scholarly journals Experimental Studies of the Influence of Dynamic Loading on the Elastic Properties of Sandstone

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6195
Author(s):  
Mikhail Guzev ◽  
Evgenii Kozhevnikov ◽  
Mikhail Turbakov ◽  
Evgenii Riabokon ◽  
Vladimir Poplygin
Keyword(s):  
Dynamic Loading ◽  
Experimental Studies ◽  
Young Modulus ◽  
Small Samples ◽  
Laser Sensor ◽  
Geomechanical Properties ◽  
Red Sandstone ◽  
Clastic Rocks ◽  
Quasistatic Loading ◽  
Quasistatic Regime

Under dynamic loading, the geomechanical properties of porous clastic rocks differ from those in quasistatic loading. A small experimental rig was built to directly assess the influence of vibrations on the uniaxial compressive strength (UCS), Young modulus, and Poisson’s ratio. A piezoelectric actuator powered by a signal from an oscillator was used in the rig as a generator of vibrations. A laser sensor and eddy current probe measured the longitudinal and transverse deformation. Tinius Hounsfield and Instron Series 4483 installations were used to determine the geomechanical properties of new red sandstone in a quasistatic regime. The boundaries of elastic deformations determined in the quasistatic loading were implemented in the dynamic loading. To perform the experiments in the elastic zone (on the graph of stress (σ)–strain (ε)), small samples with diameters ranging between 7.5 and 24.7 mm were manufactured. The investigation demonstrated that the Young’s modulus of the sandstone increased with increasing values of the dynamic load and frequency.

scholarly journals Nonlinear Young’s Modulus of New Red Sandstone: Experimental Studies

2021 ◽  
Author(s):  
Evgenii Riabokon ◽  
Vladimir Poplygin ◽  
Mikhail Turbakov ◽  
Evgenii Kozhevnikov ◽  
Dmitrii Kobiakov ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Dynamic Loading ◽  
Young's Modulus ◽  
Experimental Studies ◽  
Compressive Load ◽  
Complex Nature ◽  
Nonlinear Behaviour ◽  
Red Sandstone ◽  
Strongly Nonlinear ◽  
The University

AbstractYoung’s modulus of New Red Sandstone was investigated experimentally to gain insight into its nonlinear nature. A large experimental programme was carried out by applying a controllable quasi-static and dynamic uniaxial loading to 286 dry sandstone samples of four different sizes. The static and dynamic tests, similar to those aiming at determining the uniaxial compressive strength, were conducted using the state-of-the-art experimental facilities at the University of Aberdeen including a custom-built small experimental rig for inducing a dynamic uniaxial compressive load via a piezoelectric transducer. The obtained results have confirmed a complex nature of Young’s modulus of sandstone. Specifically, under a harmonic dynamic loading, it shows strongly nonlinear behaviour, which is hardening and softening with respect to frequency and amplitude of the dynamic loading, respectively.

Theoretical and experimental studies of impact energy and rock-drilling efficiency in vibro-impact drilling

2021 ◽  
pp. 1-17
Author(s):  
Quan Cao ◽  
Huaizhong Shi ◽  
Weiqiang Xu ◽  
Chao Xiong ◽  
Zhaoliang Yang ◽  
...  
Keyword(s):  
Dynamic Loading ◽  
Impact Energy ◽  
Penetration Rate ◽  
Experimental Studies ◽  
Impact Frequency ◽  
Optimal Frequency ◽  
Rock Drilling ◽  
Loading Waveform ◽  
Impact Parameters ◽  
The Impact

Abstract Vibro-impact drilling has been proven to be a viable technique for enhancing the Rate of Penetration (ROP) in deep and ultra-deep well drilling. It is essential to study the effects of impact parameters on impact energy and rock-drilling efficiency for impact tool design and operating parameter optimization. In this paper, the influences of impact parameters including impact frequency, dynamic loading amplitude and loading on impact energy were analyzed by theoretical method. Then a full-scale drilling experiment was conducted to study the rock-drilling efficiency. The results are as follows: the optimal frequency is higher than the resonance frequency of the rock. The impact energy increase with the dynamic loading amplitude. The penetration rate at dynamic loading amplitude of 4 KN (0.13137 mm/s) is 38.7% higher than that of 2 KN (0.09473mm/s). When the impact frequency is lower than150 Hz, the rock-drilling efficiency increases with the impact frequency and dynamic loading amplitude. The penetration rate is 0.1051 mm/s at impact frequency of 150 Hz, which is 29.8% higher than that of 10 Hz. The impact energy and penetration rate at square loading waveform are the largest. The impact energy per second at loading waveform of square, sine and triangular is 19.6 J, 12 J and 7.91 J respectively when the impact frequency is set to optimal frequency of impact energy. This study provides a theoretical guidance for the optimization design of vibro-impact drilling technology.

VI.—The Altered Clastic Rocks of the Southern Highlands, their Structure and Succession

1896 ◽  
Vol 3 (4) ◽  
pp. 167-174 ◽  
Author(s):  
Peter Macnair
Keyword(s):  
Red Sandstone ◽  
North West ◽  
Scottish Highlands ◽  
Clastic Rocks ◽  
The North

In the following paper I propose to give an account of some observations upon the structure and succession of the rocks of the Southern Highlands. By the term Southern Highlands I mean that part of the Scottish Highlands lying immediately to the north-west of the great line of fault separating the older rocks of the former area from the younger Old Red Sandstone series of the low grounds.

scholarly journals DEFORMATION MONITORING OF RETROFITTED SHORT CONCRETE COLUMNS WITH LASER SENSOR

2016 ◽  
Vol XLI-B5 ◽  
pp. 765-769
Author(s):  
E. Ö. Avsar ◽  
M. F. Celik ◽  
E. Binbir ◽  
A. E. Arslan ◽  
D. Çokkeçeci ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Reference Sample ◽  
Experimental Studies ◽  
Construction Materials ◽  
Mechanical Tests ◽  
Deformation Monitoring ◽  
Laser Sensor ◽  
Scanning Method ◽  
Compression Load ◽  
Short Columns

This paper presents one of the applications of monitoring mechanical tests carried out in Construction Materials Laboratory of Istanbul Technical University. In Turkey, as in many countries, large amount of existing buildings exposed to seismic hazard, therefore various analytical and experimental studies are being conducted to contribute to the solution of the problem. One of the new generation retrofitting techniques is to strength the structural members by using Fiber Reinforcing Polymer (FRP). This study summarize the results of monitoring of deformations short concrete column samples under the incremental compression load. In this study, result of two rectangular short columns are given. One of them was tested as a reference sample, the other sample were tested after strengthening by PET reinforced polymer composite materials. Besides conventional displacement and strain measurement systems, laser scanning method was used to get three dimensional deformed shape of sample at each selected steps.

Effect of Rock on Cement Sheath Integrity: Shale vs. Sandstone

2019 ◽  
Author(s):  
Ragnhild Skorpa ◽  
Benjamin Werner ◽  
Torbjørn Vrålstad
Keyword(s):  
Experimental Studies ◽  
Young Modulus ◽  
Surrounding Rock ◽  
Degradation Mechanisms ◽  
X Ray ◽  
Pressure Cycling ◽  
Cement Sheath ◽  
Set Up ◽  
Casing Pressure ◽  
Radial Cracks

Abstract It is crucial to understand cement sheath degradation mechanisms, since the cement sheath is an important well barrier element. Repeated pressure cycling is known to cause radial cracks and microannuli in the cement sheath, and the stiffness of the surrounding rock determines how much pressure the cement withstands before failure. However, experimental data on the effect of surrounding rock (shale vs. sandstone) on cement sheath integrity are scarce. In this paper we present experimental studies on how different surrounding rocks influence cement sheath integrity. We have used our unique downscaled experimental set-up to perform pressure cycling tests with both shale and sandstones, where cement sheath integrity is visualized in 3D by X-ray computer tomography (CT). The obtained results confirm that a cement sheath surrounded by a rock with a relative higher Young’s modulus can withstand higher casing pressure compared to a cement sheath surrounded by rock with relative lower Young modulus. All cracks were initially observed as small defects in the cement sheath prior to expanding to full radial cracks and propagation into the surrounding formation.

Experimental Studies of the Behaviour at High Strain Rates of Unfilled and Filled Polypropylenes

2006 ◽  
Vol 3-4 ◽  
pp. 363-368 ◽  
Author(s):  
N. Temimi ◽  
Noelle Billon
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
High Strain ◽  
Experimental Studies ◽  
Young Modulus ◽  
Video Camera ◽  
Image Correlation ◽  
Strain Rates ◽  
High Strain Rates ◽  
Low Velocity

Thermo mechanical behaviour of unfilled and filled polypropylenes are studied in tension from 10-4 to 102 s-1. Complementary low velocity compression and shear tests are also performed. A high-speed video camera (up to 2500 frames/s) combined with image analysis, image correlation and an infra red pyrometer allow measuring 3D-strain fields and temperature during tests. Thus, data can be processed without restrictive assumptions. Beside usual (for polymers) temperature and strain rate sensitivities it is found that plastic deformation in these materials does not obey incompressibility assumption. Voiding damage is evidenced in the polymer matrix by SEM observations that result in volume change and significant decrease in Young modulus for both materials. Moreover, an increase in the temperature of more than 10 °C is observed and is likely to modify the behaviour of each material at high strain rates. Shear and compression measurements demonstrate that yield criteria and constitutive equation depend on loading. It is concluded that apparent yield stress in semi-crystalline polypropylene can be a result of a combination of “non strain rate sensitive” “non-cohesive mechanisms” and “strain rate sensitive” “cohesive mechanisms”. Experimental characterisation on polymers should then be revisited as most of the usual assumptions are invalid and non monotonic tests should be generalized.

Buckling of Porcine Aorta Under Static and Dynamic Loading

2012 ◽  
Author(s):  
Mobin Rastgar Agah ◽  
Kaveh Laksari ◽  
Kurosh Darvish ◽  
Alexander Rachev
Keyword(s):  
Blood Vessels ◽  
Dynamic Loading ◽  
Motor Vehicle ◽  
Vascular System ◽  
Experimental Studies ◽  
Dynamic Buckling ◽  
Traumatic Rupture ◽  
Buckling Behavior ◽  
Static And Dynamic Loading ◽  
Original Configuration

Tortuosity and buckling of blood vessels are defined as the deviation from original configuration and has been observed throughout the vascular system. The blood flow in the regions down-stream of tortuous section decreases, which may cause a deficiency in blood supply to the organs and ischemia. Although tortuosity of blood vessels has been associated with aging, atherosclerosis, hypertension, genetic and other cardiovascular disease, the mechanism behind its initiation and development is not yet understood. In a series of theoretical and experimental studies, biomechanical aspects of buckling of arteries has been investigated under quasi-static loading (Han, 2007; Liu and Han, 2011); however, it has been shown theoretically that the buckling behavior of arteries under dynamic loading are different and arteries may become mechanically unstable at pressures other than the static critical loading (Rachev, 2009). This work addresses buckling of porcine aorta and experimental verification of dynamic buckling in this case. We hypothesize that dynamic buckling can partly contribute to the traumatic rupture of aorta that is a leading cause of fatality in motor vehicle crashes.

scholarly journals Evaluation of rock mechanical properties via scratch testing and its impact on energy production: comprehensive review

2020 ◽  
Vol 205 ◽  
pp. 03005
Author(s):  
Oladoyin Kolawole ◽  
Ion Ispas
Keyword(s):  
Mechanical Properties ◽  
Energy Storage ◽  
Energy Production ◽  
Experimental Studies ◽  
Scratch Test ◽  
Scratch Testing ◽  
Comprehensive Review ◽  
Geomechanical Properties ◽  
Geomechanical Parameters ◽  
Rock Mechanical Properties

The scratch test is a non-destructive method made up of pushing a tool across the surface of a weaker rock at a given penetration depth. The uniaxial rock strength (UCS), fracture toughness (KIC), and other geomechanical parameters influences how fracture nucleates, but fracture sizes and geometry adopted in hydraulic fracture design and modeling are most often overestimated. Although several researchers have attempted to evaluate UCS, KIC and other geomechanical properties in conventional and unconventional formations through scratch testing method, but there remain differing opinions on the fundamental approach and principles to be adopted in estimating those properties. Therefore, the evaluation of geomechanical parameters and their effect on hydrocarbon exploration, energy storage, and hydrocarbon exploitation remain an important issue for energy industry. In this paper, we present a comprehensive review of the methods of approach, applications, and the mechanics of rock scratching. We show the merits of scratch test over other methods of estimating rock mechanical properties. Our review focuses on over 50 previous experimental studies using scratch tests in the past few decades to investigate UCS, KIC and other geomechanical properties, including their impact on rock failure, fracture initiation and propagation. Finally, we highlight the fundamental research questions that are yet to be addressed. We envisage that advancement in our knowledge will improve optimization of hydrocarbon exploitation, energy storage, and field-scale modeling for energy production operations.

scholarly journals Experiences of a National Web-Based Heart Age Calculator for Cardiovascular Disease Prevention: User Characteristics, Heart Age Results, and Behavior Change Survey (Preprint)

2020 ◽  
Author(s):  
Carissa Bonner ◽  
Natalie Raffoul ◽  
Tanya Battaglia ◽  
Julie Anne Mitchell ◽  
Carys Batcup ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiovascular Disease ◽  
Experimental Studies ◽  
Emotional Responses ◽  
Lifestyle Changes ◽  
Small Samples ◽  
Cvd Risk ◽  
Web Based ◽  
Heart Age

BACKGROUND Heart age calculators are used worldwide to engage the public in cardiovascular disease (CVD) prevention. Experimental studies with small samples have found mixed effects of these tools, and previous reports of population samples that used web-based heart age tools have not evaluated psychological and behavioral outcomes. OBJECTIVE This study aims to report on national users of the Australian heart age calculator and the follow-up of a sample of users. METHODS The heart age calculator was launched in 2019 by the National Heart Foundation of Australia. Heart age results were calculated for all users and recorded for those who signed up for a heart age report and an email follow-up over 10 weeks, after which a survey was conducted. CVD risk factors, heart age results, and psychological and behavioral questions were analyzed using descriptive statistics and chi-square tests. Open responses were thematically coded. RESULTS There were 361,044 anonymous users over 5 months, of which 30,279 signed up to receive a heart age report and 1303 completed the survey. There were more women (19,840/30,279, 65.52%), with an average age of 55.67 (SD 11.43) years, and most users knew blood pressure levels (20,279/30,279, 66.97%) but not cholesterol levels (12,267/30,279, 40.51%). The average heart age result was 4.61 (SD 4.71) years older than the current age, including (23,840/30,279, 78.73%) with an older heart age. For the survey, most users recalled their heart age category (892/1303, 68.46%), and many reported lifestyle improvements (diet 821/1303, 63.01% and physical activity 809/1303, 62.09%). People with an older heart age result were more likely to report a doctor visit (538/1055, 51.00%). Participants indicated strong emotional responses to heart age, both positive and negative. CONCLUSIONS Most Australian users received an older heart age as per international and UK heart age tools. Heart age reports with follow-up over 10 weeks prompted strong emotional responses, high recall rates, and self-reported lifestyle changes and clinical checks for more than half of the survey respondents. These findings are based on a more engaged user sample than previous research, who were more likely to know blood pressure and cholesterol values. Further research is needed to determine which aspects are most effective in initiating and maintaining lifestyle changes. The results confirm high public interest in heart age tools, but additional support is needed to help users understand the results and take appropriate action.

Sign in / Sign up

Export Citation Format

Share Document