scispace - formally typeset
Search or ask a question
Topic

Stress relaxation

About: Stress relaxation is a research topic. Over the lifetime, 12959 publications have been published within this topic receiving 270815 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, a solution of polyγ-benzyl-L-glutamate (PBLG) in m−cresol has been investigated and the existence of a stable negative first normal stress difference is confirmed.
Abstract: A solution of poly‐γ‐benzyl‐L‐glutamate (PBLG) in m‐cresol has been investigated. Viscoelastic properties during steady state shear flow and in oscillatory flow are presented. The existence of a stable negative first normal stress difference is confirmed. The dynamic Newtonian viscosity is considerably smaller than the corresponding steady state shear value. The transient behavior after cessation of flow is studied in detail using dynamic measurements. After cessation of flow, the dynamic moduli change over a time scale which is much larger than that for stress relaxation. Effects of frequency, temperature and previous shear rate are analyzed. The structural interpretation of the data is discussed. Available models for polymeric liquid crystals have to be developed further before a comparison with the present results becomes possible.

127 citations

Journal ArticleDOI
TL;DR: In this article, the evolution of viscoelasticity during the gelation reactions of semidilute solutions of polyvinyl alcohol (PVA) in the presence of crosslinker (glutaraldehyde) has been monitored through the sol−gel transition with dynamic mechanical experiments.
Abstract: The evolution of viscoelasticity during the gelation reactions of semidilute solutions of poly(vinyl alcohol) (PVA) in the presence of cross-linker (glutaraldehyde) has been monitored through the sol−gel transition with dynamic mechanical experiments. The gelation time of the system decreased with increasing PVA and cross-linker concentrations. At the gel point, a power law frequency dependence of the dynamic storage modulus (G‘ ∝ ωn‘) and loss modulus (G‘‘ ∝ ωn‘‘) was observed with n‘ = n‘‘ = n. The power law exponent is lower than that predicted (0.7) from the percolation model. The value of n decreases with increasing polymer and cross-linker concentrations. The critical gel strength parameter (S) rises with increasing polymer and cross-linker concentrations. Some stress relaxation measurements on gelling PVA systems were also carried out. At the gel point, a power law time dependence of the relaxation modulus was detected, but the relaxation exponent was lower than the corresponding one obtained from ...

127 citations

Journal ArticleDOI
TL;DR: A creep theory is developed in which the whole of tertiary creep and, in particular, the creep lifetime are predicted from measurements made at the onset of creep, when the tendon is undamaged.
Abstract: The tail tendons from wallabies (Macropus rufogriseus) suffer creep rupture at stresses of 10 MPa or above, whereas their yield stress in a dynamic test is about 144 MPa. At stresses between 20 and 80 MPa, the time-to-rupture decreases exponentially with stress, but at 10 MPa, the lifetime is well above this exponential. For comparison, the stress on a wallaby tail tendon, when its muscle contracts isometrically, is about 13.5 MPa. Creep lifetime depends sharply on temperature and on specimen length, in contrast to strength and stiffness as observed in dynamic tests. The creep curve (strain versus time) can be considered as a combination of primary creep (decelerating strain) and tertiary creep (accelerating strain). Primary creep is non-damaging, but tertiary creep is accompanied by accumulating damage, with loss of stiffness and strength. 'Damage' is quantitatively defined as the fractional loss of stiffness. A creep theory is developed in which the whole of tertiary creep and, in particular, the creep lifetime are predicted from measurements made at the onset of creep, when the tendon is undamaged. This theory is based on a 'damage hypothesis', which can be stated as: damaged material no longer contributes to stiffness and strength, whereas intact material makes its full contribution to both.

127 citations

Journal ArticleDOI
TL;DR: In this article, the viscosity and flow stress of a bulk Pd40Ni10Cu30P20 alloy glass near the glass transition were measured as a function of temperature and strain rate under compression.
Abstract: The viscosity and flow stress of a bulk Pd40Ni10Cu30P20 alloy glass near the glass transition were measured as a function of temperature and strain rate under compression The steady-state viscosity of the glass for a given temperature remains constant at low strain rate, then decreases by many orders of magnitude above a critical strain rate A master curve in term of the viscosity ratio η/ηN and the product ηNe has been constructed, where η and ηN are, respectively, the steady-state viscosity and Newtonian viscosity, and e is the strain rate The flow stress also can be represented in terms of the product ηNe The master curves are fitted with a simple stress relaxation of the form 1−exp[−t/λ] with t=e−1

127 citations

Journal ArticleDOI
TL;DR: In this article, the creep of Nimonic 80A has been studied in torsion and tension over the range of effective stress σ from 100 to 500 MPa and at the temperature 750°C.
Abstract: With the object of observing the influence of stress system, the creep of Nimonic 80A has been studied in torsion and tension over the range of effective stress σ from 100 to 500 MPa and at the temperature 750°C For a given σ, tertiary creep and fracture occur sooner in tension than in torsion, while nucleation of cavities is faster The cavities evidently accelerate creep strain and, since creep strain produces cavities, the behaviour as regards both strain and cavitation is autocatalytic The results are expressed and explained in terms of (σ1/σ), where σ1 is the maximum principal stress, and a predictive law for fracture life is derived from constitutive relations connecting strain, cavity volume, and stress

127 citations


Network Information
Related Topics (5)
Polymer
131.4K papers, 2.6M citations
86% related
Oxide
213.4K papers, 3.6M citations
82% related
Coating
379.8K papers, 3.1M citations
82% related
Thin film
275.5K papers, 4.5M citations
82% related
Carbon nanotube
109K papers, 3.6M citations
81% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023145
2022390
2021266
2020276
2019270
2018281