NEW ANALYTICAL MODEL TO GENERALIZE THE BARCELONA TEST USING AXIAL DISPLACEMENT

The Barcelona Test has proved to be very suitable for the systematic control of the tensile properties of Fibre Reinforced Concrete (FRC). Nevertheless, the need to measure the total circumferential opening displacement (TCOD) of the specimen entails the use of an expensive circumferential extensometer. In order to simplify the test, studies from the literature propose the use of the axial displacement of the press (δ) instead of the TCOD, obtaining empirical equations to correlate the energy estimated with both measurements. However, these equations are only valid for δ ranging from 1 to 4 mm and were adjusted based on the test results of just a few types of FRC. The verification of this formulation for other types of FRC shows an average error of 51.1%, thus limiting the simplification proposed for the test. In this paper, a new analytical model to convert the δ into the TCOD is developed and validated for a wide range of FRC. Besides being applicable to the whole range of δ, the new model provides a clear physical understanding of the main mechanism observed during the test and shows an average error of only 6.7%, making it possible to simplify the Barcelona test.

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Analisis Ketepatan Pengukur Tegangan True RMS Jala-Jala Listrik Berbasis Mikrokontroler ATmega 328P

AVITEC ◽

10.28989/avitec.v2i2.734 ◽

2020 ◽

Vol 2 (2) ◽

Author(s):

Farobi Widia Nanda ◽

Freddy Kurniawan ◽

Paulus Setiawan

Keyword(s):

Input Signal ◽

Input Voltage ◽

Measuring System ◽

Signal Frequency ◽

Average Error ◽

Test Results ◽

Integer Variables ◽

Input Signal Frequency ◽

Wide Range ◽

Narrow Frequency Range

The analog AC-voltmeter usually can only measure the ideal-sinusoid voltage with narrow frequency range. Meanwhile, in fact the grid voltage is often not in the form of an ideal sinusoidal. To be able to measure a non-sinusoidal AC voltage with a wide range of frequency, a true-RMS voltmeter is needed. The research designed a true RMS measuring system using an ATmega 328P microcontroller. The input voltage is converted to pulse using Schmit triger and fed to the microcontroller’s external interrupt pin to calculate the input signal frequency. Meanwhile the microcontroller’s ADC sampled the input signal with a frequency of 128 times the signal’s frequency. RMS voltage calculations are performed using arithmetic operations for 16 and 32 bit integer variables. The test results show that the system can measure voltages with zero errors from 100 to 275 volts with a frequency of 50 Hz. The system can also measure voltages with zero errors at 220 volt with frequencies from 40 Hz to 150 Hz. However, this system can still be used to measure voltages ranging from 25 volts to 300 volts at frequencies from 35 Hz to 195 Hz with an average error of 0.21%. During RMS voltage calculation, the microcontroller’s CPU usage was 13.35%, so that this system can be further developed.

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Adding an expansive agent to increase the toughness of steel fibre reinforced concrete

HKIE Transactions ◽

10.33430/v26n4thie-2019-0001 ◽

2019 ◽

Vol 26 (4) ◽

pp. 197-208

Author(s):

Leo Gu Li ◽

Albert Kwok Hung Kwan

Keyword(s):

Reinforced Concrete ◽

Steel Fibre ◽

The Other ◽

Fibre Reinforced Concrete ◽

Test Results ◽

Compressive Properties ◽

Shrinkage Cracking ◽

Steel Fibre Reinforced Concrete ◽

Expansive Agent ◽

Concrete Matrix

Previous research studies have indicated that using fibres to improve crack resistance and applying expansive agent (EA) to compensate shrinkage are both effective methods to mitigate shrinkage cracking of concrete, and the additions of both fibres and EA can enhance the other performance attributes of concrete. In this study, an EA was added to fibre reinforced concrete (FRC) to produce concrete mixes with various water/binder (W/B) ratios, steel fibre (SF) contents and EA contents for testing of their workability and compressive properties. The test results showed that adding EA would slightly increase the superplasticiser (SP) demand and decrease the compressive strength, Young’s modulus and Poisson’s ratio, but significantly improve the toughness and specific toughness of the steel FRC produced. Such improvement in toughness may be attributed to the pre-stress of the concrete matrix and the confinement effect of the SFs due to the expansion of the concrete and the restraint of the SFs against such expansion.

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A Novel Ultrasonic TOF Ranging System Using AlN Based PMUTs

Micromachines ◽

10.3390/mi12030284 ◽

2021 ◽

Vol 12 (3) ◽

pp. 284

Author(s):

Yihsiang Chiu ◽

Chen Wang ◽

Dan Gong ◽

Nan Li ◽

Shenglin Ma ◽

...

Keyword(s):

Clock Cycle ◽

High Accuracy ◽

Ultrasonic Waves ◽

Oxide Semiconductor ◽

Average Error ◽

Cmos Process ◽

Clock Frequency ◽

Time Frequency ◽

Range Finding ◽

Wide Range

This paper presents a high-accuracy complementary metal oxide semiconductor (CMOS) driven ultrasonic ranging system based on air coupled aluminum nitride (AlN) based piezoelectric micromachined ultrasonic transducers (PMUTs) using time of flight (TOF). The mode shape and the time-frequency characteristics of PMUTs are simulated and analyzed. Two pieces of PMUTs with a frequency of 97 kHz and 96 kHz are applied. One is used to transmit and the other is used to receive ultrasonic waves. The Time to Digital Converter circuit (TDC), correlating the clock frequency with sound velocity, is utilized for range finding via TOF calculated from the system clock cycle. An application specific integrated circuit (ASIC) chip is designed and fabricated on a 0.18 μm CMOS process to acquire data from the PMUT. Compared to state of the art, the developed ranging system features a wide range and high accuracy, which allows to measure the range of 50 cm with an average error of 0.63 mm. AlN based PMUT is a promising candidate for an integrated portable ranging system.

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Novel Structure and Thermal Design and Analysis for CubeSats in Formation Flying

Aerospace ◽

10.3390/aerospace8060150 ◽

2021 ◽

Vol 8 (6) ◽

pp. 150

Author(s):

Yeon-Kyu Park ◽

Geuk-Nam Kim ◽

Sang-Young Park

Keyword(s):

Analytical Model ◽

Formation Flying ◽

Thermal Environment ◽

Thermal Analyses ◽

Thermal Design ◽

Analytical Models ◽

Test Results ◽

Solar Panels ◽

Novel Structure ◽

Micro Propulsion

The CANYVAL-C (CubeSat Astronomy by NASA and Yonsei using a virtual telescope alignment for coronagraph) is a space science demonstration mission that involves taking several images of the solar corona with two CubeSats—1U CubeSat (Timon) and 2U CubeSat (Pumbaa)—in formation flying. In this study, we developed and evaluated structural and thermal designs of the CubeSats Timon and Pumbaa through finite element analyses, considering the nonlinearity effects of the nylon wire of the deployable solar panels installed in Pumbaa. On-orbit thermal analyses were performed with an accurate analytical model for a visible camera on Timon and a micro propulsion system on Pumbaa, which has a narrow operating temperature range. Finally, the analytical models were correlated for enhancing the reliability of the numerical analysis. The test results indicated that the CubeSats are structurally safe with respect to the launch environment and can activate each component under the space thermal environment. The natural frequency of the nylon wire for the deployable solar panels was found to increase significantly as the wire was tightened strongly. The conditions of the thermal vacuum and cycling testing were implemented in the thermal analytical model, which reduced the differences between the analysis and testing.

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A Study on Estimation of Internal Pressure Creep Life Using Small Punch Creep (SPC) Tests for Boiler Pipes

Volume 6: Materials and Fabrication, Parts A and B ◽

10.1115/pvp2009-77336 ◽

2009 ◽

Author(s):

Toshimi Kobayashi ◽

Toru Izaki ◽

Junichi Kusumoto ◽

Akihiro Kanaya

Keyword(s):

Internal Pressure ◽

Residual Life ◽

Test Results ◽

Creep Life ◽

Creep Tests ◽

Good Correspondence ◽

Small Punch ◽

Uniaxial Creep ◽

Wide Range ◽

The Relationship

The small punch creep (SPC) test is possible to predict residual creep life at a high accuracy. But, the results of SPC tests cannot be compared with uniaxial creep or internal pressure creep results directly. In this report, the relationship between SPC test results and uniaxial creep test results in ASME A335 P11 (1.25Cr-0.5Mo Steel) was studied. The obtained relationship between SPC load and equivalent uniaxial creep stress formed a simple linear equation under the wide range of test temperature and test period. Then, the SPC results can be compared with uniaxial results by converting SPC loads to the equivalent uniaxial creep stresses. The relationship between SPC test results and internal pressure creep tests results was also studied. The internal creep life of as-received P11 pipe was almost same as SPC result when the hoop stress was converted to the SPC load. The creep lives of internal pressure creep influenced materials also showed good correspondence with SPC results. Therefore SPC can estimate the residual life of internal pressure creep influenced materials.

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Effects of Weld Strength Mismatch on Estimation Procedures for J and CTOD Fracture Parameters Using SE(B) Specimens

Volume 3: Design and Analysis ◽

10.1115/pvp2007-26611 ◽

2007 ◽

Cited By ~ 1

Author(s):

Gustavo H. B. Donato ◽

Claudio Ruggieri

Keyword(s):

Mouth Opening ◽

Estimation Procedure ◽

Primary Objective ◽

Weld Strength ◽

Crack Mouth Opening Displacement ◽

Opening Displacement ◽

Fracture Parameters ◽

Wide Range ◽

Estimation Procedures ◽

Fracture Specimens

This work presents an exploratory development of J and CTOD estimation procedures for welded fracture specimens under bending based upon plastic eta factors and plastic rotation factors. The techniques considered include: i) estimating J and CTOD from plastic work and ii) estimating CTOD from the plastic rotational factor. The primary objective is to gain additional understanding on the effect of weld strength mismatch on estimation techniques to determine J and CTOD fracture parameters for a wide range of a/W-ratios and mismatch levels. Very detailed non-linear finite element analyses for plane-strain models of SE(B) fracture specimens with center cracked, square groove welds provide the evolution of load with increased load-line displacement and crack mouth opening displacement which are required for the estimation procedure. The results show that levels of weld strength mismatch within the range ±20% mismatch do not affect significantly J and CTOD estimation expressions applicable to homogeneous materials, particularly for deeply cracked fracture specimens. The present analyses, when taken together with previous studies, provide a fairly extensive body of results which serve to determine parameters J and CTOD for different materials using bend specimens with varying geometries and mismatch levels.

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Multi-stable composite twisting structure for morphing applications

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2011.0631 ◽

2012 ◽

Vol 468 (2141) ◽

pp. 1230-1251 ◽

Cited By ~ 61

Author(s):

X. Lachenal ◽

P. M. Weaver ◽

S. Daynes

Keyword(s):

Analytical Model ◽

Material Properties ◽

Degrees Of Freedom ◽

Design Parameters ◽

Engineering Structures ◽

The Past ◽

Wide Range ◽

Morphing Structure ◽

Low Mass ◽

Unstable States

Conventional shape-changing engineering structures use discrete parts articulated around a number of linkages. Each part carries the loads, and the articulations provide the degrees of freedom of the system, leading to heavy and complex mechanisms. Consequently, there has been increased interest in morphing structures over the past decade owing to their potential to combine the conflicting requirements of strength, flexibility and low mass. This article presents a novel type of morphing structure capable of large deformations, simply consisting of two pre-stressed flanges joined to introduce two stable configurations. The bistability is analysed through a simple analytical model, predicting the positions of the stable and unstable states for different design parameters and material properties. Good correlation is found between experimental results, finite-element modelling and predictions from the analytical model for one particular example. A wide range of design parameters and material properties is also analytically investigated, yielding a remarkable structure with zero stiffness along the twisting axis.

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Compressibility behaviour of remoulded, fine-grained soils and correlation with index properties

Canadian Geotechnical Journal ◽

10.1139/t99-128 ◽

2000 ◽

Vol 37 (3) ◽

pp. 712-722 ◽

Cited By ~ 93

Author(s):

A Sridharan ◽

H B Nagaraj

Keyword(s):

Liquid Limit ◽

Plasticity Index ◽

Engineering Properties ◽

Test Results ◽

Index Properties ◽

Initial Water ◽

Fine Grained ◽

Wide Range ◽

The Relationship ◽

Water Contents

Correlating engineering properties with index properties has assumed greater significance in the recent past in the field of geotechnical engineering. Although attempts have been made in the past to correlate compressibility with various index properties individually, all the properties affecting compressibility behaviour have not been considered together in any single study to examine which index property of the soil correlates best with compressibility behaviour, especially within a set of test results. In the present study, 10 soils covering a sufficiently wide range of liquid limit, plastic limit, and shrinkage limit were selected and conventional consolidation tests were carried out starting with their initial water contents almost equal to their respective liquid limits. The compressibility behaviour is vastly different for pairs of soils having nearly the same liquid limit, but different plasticity characteristics. The relationship between void ratio and consolidation pressure is more closely related to the shrinkage index (shrinkage index = liquid limit - shrinkage limit) than to the plasticity index. Wide variations are seen with the liquid limit. For the soils investigated, the compression index relates better with the shrinkage index than with the plasticity index or liquid limit.Key words: Atterberg limits, classification, clays, compressibility, laboratory tests.

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A Four Novel Energy Pattern Factor Method for Computation of Weibull Parameter in Impact Strength Reliability of Fibre-Reinforced Concrete

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i3.12.16042 ◽

2018 ◽

Vol 7 (3.12) ◽

pp. 272

Author(s):

Gayathri R ◽

Murali. G ◽

Parthiban Kathirvel ◽

Haridharan M.K ◽

Karthikeyan. K

Keyword(s):

Reinforced Concrete ◽

Impact Strength ◽

Shape Parameter ◽

Failure Strength ◽

Fibre Reinforced Concrete ◽

Test Results ◽

Weibull Parameter ◽

Impact Failure ◽

Novel Method ◽

The Impact

Impact strength data is a noteworthy factor for designing airport pavements, civilian and military structures etc and it is ought to be modelled precisely. In order to achieve an appropriate modelling data, it is important to select a suitable estimation method. One such commonly used statistical tool is the two parameter Weibull distribution for modelling impact failure strength accurately besides the variations in test results. This study statistically commandsthe variations in the impact failure strength (number of blows to induce failure) of fibre reinforced concrete (FRC) subjected to drop hammer test. Subsequently, a four-different novel method for the computation of Weibull parameter (Shape parameter) based on the earlier researchers test results has been proposed. The accuracy of the proposed four novel method is demonstrated by comparing with power density method and verified with goodness of fit test. Finally, the impact failure strength of FRC is offered in terms of reliability. The proposed four NEPFM is very suitable and efficient to compute the shape parameter in impact failure strength applications.

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Design of Monitoring Tool Heartbeat Rate and Human Body Temperature Based on WEB

MATEC Web of Conferences ◽

10.1051/matecconf/201816401017 ◽

2018 ◽

Vol 164 ◽

pp. 01017 ◽

Cited By ~ 1

Author(s):

Jalinas ◽

Wahyu Kusuma Raharja ◽

Bobby Putra Emas Wijaya

Keyword(s):

Heart Rate ◽

Body Temperature ◽

Human Body ◽

Average Error ◽

Web Pages ◽

Test Results ◽

Pulse Sensor ◽

Measurement Results ◽

Human Body Temperature ◽

Error Percentage

The heart is one of the most important organs in the human body. One way to know heart health is to measure the number of heart beats per minute and body temperature also shows health, many heart rate and body temperature devices but can only be accessed offline. This research aims to design a heart rate detector and human body temperature that the measurement results can be accessed via web pages anywhere and anytime. This device can be used by many users by entering different ID numbers. The design consists of input blocks: pulse sensor, DS18B20 sensor and 3x4 keypad button. Process blocks: Arduino Mega 2560 Microcontroller, Ethernet Shield, router and USB modem. And output block: 16x2 LCD and mobile phone or PC to access web page. Based on the test results, this tool successfully measures the heart rate with an average error percentage of 2.702 % when compared with the oxymeter tool. On the measurement of body temperature get the result of the average error percentage of 2.18 %.

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