scholarly journals Dynamic stress relaxation of orthodontic thermoplastic materials in a simulated oral environment

2013 ◽  
Vol 32 (6) ◽  
pp. 946-951 ◽  
Author(s):  
Dongyu FANG ◽  
Ning ZHANG ◽  
Hui CHEN ◽  
Yuxing BAI
Keyword(s):  
Stress Relaxation ◽  
Dynamic Stress ◽  
Oral Environment

scholarly journals Dynamic stress relaxation in carbon black filled vulcanizates.

1986 ◽  
Vol 59 (5) ◽  
pp. 282-289
Author(s):  
Kunihiko FUJIMOTO ◽  
Hidehiko AKIMOTO
Keyword(s):  
Stress Relaxation ◽  
Carbon Black ◽  
Dynamic Stress

Test of Dynamic Strength Characteristics of Lishi Loess

2013 ◽  
Vol 303-306 ◽  
pp. 2902-2907 ◽  
Author(s):  
Nian Qin Wang ◽  
Xiao Ling Liu ◽  
Bo Han ◽  
Bo Tao Liu
Keyword(s):  
Stress Relaxation ◽  
Dynamic Stress ◽  
Peak Stress ◽  
Confining Pressure ◽  
Dynamic Strain ◽  
Soil Consolidation ◽  
Strength Parameters ◽  
Loading Test ◽  
Loess Slope ◽  
Effective Strength

Lishi loess is an important component of loess slope. To explore the structure and strength change characteristics of Lishi loess caused by shock (vibration) action, and to reveal the mechanism of loess slope catastrophe, the dynamic triaxial test was performed by using equivalent sine wave under strain controlling. The results show that:① There is an obvious stress relaxation phenomenon during the same cyclic loading test, the degree decreases with the increasing of dynamic strain and confining pressure. And the influence of dynamic strain variation on stress relaxation degree is less under high confining pressure than under low confining pressure;② Under a confining pressure of 40kPa, within 1% strain ranges, the needed dynamic stress to reach the specified strain is just 0.01kN, and the peak stress decreases with the augmentation of dynamic strain, when peak stress increases to 0.204kN, the sample is destructed; Under a confining pressure of 90kPa, soil radial particles are closely spaced, within 2% strain ranges also only a dynamic stress of 0.01kN is needed to reach the specified strain, and with the increase of dynamic strain, the samples are destructed when dynamic strain increases to 0.267kN. The dynamic failure stress of Lishi loess increases gradually with the increase of confining pressure, and the linear regression equation is бd=0.0011б3+0.1590, the correlation coefficient is 0.9944. ③According to Mohr-Coulomb failure criterion, the strength parameters of Lishi loess in somewhere of the north of shaanxi are C=30.33kPa，φ=14°. Under the dynamic shearing action, the dynamic effective strength parameters are obviously less than static effective strength parameters, this indicates that the soil consolidation effect reduced and the particles displaced and occluded each other.

Analysis of the Dynamic Stress Relaxometer Test Geometry and Conversion of Relaxing-Torque Data to Frequency-Dependent Viscoelastic Properties

1991 ◽  
Vol 64 (2) ◽  
pp. 254-268 ◽  
Author(s):  
E. Ray Harrell ◽  
John P. Porter ◽  
N. Nakajima
Keyword(s):  
Stress Relaxation ◽  
Dynamic Stress ◽  
Complex Viscosity ◽  
Adequate Description ◽  
Relaxation Data ◽  
Frequency Dependent ◽  
Torque Measurements ◽  
Test Geometry ◽  
And Storage ◽  
Good Agreement

Abstract The test geometry of the DSR has been mathematically modeled to provide an adequate description of the strain (and stress) distribution within a test specimen. The consideration of three separate deformation regions were required. Two of these regions, not considered in previous models, contribute 27% to 59% (depending upon the user-selectable closure height) of the total measured torque exerted on the DSR rotor. The utility of this model has been demonstrated by the agreement between the stress relaxation data obtained by converting the DSR relaxing torque measurements, using the modeled form factor, and data obtained with a uniform-strain-deformation instrument (RMS with cone and plate fixture) for four elastomer samples. Furthermore, the transformation of the converted DSR stress relaxation data to the frequency domain revealed good agreement with the frequency-dependent shear loss and storage moduli and complex viscosity obtained from RMS oscillatory experiments.

Dynamic stress relaxation of thermoplastic elastomeric biomaterials

Polymer ◽  
2009 ◽  
Vol 50 (1) ◽  
pp. 245-249 ◽  
Author(s):  
Judit E. Puskas ◽  
Miroslawa El Fray ◽  
Matthew Tomkins ◽  
Lucas M. Dos Santos ◽  
Frank Fischer ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Dynamic Stress

Dynamic stress relaxation behavior of nanogel filled elastomers

2010 ◽  
Vol 18 (4) ◽  
pp. 489-497 ◽  
Author(s):  
Suman Mitra ◽  
Santanu Chattopadhyay ◽  
Anil K. Bhowmick
Keyword(s):  
Stress Relaxation ◽  
Dynamic Stress ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Filled Elastomers

Long-Term Studies of Rubber Materials by Dynamic Mechanical Stress Relaxation

1989 ◽  
Vol 62 (3) ◽  
pp. 387-425 ◽  
Author(s):  
Folke Björk ◽  
Ola Dickman ◽  
Bengt Stenberg
Keyword(s):  
Stress Relaxation ◽  
Crosslink Density ◽  
Dynamic Stress ◽  
Life Time ◽  
Reasonable Estimate ◽  
Undesirable Characteristic ◽  
Dynamic Seal ◽  
Proper Values ◽  
Long Term Studies

Abstract The measurement of dynamic stress relaxation can reveal otherwise hidden weaknesses in rubber materials. The stress relaxation of the minimum of the restoring foce has the undesirable characteristic of being greater than the continuous stress relaxation. An increase in the amplitude of the deformation increases the decay in the minimum values of the varying retractive stress, and an increase in the prestrain makes it smaller. The normalized curve for continuous stress relaxation is found to lie somewhere between the normalized curves for the maximum and minimum of the retractive stress. The measurement of network density on specimens aged under continuous and dynamic stress relaxation indicate that the mechanism behind the degradation of the rubber network is the same in both cases. The relations between intermittent, continuous, and dynamic stress relaxation give a reasonable estimate of the dynamic stress relaxation from the other two when proper values of the coefficients are used. This relation says that results both of continuous and intermittent stress relaxation are important for predicting the life time of a dynamic seal. The relations offers an explanation of the differences between maximum and minimum values obtained during the measurement of dynamic stress relaxation and their relation to continuous stress relaxation. From these relations it can be concluded that a rubber intended for dynamic seals should contain neither reversion nor secondary crosslinking. Crosslink density should be high in order to overpower effects on crosslinking of factors in the surroundings.

Study on Dynamic Strength Characteristics of Malan Loess

2012 ◽  
Vol 170-173 ◽  
pp. 964-968 ◽  
Author(s):  
Nian Qin Wang ◽  
Xiao Ling Liu ◽  
Dong Hai Luo ◽  
Yong Yao
Keyword(s):  
Stress Relaxation ◽  
Dynamic Stress ◽  
Dynamic Strength ◽  
Friction Angle ◽  
Confining Pressure ◽  
Sine Wave ◽  
Dynamic Strain ◽  
Loading Test ◽  
Loess Slope ◽  
Malan Loess

Vibration effect is a major inducing factor of loess slope hazards and the basis of revealing loess slope mechanism, which often changes loess structure and decreases loess strength. Based on the GDS Lab System, the dynamic triaxial test was performed by using equivalent sine wave under strain controlling. The results are described as follows: ① there is an obvious phenomenon of stress relaxation during the cyclic loading test on Malan loess, and the degree of stress relaxation decreases with the increase of confining pressure and dynamic strain. Under the low confining pressure, Malan loess reaches certain strain only by small dynamic stress within 2% strain ranges. Under high confining pressure, Malan loess will also reach certain strain value by small dynamic stress within 1% strain ranges. At the same time, with the increase of confining pressure, the peak value of dynamic stress increases gradually. ②The dynamic failure stress of Malan loess increases linearly with the increase of confining pressure. The correlation coefficient is 0.99 and the linear regression equation is бd = 0.001б3 + 0.019. ③On the basis of Molar Coulomb failure criterion, the index of dynamic strength was c =3.36kPa, φ=16°. In comparison with the static strength, the internal friction angle decreases significantly while the cohesion slightly.

Sign in / Sign up

Export Citation Format

Share Document