Fiber Fracture in Continuous Fiber Ceramic Composites: Concepts and Observations

1997 ◽  
Vol 119 (1) ◽  
pp. 205-211 ◽  
Author(s):  
K. Reifsnider ◽  
K. Liao ◽  
M. McCormick ◽  
A. Tiwari
Keyword(s):  
Tensile Strength ◽  
Ceramic Composites ◽  
The State ◽  
Continuous Fiber ◽  
Fiber Fracture ◽  
Stress Strain ◽  
Strain Behavior ◽  
Physical Measurements ◽  
State Of Affairs ◽  
Strength Models

The knowledge of fiber behavior in CMCs is rather modest, and models tend to be based on concepts that are less than complete. The present paper addresses several aspects of this problem. Fundamental assumptions for tensile strength models are discussed, and some basic modeling approaches are described. The effects of fiber fracture on the quasi-static stress–strain behavior are described (from physical measurements), and some models of that behavior discussed. Finally, a summary of the “state of affairs” for this subject will be attempted, and the needs for further investigation, especially to support improved modeling, will be presented.

Fiber Fracture in Continuous Fiber Ceramic Composites: Concepts and Observations

1995 ◽  
Author(s):  
K. Reifsnider ◽  
K. Liao ◽  
M. McCormick ◽  
A. Tiwari
Keyword(s):  
Tensile Strength ◽  
Ceramic Composites ◽  
The State ◽  
Continuous Fiber ◽  
Fiber Fracture ◽  
Stress Strain ◽  
Strain Behavior ◽  
Physical Measurements ◽  
State Of Affairs ◽  
Strength Models

The knowledge of fiber behavior in CMCs is rather modest, and models tend to be based on concepts that are less than complete. The present paper addresses several aspects of this problem. Fundamental assumptions for tensile strength models are discussed, and some basic modeling approaches are described. The effects of fiber fracture on the quasi-static stress-strain behavior are described (from physical measurements), and some models of that behavior discussed. Finally, a summary of the “state of affairs” for this subject will be attempted, and the needs for further investigation, especially to support improved modeling, will be presented.

Stress-strain behavior of individual electrospun polymer fibers using combination AFM and SEM

2009 ◽  
Vol 1185 ◽  
Author(s):  
Fei Hang ◽  
Dun Lu ◽  
Shuang Wu Li ◽  
Asa H Barber
Keyword(s):  
Tensile Strength ◽  
Deformation Process ◽  
Tensile Deformation ◽  
Polymer Fibers ◽  
Electrospun Fibers ◽  
Stress Strain ◽  
Strain Behavior ◽  
Atomic Force ◽  
Resultant Stress ◽  
Scanning Electron

AbstractTensile deformation of individual electrospun polyvinyl alcohol (PVA) nanofibres was performed using a novel combination atomic force microscope (AFM)- scanning electron microscope (SEM) technique. The AFM was used to provide manipulation and mechanical testing of individual PVA nanofibers while the SEM was used to observe the deformation process. Resultant stress-strain curves show how the elastic modulus shows comparable, or even slightly increased, values to isotropic films. In addition, the electrospun fibers were tested to failure to measure their tensile strength.

Effects of Inclusions and Porosity on the Indentation Response

2002 ◽  
Vol 750 ◽  
Author(s):  
E. S. Ege ◽  
Y.-L. Shen
Keyword(s):  
Heterogeneous Systems ◽  
Ceramic Composites ◽  
Ductile Material ◽  
Porous System ◽  
Stress Strain ◽  
Soft Matrix ◽  
Strain Behavior ◽  
Hard Particles ◽  
Strain Responses ◽  
Indentation Response

ABSTRACTA combined numerical and experimental study was undertaken to investigate the effect of microstructural heterogeneity on indentation response. Finite element analyses were carried out to simulate the stress-strain behavior and the indentation response of two model heterogeneous systems: one with hard particles embedded within a soft matrix and the other with a pore-containing ductile material. For the particle-containing system, the indentation response consistently overestimates the overall strength of the composite. This is largely due to the localized increase in particle concentration directly underneath the indent. For the porous system, the indentation response consistently underestimates the overall strength due to the pore-crushing effect. Experiments on metal-ceramic composites confirmed the non-correspondence between the indentation and stress-strain responses, even when the indent size is much greater than the microstructural feature size. Implications of the present findings in utilizing indentation to quantify surface mechanical properties are discussed.

Effects of Water on the Mechanical Properties of Paper and their Relationship to the Treatment of Paper

1992 ◽  
Vol 267 ◽  
Author(s):  
Timothy Vitale
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Tap Water ◽  
Water Immersion ◽  
Exchange Process ◽  
Elastic Behavior ◽  
Elastic Fibers ◽  
Plastic Behavior ◽  
Stress Strain ◽  
Strain Behavior

ABSTRACTThrough a series of experiments the mechanical properties of paper are explored. Hydrogen bonding is fundamental to the performance of paper and its disruption results in distinctive stress-strain behavior. Stress-strain curves were generated from which tensile strength, Young's modulus, percent stretch, and work (tensile energy absorption) were obtained.It was found that the contribution of the fiber to the mechanical properties of paper is primarily elastic. Fibers are many times stronger than paper. Only fibers which have been severely deteriorated show measurable changes in stress-strain behavior. Fiber deterioration results in characteristically different stress-strain behavior than that which results from disruption of interfiber bonding.Water immersion results in the disruption of interfiber bonds in paper, leaving only 2-3% of dry tensile strength. Interfiber bonds make a profound contribution to the mechanical properties of the paper. Aqueous treatment is shown to be a radical treatment, altering the original dried-in properties of the sheet. The release of structural bonds and dried-in strains during wetting and the subsequent reformation of interfiber bonds during drying are shown to be independent of water purity, be it ultrapure water, tap water, or water containing washing aids such as Ca(OH)2, NaOH, CaCO3 or Na2CO3.The effects of immersion in organic solvents was explored. Solvents have effects on mechanical properties which are approximately proportional to the degree of swelling caused by the solvent. Water, the liquid which caused the greatest swelling of the liquids evaluated, is shown to be the most disruptive liquid followed by methanol and acetone; toluene caused virtually no change.To explore the behavior of interfiber bonds paper was taken through a solvent exchange process. A sample was immersed in water and then taken through separate ethanol and acetone immersions to toluene, and dried. The result was a sheet with little bonding and decreases in all mechanical properties. To explore the surface tension and capillary action effects of water, the solvent-exchanged sheet was re-immersed in water. Upon drying, interfiber bonding was reintroduced which resulted in the regain of mechanical properties lost.A paradigm for the mechanical behavior of paper is developed. Fibers contribute elastic behavior and interfiber bonds are a principal source of plastic behavior.

scholarly journals Characterization of Fibers Produced from Blends of Polybutylene and Polypropylene

2007 ◽  
Vol 2 (3) ◽  
pp. 155892500700200 ◽  
Author(s):  
Robert L. Shambaugh ◽  
Diana L. Ortiz
Keyword(s):  
Mechanical Properties ◽  
Differential Scanning Calorimetry ◽  
Tensile Strength ◽  
Scanning Calorimetry ◽  
Stress Strain ◽  
Strain Behavior

Blends of polybutylene (PB-1) and polypropylene were used to produce fibers at spinning speeds of 800–2100 m/min. Concentrations ranged from 0% PP to 100% PP. The stress-strain behavior of the resultant fibers was examined, and the fibers were analyzed for crystallinity via DSC (differential scanning calorimetry). Fibers produced from blends of PB-1/PP show mechanical properties that are in between the properties of the pure polymers. The tensile strength of 50% PB-1 fibers is comparable to the tensile strength of pure PP fibers. Fibers produced from blend compositions of 25 and 75% have higher tensile strengths than pure PP fibers, although these blend compositions have lower tensile strengths than pure PB fibers.

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