scholarly journals Flexural Properties and Fracture Mechanism of Three-Dimensional and Four-Directional Braided (SiO2)f/SiO2 Composites

2013 ◽  
Vol 25 (13) ◽  
pp. 7221-7224 ◽  
Author(s):  
Binbin Li ◽  
Jianxun Zhu ◽  
Zhaofeng Chen ◽  
Yun Jiang ◽  
Fangtian Hu
Keyword(s):  
Fracture Mechanism ◽  
Three Dimensional ◽  
Flexural Properties

scholarly journals Micromechanics of Stress-Softening and Hysteresis of Filler Reinforced Elastomers with Applications to Thermo-Oxidative Aging

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1350 ◽  
Author(s):  
Jan Plagge ◽  
Manfred Klüppel
Keyword(s):  
Aging Time ◽  
Fracture Mechanism ◽  
Three Dimensional ◽  
Crosslinking Density ◽  
Rubber Matrix ◽  
Oxidative Aging ◽  
Stress Softening ◽  
Chain Aggregates ◽  
Twisting Deformation ◽  
Fitting Parameters

A micromechanical concept of filler-induced stress-softening and hysteresis is established that describes the complex quasi-static deformation behavior of filler reinforced rubbers upon repeated stretching with increasing amplitude. It is based on a non-affine tube model of rubber elasticity and a distinct deformation and fracture mechanics of filler clusters in the stress field of the rubber matrix. For the description of the clusters we refer to a three-dimensional generalization of the Kantor–Webman model of flexible chain aggregates with distinct bending–twisting and tension deformation of bonds. The bending–twisting deformation dominates the elasticity of filler clusters in elastomers while the tension deformation is assumed to be mainly responsible for fracture. The cluster mechanics is described in detail in the theoretical section, whereby two different fracture criteria of filler–filler bonds are considered, denoted “monodisperse” and “hierarchical” bond fracture mechanism. Both concepts are compared in the experimental section, where stress–strain cycles of a series of ethylene–propylene–diene rubber (EPDM) composites with various thermo-oxidative aging histories are evaluated. It is found that the “hierarchical” bond fracture mechanism delivers better fits and more stable fitting parameters, though the evolution of fitting parameters with aging time is similar for both models. From the adaptations it is concluded that the crosslinking density remains almost constant, indicating that the sulfur bridges in EPDM networks are mono-sulfidic, and hence, quite stable—even at 130 °C aging temperature. The hardening of the composites with increasing aging time is mainly attributed to the relaxation of filler–filler bonds, which results in an increased stiffness and strength of the bonds. Finally, a frame-independent simplified version of the stress-softening model is proposed that allows for an easy implementation into numerical codes for fast FEM simulations

Ultralow flexural properties of copper microhelices fabricated via electrodeposition-based three-dimensional direct-writing technology

Nanoscale ◽  
2017 ◽  
Vol 9 (34) ◽  
pp. 12524-12532 ◽  
Author(s):  
Zhiran Yi ◽  
Yu Lei ◽  
Xianyun Zhang ◽  
Yining Chen ◽  
Jianjun Guo ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Flexural Properties ◽  
Direct Writing ◽  
Resonance Technique ◽  
Writing Technology ◽  
Electromechanical Resonance

The ultralow stiffness of copper microhelices fabricated by a MCED direct-writing method was studied by the electrically induced quasi-static and dynamic electromechanical resonance technique.

Properties of PVA-reinforced cement-bonded fiberboards processed with calender extrusion

2015 ◽  
Vol 22 (5) ◽  
Author(s):  
Bekir Y. Pekmezci
Keyword(s):  
Mechanical Properties ◽  
Three Dimensional ◽  
Flexural Properties ◽  
Cement Composites ◽  
Screw Head ◽  
Freeze Thaw ◽  
Novel Technique ◽  
Reinforced Cement ◽  
Pull Through ◽  
Pva Fiber

AbstractThis research investigates the application of calender extrusion as a novel technique in the production of cement fiberboards. The technique is successfully used in the production of non-structural building elements. The properties of the produced composites are discussed in this paper, particularly with regards the polyvinyl alcohol (PVA) fiber used in the study. The research involves an experiment to examine the mechanical properties and microstructure of the composites, and the results indicate that calender extrusion is a promising method for the production of thin and wide cement composites. These products can be shaped into various three-dimensional forms in the green state after processing. Based on the results, the mechanical properties of cement-bonded fiberboards vary with processing direction due to the alignment of fibers. Fiber content is the most significant factor with regards the tensile and flexural properties of fiber-reinforced cementitious products processed with calender extrusion. Moreover, processed composites have adequate screw head pull-through and freeze-thaw resistance.

Preparation of 3DP Hydroxyapatite Composite by Single and Double Pass Poly(ε-caprolactone) Infiltration

2013 ◽  
Vol 545 ◽  
pp. 69-73
Author(s):  
Faungchat Thammarakcharoen ◽  
Jintamai Suwanprateeb
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Three Dimensional ◽  
Flexural Properties ◽  
Low Molecular Weight ◽  
Double Pass ◽  
Porous Hydroxyapatite ◽  
Melt Infiltration ◽  
The Difference ◽  
Polymer Infiltration

Recently, porous hydroxyapatite was fabricated by three dimensional printing (3DP) in coupled with low temperature phosphorization to yield nanosized and low crystalline structure. However, brittleness was an intrinsic drawback for some foreseen applications. Polymer infiltration aiming to improve the toughness and mechanical integrity was thus carried out using biodegradable poly(ε-caprolactone) (PCL) as an infiltrant since it has shown good biocompatibility together with a high elongation and energy to failure as compared to other medical polymers. Three routes of infiltration were performed including melt infiltration of low molecular weight PCL (Mw ˜ 10,000), solution infiltration by 10 % high molecular weight PCL (Mw ˜ 80,000) and the combination of both melt and solution infiltration of low and high molecular weight PCL. The combination of low and high MW infiltration yielded the greatest increase in the mechanical properties and followed by the melt infiltration of low molecular weight PCL while the use of high MW infiltration yielded limited enhancement. After immersing in simulated body fluid (SBF), no significant changes in flexural properties were seen for both hydroxyapatite and high molecular weight infiltrated sample. However, flexural strength and strain at break of low molecular weight infiltrated sample largely dropped after 7 days of immersion to be closed to those of hydroxyapatite and high molecular weight infiltrated sample. The flexural properties of high-low infiltrated sample also decreased after immersion, but to a less degree and still maintained the greatest values amongst all samples. This could be associated to the difference in degradation of different molecular weight of PCL and the content of polymer infiltration induced by different infiltration routes. Calcium and phosphorus ions in the SBF were quantified and observed to be consumed continuously during immersion for all samples. Newly formed apatite crystals were observed to form on the surface of the infiltrated composites signifying that infiltration did not hinder the bioactivity of the composites.

Flexural properties of three-dimensional printed continuous wire polymer composites

2019 ◽  
Vol 35 (12) ◽  
pp. 1471-1482
Author(s):  
Yehia Ibrahim ◽  
Garrett W. Melenka ◽  
Roger Kempers
Keyword(s):  
Polymer Composites ◽  
Three Dimensional ◽  
Flexural Properties ◽  
Continuous Wire
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