Influence of the Fractal Dimension on the Mechanical Properties of Granular Materials

2013 ◽  
Vol 550 ◽  
pp. 99-106
Author(s):  
Bachir Melbouci ◽  
Saliha Yezli
Keyword(s):  
Mechanical Properties ◽  
Fractal Dimension ◽  
Granular Materials ◽  
Fractal Geometry ◽  
Mechanical Tests ◽  
Equivalent Diameter ◽  
Equivalent Sphere ◽  
Before And After ◽  
A New Technique ◽  
Degree Of Irregularity

To determine the size of a grain, we associated its form to that of a equivalent sphere. The grains size is then measured by an equivalent diameter, which is not enough to describe the behavior materials with irregular grains shape. To understand these effects, a new technique was developed by Mandelbrot (1979) which is based on the fractal geometry. To clarify this notion, the grains shape is characterized using the fractal dimension (Df), which is a number measuring the degree of irregularity or the fragmentation of a grain. Mechanical tests were performed. The fractal dimension was calculated for different grains constituting the samples before and after each test while studying its evolution after crushing. The results confirm that the fractal dimension affects the measurement of mechanical properties of the granular materials.

scholarly journals Fast Preparation of High-Performance Wood Materials Assisted by Ultrasonic and Vacuum Impregnation

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 567
Author(s):  
Hong Yang ◽  
Mingyu Gao ◽  
Jinxin Wang ◽  
Hongbo Mu ◽  
Dawei Qi
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Mechanical Tests ◽  
Vacuum Impregnation ◽  
Natural Forests ◽  
Ultrasonic Pretreatment ◽  
Fast Growing ◽  
Before And After ◽  
New Material ◽  
Ft Ir

In the absence of high-quality hardwood timber resources, we have gradually turned our attention from natural forests to planted fast-growing forests. However, fast-growing tree timber in general has defects such as low wood density, loose texture, and poor mechanical properties. Therefore, improving the performance of wood through efficient and rapid technological processes and increasing the utilization of inferior wood is a good way to extend the use of wood. Densification of wood increases the strength of low-density wood and extends the range of applications for wood and wood-derived products. In this paper, the effects of ultrasonic and vacuum pretreatment on the properties of high-performance wood were explored by combining sonication, vacuum impregnation, chemical softening, and thermomechanical treatments to densify the wood; then, the changes in the chemical composition, microstructure, and mechanical properties of poplar wood before and after treatment were analyzed comparatively by FT-IR, XRD, SEM, and mechanical tests. The results showed that with ultrasonic pretreatment and vacuum impregnation, the compression ratio of high-performance wood reached its highest level and the MOR and MOE reached their maximums. With the help of this method, fast-growing softwoods can be easily prepared into dense wood materials, and it is hoped that this new material can be applied in the fields of construction, aviation, and automobile manufacturing.

scholarly journals Tension mechanical properties of recycled glass-epoxy composite material

2012 ◽  
pp. 189-198 ◽  
Author(s):  
Jelena Petrovic ◽  
Darko Ljubic ◽  
Marina Stamenovic ◽  
Ivana Dimic ◽  
Slavisa Putic
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Composite Material ◽  
Composite Materials ◽  
Modulus Of Elasticity ◽  
Epoxy Composite ◽  
Raw Materials ◽  
Mechanical Tests ◽  
Recycled Glass ◽  
Before And After

The significance of composite materials and their applications are mainly due to their good properties. This imposes the need for their recycling, thus extending their lifetime. Once used composite material will be disposed as a waste at the end of it service life. After recycling, this kind of waste can be used as raw materials for the production of same material, which raises their applicability. This indicates a great importance of recycling as a method of the renowal of composite materials. This study represents a contribution to the field of mechanical properties of the recycled composite materials. The tension mechanical properties (tensile strength and modulus of elasticity) of once used and disposed glass-epoxy composite material were compared before and after the recycling. The obtained results from mechanical tests confirmed that the applied recycling method was suitable for glass-epoxy composite materials. In respect to the tensile strength and modulus of elasticity it can be further assessed the possibility of use of recycled glass-epoxy composite materials.

Effects of Aged Conditions on the Fracture Surface Fractal Dimension and Mechanical Behavior of an Austenitic Stainless Steel

2000 ◽  
Vol 6 (S2) ◽  
pp. 768-769
Author(s):  
O. A. Hilders ◽  
A. Quintero ◽  
L. Berrio ◽  
R. Caballero ◽  
L. Sáenz ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Fractal Dimension ◽  
Fractal Geometry ◽  
Fracture Behavior ◽  
Main Part ◽  
Room Temperature ◽  
Fracture Topography ◽  
Type Stainless Steel ◽  
Strength And Ductility

There have been several attempts to find a relation between the fractal morphology of the fracture surfaces and the mechanical properties of engineering materials., although the current resuls are inconclusive. If there are correlations between the fractal dimension and such properties, this parameter could be very useful to predict them and to improve the resistance to fracture. The main part of the investigations concerned with the fractal geometry and fracture behavior concentrate on the relations between roughness and fracture toughness . In the present work, the effects of thermal aging at 850°C on the fracture topography developed during the rupture in tension at room temperature of a 304 type stainless steel and their relation with the strength and ductility, were studied using the fractal geometry approach.

Microstructure and Mechanical Properties of Inconel 718 Produced by SLM and Subsequent Heat Treatment

2015 ◽  
Vol 651-653 ◽  
pp. 665-670 ◽  
Author(s):  
Anatoly A. Popovich ◽  
Vadim Sh. Sufiiarov ◽  
Igor A. Polozov ◽  
Evgenii V. Borisov
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Selective Laser Melting ◽  
Inconel 718 ◽  
Elevated Temperatures ◽  
Ductile Failure ◽  
Mechanical Tests ◽  
Laser Melting ◽  
Microstructure And Mechanical Properties ◽  
Before And After

The article presents results of selective laser melting of Inconel 718 superalloy. It was studied phase microstructure of the material obtained by selective laser melting and also the material after heat treatment. The phase composition of the initial powder material, the specimens after selective laser melting before and after heat treatment was studied. The effect of heat treatment on microstructure and mechanical properties of the specimens was shown. It was studied the mechanical behavior of the manufactured specimens before and after heat treatment at room and elevated temperatures as well. The results of impact tests and fractography of the specimens are presented. Mechanical tests showed that the specimens after heat treatment have decent mechanical properties comparable to hot-rolled material. Fractography showed that the obtained material is characterized by ductile failure mode with local elements of brittle fracture.

scholarly journals Evaluation Microstructure and the Mechanical Properties of Composite Material for Al-Matrix Reinforced by Ceramic Materials (Sic And Al2O3)

2018 ◽  
Vol 24 (8) ◽  
pp. 19
Author(s):  
Lamyaa Kalel
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Hardness Test ◽  
Ceramic Materials ◽  
Mechanical Tests ◽  
Strain Hardening Exponent ◽  
Matrix Composites ◽  
Before And After

In this investigation, the mechanical properties and microstructure of Metal Matrix Composites (MMCs) of Al.6061 alloy reinforced by ceramic materials SiC and Al2O3 with different additive percentages 2.5, 5, 7.5, and 10 wt.% for the particle size of 53 µm are studied. Metal matrix composites were prepared by stir casting using vortex technique and then treated thermally by solution heat treatment at 530 0C for 1 hr. and followed by aging at 175 0C with different periods. Mechanical tests were done for the samples before and after heat treatment, such as impact test, hardness test, and tensile test. Also, the microstructure of the metal matrix composites was examined by optical microscopy before and after heat treatment. The results of this work showed that precipitation of Mg2Si as a secondary phase and improvements in mechanical properties with increase in the percentage of SiC and Al2O3.  Also, the results of SiC revealed an improvement in mechanical properties more than for Al2O3 such as hardness, impact strength, yield strength, tensile strength, increasing the plasticity constant (k) and decreasing the strain hardening exponent (n).   

scholarly journals NM R Determination of the Fractal Geometry of Gels Around the Collapse Transition

1989 ◽  
Vol 44 (2) ◽  
pp. 163-164 ◽  
Author(s):  
R. Blinc ◽  
O. Jarh ◽  
A. Zidanšek ◽  
A. Blinc
Keyword(s):  
Fractal Dimension ◽  
Fractal Geometry ◽  
Relaxation Times ◽  
Volume Ratio ◽  
Liquid Component ◽  
Collapse Transition ◽  
Spin Lattice ◽  
Before And After ◽  
The Masses

Abstract The increase in the surface to volume ratio at the collapse transition of gels can be exploited to allow for an NMR determination of the fractal dimension of the gel surface in the liquid state where this quantity is hard to measure with other techniques. The measured quantities are the ratio be­tween the spin-lattice and spin-spin relaxation times T1/T2 of the liquid component and the ratio of the masses or volumes of the gel before and after the collapse transition. The technique has been used to determine the surface fractal dimen­sion of a blood plasma gel.

scholarly journals Modulating the Mechanical Properties of Electrospun PHB/PCL Materials by Using Different Types of Collectors and Heat Sealing

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 693 ◽  
Author(s):  
Irena Borisova ◽  
Olya Stoilova ◽  
Nevena Manolova ◽  
Iliya Rashkov
Keyword(s):  
Mechanical Properties ◽  
Mechanical Tests ◽  
Fibrous Materials ◽  
Scanning Calorimetry ◽  
Before And After ◽  
Ft Ir ◽  
Improved Performance ◽  
Tunable Mechanical Properties ◽  
Cutting Direction ◽  
Ft Ir Spectroscopy

Two-component fibrous materials based on poly(3-hydroxybutyrate) (PHB, Tm = 160 °C) and poly(ε-caprolactone) (PCL, Tm = 60 °C) were successfully fabricated by dual-jet electrospinning of their separate spinning solutions. The desired alignment of the fibers that compose PHB/PCL mats was achieved by using three types of rotating collectors—drum (smooth), blade and grid. Additional fiber alignment in the direction of collector rotation was achieved by rotating at 2200 rpm. Moreover, the selected concentration of PCL spinning solution resulted in fibers with spindle-like defects along their length. Thus, “segment” sealing of the PHB (high-melting) fibers by the molten PCL (low-melting) fibers/defects sites was achieved after heating the PHB/PCL mats above the melting temperature (Tm) of PCL. The surface morphology, thermal behavior and mechanical properties of the PHB/PCL mats before and after thermal treatment were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and mechanical tests. The results indicated that regardless of the cutting direction of the specimens (0° or 90°), thermal treated PHB/PCL mats reveal enhanced mechanical properties. Therefore, this work provides an easily feasible route for the fabrication of electrospun PHB/PCL mats with tunable mechanical properties and improved performance.

scholarly journals Experimental Study of Crushed Granular Materials by the Notion of Fractal Dimension in 2D and 3D.

2021 ◽  
Author(s):  
Houria BOUZEBOUDJA ◽  
Bachir MELBOUCI ◽  
Aldjia BOUZEBOUDJA
Keyword(s):  
Fractal Dimension ◽  
Los Angeles ◽  
Three Dimensional ◽  
Fractal Dimensions ◽  
Mechanical Tests ◽  
Box Counting ◽  
Before And After ◽  
The Difference ◽  
Box Counting Method ◽  
2D And 3D

Abstract The micro-texture of the aggregates of a pavement layer has a direct influence on their resistance. Whatever the position of these aggregates in a pavement structure, they must withstand, during construction or during life, the stresses of attrition and impact. In this study, a series of mechanical tests (Proctor, Los-Angeles and Micro-Deval) are carried out on grains of local materials (limestone and shale), the degree of crushing of the grains has been quantified using the concept of fractal dimension. The fractal dimension was calculated for the different grains constituting the samples before and after each test, with the use of two two-dimensional 2D methods (Masses Method at the scale of a sample and the Box Counting Method at the scale of a grain) and a three-dimensional 3D method (Blanket on a grain scale) which is based on the use of the difference between erosion and dilation. We seek to determine from these methods the correlation between the two fractal dimensions, namely 2D and 3D and study the influence of different parameters on the mechanical characteristics of the materials chosen: the shape and size of the grains, the presence or absence of water, the stress intensity as well as the nature of the material. The results obtained show that the three-dimensional method has a positive effect on the description of the 3D microstructure of the surface of the grains subjected to the various mechanical tests.

Effect of silver nitrate on some mechanical properties of heat polymerizing acrylic resins

2019 ◽  
Vol 14 (1) ◽  
pp. 110
Author(s):  
Assiss. Prof. Dr. Sabiha Mahdi Mahdi ◽  
Dr. Firas Abd K. Abd K.
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Silver Nitrate ◽  
Surface Hardness ◽  
Mechanical Tests ◽  
Hardness Tester ◽  
Acrylic Resins ◽  
The Difference

Aim: The aimed study was to evaluate the influence of silver nitrate on surfacehardness and tensile strength of acrylic resins.Materials and methods: A total of 60 specimens were made from heat polymerizingresins. Two mechanical tests were utilized (surface hardness and tensile strength)and 4 experimental groups according to the concentration of silver nitrate used.The specimens without the use of silver nitrate were considered as control. Fortensile strength, all specimens were subjected to force till fracture. For surfacehardness, the specimens were tested via a durometer hardness tester. Allspecimens data were analyzed via ANOVA and Tukey tests.Results: The addition of silver nitrate to acrylic resins reduced significantly thetensile strength. Statistically, highly significant differences were found among allgroups (P≤0.001). Also, the difference between control and experimental groupswas highly significant (P≤0.001). For surface hardness, the silver nitrate improvedthe surface hardness of acrylics. Highly significant differences were statisticallyobserved between control and 900 ppm group (P≤0.001); and among all groups(P≤0.001)with exception that no significant differences between control and150ppm; and between 150ppm and 900ppm groups(P>0.05).Conclusion: The addition of silver nitrate to acrylics reduced significantly the tensilestrength and improved slightly the surface hardness.

Optimal Density Determination of Bouguer Anomaly Using Fractal Analysis (Case of study: Charak area,IRAN)

2005 ◽  
Vol 1 (1) ◽  
pp. 21-24
Author(s):  
Hamid Reza Samadi
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Fractal Analysis ◽  
Fractal Geometry ◽  
Host Rock ◽  
Bouguer Anomaly ◽  
Research Area ◽  
Density Difference ◽  
Optimal Density

In exploration geophysics the main and initial aim is to determine density of under-research goals which have certain density difference with the host rock. Therefore, we state a method in this paper to determine the density of bouguer plate, the so-called variogram method based on fractal geometry. This method is based on minimizing surface roughness of bouguer anomaly. The fractal dimension of surface has been used as surface roughness of bouguer anomaly. Using this method, the optimal density of Charak area insouth of Hormozgan province can be determined which is 2/7 g/cfor the under-research area. This determined density has been used to correct and investigate its results about the isostasy of the studied area and results well-coincided with the geology of the area and dug exploratory holes in the text area

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