Internal vibration and the lateral pressure exerted by fresh concrete

1979 ◽  
Vol 6 (4) ◽  
pp. 592-600 ◽  
Author(s):  
N. J. Gardner ◽  
A. R. Quereshi
Keyword(s):  
Experimental Investigation ◽  
United Kingdom ◽  
Lateral Pressure ◽  
Fresh Concrete ◽  
American Concrete Institute ◽  
Experimental Results ◽  
Internal Vibration ◽  
Low Friction ◽  
Design Recommendations ◽  
Vibration Parameters

The design of formwork for vertical surfaces is dependent upon the magnitude of the lateral pressure assumed to act on the form face. This paper describes an experimental investigation to determine the variation of the lateral pressure exerted by fresh concrete with depth of immersion of the vibrator, duration of vibration, and power of the vibrator while keeping the rate of pour, form dimensions, and slump nominally constant and measuring the temperature.It was concluded that the lateral pressure is dependent upon the vibration parameters of depth of immersion of the vibrator, duration of vibration, and power of the vibrator and varies inversely with the temperature of the concrete mix.The experimental results were compared with the CIRIA (Civil Industries Research and Information Association, United Kingdom) and ACI (American Concrete Institute) design recommendations. It was concluded that the CIRIA arching criterion should be used with caution as it was not conservative for low friction formwork surfaces, and that both the CIRIA stiffening criterion and the ACI recommendations are conservative.

Evaluation of Compacting of Fresh Concrete through Vibration Based on the Newton Viscous Model

2018 ◽  
Vol 880 ◽  
pp. 347-352 ◽  
Author(s):  
Ramona Pinţoi ◽  
Adriana Ionescu
Keyword(s):  
Dynamic Modeling ◽  
Fresh Concrete ◽  
Dynamic Compaction ◽  
Experimental Results ◽  
Dissipated Energy ◽  
Displacement Curve ◽  
Vibration Frequencies ◽  
Stationary Vibration ◽  
Vibration Parameters ◽  
Compaction Degree

The paper is based on dynamic modeling research and experimental results obtained for freshly compacted concrete under stationary vibration. Thus, computational relationships and laws for vibration parameters and dissipated energy will be presented. In correlation with the dissipated energy, it will be evidenced by the evolution of the compaction degree and the resistance of the concrete depending on the vibration duration. It is noted that significant correlations have been established between the displacement curve of the dissipated energy and the loop hysteresis area for several vibration frequencies specific to the dynamic compaction regime

Experimental Investigation of Strengthening and Polishing Aeroengine Blades

2011 ◽  
Vol 101-102 ◽  
pp. 909-912
Author(s):  
Guo Ying Zeng ◽  
Deng Feng Zhao
Keyword(s):  
Surface Roughness ◽  
Experimental Investigation ◽  
Fatigue Strength ◽  
Surface Quality ◽  
Three Dimensional ◽  
Experimental Results ◽  
Technological Parameters ◽  
Polishing Process ◽  
Optimum Parameters ◽  
The Media

The three-dimensional vibratory strengthening and polishing technology was used to strengthen and polish aeroengine blades with complicated surfaces. At first, the principle of the strengthening and polishing process was introduced, which combined strengthening process with polishing process. Then, the technological parameters influenced on the surface quality were investigated. The principal variables were the media hardness, the frequency and amplitude of the vibration, and duration of the vibratory strengthening and polishing. The optimum parameters were obtained. Experimental results revealed that, after strengthening and polishing, the surface roughness of aeroengine blades was reduced from Ra0.35-0.5μm to Ra0.1-0.12μm, and fatigue strength was increased by approximately 50%.

Experimental Investigation of Flowrate Irregularity in Rotary Gear Pumps

1992 ◽  
Author(s):  
G. Mimmi
Keyword(s):  
Experimental Investigation ◽  
Flow Rate ◽  
Experimental Tests ◽  
Periodic Variation ◽  
Experimental Results ◽  
Gear Pump ◽  
Gear Pumps ◽  
Hot Film ◽  
Instantaneous Flow Rate ◽  
External Gear Pump

Abstract In a previous paper the author proposed a method to reduce the periodic variation in flow rate for an external gear pump. To verify the experimental results, a series of experimental tests on a expressly realized gear pump, was carried out. The pump was equipped with relieving grooves milled into the side plates. The tests were done on a closed piping specifically realized and equipped for measuring the instantaneous flow rate of the fluid through a wedge-shaped hot film probe.

Temperature during the vibration-assisted compression of alfalfa

BioResources ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 141-150
Author(s):  
Xiaoyu Wu ◽  
Shuai Yang ◽  
Chundong Song ◽  
Kun Ding ◽  
Chuanzhong Xuan ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Vibration Frequency ◽  
Experimental Results ◽  
Maximum Temperature ◽  
Compression Time ◽  
Vibration Parameters ◽  
Reducing Energy ◽  
Compression Temperature

Compression of alfalfa into briquettes is an effective way to solve the problem of storage and transportation. In the process of compression, heat is generated and the temperature is raised in the material. In fact, the appropriate temperature can improve the quality of alfalfa briquettes and reduce the energy consumption of densification. In this study, the effect of assisted vibration on the compression temperature was tested. The results showed that when the vibration frequency was below 15 Hz, the temperature at the center and side in compressed alfalfa increased slowly with compression time. When the vibration frequency was above 20 Hz, it increased first and then decreased with the increase of time. Moreover, the maximum temperature value increased remarkably when the frequency was above 20 Hz. In the same vibration frequency and compression time, the center temperature in the compressed alfalfa was higher than the side temperature. The experimental results provide a reference for the determination of reasonable vibration parameters, and explanation of the effect of vibration on reducing energy consumption.

An Experimental Investigation for Flow Past a Circular Cylinder With Rectangular Strips

2002 ◽  
Author(s):  
Chuan He ◽  
Tianyu Long ◽  
Mingdao Xin ◽  
Benjamin T. F. Chung
Keyword(s):  
Experimental Investigation ◽  
Fluid Flow ◽  
Circular Cylinder ◽  
Drag Coefficient ◽  
Experimental Results ◽  
Sharp Edge ◽  
Flow Past ◽  
Rectangular Strips

This paper reports an experimental investigation for fluid flow past a circular cylinder with two small rectangular strips and single sharp-edge strips on its surface. The experimental results reflected that different arrangements or dimensions of the strips produced significantly different effects on the flow. The forward step caused a stronger disturbance with a small increase in drag. The backward step arrangement softened the disturbance but reduced the drag coefficient by 33%.

scholarly journals Experimental and Numerical Evaluation of Shear Strength of Directly and Indirectly Loaded Flanged Recycled Self-Compacted Reinforced Concrete Deep Beams

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Thamer Hussein Amer Alhussein ◽  
Jamal Abdul Samad Khudhair
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Ultimate Load ◽  
American Concrete Institute ◽  
Shear Capacity ◽  
Recycled Concrete ◽  
Experimental Results ◽  
Experimental Result ◽  
Deep Beams ◽  
Aashto Lrfd

Experimental and numerical investigations of the behavior of directly and indirectly loaded flanged reinforced concrete (RC) deep beams cast with self-compacted concrete (SCC) containing recycled concrete as coarse aggregate (RCA) were conducted in this research. Seventeen RC deep flanged beams were designed to fail in shear. These beams were divided into three groups: twelve indirectly loaded beams without shear reinforcement; three directly loaded beams without stirrups; and two indirectly loaded beams with vertical stirrups. These beams were also classified according to the RCA ratio and shear span-to-effective depth (a/d) ratio, which will be detailed later. The RCA ranged from 0% to 75%, while the a/d ratio was taken as 1.0, 1.35, and 1.7. Experimental results show that the use of RCA reduces the cracking and ultimate capacities, and this finding complies with the conclusions of several research studies in the literature as will be detailed later. It was observed that beams with higher RCA exhibited higher deflection, strain, and crack width. Furthermore, by increasing the a/d ratio, the ultimate load was decreased due to the lower contribution of arch action shear transfer in the beam. A web reinforcement spaced at 100 mm and 50 mm increases the ultimate load by 35% and 48%, respectively. Strut and tie model (STM) presented by the American Concrete Institute (ACI) 318-14 and the American Association of State Highway and Transportation Officials (AASHTO LRFD 2012) was used to predict the ultimate shear capacity of the beams. STM predicted lower beam capacity than the experimental result. The ultimate strength calculated using ACI318-14 and AASHTO LRFD 2012 was on average 38% and 52% lower than the experimental data, respectively, which reflects the conservative nature of this approach. Finally, 3D finite element models were created to investigate the responses of the beams. The FE results showed very good agreement with the experimental data, where FE-predicted shear capacities were on average 9% higher than the experimental results.

Experimental Investigation of the Maximum Heat Transport in Triangular Grooves

1996 ◽  
Vol 118 (3) ◽  
pp. 740-746 ◽  
Author(s):  
H. B. Ma ◽  
G. P. Peterson
Keyword(s):  
Experimental Investigation ◽  
Heat Transport ◽  
Heat Pipes ◽  
Effective Area ◽  
Experimental Results ◽  
Test Facility ◽  
Working Fluid ◽  
Maximum Heat ◽  
Pressure Losses ◽  
Micro Heat Pipes

An experimental investigation was conducted and a test facility constructed to measure the capillary heat transport limit in small triangular grooves, similar to those used in micro heat pipes. Using methanol as the working fluid, the maximum heat transport and unit effective area heat transport were experimentally determined for ten grooved plates with varying groove widths, but identical apex angles. The experimental results indicate that there exists an optimum groove configuration, which maximizes the capillary pumping capacity while minimizing the combined effects of the capillary pumping pressure and the liquid viscous pressure losses. When compared with a previously developed analytical model, the experimental results indicate that the model can be used accurately to predict the heat transport capacity and maximum unit area heat transport when given the physical characteristics of the working fluid and the groove geometry, provided the proper heat flux distribution is known. The results of this investigation will assist in the development of micro heat pipes capable of operating at increased power levels with greater reliability.

Nucleation Phenomena in Flowing High-Pressure Steam: Experimental Results

1989 ◽  
Vol 203 (3) ◽  
pp. 195-200 ◽  
Author(s):  
F Bakhtar ◽  
K Zidi
Keyword(s):  
Experimental Investigation ◽  
High Pressure ◽  
Test Section ◽  
Experimental Results ◽  
Axial Pressure ◽  
High Pressure Steam ◽  
Pressure Distributions ◽  
Pressure Steam

The paper describes the results of an experimental investigation of limiting supersaturation in high-pressure steam. It follows an earlier investigation and to avoid the uncertainties associated with leakage past sliding profiles, the test section has been redesigned and the measurements taken with fixed nozzles. Three convergent-divergent nozzles with nominal rates of expansion of 3000, 5000 and 10000 per second have been used and the inlet stagnation pressures cover the range 25–35 bar. The data consist mainly of axial pressure distributions but some droplet measurements have also been recorded.

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