relaxation characteristics
Recently Published Documents


TOTAL DOCUMENTS

235
(FIVE YEARS 45)

H-INDEX

22
(FIVE YEARS 2)

2021 ◽  
Vol 14 (24) ◽  
Author(s):  
Xiang Xin ◽  
Fan Lei ◽  
Sun Zhiyu ◽  
Zhang Guangcheng ◽  
Zhang Shu ◽  
...  

2021 ◽  
Vol 9 ◽  
Author(s):  
Jun Yu ◽  
Qiang Zhang ◽  
Weiya Xu ◽  
Rubin Wang ◽  
Han Zhang

We aim to understand the relaxation of columnar joint rock masses during the excavation process of the diversion tunnel of the Baihetan hydropower station. This paper inverts the deformation parameters of the relaxed columnar joint rock based on the displacement monitoring data, and introduces a relaxation factor to describe the deterioration degree of anisotropic parameters of the relaxed columnar jointed rock. The equivalent strain is proposed as the criterion of unloading relaxation and the threshold is also given. Based on the software Flac3d, a program for calculating anisotropic elastoplastic model is developed. The distribution of the relaxation zone of the diversion tunnel after excavation is simulated, and compared with the results of the acoustic detection to verify the correctness and rationality of the program, which can provide a necessary reference for the design and construction of hydropower projects.


2021 ◽  
Vol 11 (21) ◽  
pp. 9959
Author(s):  
Jun Wang ◽  
Hongwen Zhang ◽  
Lei Wang ◽  
Ximei Wei ◽  
Meng Wang ◽  
...  

Seed cotton compression molding solves the inconvenience of seed cotton transportation and storage after mechanical harvesting. Stress relaxation is closely related to the performance of the compressed seed cotton. In this study, an electronic universal testing machine with a homemade compression device was used to study the stress relaxation characteristics of machine-harvested seed cotton. The stress relaxation model of machine-harvested seed cotton was established, the influence of test factors on the response indexes was analyzed and, finally, stress relaxation characteristics of machine-harvested seed cotton were simulated. Results show that machine-harvested seed cotton stress relaxation characteristics can be described by the five-element Maxwell model. The equilibrium elastic modulus is negatively correlated with moisture content and cross-section dimensions, and the equilibrium elastic modulus is positively correlated with trash content and compression density. The rapid decay time and the residual stress ratio are negatively correlated with moisture content and compression density, but the influence of trash content and cross-section dimensions are limited. The stress relaxation process of machine-harvested seed cotton was simulated using virtual prototype technology, and the maximum error between the experimental and simulated values was obtained as 4.96%. The feasibility of the virtual prototype technique for the viscoelastic simulation of biomaterials was demonstrated.


Author(s):  
Oleg Savenko ◽  
Valeriy Martynyuk ◽  
Mykola Fedula ◽  
Liudmyla Koretska ◽  
Denys Makaryshkin

2021 ◽  
Vol 899 ◽  
pp. 752-758
Author(s):  
Yulia A. Naumova ◽  
L.R. Lyusova ◽  
S.V. Kotova ◽  
A.O. Volkov

The work presents the results of testing new eco-oils in elastomeric materials based on nitrile butadiene rubber (NBR). The influence of eco-oils grade and content on the rubber mixes based on NBR 2665 processing was studied. It is established that Phytonorman 212 acts as a technologically active additive that improves the rheological and relaxation characteristics of rubber mixes. Phytonorman 213 acts as an activator of the vulcanization process when eco-oils content is 2 phr. To maintain the complex of physical, mechanical and working performances, so as to prevent the slowdown of the vulcanization process at 7 phr eco-oil content it is recommended to adjust vulcanizing group component content and filler grade.


Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4601
Author(s):  
Yuanjin Liu ◽  
Lixiao Yao ◽  
Yue Bu ◽  
Qing Sun

Epoxy composite materials are widely used in power equipment. As the voltage level increases, the requirement of material properties, including electrical, thermal, and mechanical, has also increased. Introducing thermally conductive nanofiller to the epoxy/liquid rubber composites system is an effective approach to improve heat performance, but the effects of thermally conductive nanofillers on relaxation characteristics remain unclarified. In this paper, nano-alumina (nano-Al2O3) and nano-boron nitride (nano-BN) have been employed to modify the epoxy/carboxyl-terminated liquid nitrile–butadiene rubber (epoxy/CTBN) composites system. The thermal conductivity and glass transition temperature of different formula systems have been measured. The effect of the nanofillers on the relaxation behaviors of the resin matrix has been investigated. Results show that the different kinds of nanofillers will introduce different relaxation processes into the matrix and increase the conductivity at the same time. This study can provide a theoretical basis for the synergistic improvement of multiple properties of epoxy resin composites.


2021 ◽  
Author(s):  
Desheng Zhu ◽  
Yuanyang Zhao ◽  
Yourui Tu ◽  
Ruifeng Li ◽  
Keyan Liu ◽  
...  

2021 ◽  
pp. 110635
Author(s):  
Jing Zhang ◽  
Jun Wang ◽  
Shuang Gu ◽  
Chengyu Zheng ◽  
Dongdong Du

Sign in / Sign up

Export Citation Format

Share Document