Estimation of statistical strength distribution of Carborundum polycrystalline SiC fiber using the single fiber composite with consideration of the matrix hardening

2008 ◽  
Vol 68 (15-16) ◽  
pp. 3067-3072 ◽  
Author(s):  
T. Okabe ◽  
M. Nishikawa ◽  
W.A. Curtin
2007 ◽  
Vol 334-335 ◽  
pp. 333-336
Author(s):  
Souta Kimura ◽  
Jun Koyanagi ◽  
Takayuki Hama ◽  
Hiroyuki Kawada

A shear-lag model is developed to predict the stress distributions in and around an isolated fiber in a single-fiber polymer matrix composite (PMC) subjected to uniaxial tensile loading and unloading along the fiber direction. The matrix is assumed to be an elasto-plastic material that deforms according to J2 flow theory. The stress distributions are obtained numerically and compared with a different shear-lag model that employs total strain theory as a constitutive equation of the matrix material. An effect of the difference between the models on the derived stress state is discussed.


Author(s):  
G. Das ◽  
R. E. Omlor

Fiber reinforced titanium alloys hold immense potential for applications in the aerospace industry. However, chemical reaction between the fibers and the titanium alloys at fabrication temperatures leads to the formation of brittle reaction products which limits their development. In the present study, coated SiC fibers have been used to evaluate the effects of surface coating on the reaction zone in the SiC/IMI829 system.IMI829 (Ti-5.5A1-3.5Sn-3.0Zr-0.3Mo-1Nb-0.3Si), a near alpha alloy, in the form of PREP powder (-35 mesh), was used a茸 the matrix. CVD grown AVCO SCS-6 SiC fibers were used as discontinuous reinforcements. These fibers of 142μm diameter contained an overlayer with high Si/C ratio on top of an amorphous carbon layer, the thickness of the coating being ∽ 1μm. SCS-6 fibers, broken into ∽ 2mm lengths, were mixed with IMI829 powder (representing < 0.1vol%) and the mixture was consolidated by HIP'ing at 871°C/0. 28GPa/4h.


Author(s):  
Warren J. Moberly ◽  
Daniel B. Miracle ◽  
S. Krishnamurthy

Titanium-aluminum alloy metal matrix composites (MMC) and Ti-Al intermetallic matrix composites (IMC), reinforced with continuous SCS6 SiC fibers are leading candidates for high temperature aerospace applications such as the National Aerospace Plane (NASP). The nature of deformation at fiber / matrix interfaces is characterized in this ongoing research. One major concern is the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. This can lead to thermal stresses upon cooling down from the temperature incurred during hot isostatic pressing (HIP), which are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application, A second concern is the load transfer, from fiber to matrix, that is required if/when fiber fracture occurs. In both cases the stresses in the matrix are most severe at the interlace.


2021 ◽  
Author(s):  
NITHIN K. PARAMBIL ◽  
BRANNDON R. CHEN ◽  
JOSEPH M. DEITZEL ◽  
JOHN W. GILLESPIE, JR. ◽  
LOAN T. VO ◽  
...  

A computational model of residual stress is developed for AS4/polypropylene composites and implemented via user material subroutine (UMAT) in ABAQUS. The main factors included in the model are the cooling-rate dependent crystallinity, temperature-dependent elastic modulus, and temperature-dependent coefficient of thermal expansion (CTE) of the matrix, and the temperature-independent transversely isotropic properties of the carbon fiber. Numerical results are generated for the case of a single fiber embedded in a thin film of polypropylene sample to replicate the process history and test configuration. During single fiber composite processing, a precalculated weight (tensile preload) is applied at the fiber ends to eliminate buckling/waviness of the carbon fiber induced by matrix shrinkage in the axial direction of the fiber. Experiments and Finite element (FE) analysis have been conducted with different preloads (1g, 4g, and 8g) at 25°C. Micro-Raman spectroscopy is utilized to validate the residual strain with different preloads at the bulk. The measured strain values show a good correlation with the predicted residual strain for various preload conditions.


2018 ◽  
Vol 58 (9) ◽  
pp. 1451-1467 ◽  
Author(s):  
I. Tabiai ◽  
R. Delorme ◽  
D. Therriault ◽  
M. Levesque

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Sri Hastuti ◽  
Catur Pramono ◽  
Yafi Akhmad

The Eichornia crassipes fiber have potentially as a composite reinforcing material. The advantage of composites with natural fibers like to light weight, corrosion resistance, water resistance, attractive performance, and without machining process. The purpose of using natural fiber as an alternative material to replace glass fiber composite material with Eichornia crassipes fibers are friendly and cheap. The research material used Eichornia crassipes fiber, NaOH, Etanol, and H2O. Processing of Eichornia crassipes fiber is washing with water, natural drying ± 10 days in eviromental, fiber taking with steel brush. Dry fibre were subjected to 10%, 20%, 30% NaOH and ethanol solution with variations of immersion time of 2, 4, 6 hours, neutralization with H20, and drying at room temperature. The Single fiber tensile test specimens were made with variations of treatment type in NaOH and Ethanol solution (10%, 20%, 30%), immersion time of 2, 4, and 6 hours. Single fiber test specimens refer to standard ASTM D 3379. Optimum tensile strength test results on NaOH treatment 20% variation of immersion time 4 hours: 28.402 N / mm2 and on ethanol treatment 20% variation of immersion time 2 hours: 48.197 N / mm2.


2021 ◽  
Vol 12 (5) ◽  
pp. 6148-6163

Oil palm empty fruit bunch (OPEFB) single fibers and reinforced composites were comprehensively characterized through tensile tests to assess their performance as potential reinforcing materials in polymer composites. The performances of OPEFB single fibers and reinforced composites with untreated and treated fibers conditions were compared. The fibers were variously treated with 3% sodium hydroxide, 2% silane, 3% sodium hydroxide mixed with 2% silane, and 3% sodium hydroxide prior to 2% silane for 2 hours soaking time. The highest toughness of the single fibers test was then selected to proceed with composites fabrication. The OPEFB composites were fabricated in 90:10, 80:20, 70:30, and 60:40 epoxy-fibre fractions. The result shows that the selected treated fiber composite exhibits better performance. The selected treated fiber composite increased the highest ultimate tensile strength by 145.3% for the 90:10 fraction. The highest Young’s Modulus was increased by about 166.7% for 70:30 fraction. Next, the highest toughness was increased by 389.5% for the 30:70 fraction. The treated fibers provided a better interlocking mechanism between the matrix and fibers in reinforced composites, thus improving their interfacial bonding.


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