scholarly journals EFFECT OF SHORT FIBERS ORIENTATION ON MECHANICAL PROPERTIES OF COMPOSITE MATERIAL – FIBER REINFORCED CONCRETE

2017 ◽  
Vol 23 (8) ◽  
pp. 1091-1099 ◽  
Author(s):  
Vitalijs LUSIS ◽  
Andrejs KRASNIKOVS ◽  
Olga KONONOVA ◽  
Videvuds-Arijs LAPSA ◽  
Rimvydas STONYS ◽  
...  
Keyword(s):  
Fiber Reinforced Concrete ◽  
Fracture Mechanisms ◽  
Short Fibers ◽  
Structural Element ◽  
Fibre Concentration ◽  
Four Point Bending ◽  
Fibre Concrete ◽  
Simulation Results ◽  
Fibers Orientation ◽  
Short Steel Fibres

Traditional fiberconcrete structures have fibres in the mix oriented in all spatial directions, distributed in the struc­tural element volume homogenously, what not easy to obtain in practice. In many situations, structurally more effective is the insertion of fibres into the concrete structural element body by forming layers, with a predetermined fibre concentration and orientation in every layer. In the present investigation, layered fibre concrete is under investigation. Short steel fibres were at­tached to flexible warps with the necessary fibres concentration and orientation. Warps were placed into the prismatic mould separating them by concrete layers without fibres. Prisms were matured and tested under four-point bending. The bending-affected mechanical behaviour of cracked fibre concrete was simulated numerically by using a developed struc­tural model. Comparing the simulation results with experimental data, material micromechanical fracture mechanisms were analysed and evaluated.

scholarly journals Damage Evolution and Fracture Events Sequence Analysis of Core-Shell Nanoparticle Modified Bone Cements by Acoustic Emission Technique

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 208
Author(s):  
O.F. Pacheco-Salazar ◽  
Shuichi Wakayama ◽  
L.A. Can-Herrera ◽  
M.A.A. Dzul-Cervantes ◽  
C.R. Ríos-Soberanis ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Bone Cement ◽  
Solid Phase ◽  
Bending Test ◽  
Fracture Mechanisms ◽  
Core Shell ◽  
Bone Cements ◽  
Four Point Bending ◽  
Ae Signals ◽  
Cement Formulation

In this research, damage in bone cements that were prepared with core-shell nanoparticles was monitored during four-point bending tests through an analysis of acoustic emission (AE) signals. The core-shell structure consisted of poly(butyl acrylate) (PBA) as rubbery core and methyl methacrylate/styrene copolymer (P(MMA-co-St)) as a glassy shell. Furthermore, different core-shell ratios 20/80, 30/70, 40/60, and 50/50 were prepared and incorporated into the solid phase of the bone cement formulation at 5, 10, and 15 wt %, respectively. The incorporation of a rubbery phase into the bone cement formulation decreased the bending strength and bending modulus. The AE technique revealed that the nanoparticles play an important role on the fracture mechanism of the bone cement, since a higher amount of AE signals (higher amplitude and energy) were obtained from bone cements that were prepared with the nanoparticles in comparison with those without nanoparticles (the reference bone cement). The SEM examination of the fracture surfaces revealed that all of the bone cement formulations exhibited stress whitening, which arises from the development of crazes before the crack propagation. Finally, the use of the AE technique and the fracture surface analysis by SEM enabled insight into the fracture mechanisms that are presented during four-point bending test of the bone cement containing nanoparticles.

scholarly journals Research on Extrusion of Rubber Composites Reinforced by Short Fibers Orientation Based on FEA

2018 ◽  
Vol 38 ◽  
pp. 02022
Author(s):  
Dewei Zhang ◽  
Chuansheng Wang ◽  
Bo Shen ◽  
Shaoming Li ◽  
Huiguang Bian
Keyword(s):  
Flow Field ◽  
Extrusion Process ◽  
Short Fiber ◽  
Rubber Matrix ◽  
Real Problem ◽  
Short Fibers ◽  
Rubber Composites ◽  
Field Velocity ◽  
Fibers Orientation ◽  
Cut Resistance

In recent years, rubber composites reinforced by short fibers has been researched deeply, because of its good performances such as higher wear resistance, higher cut resistance and so on. Some research results indicated that if short fibers get orientation in rubber composites, the performances of rubber products could be promoted greatly. But how to make short fibers get orientation in rubber matrix during extrusion is still a real problem. And there are many parameters affect the short fibers orientation. So, in this paper, the effects of die structure including expansion-die and dam-expansion-die on extrusion flow field of short fiber and rubber composite material during extrusion process has been researched by Polyflow. And the FEA results about the pressure field, velocity field and the velocity vector of the rubber composites flow field indicate that, comparing with expansion-die and the dam-expansion-die, the latter one is better for the extrusion process of rubber composites and making short fibers get radial orientation in rubber matrix.

Carbon Fiber Reinforced Concrete as an Intrinsically Smart Concrete for Damage Assessment During Dynamic Loading

1994 ◽  
Vol 360 ◽  
Author(s):  
Pu-Woei Chen ◽  
D.D.L. Chung
Keyword(s):  
Carbon Fibers ◽  
Inelastic Deformation ◽  
Fiber Reinforced Concrete ◽  
Short Fibers ◽  
Conduction Path ◽  
Electrically Conducting ◽  
Pull Out ◽  
Deformation And Fracture ◽  
Short Carbon ◽  
Smart Concrete

AbstractConcrete containing short carbon fibers (0.2-0.5 vol.%) was found to be an intrinsically smart concrete that can sense elastic and inelastic deformation, and fracture. The signal provided is the change in electrical resistance, which is reversible for elastic deformation and irreversible for inelastic deformation and fracture. The presence of electrically conducting short fibers is necessary for the concrete to sense elastic or inelastic deformation, but the sensing of fracture does not require fibers. The fibers serve to bridge the cracks and provide a conduction path. The resistance increase is due to conducting fiber pull-out in the elastic regime, conducting fiber breakage in the inelastic regime, and crack propagation at fracture.

scholarly journals Fracture Mechanisms of Bone: A Comparative Study between Antler and Bovine Femur

2008 ◽  
Vol 1132 ◽  
Author(s):  
P.Y. Chen ◽  
F.A. Sheppard ◽  
J.M. Curiel ◽  
J. McKittrick
Keyword(s):  
Fracture Toughness ◽  
Cervus Elaphus ◽  
Fracture Mechanisms ◽  
Transverse Orientation ◽  
Single Edge ◽  
Bending Tests ◽  
Degree Of Hydration ◽  
Four Point Bending ◽  
Longitudinal Orientation ◽  
Uncracked Ligament

ABSTRACTIn this study, fracture toughness of North American elk (Cervus elaphus canadensis) antler and bovine femur were measured using four-point bending tests on single-edge notched compact samples (ASTM C1421). Tests were conducted on crack growth directions longitudinal and transverse to the long axis of antler and bone in both dry and hydrated conditions to study the effects of fiber orientation and hydration. Fracture toughness results in the transverse orientation were much higher than that in the longitudinal orientation and increased with degree of hydration for both antler and bovine femur. The fracture toughness of antler was ∼ 50% higher than that of bovine femur. The highest fracture toughness value was obtained from the hydrated antler in the transverse orientation, which reached 10.31 MPa·m1/2 compared to that measured from bovine femur, which was 6.35 MPa·m1/2. The crack propagation and fracture surface were characterized using scanning electron microscopy. Toughening mechanisms, including crack deflection by osteons, uncracked ligament bridging, and microcracks formation, are observed and discussed. Comparisons between antler and bone are made.

A study on alkali resistant glass fibre concrete and its exposure to elevated temperatures

2020 ◽  
Vol 1 (103) ◽  
pp. 5-15
Author(s):  
S. Hussain ◽  
J.S. Yadav
Keyword(s):  
Glass Fiber ◽  
Elevated Temperatures ◽  
Glass Fibers ◽  
Fiber Reinforced Concrete ◽  
Split Tensile Strength ◽  
Conventional Concrete ◽  
Glass Fiber Reinforced ◽  
Fibre Concrete ◽  
Percentage Weight ◽  
Temperature Exposure

Purpose: Cement concrete is characterized as brittle in nature, the loading capacity of which is completely lost once failure is initiated. This characteristic, which limits the application of the material, can in one way be overcome by the addition of some small amount of short randomly distributed fibers (steel, glass, synthetic). Design/methodology/approach: The present study deals with the inclusion of alkali resistant glass fibers in concrete by percentage weight of cement. The mechanical properties such as compressive strength and split tensile strength have been studied after exposing the concrete samples to elevated temperatures of up to 500°C. Water binder ratios of 0.4, 0.45, 0.5, 0.55 and 0.6 have been used to prepare design mix proportions of concrete to achieve a characteristic strength of 30 MPa. The depth of carbonation post elevated temperature exposure has been measured by subjecting the concrete samples to an accelerated carbonation (5%) condition in a controlled chamber. Findings: Conclusions have been drawn in accordance to the effect of fiber replacement and temperature increment. The concrete mixes with fiber content of 1% by weight of cement had shown better strength in compression and tension compared to the other dosages and conventional concrete (without fiber). Microcracking due to internal stream pressure reduced the mechanical strengths of concrete at elevated temperatures. Also, from TGA it was observed that the amount of calcium carbonate in samples with fiber added, post carbonation was less than the mixes without fiber in it. Research limitations/implications: The present study has been limited to alkali resistant glass fibers as the conventional glass fibers undergo corrosion due to hydration. Practical implications: The glass fiber reinforced concrete can be used in the building renovation works, water and drainage works, b ridge and tunnel lining panels etc. Originality/value: Based upon the available literature, very seldom the studies are addressing the behaviour of alkali resistant glass fiber concrete and its exposure to elevated temperatures.

scholarly journals Experimental Investigation and Modelling of the Layered Concrete with Different Concentration of Short Fibers in the Layers

Fibers ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 76
Author(s):  
Vitalijs Lusis ◽  
Olga Kononova ◽  
Arturs Macanovskis ◽  
Rimvydas Stonys ◽  
Inga Lasenko ◽  
...  
Keyword(s):  
Experimental Data ◽  
Bearing Capacity ◽  
Fracture Process ◽  
Fiber Reinforced Concrete ◽  
Short Fibers ◽  
Steel Fiber Reinforced Concrete ◽  
Load Bearing Capacity ◽  
Fiber Concentration ◽  
Load Bearing ◽  
Pull Out

The use of steel fiber reinforced concrete (SFRC) in structures with high physical-mechanical characteristics allows engineers to reduce the weight and costs of the structures, to simplify the technology of their production, to reduce or completely eliminate the manual labor needed for reinforcement, at the same time increasing reliability and durability. Commonly accepted technology is exploiting randomly distributed in the concrete volume fibers with random each fiber orientation. In structural members subjected to bending, major loads are bearing fibers located close to outer member surfaces. The majority of fibers are slightly loaded. The aim of the present research is to create an SFRC construction with non-homogeneously distributed fibers. We prepared layered SFRC prismatic specimens. Each layer had different amount of short fibers. Specimens were tested by four point bending till the rupture. Material fracture process was modelled based on the single fiber pull-out test results. Modelling results were compared with the experimental curves for beams. Predictions generated by the model were validated by 4PBT of 100 × 100 × 400 mm prisms. Investigation had shown higher load-bearing capacity of layered concrete plates comparing with plate having homogeneously distributed the same amount of fibers. This mechanism is strongly dependent on fiber concentration. A high amount of fibers is leading to new failure mechanisms—pull-out of FRC blocks and decrease of load-bearing capacity. Fracture surface analysis was realized for broken prisms with the goal to analyze fracture process and to improve accuracy of the elaborated model. The general conclusion with regard to modelling results is that the agreement with experimental data is good, numeric modelling results successfully align with the experimental data. Modelling has indicated the existence of additional failure processes besides simple fiber pull-out, which could be expected when fiber concentration exceeds the critical value.

scholarly journals Mechanical Properties of PVA & Steel Hybrid Fiber Reinforced Concrete

2021 ◽  
Vol 309 ◽  
pp. 01174
Author(s):  
K Sharmila Sai Sree ◽  
Srikanth Koniki
Keyword(s):  
Mechanical Properties ◽  
Single Fibre ◽  
Fiber Reinforced Concrete ◽  
Hybrid Fiber ◽  
Normal Concrete ◽  
Flexure Strength ◽  
Strain Behavior ◽  
Crack Behavior ◽  
Fibre Concrete ◽  
Compressive Strength Test

Combining various kinds of fibre to achieve good response and strength from the concrete by using different experiments is shown in this research. Here PVA which is polyvinyl alcohol and HS hooked end steel fibres are used to gain more strength compared with normal concrete or single fibre concrete. Here first we take PVA specimens results by considering optimum dosage 0.15% result & HS fibre is taken as HFRC concrete by this the strength of the concrete can control the crack behavior occurred in specimens. Mechanical properties such as compressive strength test, flexure strength, and stress-strain behavior are studied. Combining different fibers HFRC is mainly useful for longstanding structures. This method can be easy to understand and economical.

scholarly journals EXPERIMENTAL STUDY AND NUMERICAL MODELLING FOR FLEXURAL CAPACITY OF FRC STRUCTURAL ELEMENTS

2021 ◽  
Vol 3 ◽  
pp. 30-35
Author(s):  
Liva Luize Bleive ◽  
Vitalijs Lusis
Keyword(s):  
Program Analysis ◽  
Fracture Process ◽  
Stress Distributions ◽  
Structural Elements ◽  
Steel Fibre Reinforced Concrete ◽  
Four Point Bending ◽  
Brittle Matrix Composite ◽  
Linear Behaviour ◽  
Concrete Matrix ◽  
Short Steel Fibres

Concrete reinforced by short steel fibres is typical brittle matrix composite, in which fibres are impeding cracks growth, such way increasing material’s tensile strength. The use of steel fibre reinforced concrete (SFRC) in structures with high physical and mechanical characteristics makes possible to reduce their weight and cost, to simplify their production technology, to reduce or eliminate reinforcement labour, at the same time increasing reliability and durability. Randomly distributed discontinuous fibres are bridging the crack’s flanks providing material’s “ductility”- like non-linear behaviour at cracking stage. The current study is focused on one formulation of a specific type of concrete matrix with added fibres and without fibres. Concrete cubes and prisms without fibres and having in every situation the same content of 60 mm long fibres were fabricated. Cubes (100×100×100 mm) were tested in compression and beams (100×100×400 mm prisms) were tested under four-point bending (4PBT). Fracture process (crack growth) in the material was modelled, based on experimental results (part of experimental data was used). Finite element method (FEM) using the ANSYS program analysis were realized modelling stress distributions in the broken beams with the goal to predict fracture process. Model’s prediction was validated.

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