The stress relaxation of molten PMMA at large deformations and its theoretical interpretation

1980 ◽  
Vol 19 (1) ◽  
pp. 68-75 ◽  
Author(s):  
G. Marrucci ◽  
B. de Cindio
Keyword(s):  
Stress Relaxation ◽  
Large Deformations ◽  
Theoretical Interpretation

Viscoelastic Behavior of High Polymers at Large Deformations

1969 ◽  
Vol 42 (2) ◽  
pp. 373-380 ◽  
Author(s):  
G. W. Becker ◽  
H.-J. Rademacher
Keyword(s):  
Stress Relaxation ◽  
Entire Range ◽  
Large Deformations ◽  
Viscoelastic Behavior ◽  
Stress Dependence ◽  
Plasticized Pvc ◽  
Stress Region ◽  
Deformation Dependence ◽  
Different Strains ◽  
High Polymers

Abstract Stress relaxation at different strains, and retarded deformation at different stresses were measured for rod-shaped test specimens of plasticized PVC in tension. Temperature was varied in such a way that changes in properties of the material, within the entire range from the glassy-amorphous to the quasi rubber-elastic states, could be comprehended. From results of the two types of experiment it was concluded that outside of the linear stress region, and at all temperatures, the time and deformation dependence of stress could be separated, but this was not possible for the time and stress dependence of strain.

The application of Boltzmann’s superposition theory to materials exhibiting reversible β flow

1951 ◽  
Vol 206 (1084) ◽  
pp. 72-86 ◽  
Keyword(s):  
Stress Relaxation ◽  
Experimental Work ◽  
Large Deformations ◽  
Elastic Region ◽  
Creep Recovery ◽  
Metallic Materials ◽  
Substantial Agreement ◽  
Creep Equation ◽  
Existing Data ◽  
Theory And Experiment

Boltzmann’s theory of superposition is applied to the flow and recovery of a material in the so-called anelastic region, in which deformations outside the elastic region are slowly recoverable on removing the stress, and experimental work to test the theory is described. It is shown that the Andrade creep equation applies not only to large deformations of a completely irreversible character, but in this region also. Formulae have been worked out which give the amount of creep recovery, and of stress relaxation at constant strain, after any duration of an applied constant stress, for a material which at larger stresses exhibits the Andrade β flow. On comparing the formulae with existing data and with the results of experiments described in the paper, for both metallic and non-metallic materials, it is found that theory and experiment are in substantial agreement.

Stress as a Reduced Variable: Stress Relaxation of SBR Rubber at Large Strains

1961 ◽  
Vol 34 (3) ◽  
pp. 884-896
Author(s):  
Robert F. Landel ◽  
Paul J. Stedry
Keyword(s):  
Stress Relaxation ◽  
Large Deformations ◽  
Strain Curve ◽  
Large Strains ◽  
Stress Strain Curve ◽  
Breaking Strain ◽  
Reduced Modulus ◽  
Relaxation Measurements ◽  
Initial Strains ◽  
Strain Function

Abstract Stress relaxation measurements on SBR were carried out at temperatures from −5 to +60° C and at initial strains of up to 550%. The effects of strain and time were found to be factorable, so that the isochronal stress-strain curve may be written as a modified Hooke's law with a time-dependent modulus: S=E(t)eƒ(α), where ƒ(α) is an appropriate function of the strain. By defining a strain-reduced stress S*=S/∫(α), i.e., a strain-reduced modulus E*(t)=E(t)ƒ(α), it can be shown that Ferry's method of reduced variables may be extended to large deformations. An appropriate strain function was obtained from the empirical Martin-Roth-Stiehler equation as ƒ(α)=α−2 exp A(α−α−1) with A=0.40. Although it cannot yet be certain that A is truly a constant and the same for all elastomers, this equation has the advantage of being valid right out to the breaking strain.

Stress Relaxation and the Formation of Silicides in the Process of the Crystallization of NI-NB Films on SI

1991 ◽  
Vol 49 ◽  
pp. 898-899
Author(s):  
N. Rozhanski ◽  
V. Lifshitz
Keyword(s):  
Thin Films ◽  
Stress Relaxation ◽  
Integrated Circuits ◽  
Direct Evidence ◽  
Alloy Film ◽  
Diffusion Barriers ◽  
Effective Barrier

Thin films of amorphous Ni-Nb alloys are of interest since they can be used as diffusion barriers for integrated circuits on Si. A native SiO2 layer is an effective barrier for Ni diffusion but it deformation during the crystallization of the alloy film lead to the appearence of diffusion fluxes through it and the following formation of silicides. This study concerns the direct evidence of the action of stresses in the process of the crystallization of Ni-Nb films on Si and the structure of forming NiSi2 islands.

BDNF Val⁶⁶Met polymorphism to generalized anxiety disorder pathways: Indirect effects via attenuated parasympathetic stress-relaxation reactivity.

2020 ◽  
Vol 129 (3) ◽  
pp. 237-247 ◽  
Author(s):  
Hsin-An Chang ◽  
Wen-Hui Fang ◽  
Yia-Ping Liu ◽  
Nian-Sheng Tzeng ◽  
Jia-Fwu Shyu ◽  
...  
Keyword(s):  
Anxiety Disorder ◽  
Stress Relaxation ◽  
Generalized Anxiety Disorder ◽  
Indirect Effects ◽  
Generalized Anxiety
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