior of such aggregates under low frequency torsional loading is studied. Results show that the properties of such artificial soils match with those reported in the literature for specific natural soils.

scholarly journals Dynamic Compressive Strength of Recycled Aggregate Concrete

2021 ◽  
Vol 8 ◽  
pp. 56-61
Author(s):  
Shamsoon Fareed ◽  
Asad-ur-Rehman Khan ◽  
Samra Masood
Keyword(s):  
Dynamic Properties ◽  
Compressive Loading ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Maximum Height ◽  
Environmental Preservation ◽  
Aggregate Concrete ◽  
Drop Hammer ◽  
Static Mechanical

Over the years the construction waste has enormously increased, this may be attributed to different factors such as (i) demolition (ii) accidents (iii) impact loads (iv) earthquakes. These activities have caused an increasing burden on already exhausted waste management system globally. As a result, the concrete waste produced in a large quantity has become a major issue to manage due to limited landfill sites. Therefore, the recycling of waste concrete can prove to be beneficial and necessary for the environmental preservation and effective utilization of natural resources. Number of studies have been conducted to study the static mechanical properties of recycled aggregate concrete; however, limited test data has been published which focused on the dynamic properties of the concrete prepared with recycled coarse aggregates. Therefore, in this investigation aim was to study the behavior of recycled aggregates concrete under increasing dynamic compressive loading. For this purpose, cylindrical specimens having a diameter of 100 mm and height of 200 mm were used. These specimens have been prepared with constant concrete mix ratio, having varying percentages of RA such as 0%, 30%, and 50% 70 % and 100%. The dynamic compressive behaviour was studied by using drop hammer system. The height drop hammer system consist of a frame having a maximum height of 15ft. Firstly, three samples (1, 1R, 2R) from each percentage replacement (0%, 30%, 50%, 70% and 100%) were tested on six different velocities of 2.44m/s, 3.45m/s, 4.23m/s, 4.89m/s, 5.46m/s and 7.45m/s with varying strain rates of 12.04/s, 17.00/s, 20.83/s, 24.08/s, 26.89/s and 36.73/s respectively. Weight of the drop hammer was 10 kg. Based on the detailed experimental investigation, it was found that the behaviour of the recycled aggregate concrete under dynamic loading differ significantly from the static loading.

Observation of chloride permeability between normal aggregates concrete and recycled aggregates concrete Containing fly ash and clay

2018 ◽  
Vol 9 (4) ◽  
pp. 103
Author(s):  
Md. Shafiqul Islam ◽  
Pronab Kanti Baul ◽  
Oarda Haque
Keyword(s):  
Fly Ash ◽  
Water Absorption ◽  
Chloride Ion ◽  
Point Of View ◽  
Recycled Aggregates ◽  
Chloride Permeability ◽  
Environmental Preservation ◽  
Effective Utilization ◽  
Chloride Attack ◽  
High Chloride

Recycling of concrete is needed based on environmental preservation and effective utilization of resources point of view. Chloride attack has become a major concern in modern construction. Chloride ion is very dangerous for concrete structures because it leads to corrosion of the reinforcements in concrete. Many researchers have carried out numerous investigations on the chloride permeability of normal aggregates concrete. The purpose of this paper is to compare the chloride permeability between normal aggregates concrete and recycled aggregates concrete containing fly ash and clay. Water absorption in recycled aggregates concrete is also shown. The cylindrical concrete specimens made with recycled aggregates were subjected to high chloride permeability. Clay and ash were mixed in separate specimens in different proportions to reduce the porosity of concrete and hence to decrease the chloride permeability. The objective of this paper is to show the decrease chloride permeability in recycled aggregates concrete which is almost same for normal aggregates concrete and to make a relationship between water absorption and chloride permeability.

scholarly journals Influence of dynamic properties on scaffoldings safety

2021 ◽  
Vol 21 (4) ◽  
Author(s):  
Ewa Błazik-Borowa ◽  
Jarosław Bęc
Keyword(s):  
Natural Frequency ◽  
Dynamic Behavior ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Low Frequency ◽  
Mode Shapes ◽  
Natural Mode ◽  
Longitudinal Vibrations ◽  
Dynamic Simulations ◽  
Dangerous Situation

AbstractScaffoldings are used for works at height and in places that are hard to reach, which makes such works dangerous to employees and accidents occur frequently. Loads generated by scaffolding users cannot be avoided. Moving workers excite low-frequency (1–2 Hz) vibrations and scaffoldings as slender structures are prone to such dynamic action. The method for determining the probability of vibrations excitation is presented here. The quantity representing this probability is called the predictor of occurrence of a dangerous situation due to vibrations induced by a walking employee. The predictor of resonance with ith natural frequency requires an analysis of the scaffolding dynamic behavior. The frequencies and the natural mode shapes of vibrations were determined. Numerical dynamic simulations of the worker's movement on the penultimate decks of two scaffoldings were carried out, as well. Predictor analysis was made for single frequencies and combinations of frequency pairs. The predictor values calculated for the first frequency or combinations with it are the highest ones, however the probability of resonance is not only affected by the first frequency. To improve safety, the natural frequencies should be increased. For longitudinal vibrations, this can be done by adding more bracing or reducing lengths of anchors. Increasing the number of anchors gives good results in both directions. During scaffolding design of both typical and atypical constructions, one must determine the natural frequencies and then, if the first natural frequency is less than 4.0 Hz, perform a dynamic scaffolding analysis.

Dynamic Damping and Stiffness Characteristics of the Rolling Tire

2001 ◽  
Vol 29 (4) ◽  
pp. 258-268 ◽  
Author(s):  
G. Jianmin ◽  
R. Gall ◽  
W. Zuomin
Keyword(s):  
Dynamic Behavior ◽  
Variable Parameter ◽  
Low Frequency ◽  
Vertical Load ◽  
Frequency Range ◽  
Inflation Pressure ◽  
Vehicle Simulation ◽  
Dynamic Damping ◽  
Speed Range ◽  
Stiffness Characteristics

Abstract A variable parameter model to study dynamic tire responses is presented. A modified device to measure terrain roughness is used to measure dynamic damping and stiffness characteristics of rolling tires. The device was used to examine the dynamic behavior of a tire in the speed range from 0 to 10 km/h. The inflation pressure during the tests was adjusted to 160, 240, and 320 kPa. The vertical load was 5.2 kN. The results indicate that the damping and stiffness decrease with velocity. Regression formulas for the non-linear experimental damping and stiffness are obtained. These results can be used as input parameters for vehicle simulation to evaluate the vehicle's driving and comfort performance in the medium-low frequency range (0–100 Hz). This way it can be important for tire design and the forecasting of the dynamic behavior of tires.

scholarly journals Dynamics and Protein–Solvent Interactions of Hemoglobin in T and R Quaternary Conformation

2002 ◽  
Vol 16 (3-4) ◽  
pp. 227-233 ◽  
Author(s):  
Chiara Caronna ◽  
Antonio Cupane
Keyword(s):  
Quaternary Structure ◽  
Dynamic Properties ◽  
Low Frequency ◽  
Helical Structure ◽  
Blue Shift ◽  
Peak Frequency ◽  
The Other ◽  
Solvent Interactions ◽  
Reported Data ◽  
Increasing Temperature

In this work we report the thermal behaviour of the amide I′ band of carbonmonoxy and deoxy hemoglobin in 65% v/v glycerolD8/D2O solutions and in the temperature interval 10–295 K. Following recent suggestions in the literature, we analyze the amide I′ band in terms of two components, one at about 1630 cm−1and the other at about 1650 cm−1, that are assigned to solvent‒exposed and buried α‒helical regions, respectively.For deoxy hemoglobin (in T quaternary structure) both components are narrower with respect to carbonmonoxy hemoglobin (in R quaternary structure), while the peak frequency blue shift observed, upon increasing temperature, for the component at about 1630 cm−1is smaller. The reported data provide evidence of the dependence of hemoglobin dynamic properties upon the protein quaternary structure and suggest a more compact α‒helical structure of hemoglobin in T conformation, with reduced population of low‒frequency modes involving the solvent and protein.

scholarly journals Experimental Study on Recycling of Bituminous Aggregate in Cement Concrete

2021 ◽  
Vol 9 (VI) ◽  
pp. 5392-5398
Author(s):  
Manoj Kumar Mishra
Keyword(s):  
Experimental Study ◽  
Road Construction ◽  
Construction Cost ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Cement Concrete ◽  
Cost Component ◽  
The Road ◽  
Total Construction Cost ◽  
Recycled Material

Recycling of bituminous aggregates in cement concrete has been selected for the present study to determine suitability of recycled material in road construction. This will help in achieving economy in road construction as well as saving on environment degradation in term of reduced mining and less pollution. Construction and maintenance of roads and highways involve millions of tonnes of aggregate. Considering the scarcity of fresh aggregate, replacement of part of the fresh aggregate with recycled aggregate is considered in the present study. Construction of the road is quite cost intensive. Material alone cost more than 60% of the total construction cost, out of which aggregate cost component, is approximately 30%. We can use recycled aggregate in place of fresh aggregate in construction of road and provide economy to the project. For making best use of recycled aggregates, it is essential to study the suitability of the same in various pavement components. In the present study recycled aggregate are used in Granular Sub Base (GSB) and Wet Mix Macadam (WMM).

DYNAMIC PROPERTIES OF SEQUENTIAL TUNNELING THROUGH DOUBLE-BARRIER SYSTEMS

1993 ◽  
Vol 07 (26) ◽  
pp. 1677-1686 ◽  
Author(s):  
L.Y. CHEN
Keyword(s):  
Power Density ◽  
Dynamic Properties ◽  
Low Frequency ◽  
Frequency Noise ◽  
Charge Accumulation ◽  
Significant Suppression ◽  
Finite Frequency ◽  
Double Barrier ◽  
Noise Current ◽  
Dynamic Conductance

In this paper, we present an analytical stochastical approach to the dynamic properties of sequential tunneling through double-barrier systems. The effect of charge accumulation is included in the investigation of dynamic conductance and noise current power density at finite frequency. Albeit in the sequential tunneling limit the quantum phase coherence of electron waves is destroyed by inelastic scattering while traversing the junction, the occupation of resonance states by fermionic particles sojourning in the well along with the charge accumulation within and around the structure still give rise to strong correlation among tunneling events. This correlation determines the characteristic frequency of the system and leads to significant suppression of shot noise. The low frequency noise current power density compares agreeably with experimental measurements.

Modeling and Experimental Characterization of Viscoelastic 3D Printed Spring/Damper Systems

2017 ◽  
Author(s):  
Heather L. Lai ◽  
Cuiyu Kuang ◽  
Jared Nelson
Keyword(s):  
Dynamic Behavior ◽  
Material Properties ◽  
Dynamic Properties ◽  
Viscoelastic Materials ◽  
Vibration Isolators ◽  
Damping Behavior ◽  
Wide Range ◽  
3D Printed ◽  
Printed Materials

The development of flexible, viscoelastic materials for consumer 3D printers has provided the opportunity for a wide range of devices with damping behavior such as tuned vibration isolators to be innovatively developed and inexpensively manufactured. However, there is currently little information available about the dynamic behavior of these 3D printed materials necessary for modeling of dynamic behavior prior to print. In order to fully utilize these promising materials, a deeper understanding of the material properties, and the subsequent dynamic behavior is critical. This study evaluates the use of three different types of models: transient response, frequency response and hysteretic response to predict the dynamic behavior of viscoelastic 3D printed materials based on static and dynamic material properties. Models of viscoelastic materials are presented and verified experimentally using two 3D printable materials and two traditional viscoelastic materials. The experimental response of each of the materials shows agreement with the modeled behavior, and underscores the need for improved characterization of the dynamic properties of viscoelastic 3D printable materials.

Effect of Aging Treatment on Dynamic Behavior of Mg-Gd-Y Alloy

2012 ◽  
Vol 13 (2) ◽  
pp. 111-116
Author(s):  
Lin Wang ◽  
Qiao-Yun Qin ◽  
Fan Zhang ◽  
Cheng-Wen Tan
Keyword(s):  
Plastic Deformation ◽  
Rare Earth ◽  
Magnesium Alloy ◽  
Dynamic Behavior ◽  
Deformation Mechanism ◽  
Dynamic Properties ◽  
Dynamic Compression ◽  
Aging Treatment ◽  
Dislocation Slip ◽  
Plastic Deformation Mechanism

Abstract Magnesium alloy is very attractive in many industrial applications due to its low density. The structure-property relationships of the magnesium alloy under quasi-static loading have been extensively investigated. However, the dynamic behavior, particularly the mechanism of high-rate plastic deformation, of the magnesium alloy requires more in-depth investigations. In this paper, the effect of aging treatment on the quasi-static and dynamic properties of a typical rare earth Mg-Gd-Y magnesium alloy is investigated. In particular, the plastic deformation mechanism under dynamic compression loading is discussed. Split Hopkinson Pressure Bar (SHPB) was used to carry out dynamic compression tests with controllable plastic deformation by using stopper rings. The experimental results demonstrate that both static and dynamic properties of the Mg-Gd-Y alloy vary under various aging treatment conditions (under-aged, peak-aged and over-aged conditions), due to two different kinds of second phases: remnant micro size phase from solid solution treatment and nano precipitation from aging treatment. The results of microstructure characterization and statistic analysis of the metallographic phase are presented. The area fraction of the twinned grains increases due to aging treatment and dynamic loading. The main plastic deformation mechanism of the rare earth Mg-Gd-Y magnesium alloy is possibly dislocation slip, rather than twinning for the conventional AZ31 magnesium alloy under high strain rate loading.

scholarly journals Studies on Dynamic Properties of Ultracapacitors Using Infinite r–C Chain Equivalent Circuit and Reverse Fourier Transform

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4583
Author(s):  
Shailendra Rajput ◽  
Alon Kuperman ◽  
Asher Yahalom ◽  
Moshe Averbukh
Keyword(s):  
Mathematical Model ◽  
Fourier Transform ◽  
Equivalent Circuit ◽  
Dynamic Behavior ◽  
Double Layer ◽  
Electrochemical Impedance ◽  
Dynamic Properties ◽  
Internal Resistance ◽  
Simulation Software ◽  
Specific Power

The specific power storage capabilities of double-layer ultracapacitors are receiving significant attention from engineers and scientific researchers. Nevertheless, their dynamic behavior should be studied to improve the performance and for efficient applications in electrical devices. This article presents an infinite resistor–capacitor (r–C) chain-based mathematical model for the analysis of double layer ultracapacitors. The internal resistance and capacitance were measured for repetitive charging and discharging cycles. The magnitudes of internal resistance and capacitance showed approximately ±10% changes for charge-discharge processes. Electrochemical impedance spectroscopy investigations revealed that the impedance of a double-layer ultracapacitor does not change significantly in the temperature range of (−30 °C to +30 °C) and voltage range of (0.3376–2.736 V). The analysis of impedance data using the proposed mathematical model showed good agreement between the experimental and theoretical data. The dynamic behavior of the ultracapacitor was successfully represented by utilizing the proposed infinite r–C chains equivalent circuit, and the reverse Fourier transform analysis. The r–C electrical equivalent circuit was also analyzed using the PSIM simulation software to study the dynamic behavior of ultracapacitor parameters. The simulation study yields an excellent agreement between the experimental and calculated voltage characteristics for repetitive charging-discharging processes.

Sign in / Sign up

Export Citation Format

Share Document