scholarly journals A Numerical Model to Predict the Anisotropy of Polymer Composites Reinforced with High-Aspect-Ratio Short Aramid Fibers

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Jianhong Gao ◽  
Xiaoxiang Yang ◽  
Lihong Huang
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Orientation Distribution ◽  
Composite Fiber ◽  
Fe Model ◽  
Fiber Types ◽  
Aramid Fibers ◽  
Simple Method ◽  
Fiber Orientation Distribution ◽  
Nonlinear Matrix

Some fiber types have a high aspect ratio and it is very difficult to predict their composites using traditional finite element (FE) modeling. In this study, an FE model was developed to predict the anisotropy of composites reinforced by short aramid fibers. Three fiber distribution types were studied as follows: perfectly aligned, normally distributed, and randomly distributed fibers. The elastic constants were obtained, and, for different alignment angles and parameters in the fiber orientation distribution function, their numerical results were compared to those of the Mori–Tanaka model. Good agreement was obtained; thus, the employed FE model is an excellent and simple method to predict the isotropy and anisotropy of a composite with high-aspect-ratio fibers. Therefore, the FE model was employed to predict the orientation distribution of a composite fiber with a nonlinear matrix. The predicted and experimental results agree well.

A simple method for fabrication of high-aspect-ratio all-silicon grooves

2013 ◽  
Vol 284 ◽  
pp. 372-378 ◽  
Author(s):  
Yuncan Ma ◽  
An Pan ◽  
Jinhai Si ◽  
Tao Chen ◽  
Feng Chen ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Simple Method

FABRICATION OF PERIODIC STANDING ROD ARRAYS BY THE SHADOW CONE METHOD

2006 ◽  
Vol 05 (06) ◽  
pp. 815-819 ◽  
Author(s):  
HIROFUMI TANAKA ◽  
PAUL S. WEISS ◽  
MARK W. HORN
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Low Cost ◽  
Industrial Applications ◽  
Silicon Substrates ◽  
Simple Method ◽  
Periodic Arrays

A simple method for fabricating periodic arrays of high aspect ratio (1:20) standing nanorods on silicon substrates is described. It is based on shadow deposition onto periodically arranged arrays of mini-rods on a rotating sample stage. Consequently, such nanostructures can be prepared on relatively large areas and at low cost, making the method suitable for industrial applications.

REPLICATION BEHAVIOR FOR MICRO SURFACE FEATURES WITH HIGH ASPECT RATIO AND STRUCTURE DEVELOPMENT IN INJECTION COMPRESSION MOLDING

2012 ◽  
Vol 06 ◽  
pp. 563-569 ◽  
Author(s):  
HAJIME SUZUKI ◽  
TETSUO TAKAYAMA ◽  
HIROSHI ITO
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Molecular Orientation ◽  
Orientation Distribution ◽  
Compression Molding ◽  
Short Delay ◽  
Surface Features ◽  
Compression Stroke ◽  
Short Shot ◽  
Injection Compression Molding

Injection compression molding (ICM) with high aspect ratio surface features was performed to clarify the effect of molding conditions on replication characteristics and molecular orientation distribution. Short-shot defects and surface replication were better when using ICM than when using conventional injection molding. A long compression stroke and short delay time condition were optimum conditions to used to achieve uniform surface replication. Molecular orientation was also reduced by the long compression stroke. To reduce molecular orientation, the compression motion should be carried out immediately after injection motion in the case of 0.2 mm thickness. For 0.6 mm thickness, the compression motion was conducted after the shear stress relaxation to reduce the molecular orientation. Short-shot tests revealed distinctive replication behavior in ICM. Results show that replication behavior and local molecular orientation are generated by a slightly frozen layer at the filling area before compression.

Effect of Fiber Aspect Ratio and Area Ratio Getting to Accuracy of Intensity Method in Fiber Orientation Angle Distribution Measurement

2006 ◽  
Vol 326-328 ◽  
pp. 1817-1820
Author(s):  
Jin Woo Kim ◽  
Dong Gi Lee
Keyword(s):  
Aspect Ratio ◽  
Fiber Orientation ◽  
Orientation Angle ◽  
Orientation Distribution ◽  
Angle Distribution ◽  
Fiber Aspect Ratio ◽  
Orientation Function ◽  
Fiber Orientation Distribution ◽  
Fiber Orientation Angle ◽  
Distribution State

Measurement of fiber orientation distribution state is very important constituent to find out decision of processing condition of product or mechanical special quality of moldings in fiber reinforced polymer composite material. Therefore, reliable measurement method of fiber orientation angle distribution is established, and need researcher about simplicity measuring method urgently the nondestructiveness. In this research, to investigate about accuracy of fiber orientation angle distribution measurement of fiber reinforced composite material by intensity method, find fiber orientation function value that is measure of fiber orientation distribution state constructing fiber orientation simulation picture by plotter changing diameter and length and orientation state of fiber. Recognize this fiber orientation simulation picture by image scanner, and measure fiber orientation angle distribution state by this realized intensity information. This time, I wish to measure reliable fiber orientation angle distribution comparing fiber orientation function calculation value saving in the advance with fiber orientation function value that is measured by intensity method. The results show that measurement accuracy of the fiber orientation angle distribution by intensity method is affected by the fiber aspect ratio when the total length of oriented fiber is same. The average gradient of fiber orientation function is 0.94 for 1000mm of the total fiber length and is 0.93 for 2000mm when the fiber aspect ratio is over 50. Measurement accuracy by intensity method is about 94% and the reliable data can be obtained by intensity method.

Simple Nanoimprint Lithography with 50 nm Resolution Using Vacuum Packing

2010 ◽  
Vol 459 ◽  
pp. 111-115 ◽  
Author(s):  
Kazuo Itoh ◽  
Hirokazu Hirai ◽  
Tetsuya Ando ◽  
Kazuya Takagi ◽  
Katsuya Noguchi
Keyword(s):  
Aspect Ratio ◽  
Line Width ◽  
High Aspect Ratio ◽  
Glass Substrate ◽  
Atmospheric Pressure ◽  
Nanoimprint Lithography ◽  
Viscous Force ◽  
Pressing Pressure ◽  
Simple Method ◽  
Fine Pattern

We demonstrated a simple UV nanoimprint method using vacuum packing. A glass substrate and a Si mold dropped with a photo-curable resist were vacuum-packed together in a packing sheet. They were pressed by atmospheric pressure and easily fixed without a complicated apparatus. We obtained a successful nanoimprint result for 100 nm width lines with high aspect ratio of 3.2. Further fine pattern of about 50 nm line width was also replicated using our simple method. The remaining thickness of the resist after imprint decreased with increasing the pressing pressure　whereas it saturated due to the viscosity of the resist. This saturation tendency is well explained by the balance between the pressing force and the viscous force of the resist.

Elastic Compression of a Fiber Network

1995 ◽  
Vol 62 (1) ◽  
pp. 223-226 ◽  
Author(s):  
S. Toll ◽  
J.-A. E. Manson
Keyword(s):  
Constitutive Equation ◽  
Aspect Ratio ◽  
Glass Fiber ◽  
Fiber Orientation ◽  
Orientation Distribution ◽  
Large Aspect Ratio ◽  
Transverse Compression ◽  
Fiber Network ◽  
Fiber Orientation Distribution ◽  
Uniform Diameter

A constitutive equation for a planar fiber network under transverse compression is derived allowing for an in-plane fiber orientation distribution. The fibers are assumed to be well dispersed in space and to have a large aspect ratio and uniform diameter. A compression experiment, performed on a glass-fiber network obtained by ashing a commercial composite preform, is accurately described by the theory.

Sharp Silicon Nano-Needles Based on Boron Etch-Stop in TMAH Solutions

2011 ◽  
Vol 1301 ◽  
Author(s):  
Sheping Yan ◽  
Yang Xu ◽  
Junyi Yang ◽  
Huiquan Wang ◽  
Zhonghe Jin ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Analytical Model ◽  
Integrated Circuit ◽  
High Aspect Ratio ◽  
Ammonium Hydroxide ◽  
Living Cells ◽  
Molecular Devices ◽  
Simple Method ◽  
Tetramethyl Ammonium Hydroxide ◽  
Etch Stop

ABSTRACTOperations on biological living cells and molecular devices have driven research towards implementation of high-aspect-ratio nano-needles. However, current nano-needle fabrication is complicated to control the sizes and angles. In this work, we develop a simple method to fabricate repeatable and integrated circuit (IC)-compatible sharp silicon nano-needles based on boron etch-stop in tetramethyl ammonium hydroxide (TMAH) solutions, and the needle angles can be accurately controlled. An analytical model is proposed to efficiently predict the needle sizes and explain the etching evolution of silicon nano-needles.

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