scholarly journals Compressive Stress Relaxation and Creep Properties of Synthetic Fiber and Regenerated Fiber Assemblies

Polyester ◽  
10.5772/48546 ◽  
2012 ◽  
Author(s):  
Yoneda Morihiro ◽  
Nakajima Chie
Keyword(s):  
Stress Relaxation ◽  
Compressive Stress ◽  
Synthetic Fiber ◽  
Creep Properties

Post-Fatigue Creep and Stress Relaxation Response of a Hybrid Polymer Composite

2017 ◽  
Author(s):  
Raghu V. Prakash ◽  
Monalisha Maharana
Keyword(s):  
Stress Relaxation ◽  
Polymer Composites ◽  
Polymer Composite ◽  
Fatigue Loading ◽  
Synthetic Fiber ◽  
Relaxation Response ◽  
Hybrid Polymer ◽  
Fatigue Cycling ◽  
Creep And Stress Relaxation ◽  
Hybrid Polymer Composite

Polymer composites have a characteristic, composition specific visco-elastic property which influences the damage progression during fatigue cycling. While some researchers have studied the time dependent constitutive response of polymer composites during the first cycle of fatigue loading, very few have experimentally investigated the dependence of visco-elastic response of built-up polymer composite materials at various stages of fatigue cycling [1]. Our earlier studies on fatigue response of polymer composites focused primarily on the stiffness degradation as a function of applied cycles of loading, which represents the gross response of the material [2]. While doing such an experiment, complimentary experimental techniques to measure the temperature evolution was attempted through the use of infrared thermal imaging technique, which gave some insight into the change in temperature response as a function of fatigue cycling. However, there was no systematic measurement of creep and stress relaxation response of the composite material as a function of induced fatigue damage. The present paper describes the results of creep and stress-relaxation obtained during uni-axial fatigue loading of a hybrid polymer composite material. For this purpose, a woven carbon fiber mat was chosen as the synthetic fiber and Flax fiber in the unidirectional form was chosen as the natural fiber that is laid between the two layers of woven carbon fiber mat. Epoxy LY 556 and hardener Araldite® was used for building up of composite laminate by hand-lay-up technique. Dog-bone shaped tensile specimens with a gage width of 13 mm and gage length of 57 mm were extracted from the 250 × 250 mm sq. plate laminate of 2.1 mm thickness using a numerical controlled milling machine. The specimens were tested at 35% of their median tensile strengths under fatigue at a positive stress ratio (Pmin/Pmax) of 0.1 in tension-tension loading. Prior to start of fatigue loading, the specimens were held in load control and the strain in the gage length was measured for understanding the creep response over 2500 seconds. For stress-relaxation characterization, the specimens were held in extensometer control over a period of 2500 sec. The creep and stress relaxation tests were carried out after periodic intervals of fatigue cycling. It was observed that in the case of un-impacted specimens, the creep rate is consistent with the stiffness variation, which in turn, is dependent on the number of fatigue cycles - till it showed signs of de-lamination. Thereafter it was governed by the woven synthetic fiber response. Similarly, the stress relaxation response was found to decrease with increasing fatigue cycles. In case of impacted specimens, the local deformation had a prominent role in terms of creep and stress relaxation response.

How to exploit ion-induced stress relaxation to grow thick c-BN films

2002 ◽  
Vol 74 (3) ◽  
pp. 489-492 ◽  
Author(s):  
P. Ziemann ◽  
H.-G. Boyen ◽  
N. Deyneka ◽  
P. Widmayer ◽  
F. Banhart
Keyword(s):  
Stress Relaxation ◽  
Compressive Stress ◽  
Ion Irradiation ◽  
Cubic Phase ◽  
Medium Energy ◽  
High Quality ◽  
Induced Stress

A recently developed procedure is reviewed allowing thick (>1 mm), high-quality c-BN films (>80 % c-BN) to be grown. It is based on the observation that compressive stress inevitably present in such films can be released by medium-energy (some hundred keV) ion irradiation without destroying the cubic phase.

Effect of Deposition Conditions on Intrinsic Stress, Phase Transformation and Stress Relaxation in Tantalum Thin Films

1991 ◽  
Vol 239 ◽  
Author(s):  
A. Mutscheller ◽  
L. A. Clevenger ◽  
J.M.E. Harper ◽  
C. Cabrai ◽  
K. Barmakt
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Phase Transformation ◽  
Stress Relaxation ◽  
Compressive Stress ◽  
Stress Relief ◽  
Beta Phase ◽  
Alpha Phase ◽  
Intrinsic Stress

AbstractWe demonstrate that the high temperature polymorphic tantalum phase transition from the tetragonal beta phase to the cubic alpha phase causes complete stress relaxation and a large decrease in the resistance of tantalum thin films. 100 nm beta tantalum thin films were deposited onto thermally oxidized <100> silicon wafers by dc magnetron sputtering with argon. In situ stress and resistance at temperature were measured during temperature-ramped annealing in purified He. Upon heating, films that were initially compressively stressed showed increasing compressive stress due to thermo-elastic deformation from 25 to 550°C, slight stress relief due to plastic deformation from 550 to 700°C and complete stress relief due to the beta to alpha phase transformation at approximately 700–800°C. Incomplete compressive stress relaxation was observed at high temperatures if the film was initially deposited in the alpha phase or if the beta phase did not completely transform into alpha by 800°C. This incomplete beta to alpha phase transition was most commonly observed on samples that had radio frequency substrate bias greater than -100 V. We conclude that the main stress relief mechanism for tantalum thin films is the beta to alpha phase transformation that occurs at 700 to 800°C.

A Comparative Study of UHMWPE Multifilament and Aramid Multifilament

2013 ◽  
Vol 709 ◽  
pp. 84-88 ◽  
Author(s):  
Lu Yu Zhou ◽  
Xian Bo Li
Keyword(s):  
Stress Relaxation ◽  
Comparative Study ◽  
Creep Resistance ◽  
Element Model ◽  
Matlab Software ◽  
Creep Properties ◽  
Basic Performance

In order to analyze the creep properties of UHMWPE multifilament and aramid multifilament, four-element model and Matlab software were used to get creep fitting curve, the corresponding mechanical fitting equation and microscopic parameters. The creep properties of the two kinds of multifilament were discussed by microscopic parameters. At the same time, the tensile and relaxation performance of UHMWPE multifilament and aramid filament were studied. Compared with aramid multifilament, UHMWPE multifilament has higher strength, better elongation, lower creep resistance and obvious the phenomenon of stress relaxation. This article will provide some basic performance reference to the application of UHMWPE multifilament.

scholarly journals A Study on the Compressive Stress Relaxation of Cotton Fiber Assemblies

1974 ◽  
Vol 27 (11) ◽  
pp. T177-T182 ◽  
Author(s):  
Tooru Nogai ◽  
Yutaka Narumi ◽  
Ken Tanaka
Keyword(s):  
Stress Relaxation ◽  
Compressive Stress ◽  
Cotton Fiber
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