Investigation on the microstructural characteristics and quasi-static puncture resistance of both domesticated and wild silkworm cocoons

The very thin and lightweight silkworm cocoon has outstanding mechanical properties attributed to its specific composite microstructure. However, the microstructures of the cocoons have not been studied quantitatively, and their anti-puncture performance has not been examined as well. In this study, both domesticated ( Bombyx mori) and wild silkworm cocoons ( Antheraea pernyi, Antheraea mylitta and Samia canningi) were investigated for their microstructures using fractal theory, and their quasi-static puncture resistance was tested and compared. In addition, the effects of cocoon layers and hot-press treatments on the puncture resistance of two cocoon types ( B. mori and A. pernyi) were investigated. The three wild cocoons demonstrated significantly higher fractal dimensions, higher fiber intersectional densities and low porosities, indicating their structures are more optimized. They also displayed better puncture resistance than B. mori. Increased layer numbers could significantly increase the puncture resistance of both cocoon types and A. pernyi showed more remarkable increases. Moreover, the two cocoon types showed optimum puncture resistance after heat treatment with hot-press temperature of 135℃ and pressure of 25 MPa, and A. pernyi showed better puncture resistance after such treatment. Finally, both the maximum puncture force and puncture energy of cocoons displayed a linear increase with the increasing fractal dimensions. The new insights can guide the development of novel protective fiber composites with desirable and predictable anti-puncture performance.

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Dynamic characteristics and fractal representations of crack propagation of rock with different fissures under multiple impact loadings

Scientific Reports ◽

10.1038/s41598-021-92277-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Bing Sun ◽

Shun Liu ◽

Sheng Zeng ◽

Shanyong Wang ◽

Shaoping Wang

Keyword(s):

Fractal Dimension ◽

Crack Propagation ◽

Crack Growth ◽

Impact Test ◽

Fractal Theory ◽

Dynamic Change ◽

Fractal Dimensions ◽

Peak Stress ◽

Dynamic Mechanical Properties ◽

Gravitational Potential Energy

AbstractTo investigate the influence of the fissure morphology on the dynamic mechanical properties of the rock and the crack propagation, a drop hammer impact test device was used to conduct impact failure tests on sandstones with different fissure numbers and fissure dips, simultaneously recorded the crack growth after each impact. The box fractal dimension is used to quantitatively analyze the dynamic change in the sandstone cracks and a fractal model of crack growth over time is established based on fractal theory. The results demonstrate that under impact test conditions of the same mass and different heights, the energy absorbed by sandstone accounts for about 26.7% of the gravitational potential energy. But at the same height and different mass, the energy absorbed by the sandstone accounts for about 68.6% of the total energy. As the fissure dip increases and the number of fissures increases, the dynamic peak stress and dynamic elastic modulus of the fractured sandstone gradually decrease. The fractal dimensions of crack evolution tend to increase with time as a whole and assume as a parabolic. Except for one fissure, 60° and 90° specimens, with the extension of time, the increase rate of fractal dimension is decreasing correspondingly.

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Investigations on Dynamic Puncture Behaviors of Integrated Composite Reinforced with Varying Fabrics

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.365-366.1070 ◽

2013 ◽

Vol 365-366 ◽

pp. 1070-1073 ◽

Cited By ~ 1

Author(s):

Chia Chang Lin ◽

Ting Ting Li ◽

Ching Wen Lou ◽

Jan Yi Lin ◽

Jia Horng Lin

Keyword(s):

Performance Improvement ◽

Cost Reduction ◽

Body Armor ◽

Packaging Materials ◽

Puncture Resistance ◽

Fabric Reinforcement ◽

Number Of Layers ◽

Layer Composite ◽

Puncture Force ◽

And Performance

The dynamic puncture resistance of multi-layer integrated composite which was comprised of glass fabric reinforcement or Kevlar fabric reinforcement and nonwovens were discussed as related to recycled Kevlar fibers amount, number of layer and K-ply position for purpose of cost reduction and performance improvement. The result shows that, 20 wt% Kevlar fibers contained in nonwovens have the optimum puncture resistance. And the dynamic puncture force increases linearly with number of layers, and also improves proportionally as increasing number of K-ply. The resultant multi-layer composite is expected to be used as body armor interlayer and packaging materials.

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Development of Back-calculation Model for Aggregate Gradation Determination Using Fractal Theory

MATEC Web of Conferences ◽

10.1051/matecconf/201815901006 ◽

2018 ◽

Vol 159 ◽

pp. 01006

Author(s):

Bagus Hario Setiadji ◽

Supriyono ◽

Djoko Purwanto

Keyword(s):

Fractal Dimension ◽

Fractal Theory ◽

Asphalt Mixture ◽

Fractal Dimensions ◽

Calculation Model ◽

Careful Consideration ◽

Upper And Lower Bounds ◽

Aggregate Gradation ◽

Fractal Characteristic ◽

Fractal Characteristics

Several studies have shown that fractal theory can be used to analyze the morphology of aggregate materials in designing the gradation. However, the question arises whether a fractal dimension can actually represent a single aggregate gradation. This study, which is a part of a grand research to determine aggregate gradation based on known asphalt mixture specifications, is performed to clarify the aforementioned question. To do so, two steps of methodology were proposed in this study, that is, step 1 is to determine the fractal characteristics using 3 aggregate gradations (i.e. gradations near upper and lower bounds, and middle gradation); and step 2 is to back-calculate aggregate gradation based on fractal characteristics obtained using 2 scenarios, one-and multi-fractal dimension scenarios. The results of this study indicate that the multi-fractal dimension scenario provides a better prediction of aggregate gradation due to the ability of this scenario to better represent the shape of the original aggregate gradation. However, careful consideration must be observed when using more than two fractal dimensions in predicting aggregate gradation as it will increase the difficulty in developing the fractal characteristic equations.

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FRACTAL APPROACH TO MECHANICAL AND ELECTRICAL PROPERTIES OF GRAPHENE/SIC COMPOSITES

Facta Universitatis Series Mechanical Engineering ◽

10.22190/fume201212003z ◽

2021 ◽

Vol 19 (2) ◽

pp. 271

Author(s):

Yu-Ting Zuo ◽

Hong-Jun Liu

Keyword(s):

Carbon Nanotubes ◽

Electrical Properties ◽

Fractal Theory ◽

Bright Light ◽

Fractal Dimensions ◽

Mechanical Analysis ◽

New Era ◽

Fractal Approach ◽

Mechanical And Electrical Properties ◽

Sic Composites

Graphene and carbon nanotubes have a Steiner minimum tree structure, which endows them with extremely good mechanical and electronic properties. A modified Hall-Petch effect is proposed to reveal the enhanced mechanical strength of the SiC/graphene composites, and a fractal approach to its mechanical analysis is given. Fractal laws for the electrical conductivity of graphene, carbon nanotubes and graphene/SiC composites are suggested using the two-scale fractal theory. The Steiner structure is considered as a cascade of a fractal pattern. The theoretical results show that the two-scale fractal dimensions and the graphene concentration play an important role in enhancing the mechanical and electrical properties of graphene/SiC composites. This paper sheds a bright light on a new era of the graphene-based materials.

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Studies on the Fabrication and Stab Resistance Characterization of Novel Thermoplastic-Kevlar Composites

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.136.83 ◽

2008 ◽

Vol 136 ◽

pp. 83-92 ◽

Cited By ~ 10

Author(s):

M.V. Hosur ◽

Jessie B. Mayo Jr. ◽

E. Wetzel ◽

S. Jeelani

Keyword(s):

Dynamic Testing ◽

Hot Press ◽

Good Resistance ◽

Puncture Resistance ◽

Dynamic Conditions ◽

Low Resistance ◽

Film Type ◽

National Institute Of Justice ◽

Stab Resistance

Kevlar has demonstrated the ability to protect well against ballistic threats but has low resistance to puncture. Correctional Kevlar has shown good resistance to puncture. However, the fabric is expensive, difficult to manufacture because of its tight weave construction, and has limited protection against ballistic threats. In an effort to produce materials that are less bulky, more flexible, and resistant to puncture, thermoplastic-Kevlar (TP-Kevlar) composites have been examined. Kevlar fabric was impregnated with thermoplastic film using a hot press to produce the composites. Static and dynamic puncture resistant properties of the TP-Kevlar composites were investigated using a National Institute of Justice (NIJ Standard 0115.00) Stab Tower. The TP-films used in this study were polyethylene, Surlyn, and co extruded-Surlyn, which is a co extrusion of Surlyn and polyethylene. Response of the polyethylene (PE)-Kevlar composites, Surlyn-Kevlar composites, and co extruded (COEX)-Kevlar composites to spike and knife threats under static and dynamic conditions were compared with that of neat Kevlar. The infusion of thermoplastic films into the Kevlar fabric was shown to dramatically increase puncture resistance during quasi-static and dynamic testing with spikes. The TP-film type also made a difference when examining the resistance on a comparative basis of the TP-Kevlar targets. The TP-Kevlar composite targets showed more resistance to quasi-static spike testing than quasi-static knife testing. Weapon comparisons revealed that the TP-Kevlar composite targets had more resistance to dynamic knife testing than dynamic spike testing.

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Application of Fractal Theory in Aggregate Gradation Research

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.204-208.1923 ◽

2012 ◽

Vol 204-208 ◽

pp. 1923-1928

Author(s):

Bo Tan ◽

Rui Hua Yang ◽

Yan Ting Lai

Keyword(s):

Fractal Dimension ◽

Fractal Theory ◽

Asphalt Mixture ◽

Fractal Dimensions ◽

Aggregate Gradation ◽

Structure Characteristics ◽

Aggregate Distribution ◽

Dimension Formula ◽

Mass Fractal ◽

Fractal Characteristics

The paper presents the fractal dimension formula of distribution of asphalt mixture aggregate diameter by the deducing mass fractal characteristics function. Taking AC-20 and SMA-20 as examples, selected 6 groups of representative grading curves within the grading envelope proposed by the present specification, and calculated their fractal dimensions. The asphalt mixture gradation has fractal dimension D (D∈(1,3)), and the fractal of continuous gradation is single while the fractal of gap-gradation shows multi-fractal with 4.75 as the dividing point. Fractal dimension of aggregate gradation of asphalt mixture reflect the structure characteristics of aggregate distribution, that is, finer is aggregate, bigger is the fractal dimension.

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Research On The Fractal and Percolation Characteristics of Coal-Based Porous Media For Filtration and Impregnation

10.21203/rs.3.rs-948994/v1 ◽

2021 ◽

Author(s):

Qili Wang ◽

Jiarui Sun ◽

Yuehu Chen ◽

Yuyan Qian ◽

Shengcheng Fei ◽

...

Keyword(s):

Porous Media ◽

Fractal Structure ◽

Mercury Intrusion Porosimetry ◽

Fractal Theory ◽

Fractal Dimensions ◽

Infinite Cluster ◽

Porous Graphite ◽

Local Aggregation ◽

Gradual Expansion ◽

The Difference

Abstract In order to distinguish the difference in the heterogeneous fractal structure of porous graphite used for filtration and impregnation, the fractal dimensions obtained through the mercury intrusion porosimetry (MIP) along with the fractal theory were used to calculate the volumetric FD of the graphite samples. The FD expression of the tortuosity along with all parameters from MIP test was optimized to simplify the calculation. In addition, the percolation evolution process of mercury in the porous media was analyzed in combination with the experimental data. As indicated in the analysis, the FDs in the backbone formation regions of sample vary from 2.695 to 2.984, with 2.923 to 2.991 in the percolation regions and 1.224 to 1.544 in the tortuosity. According to the MIP test, the mercury distribution in porous graphite manifested a transitional process from local aggregation, gradual expansion, and infinite cluster connection to global connection.

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Complexity-Based Analysis of the Relation between Human Muscle Reaction and Walking Path

Fluctuation and Noise Letters ◽

10.1142/s021947752050025x ◽

2020 ◽

Vol 19 (03) ◽

pp. 2050025 ◽

Cited By ~ 12

Author(s):

Shahul Mujib Kamal ◽

Sue Sim ◽

Rui Tee ◽

Visvamba Nathan ◽

Hamidreza Namazi

Keyword(s):

Fractal Dimension ◽

Statistical Analysis ◽

Fractal Theory ◽

Contact Point ◽

Fractal Dimensions ◽

Human Muscle ◽

Physiological Signals ◽

Eeg Signal ◽

Leg Muscles ◽

Emg Signal

Legs are the contact point of humans during walking. In fact, leg muscles react when we walk in different conditions (such as different speeds and paths). In this research, we analyze how walking path affects leg muscles’ reaction. In fact, we investigate how the complexity of muscle reaction is related to the complexity of path of movement. For this purpose, we employ fractal theory. In the experiment, subjects walk on different paths that have different fractal dimensions and then we calculate the fractal dimension of Electromyography (EMG) signals obtained from both legs. The result of our analysis showed that the complexity of EMG signal increases with the increment of complexity of path of movement. The conducted statistical analysis also supported the result of analysis. The method of analysis used in this research can be further applied to find the relation between complexity of path of movement and other physiological signals of humans such as respiration and Electroencephalography (EEG) signal.

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Impacts of Pore-Throat System on Fractal Characterization of Tight Sandstones

Geofluids ◽

10.1155/2020/4941501 ◽

2020 ◽

Vol 2020 ◽

pp. 1-17 ◽

Cited By ~ 47

Author(s):

Dengke Liu ◽

Zhaolin Gu ◽

Ruixiang Liang ◽

Junwei Su ◽

Dazhong Ren ◽

...

Keyword(s):

Experimental Data ◽

Prediction Models ◽

Dominant Role ◽

Fractal Theory ◽

Fractal Dimensions ◽

Optical Observations ◽

Reservoir Quality ◽

Pore Throat ◽

Tight Sandstone ◽

Reservoir Type

The pore-throat structures play a dominant role in the evaluation of properties of tight sandstone, but it remains difficult to determine the related parameters and understand their impact on reservoir quality. Hence, toward this end, we analyze the experimental data that are indicative of the pore-throat system, then we investigate the effect of fractal dimensions of pore-throat structures on petrologic and physical properties, and finally, the optical observations, fractal theory, and prediction model were integrated to explore the qualities of various reservoir types in tight sandstones. The results show that the fractal dimensions of the mercury intrusion curve correspond to three pore-throat types and those of the mercury extrusion curve could correspond to two pore-throat types. Five types of reservoirs were identified, the best reservoir type has a high percentage of interparticle and dissolution pores but a low proportion of clay-related pores, and the differences in pore-throat connectivity of various types affect storage capacity significantly. The storage ability prediction models of various reservoir types are raised by integrated experimental data. This work employed a comprehensive fractal theory based on capillary pressure curves and helps to explore how pore-throat systems influence reservoir quality in tight sandstones.

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