A New Approach to Microbuckling of Fibrous Composites

1991 ◽  
Vol 58 (2) ◽  
pp. 473-479 ◽  
Author(s):  
Dimitris C. Lagoudas ◽  
Iradj Tadjbakhsh ◽  
Nabil Fares
Keyword(s):  
Compressive Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Fibrous Composite ◽  
Compressive Strain ◽  
Fibrous Composites ◽  
Small Perturbations ◽  
New Approach ◽  
The Stability ◽  
Stability Of Small Perturbations

A new approach for the evaluation of the compressive strength of fibrous composites due to microbuckling is considered in this paper. Most of the proposed models, thus far, have tried to improve on the classical analysis by Rosen regarding both phases as separate continua with appropriate interface conditions. In this work the fibrous composite is represented by an inhomogeneous two-dimensional continuum with spatial variation in the axial Young’s modulus to account for fibers and matrix. The periodicity of the microstructure is taken into account by expanding the axial Young’s modulus in a Fourier series with wavelength the average spacing between fibers. The compressive strength is determined by examining the stability of small perturbations superimposed on a uniform applied compressive strain. It is found that the compressive strength depends on the wavelength of initial imperfections and bound estimates for minimum and maximum imperfection sizes are derived. The upper bound corresponds to perfectly aligned fibers without any imperfections and coincides with Rosen’s prediction of the compressive strength, while the lower bound corresponds to the more realistic case of imperfect systems and correlates well with experimental data.

scholarly journals Compressive Behaviours of Oil Bean Shell and Wood Particulates/ Epoxy Composite Board

2019 ◽  
pp. 1-8
Author(s):  
E. O. Edafiadhe ◽  
O. Nyorere ◽  
Uguru Hilary
Keyword(s):  
Compressive Strength ◽  
Young’S Modulus ◽  
Failure Time ◽  
Epoxy Composite ◽  
Young's Modulus ◽  
Sodium Hydroxide Solution ◽  
Compressive Strain ◽  
Testing Machine ◽  
Filler Materials ◽  
Composite Board

The compressive behaviours (compressive strength, compressive energy, Young’s modulus, failure time, and compressive strain) of epoxy composite board, reinforced with oil bean pod shell particulates (OBPS) and mahogany timber saw dust (SD) were investigated in this research. The samples were prepared with five different fillers (OBPS and SD) percentage (10, 15, 20, 25 and 30 vol.%) in the ratio of 1:1. Both filler materials where treated with 5(w/v)% Sodium hydroxide solution to enhance their mechanical properties. All the composite samples were tested according to ASTM standards, by using the Universal Testing Machine. Results obtained from the research showed that fillers loading had significant (P ≤0.05) effect on all the compressive behaviours investigated. In addition, the results showed that the fillers significantly improved all the compressive parameters. The compressive strength of the composite increased from 14.54 to 48.19 MPa, as the fillers loading increased from 10 to 30 wt.%, while the Young’s modulus increased by 49%.  The compressive energy increased from 21.4 to 146 Nm. Data gotten from this research can be useful in the production of composite boards for engineering applications.  

scholarly journals Mechanical Properties and Environmental Evaluation of Ultra-High-Performance Concrete with Aeolian Sand

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3148 ◽  
Author(s):  
Hongyan Chu ◽  
Fengjuan Wang ◽  
Liguo Wang ◽  
Taotao Feng ◽  
Danqian Wang
Keyword(s):  
Compressive Strength ◽  
Environmental Impact ◽  
Young’S Modulus ◽  
High Performance ◽  
High Performance Concrete ◽  
Young's Modulus ◽  
Ultra High Performance Concrete ◽  
Aeolian Sand ◽  
Binder Ratio ◽  
Water Binder Ratio

Ultra-high-performance concrete (UHPC) has received increasing attention in recent years due to its remarkable ductility, durability, and mechanical properties. However, the manufacture of UHPC can cause serious environmental issues. This work addresses the feasibility of using aeolian sand to produce UHPC, and the mix design, environmental impact, and mechanical characterization of UHPC are investigated. We designed the mix proportions of the UHPC according to the modified Andreasen and Andersen particle packing model. We studied the workability, microstructure, porosity, mechanical performance, and environmental impact of UHPC with three different water/binder ratios. The following findings were noted: (1) the compressive strength, flexural strength, and Young’s modulus of the designed UHPC samples were in the ranges of 163.9–207.0 MPa, 18.0–32.2 MPa, and 49.3–58.9 GPa, respectively; (2) the compressive strength, flexural strength, and Young’s modulus of the UHPC increased with a decrease in water/binder ratio and an increase in the steel fibre content; (3) the compressive strength–Young’s modulus correlation of the UHPC could be described by an exponential formula; (4) the environmental impact of UHPC can be improved by decreasing its water/binder ratio. These findings suggest that it is possible to use aeolian sand to manufacture UHPC, and this study promotes the application of aeolian sand for this purpose.

scholarly journals Sea-Ice Investigations In The Weddell Sea During The German Antarctic Expedition 1979-80

1983 ◽  
Vol 4 ◽  
pp. 246-252 ◽  
Author(s):  
Joachim Schwarz
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Sea Ice ◽  
Young’S Modulus ◽  
Uniaxial Compressive Strength ◽  
Young's Modulus ◽  
Weddell Sea ◽  
Ice Shelves ◽  
Antarctic Expedition ◽  
Ice Conditions

In the austral winter of 1979-80, a German Antarctic expedition was sent by ship to the Filchner and Ronne ice shelves in order to find a suitable site for the establishment of a permanent Antarctic station. During this expedition, investigations were carried out on sea ice in the Weddell Sea in order to evaluate the accessibility of the site for icebreaking ships which are intended to convey construction materials to the site and, later on, to supply the station annually.This paper covers the results of investigations on sea-ice conditions during the voyage along the ice shelves from Cape Fiske (at the base of the Antarctic Peninsula) to Atka Bay with emphasis on sea-ice conditions in the area about 100 km north-west of Berkner Island (Fig.1.). In addition to the drift conditions (speed, direction), a special feature of multi-year sea ice is described. The main part of the paper deals with mechanical properties such as flexural strength, uniaxial compressive strength and Young’s modulus of columnar-grained sea ice from the southern border of the Weddell Sea. Salinities and temperatures were measured over the depth of the ice and used for calculating the flexural strength and the Young’s modulus of the ice. The uniaxial compressive strength was investigated as a function of strain-rate, brine volume and temperature on a closed-loop testing machine on samples which were carried back from Antarctica to Hamburg.

Materials for Well Integrity: Characterization of Short-Term Mechanical Properties

2020 ◽  
Author(s):  
Mohammadreza Kamali ◽  
Mahmoud Khalifeh ◽  
Arild Saasen ◽  
Laurent Delabroy
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Strength Reduction ◽  
Indirect Tensile Strength ◽  
Short Term ◽  
Indirect Tensile ◽  
Expansive Cement

Abstract Integrated zonal isolation is well-known as a key parameter for safe drilling operation and well completion of oil and gas wells. An extensive research on alternative materials has been conducted in the past concerning primary cementing, overcoming annular leaks, and permanent well abandonment. The present article focuses on geopolymers, expansive cement, pozzolan based sealant and thermosetting resins. The viscous behavior and the pumpability of the different materials have been investigated and benchmarked with the properties of neat class G Portland cement. The current study includes short-term mechanical properties of the above-mentioned materials. These properties include compressive strength development, Young’s modulus, indirect tensile strength, and sonic strength. The tests are performed in accordance with API 10B-2 and ASTM D3967-16 for all the materials for 1, 3, 5, and 7-day of curing at 90°C and elevated (172 bar) and atmospheric pressures. Our results show a mixed behavior from the materials. According to uniaxial compressive test results, all the candidate barrier materials developed strength during the considered period; however, the geopolymer and pozzolanic-based mixture did not develop early strength. The expansive cement showed an acceptable early compressive strength, but strength reduction was noticed after some time. The strength reduction of expansive cement was also observed for the indirect tensile strength. All the materials become stiffer overtime as they made more strength. For the neat class G cement and expansive cement, the Young’s modulus showed a minimum after 5 days, but it was increased.

Sea-Ice Investigations In The Weddell Sea During The German Antarctic Expedition 1979-80

1983 ◽  
Vol 4 ◽  
pp. 246-252
Author(s):  
Joachim Schwarz
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Sea Ice ◽  
Young’S Modulus ◽  
Uniaxial Compressive Strength ◽  
Young's Modulus ◽  
Weddell Sea ◽  
Ice Shelves ◽  
Antarctic Expedition ◽  
Ice Conditions

In the austral winter of 1979-80, a German Antarctic expedition was sent by ship to the Filchner and Ronne ice shelves in order to find a suitable site for the establishment of a permanent Antarctic station. During this expedition, investigations were carried out on sea ice in the Weddell Sea in order to evaluate the accessibility of the site for icebreaking ships which are intended to convey construction materials to the site and, later on, to supply the station annually.This paper covers the results of investigations on sea-ice conditions during the voyage along the ice shelves from Cape Fiske (at the base of the Antarctic Peninsula) to Atka Bay with emphasis on sea-ice conditions in the area about 100 km north-west of Berkner Island (Fig.1.). In addition to the drift conditions (speed, direction), a special feature of multi-year sea ice is described. The main part of the paper deals with mechanical properties such as flexural strength, uniaxial compressive strength and Young’s modulus of columnar-grained sea ice from the southern border of the Weddell Sea. Salinities and temperatures were measured over the depth of the ice and used for calculating the flexural strength and the Young’s modulus of the ice. The uniaxial compressive strength was investigated as a function of strain-rate, brine volume and temperature on a closed-loop testing machine on samples which were carried back from Antarctica to Hamburg.

Radiation and thermal effects on polymeric immobilization devices used in patients submitted to radiotherapy

2011 ◽  
Vol 11 (2) ◽  
pp. 101-106
Author(s):  
C. Pereira-Loch ◽  
R. Benavides ◽  
M. Fogliato S. Lima ◽  
B.M. Huerta
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Young’S Modulus ◽  
Thermal Effects ◽  
Young's Modulus ◽  
Thermal Conditions ◽  
Joint Effect ◽  
Hot Water ◽  
Slight Variation ◽  
The Stability

AbstractImmobilization devices in radiotherapy are made of a soft plastic easy to mould when immersed in hot water. Same item is usually used for 6 patients (according to protocol), but at Hospital Sao Jose (HSJ) they have been showing some deformation during the re-utilization process. The latter is the reason for this research where devices were treated with 6 thermal conditions, 6 irradiation procedures and the joint effect of both treatments. DSC, TGA and WAXD indicated devices are made of polycaprolactone (PCL), but no signs of degradation, except a slight variation in crystalinity; however, mechanical properties by means of Young’s modulus steadily increase its values through number of treatments up to a 20%. Activation energy (Ea) obtained by multi-ramps of TGA-Arrhenius evaluated for the most treated samples (6th treatment) indicates that temperature facilitates degradation while irradiation and joint treatments enhance the stability of PCL, apparently by crosslinking.

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