Assessment of Relaxation Loss Estimates for Strands

1982 ◽  
Vol 108 (12) ◽  
pp. 2819-2836
Author(s):  
Arcady V. Koretsky ◽  
Ross W. Pritchard
Keyword(s):  
Relaxation Loss

Relaxation behavior of prestressing basalt fiber-reinforced polymer tendons considering anchorage slippage

2016 ◽  
Vol 51 (9) ◽  
pp. 1275-1284 ◽  
Author(s):  
Jianzhe Shi ◽  
Xin Wang ◽  
Huang Huang ◽  
Zhishen Wu
Keyword(s):  
Relaxation Rate ◽  
Basalt Fiber ◽  
Relaxation Behavior ◽  
Fiber Reinforced Polymer ◽  
Initial Stresses ◽  
Fiber Reinforced ◽  
Relaxation Rates ◽  
Reinforced Polymer ◽  
Relaxation Loss ◽  
Basalt Fiber Reinforced Polymer

Relaxation is a key factor that controls the application of prestressing fiber-reinforced polymer tendons. This paper focuses on the evaluation of the relaxation behavior of newly developed basalt fiber-reinforced polymer tendons through an approach considering anchorage slippage. A series of relaxation tests on basalt fiber-reinforced polymer tendons subjected to three levels of initial stresses (0.4 fu, 0.5 fu, and 0.6 fu, where fu = ultimate strength) were conducted using a specially designed test setup that eliminates the impact of slippage at the anchor zone. An additional group of tests was conducted to validate the enhancement effect of pretension on the relaxation behavior. The relaxation rates at one million hours were predicted based on experimental fitting. Finally, the relaxation rates at 1000 h were predicted using the correlation between the relaxation and creep and were validated with the experimental relaxation rates. The results demonstrate the effectiveness of the proposed setup in measuring the relaxation loss of specimens and reveal that the relaxation rates of untreated basalt fiber-reinforced polymer tendons at 1000 h are 4.2%, 5.3%, and 6.4% at 0.4 fu, 0.5 fu, and 0.6 fu, respectively. Pretension treatment performs effective in relaxation loss controlling. BFRP tendons are recommended to be applied at an initial stress of 0.5 fu after pretension treatment, with one-million-hour relaxation rate equal to 6.7%. Furthermore, the relaxation rate at 1000 h can be predicted accurately based on the creep behavior. The conclusions of this study can provide guidance for the prestressing applications of basalt fiber-reinforced polymer tendons.

scholarly journals Electroactive Composites with Block Copolymer-Templated Iron Oxide Nanoparticles for Magnetic Hyperthermia Application

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1430
Author(s):  
Shu-Chian Yang ◽  
Chun-Yu Chen ◽  
Hung-Yu Wan ◽  
Szu-Ying Huang ◽  
Ta-I Yang
Keyword(s):  
Iron Oxide ◽  
Block Copolymer ◽  
Magnetic Particles ◽  
Magnetic Hyperthermia ◽  
Promising Technique ◽  
Cathodic Current ◽  
Heating Performance ◽  
Relaxation Loss ◽  
And Control ◽  
Human Death

Cancer has been one of the leading causes of human death for centuries. Magnetic hyperthermia is a promising technique to confine and control cancers. However, particles used in magnetic hyperthermia leaking from where the cancers are located could compromise human health. Therefore, we developed electroactive iron oxide/block copolymer composites to tackle the leakage problem. Experimental results show that oleylamine-modified magnetic iron oxide (Fe3O4) particles and electroactive tetraaniline (TA) could be templated in the self-assembled microstructures of sulfonated [styrene-b-(ethylene-ran-butylene)-b-styrene] (S-SEBS) block copolymers. Various amounts of Fe3O4 particles and TA oligomer were incorporated in S-SEBS block copolymer and their electroactive behavior was confirmed by exhibiting two pairs of well-defined anodic and cathodic current peaks in cyclic voltammetry tests. The heating performance of the resultant TA/Fe3O4/polymer composites improved on increasing the added amount of Fe3O4 particles and TA oligomers. Both Fe3O4 and TA can contribute to improved heating performance, but Fe3O4 possesses a greater contribution than TA does. Hence, the main source for increasing the composites’ temperature is Neel relaxation loss from Fe3O4 magnetic particles.

scholarly journals Experimental Study of the Relaxation Properties of Carbon Fiber Cloth

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3603
Author(s):  
Qiang Wang ◽  
Hua-Lin Song ◽  
Chun-Ling Lu ◽  
Wan-Xu Zhu ◽  
Jia-Zhu Huang
Keyword(s):  
Carbon Fiber ◽  
Relaxation Rate ◽  
Calculation Model ◽  
Test Results ◽  
Relaxation Properties ◽  
Reinforced Plastics ◽  
Axial Tension ◽  
Carbon Fiber Cloth ◽  
Relaxation Loss ◽  
Rate Calculation

In this study, a new method was proposed to study the relaxation properties of carbon fiber reinforced plastics (CFRP) fabric under axial tension. Under the condition of constant temperature and humidity, six groups of 168 h stress relaxation tests were conducted. Considering the influence of the prestress level, the size of CFRP cloth, and the surface coating of CFRP cloth on the relaxation performance, the measures to reduce the relaxation loss were proposed. The relaxation rate calculation model was established based on the test results of the authors and other scholars and was validated through comparisons with the test results. The results indicate that the relaxation rate of CFRP cloth was between 1.92% and 6.1%. When the prestress level was smaller than 0.3 fu, the relaxation rate of CFRP cloth decreased with the increase of prestress level. When the prestress level was greater than 0.3 fu, the relaxation rate increased with the increase of the prestress level. Under the same conditions, the relaxation rate of the CFRP specimens coated with glue was smaller than the uncoated samples by 3.21–6.28%. The calculation model could well estimate the relaxation rate of CFRP cloth.

Energy basis of dielectric relaxation loss

Nature ◽  
1978 ◽  
Vol 271 (5646) ◽  
pp. 645-648 ◽  
Author(s):  
D. C. SALTER
Keyword(s):  
Dielectric Relaxation ◽  
Relaxation Loss

Abstract P2023: Perivascular Adipose Tissue Assists Arterial Stress Relaxation: Loss of Assistance in Obesity-Associated Hypertension

Hypertension ◽  
2019 ◽  
Vol 74 (Suppl_1) ◽  
Author(s):  
Sara Roccabianca ◽  
Emma Flood ◽  
Hannah Garver ◽  
Gregory Fink ◽  
Stephanie W Watts
Keyword(s):  
Adipose Tissue ◽  
Stress Relaxation ◽  
Perivascular Adipose Tissue ◽  
Relaxation Loss

scholarly journals Improved Water-Tree Resistances of SEBS/PP Semi-Crystalline Composites under Crystallization Modifications

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3669
Author(s):  
Jun-Qi Chen ◽  
Xuan Wang ◽  
Wei-Feng Sun ◽  
Hong Zhao
Keyword(s):  
Accelerated Aging ◽  
Dynamic Mechanical Properties ◽  
Melt Crystallization ◽  
Dynamic Relaxation ◽  
Scanning Calorimetry ◽  
Polarizing Microscopy ◽  
Water Tree ◽  
Relaxation Loss ◽  
Pp Composites ◽  
Lower Size

Water-tree resistances of styrene block copolymer/polypropylene (SEBS/PP) composites are investigated by characterizing crystallization structures in correlation with the dynamic mechanical properties to elucidate the micro-structure mechanism of improving insulation performances, in which the accelerated aging experiments of water trees are performed with water-knife electrodes. The water-tree morphology in spherulites, melt-crystallization characteristics and lamella structures of the composite materials are observed and analyzed by polarizing microscopy (PLM), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), respectively. Dynamic relaxation and stress-strain characteristics are specifically studied by means of a dynamic thermomechanical analyzer (DMA) and electronic tension machine, respectively. No water-tree aging occurs in both the highly crystalline PP and the noncrystalline SEBS elastomer, while the water trees arising in SEBS/PP composites still has a significantly lower size than that in low-density polyethylene (LDPE). Compared with LDPE, the PP matrix of the SEBS/PP composite represent a higher crystallinity with a larger crystallization size in consistence with its higher mechanical strength and lower dynamic relaxation loss. SEBS molecules agglomerate as a “island” phase, and PP molecules crystallize into thin and short lamellae in composites, leading to the blurred spherulite boundary and the appreciable slips between lamellae under external force. The high crystallinity of the PP matrix and the strong resistance to slips between lamellae in the SEBS/PP composite essentially account for the remarkable inhibition on water-tree growth.

High Frequency Dielectric Properties and Thermal Conductivity of AlN-BN Composites by Spark Plasma Sintering

2012 ◽  
Vol 512-515 ◽  
pp. 902-907 ◽  
Author(s):  
Zhi Xue Qu ◽  
Wang Qun ◽  
Chang Chun Cui ◽  
Yao Hui Zhang
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Properties ◽  
Spark Plasma Sintering ◽  
High Frequency ◽  
Sintering Process ◽  
Sintering Additives ◽  
Multiple Components ◽  
Plasma Sintering ◽  
Relaxation Loss ◽  
Spark Plasma

AlN-BN composite is considered to be a promising material for microwave transparent applications. In this paper, a series of AlN-BN composites with various content of BN (0 wt%, 5 wt%, 15 wt% and 30 wt%) were prepared by spark plasma sintering with multiple components sintering additives at a low temperature (1650 °C), and the effect of sintering conditions and composition on the thermal conductivity and high frequency dielectric properties within frequency range from 10 MHz to 1.5 GHz was investigated. The results show that the spark plasma sintering process and the multiple components of the sintering additives promote the densification of the samples. The thermal conductivity and dielectric constant of samples decrease with increasing BN content, while the variation of the dielectric loss depends on the content of residual carbon and other impurities which may result in the relaxation loss of electronic polarization and conductive loss.

The Effect of Annealing on the Internal Friction in ECAP-Modified Ultrafine Grained Copper

2012 ◽  
Vol 184 ◽  
pp. 289-294 ◽  
Author(s):  
Igor S. Golovin ◽  
P.P. Pal-Val ◽  
L.N. Pal-Val ◽  
E.N. Vatazhuk ◽  
Yuri Estrin
Keyword(s):  
Activation Energy ◽  
Activation Parameters ◽  
Coarse Grained ◽  
Relaxation Processes ◽  
Exponential Factor ◽  
Mean Values ◽  
Thermally Activated ◽  
Ultrafine Grained ◽  
Relaxation Loss ◽  
The Mean

A detailed study of anelastic effects in submicrocrystalline copper using resonance (~70 kHz, 2 K to 320 K) and sub-resonance (0.05-100 Hz, 300 K to 675 K) techniques was carried out. Several relaxation processes were found in the temperature range of 2 K - 675 K: the relaxation loss peaks (Q-1) near 35 (P1) and 90K (P2) with the activation energy and the pre-exponential factor (H1≈ 0.02 eV,το1≈ 10-9s andH2≈ 0.09 eV,το2≈ 10-11s) similar to those of the Bordoni and the Niblett-Wilks peaks in coarse-grained Cu. This suggests that the peaks are due to the thermally activated motion of dislocation kinks in the primary and secondary Peierls relief. The mean values of activation parameters (H3≈1.4-1.6 eV,το3≈10-17s) of a third thermally activated peak (P3), which was significantly broadened, can be interpreted as a grain boundary peak with uncoupled activation parametersH3*≈0.45 eV andτο3*≈10-14s. A pseudo peak PRis associated with irreversible recrystallization processes. The influence of annealing on the observed effects is also discussed.

Bi2O3 Solubility of Bi-based Pyrochlores and Related Phases

2002 ◽  
Vol 17 (5) ◽  
pp. 1178-1182 ◽  
Author(s):  
Juan C. Nino ◽  
Hyuk J. Youn ◽  
Michael T. Lanagan ◽  
Clive A. Randall
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Dielectric Relaxation ◽  
Bismuth Oxide ◽  
Loss Peak ◽  
Solubility Behavior ◽  
Relaxation Loss ◽  
Systematic Shift ◽  
The Relationship ◽  
Oxide Solubility

Bismuth oxide solubility in Bi2O3–ZnO–Nb2O5 and Bi2O3–MgO–Nb2O5 (BMN) pyrochlore systems was investigated and the solubility limits were identified. Differences in the solubility behavior between the two Bi-pyrochlore systems investigated were analyzed and explained through crystal chemistry concepts. For the BMN system, the dielectric constant was enhanced, and a systematic shift occurred in the dielectric relaxation loss peak to higher temperatures with increases in the excess bismuth are reported in the BMN system. The relationship between solubility and the shift in the dielectric loss curve was analyzed under the scope of possible relaxation mechanisms.

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