scholarly journals The Effects of Fiber Inclusion on the Evolution of Desiccation Cracking in Soil-Cement

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4974
Author(s):  
Yaxing Xu ◽  
Xin Yao ◽  
Yan Zhuang ◽  
Wei Duan ◽  
Xidong Zhang ◽  
...  
Keyword(s):  
Strain Field ◽  
Evaporation Rate ◽  
Image Correlation ◽  
Experimental Investigations ◽  
Drying Process ◽  
Polyvinyl Alcohol Fiber ◽  
Soil Cement ◽  
Crack Monitoring ◽  
Desiccation Cracking ◽  
Propagation Pattern

Desiccation cracking frequently occurs in mud, clay, and pavement. Understanding the evolution of desiccation cracking may facilitate the development of techniques to mitigate cracking and even prevent it from developing altogether. In this study, experimental investigations were performed focusing on the effects of fibers on the evolution of desiccation cracking in soil-cement. Varied types of fibers (i.e., jute fiber and polyvinyl alcohol fiber (PVA)) and fiber contents (i.e., 0%, 0.25%, 0.5%, and 1%) were involved. The digital image correlation (DIC) method was employed to capture the evolution and propagation of cracks in the soil-cement specimens when subjected to desiccation. The results show that the presence of fibers imposes significant effects on the crack propagation pattern as well as the area and length of the cracks in the soil-cement during shrinkage. The addition of fibers, however, insignificantly affects the evaporation rate of the specimens. The crack area and crack length of the specimens decreased significantly when more fibers were included. There were no macroscopic cracks observed in the specimens where the fiber content was 1%. The DIC method effectively helped to determine the evolution of displacement and strain field on the specimens’ surface during the drying process. The DIC method is therefore useful for crack monitoring.

Methodology for in situ stress intensity factor determination on cracked structures by digital image correlation

2010 ◽  
Vol 1 (4) ◽  
pp. 344-357 ◽  
Author(s):  
V. Richter‐Trummer ◽  
P.M.G.P. Moreira ◽  
S.D. Pastrama ◽  
M.A.P. Vaz ◽  
P.M.S.T. de Castro
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Digital Image Correlation ◽  
Intensity Factor ◽  
Digital Image ◽  
Strain Field ◽  
Image Correlation ◽  
Content Type ◽  
Cracked Structures

PurposeThe purpose of this paper is to develop a methodology for in situ stress intensity factor (SIF) determination that can be used for the analysis of cracked structures. The technique is based on digital image correlation (DIC) combined with an overdetermined algorithm.Design/methodology/approachThe linear overdeterministic algorithm for calculating the SIF based on stress values around the crack tip is applied to a strain field obtained by DIC.FindingsAs long as the image quality is sufficiently high, a good accuracy can be obtained for the measured SIF. The crack tip can be automatically detected based on the same strain field. The use of the strain field instead of the displacement field, eliminates problems related to the rigid body motion of the analysed structure.Practical implicationsIn future works, based on the applied techniques, the SIF of complex cracked plane stress structures can be accurately determined in real engineering applications.Originality/valueThe paper demonstrates application of known techniques, refined for other applications, also the use of stress field for SIF overdeterministic calculations.

scholarly journals A Numerical Strategy to Identify the FSW Process Optimal Parameters of a Butt-Welded Joint of Quasi-Pure Copper Plates: Modelling and Experimental Validation

2021 ◽  
Author(s):  
Monica Daniela IORDACHE ◽  
Claudiu BADULESCU ◽  
Malick DIAKHATE ◽  
Adrian CONSTANTIN ◽  
Eduard Laurentiu NITU ◽  
...  
Keyword(s):  
Welded Joint ◽  
Pure Copper ◽  
Correlation Method ◽  
Image Correlation ◽  
Experimental Investigations ◽  
Optimal Parameters ◽  
Friction Stir ◽  
Mass Scaling ◽  
Surface Response ◽  
Fsw Parameters

Abstract Determining the optimal parameters of the Friction Stir Welding (FSW) process, which are suitable for a given joint configuration, remains a great challenge and is often achieved through extremely time-consuming and costly experimental investigations. The present paper aims to propose a strategy for the identification of the optimal parameters for a butt-welded joint of 3-mm thick quasi-pure copper plates. This strategy is based on FEM (finite elements method) simulations and the optimal temperature that is supposedly known. A robust and efficient finite element model that is based on the Coupled Eulerian-Lagrangian (CEL) approach has been adopted and a temperature-dependent friction coefficient has been used. Besides, the mass scaling technique has been used to significantly reduce the simulation time. The thermo-mechanical behavior of the butt-welded joint was modeled using a Johnson-Cook plasticity model that was identified through lab tests at different temperatures. The results of the parametric study help to define the numerical surface response, and based on this latter one can found the optimal parameters, advancing (υa) and rotational (υr) speeds, of the FSW process. This numerical surface response has been validated with good agreement between the numerical prediction of the model and the experimental results. Furthermore, experimental investigations involving x-ray radiography, digital image correlation method, and fracture surface analysis have helped a better understanding of the effects of FSW parameters on the welded joint quality.

scholarly journals A new methodology to identify minimum strain anatomical lines based on 3-D digital image correlation

2017 ◽  
Vol 8 (2) ◽  
pp. 337-347 ◽  
Author(s):  
Jorge Barrios-Muriel ◽  
Francisco Javier Alonso Sánchez ◽  
David Rodríguez Salgado ◽  
Francisco Romero-Sánchez
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Field ◽  
Three Dimensional ◽  
Wearable Devices ◽  
Plane Motion ◽  
Human Motion ◽  
The Body ◽  
Image Correlation ◽  
Minimum Deformation

Abstract. Today there is continuous development of wearable devices in various fields such as sportswear, orthotics and personal gadgets, among others. The design of these devices involves the human body as a support environment. Based on this premise, the development of wearable devices requires an improved understanding of the skin strain field of the body segment during human motion. This paper presents a methodology based on a three dimensional digital image correlation (3D-DIC) system to measure the skin strain field and to estimate anatomical lines with minimum deformation as design criteria for the aforementioned wearable devices. The errors of displacement and strain measurement related to 3-D reconstruction and out-of-plane motion are investigated and the results are acceptable in the case of large deformation. This approach can be an effective tool to improve the design of wearable devices in the clinical orthopaedics and ergonomics fields, where comfort plays a key role in supporting the rehabilitation process.

KINETICS OF EVAPORATION OF A MODEL SOLUTION OF DISTILLERY DREGS CONTAINING PROTEIN, OIL AND SUGAR

2021 ◽  
Author(s):  
А.С. ДАНИЛЬЧЕНКО ◽  
Т.Г. КОРОТКОВА ◽  
С.Ю. КСАНДОПУЛО
Keyword(s):  
Evaporation Rate ◽  
Experimental Studies ◽  
Petri Dish ◽  
Model Solution ◽  
Soluble Carbohydrates ◽  
Drying Process ◽  
Sugar Water ◽  
Oil Water ◽  
Drying Model ◽  
Kinetics Of

Рассмотрена кинетика сушки послеспиртовой барды при 60°С. Объектом исследований была модельная смесь, состоящая из воды, белков, жиров и растворимых углеводов. Представлены результаты исследований кинетики испарения воды и смесей вода–масло, вода–белок, вода–сахар, вода–масло–белок–сахар, помещенных в чашку Петри. Процесс испарения в изотермических условиях протекал в сушильном шкафу Memmert. Установлено, что добавление вещества в воду снижает скорость испарения воды в периоде постоянной скорости сушки, в периоде падающей скорости сушки продолжительность испарения возрастает. По результатам кинетики сушки модельных смесей можно определять коэффициенты активности компонентов и проводить исследование процесса сушки реальных смесей при проектировании сушилок. The kinetics of drying of the distillery dregs at 60°C is considered. The model mixture containing water, proteins, oils and soluble carbohydrates was the object of research. The results of experimental studies of the kinetics of evaporation of water and mixtures of water-oil, water-protein, water-sugar, water-oil-protein-sugar, placed in a Petri dish, are presented. Evaporation under isothermal conditions was carried out in a Memmert drying cabinet. It is established that the addition of the substance into the water reduces the evaporation rate of water in the period of constant drying speed, the duration of evaporation in the period of falling drying speed increases. According to the results of the kinetics of drying model mixtures, it is possible to determine the activity coefficients of the components and conduct a study of the drying process of real mixtures in the design of dryers.

scholarly journals Strain field evolution at the ductile-to-brittle transition: a case study on ice

Solid Earth ◽  
2017 ◽  
Vol 8 (5) ◽  
pp. 943-953 ◽  
Author(s):  
Thomas Chauve ◽  
Maurine Montagnat ◽  
Cedric Lachaud ◽  
David Georges ◽  
Pierre Vacher
Keyword(s):  
Stress Concentration ◽  
Dynamic Recrystallization ◽  
Strain Field ◽  
Crack Opening ◽  
Local Stress ◽  
Image Correlation ◽  
Brittle Transition ◽  
Field Evolution ◽  
Crack Tips ◽  
Ductile To Brittle Transition

Abstract. This paper presents, for the first time, the evolution of the local heterogeneous strain field around intra-granular cracking in polycrystalline ice, at the onset of tertiary creep. Owing to the high homologous temperature conditions and relatively low compressive stress applied, stress concentration at the crack tips is relaxed by plastic mechanisms associated with dynamic recrystallization. Strain field evolution followed by digital image correlation (DIC) directly shows the redistribution of strain during crack opening, but also the redistribution driven by crack tip plasticity mechanisms and recrystallization. Associated local changes in microstructure induce modifications of the local stress field evidenced by crack closure during deformation. At the ductile-to-brittle transition in ice, micro-cracking and dynamic recrystallization mechanisms can co-exist and interact, the later being efficient to relax stress concentration at the crack tips.

scholarly journals Experimental Investigations of Impact Damage Influence on Behavior of Thin-Walled Composite Beam Subjected to Pure Bending

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1127 ◽  
Author(s):  
Tomasz Kubiak ◽  
Lukasz Borkowski ◽  
Nina Wiacek
Keyword(s):  
Impact Damage ◽  
Full Range ◽  
Image Correlation ◽  
Bending Test ◽  
Beam Deflection ◽  
Experimental Investigations ◽  
Pure Bending ◽  
Channel Section ◽  
Thin Walled ◽  
The Impact

The paper deals with buckling, postbuckling, and failure of pre-damaged channel section beam subjected to pure bending. The channel section beams made of eight-layered GFRP laminate with different symmetrical layups have been considered. The specimens with initially pre-damaged web or flange were investigated to access the influence of impact damage on work of thin-walled structure in the full range of load till failure. The bending tests of initially pre-damage beams have been performed on a universal tensile machine with especially designed grips. The digital image correlation system allowing to follow the beam deflection have been employed. The experimentally obtained results are presented in graphs presenting load-deflection or load vs. angle of rotation relations and in photos presenting impact damages areas before and after bending test. The results show that the impact pre-damages have no significant influence on the work of channel section beams.

Estimation of evaporation rate of water droplet group in spray drying process

2020 ◽  
Vol 227 ◽  
pp. 115938 ◽  
Author(s):  
Sayaka Okada ◽  
Shuji Ohsaki ◽  
Hideya Nakamura ◽  
Satoru Watano
Keyword(s):  
Spray Drying ◽  
Water Droplet ◽  
Evaporation Rate ◽  
Drying Process

scholarly journals Risk of damage and desiccation cracking of construction materials based on raw earth

2019 ◽  
Vol 281 ◽  
pp. 01018 ◽  
Author(s):  
Ahmad El Hajjar ◽  
Joanna Eid ◽  
Tariq Ouahbi ◽  
Said Taibi
Keyword(s):  
Digital Image Correlation ◽  
Construction Materials ◽  
Image Correlation ◽  
Correlation Technique ◽  
Digital Image Correlation Technique ◽  
Initiation And Propagation ◽  
Desiccation Cracking ◽  
Natural Aggregates ◽  
Raw Earth ◽  
Homogeneous Strain

Nowadays, structures are mainly constructed using natural aggregates as sand and gravels. In the future, we would increasingly have to consider replacing them by more abundant and ecological natural materials such as raw earth. However, despite its many qualities (low gray energy, thermal and hygrometric isolation), this eco-material has some defects: cracking by desiccation. The later prevent its widespread diffusion. This study aims to understand the mechanisms of appearance and propagation of cracks in order to try to either prevent or repair it. To carry out this study, digital image correlation technique is used. It consists in performing free desiccation tests to follow the initiation and propagation of cracks, from the beginning of homogeneous strain until the appearance of discontinuity, in order to determine the strains tensor in the massif. In order to understand the origin of cracking, desiccation is studied for different boundary conditions and according to different intrinsic characteristics of the material.

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