scholarly journals EXPERIMENTAL AND THEORETICAL RESEARCH ON REINFORCED LIGHTWEIGHT CONCRETE FLEXURAL ELEMENTS / ARMUOTOJO LENGVOJO BETONO LENKIAMŲJŲ ELEMENTŲ EKSPERIMENTINIAI IR TEORINIAI TYRIMAI

2014 ◽  
Vol 6 (5) ◽  
pp. 480-487
Author(s):  
Deividas Rumšys ◽  
Darius Bačinskas ◽  
Edmundas Spudulis ◽  
Eugenijus Gudonis ◽  
Aleksandr Sokolov
Keyword(s):  
High Speed ◽  
Lightweight Concrete ◽  
Image Correlation ◽  
Theoretical Research ◽  
Correlation Technique ◽  
Video Cameras ◽  
Strain Behavior ◽  
Four Point Bending ◽  
Vertical Displacements ◽  
Bending Loading

The paper deals with analysis of structural lightweight concrete. New lightweight concrete mixture made with expanded clay aggregate has been proposed and applied for experimental rein-forced concrete beams. Totally 8 beams with different rein-forcement ratios (0.309%, 0.557%, 0.895% and 1.255%) were tested under short-term four point bending loading. Stress-strain behavior of the beams under considerations has been investigated. Average strains at 4 different levels of pure bend-ing zone and vertical displacements at 12 different points of the beam were measured. During the test, deformations and crack-ing of the pure bending zone were additionally observed using high-speed digital video cameras. The data obtained by cameras were analyzed using digital image correlation technique. Applying the test data bending moments and curvature diagrams were derived for each beam. The obtained relationships were compared with theoretical results calculated using design code methods LST EN and STR. Using the inverse algorithm developed by VGTU, tension reinforced lightweight concrete stress and strain diagrams were obtained, which were adapted to numerical modeling by software ATENA. Moment and curvature diagrams obtained by finite elements program were compared with experimental moment and curvature diagrams. Good agreement between both diagrams has been obtained. Straipsnyje aprašytas naujai sukurtas konstrukcinis lengvasis betonas ir jo panaudojimas eksperimentinių armuotojo lengvojo betono sijų gamybai. Atlikti trumpalaike apkrova veikiamų plieniniais strypais armuotų lengvojo betono sijų eksperimentiniai tyrimai, kuriuose nagrinėtas sijų įtempių ir deformacijų būvis. Laboratorijoje išbandyti 8 lenkiamieji elementai, kurių armavimo procentai: 0,309 %, 0,557 %, 0,895 % ir 1,255 %. Tyrimų metu matuotos vidutinės elemento deformacijos grynojo lenkimo zonoje 4 skirtinguose lygmenyse bei sijų poslinkiai ties atramomis, jėgos pridėjimo vietose ir viduriniame pjūvyje (iš viso 12 matavimo taškų). Bandymo metu grynojo lenkimo zonos deformacijos bei pleišėjimas papildomai stebėti greitaeige vaizdo kamera. Gauti rezultatai panaudoti sudarant eksperimentines lenkimo momentų ir kreivių diagramas, kurios palygintos su teoriškai apskaičiuotomis taikant Lietuvoje galiojančių LST EN ir STR projektavimo normų metodikas. Taikant VGTU sukurtą atvirkštinio uždavinio algoritmą, gautos tempiamo armuotojo lengvojo betono įtempių ir deformacijų diagramos, kurios pritaikytos atliekant skaitinį modeliavimą baigtinių elementų programa ATENA. Gautos momentų ir kreivių diagramos baigtinių elementų programa palygintos su eksperimentų metu gautomis momentų ir kreivių diagramomis. Gautas geras šių diagramų sutapimas.

scholarly journals Evolution of the reinforced I-beam strain state

2018 ◽  
Vol 143 ◽  
pp. 01017 ◽  
Author(s):  
Artem Ustinov ◽  
Anatolij Klopotov ◽  
Aleksandr Potekaev ◽  
Vasilij Plevkov ◽  
Ekaterina Marchenko
Keyword(s):  
Composite Material ◽  
Strain State ◽  
Image Correlation ◽  
Correlation Technique ◽  
Digital Image Correlation Technique ◽  
Load Bearing Capacity ◽  
Four Point Bending ◽  
Reinforced Beams ◽  
State Evolution ◽  
Bending Loading

The paper presents experimental results of the strain state evolution of the steel I-beam reinforced with composite material under four-point bending loading. Digital image correlation technique was used to trace the evolution of plastic strain zones distribution. The images of longitudinal relative strain on the lateral surface of the reinforced I-beam web were obtained and analyzed. It was found that the increase of load-bearing capacity of the reinforced beams can exceed 26 %.

scholarly journals Modeling of Bimodular Bone Specimen under Four-Point Bending Fatigue Loading

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 474
Author(s):  
Yufan Yan ◽  
Xianjia Meng ◽  
Chuanyong Qu
Keyword(s):  
Compressive Strain ◽  
Fatigue Loading ◽  
Degradation Process ◽  
Neutral Axis ◽  
Image Correlation ◽  
Bending Test ◽  
Correlation Technique ◽  
Fatigue Process ◽  
Four Point Bending ◽  
Bone Properties

The fatigue damage behavior of bone has attracted significant attention in both the mechanical and orthopedic fields. However, due to the complex and hierarchical structure of bone, describing the damage process quantitively or qualitatively is still a significant challenge for researchers in this area. In this study, a nonlinear bi-modulus gradient model was proposed to quantify the neutral axis skewing under fatigue load in a four-point bending test. The digital image correlation technique was used to analyze the tensile and compressive strains during the fatigue process. The results showed that the compressive strain demonstrated an obvious two-stage ascending behavior, whereas the tensile strain revealed a slow upward progression during the fatigue process. Subsequently, a theoretical model was proposed to describe the degradation process of the elastic modulus and the movement of the neutral axis. The changes in the bone properties were determined using the FEM method based on the newly developed model. The results obtained from two different methods exhibited a good degree of consistency. The results obtained in this study are of help in terms of effectively exploring the damage evolution of the bone materials.

Effects of Carbon Fibre Geogrid Reinforcement on Propagation of Cracking in Pavement and Augmentation of Flexible Pavement Life

2014 ◽  
Vol 891-892 ◽  
pp. 1533-1538 ◽  
Author(s):  
Amir Barry Dizaj ◽  
Hasan Ziari ◽  
Mahmood Ahmadi Nejhad
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Crack Propagation ◽  
Carbon Fibre ◽  
High Speed ◽  
Flexible Pavement ◽  
Fatigue Specimen ◽  
Four Point Bending ◽  
Bending Loading

Most of the distresses in flexible pavement are due to cracking and rutting. Geogrids distribute the street and loads to adequate area and cause augmentation bearing capacity. This project surveys the function of carbon and Glass fiber Geogrids on Delay of Crack propagation in flexible pavement and placement configuration in pavement structure. Four point bending loading applied to beams with dimension 50.8*63.5*381 mm and 6.5 mm tolerance (AASHTO TP8-96). According to the received specimen from cutting slabs of case study toward chart fatigue life, for each condition reinforced and unreinforced beams 3 sample in 4-strain level were experimented. Simulatedrepeated loading with a frequency 10 Hz simulate high-speed traffic was applied to beam fatigue specimen. Based on definition (AASHTO T321-07) assumed achieving to 50% first bending stiffness for end of the fatigue life indicate a significant reduction in the rate of crack propagation in reinforced samples with carbon geogrids compared to unreinforced ones, augmentation service life is up to 3.5fold and placing the geogrid at a one-third depth of overlay thickness from the bottom provide the maximum service life.

The Influence of Facet Size on the Accuracy of Modal Parameters Determined by Digital Image Correlation Technique

2014 ◽  
Vol 611 ◽  
pp. 496-500 ◽  
Author(s):  
Róbert Huňady ◽  
Martin Hagara ◽  
František Šimčák
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
High Speed ◽  
Image Correlation ◽  
Modal Parameters ◽  
Correlation Technique ◽  
Correlation System ◽  
Correlation Process ◽  
The Impact ◽  
Facet Size

The paper deals with measurements of modal parameters using high-speed digital image correlation and assesses how the size of image elements (facets) influences the accuracy of modal parameters of the analyzed structure. The facet size is an important parameter that significantly affects the correlation process and its results. In the paper the experimental modal analysis of steel circular plate that has been excited by the impact hammer is described. Correlation system Q-450 Dantec Dynamics was used to measure the responses of the analyzed structure.

Stent Expansion in Curved Vessel and Their Interactions: An In Vitro Study

2014 ◽  
Author(s):  
Shijia Zhao ◽  
Shengmao Lin ◽  
Linxia Gu
Keyword(s):  
High Speed ◽  
In Vitro Study ◽  
Image Correlation ◽  
Correlation Technique ◽  
Digital Image Correlation Technique ◽  
Stent Expansion ◽  
Curved Artery ◽  
Induced Changes ◽  
Stenting Procedure

The objective of this work is to characterize the interaction between balloon-expandable stents and curved artery simulants. The deformation at the outer surface of the curved artery simulant was monitored using two high-speed cameras, and the corresponding strain map was obtained with 3-D digital image correlation technique. The anisotropic variations in the arterial mechanics were clearly observed. Results indicated three distinct phases during the stenting procedure, i.e., expansion, recoil and stabilization. The stent expansion dramatically altered the strain field of the curved artery simulant, and larger strain was observed around the center of stent than its two ends. In addition, the change in curvature of the simulant during the implantation of stent was quantified. This work characterized and quantified the interaction between stent and artery simulant in a laboratory setting, which could facilitate the optimization of the stent design for minimizing the stent-induced changes in the mechanical environment of artery.

scholarly journals Passive arching in rubberized sand backfills

2020 ◽  
Vol 57 (4) ◽  
pp. 549-567
Author(s):  
Hamidreza Khatami ◽  
An Deng ◽  
Mark Jaksa
Keyword(s):  
Deformation Process ◽  
High Speed ◽  
Pressure Sensors ◽  
Coarse Sand ◽  
Image Correlation ◽  
Correlation Technique ◽  
High Speed Imaging ◽  
Digital Image Correlation Technique ◽  
Stress Profiles ◽  
Stress Variations

The deformation and stress profiles of passive arching in a coarse sand and two rubberized sand backfills were investigated using a trapdoor apparatus. The trapdoor apparatus was instrumented with high-speed imaging equipment and a series of pressure sensors. The images of the deformation process in the backfills were analysed using the digital image correlation technique. The effect of a local surcharge on the deformation and stress profiles was also examined. It was observed that the rubber inclusions helped reduce the deformation of the backfills. Passive arching moduli and stress variations between the backfills examined are compared.

Sign in / Sign up

Export Citation Format

Share Document