Comparison of short and long term creep testing in high performance polymers

2019 ◽  
Vol 78 ◽  
pp. 105979 ◽  
Author(s):  
A. Fairhurst ◽  
M. Thommen ◽  
C. Rytka
Keyword(s):  
High Performance ◽  
Creep Testing ◽  
High Performance Polymers ◽  
Short And Long Term ◽  
Term Creep

Auscultation d'une culée du pont de Portneuf à l'aide d'une inclusion de béton instrumentée (CIUS)

1996 ◽  
Vol 23 (5) ◽  
pp. 1129-1136
Author(s):  
Axel-Pierre Bois ◽  
Mohamed Lachemi ◽  
Gérard Ballivy
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Coefficient Of Thermal Expansion ◽  
Concrete Bridge ◽  
Thermal Gradients ◽  
Bridge Monitoring ◽  
Shrinkage And Creep ◽  
First Results ◽  
Short And Long Term

The Portneuf Bridge, built in 1992, is the first air-entrained high-performance concrete bridge in North America. To understand its short and long term behaviour, an auscultation program has been set. Hence, a cylindrical concrete inclusion of the Université de Sherbrooke was installed in one of the abutments of the bridge. The aim of this study is to present the first results thus acquired. The analysis of the results allowed to calculate the coefficient of thermal expansion of the concrete and to assess deformation variations due to shrinkage and creep and the effects of rebar–concrete interaction in the upper abutment region. Moreover, the presence of thermal gradients, which creates nonisotropic deformations, has been established. Key words: high-performance concrete, deformations, thermal gradients, instrumentation, bridge, monitoring. [Journal translation]

scholarly journals Short and Long-Term Properties of High-Performance Concrete Containing Silica Fume for Bridge Deck Overlay

2005 ◽  
Vol 17 (5) ◽  
pp. 743-750
Author(s):  
Jong-Pil Won ◽  
Jung-Min Seo ◽  
Chang-Soo Lee ◽  
Hae-Kyun Park ◽  
Myeong-Sub Lee
Keyword(s):  
Silica Fume ◽  
High Performance ◽  
Bridge Deck ◽  
High Performance Concrete ◽  
Short And Long Term ◽  
Bridge Deck Overlay

Nonlinear Hierarchical MPC for Maximizing Aircraft Thermal Endurance

2020 ◽  
Author(s):  
Daniel D. Leister ◽  
Justin P. Koeln
Keyword(s):  
High Performance ◽  
Linear Models ◽  
Critical Role ◽  
Effective Control ◽  
Thermal Management System ◽  
Short And Long Term ◽  
Upper Level ◽  
Control Of Linear Systems ◽  
High Computational Efficiency

Abstract In modern high-performance aircraft, the Fuel Thermal Management System (FTMS) plays a critical role in the overall thermal energy management of the aircraft. Actuator and state constraints in the FTMS limit the thermal endurance and capabilities of the aircraft. Thus, an effective control strategy must plan and execute optimized transient fuel mass and temperature trajectories subject to these constraints over the entire course of operation. For the control of linear systems, hierarchical Model Predictive Control (MPC) has shown to be an effective approach to coordinating both short- and long-term system operation with reduced computational complexity. However, for controlling nonlinear systems, common approaches to system linearization may no longer be effective due to the long prediction horizons of upper-level controllers. This paper explores the limitations of using linear models for hierarchical MPC of the nonlinear FTMS found in aircraft. Numerical simulation results show that linearized models work well for lower-level controllers with short prediction horizons but lead to significant reductions in aircraft thermal endurance when used for upper-level controllers with long prediction horizons. Therefore, a mixed-linearity hierarchical MPC formulation is presented with a nonlinear upper-level controller and a linear lower-level controller to achieve both high performance and high computational efficiency.

scholarly journals Study on short- and long-term creep behavior of plastics geogrid

2005 ◽  
Vol 24 (6) ◽  
pp. 793-798 ◽  
Author(s):  
Yi-Chong Guo ◽  
Chun-Ling Xin ◽  
Ming-Shi Song ◽  
Ya-Dong He
Keyword(s):  
Creep Behavior ◽  
Short And Long Term ◽  
Term Creep

Theoretical-Experimental Method for Determining the Short- and Long-Term Creep Parameters of Technical Rubber in Shear

2019 ◽  
Vol 55 (4) ◽  
pp. 435-454
Author(s):  
V. N. Paimushin ◽  
V. A. Firsov ◽  
R. K. Gazizullin ◽  
S. A. Kholmogorov ◽  
V. M. Shishkin
Keyword(s):  
Experimental Method ◽  
Short And Long Term ◽  
Term Creep

Evaluation of Short- and Long-Term Creep Rupture Properties for Grade 91 Materials

2005 ◽  
Author(s):  
Marvin J. Cohn
Keyword(s):  
Good Method ◽  
Creep Rupture ◽  
Material Degradation ◽  
Rupture Data ◽  
Short And Long Term ◽  
Grade 91 ◽  
Metal Properties ◽  
Term Creep ◽  
Rupture Properties

Recent literature indicates that there is a concern regarding the short-term vs. long-term creep rupture base metal properties for Grade 91 material. Evaluations of recent creep rupture data suggest that the material properties degrade more severely than expected and extrapolated creep rupture properties may be very optimistic. One of the approaches to evaluate creep rupture data is with a parameterized master curve such as the Larson-Miller parameter. Evaluations of creep rupture data indicate that the effects of material degradation can be considered with appropriate stress, time and temperature relationships. Using the Larson-Miller parameter methodology, the selected heats of Grade 91 creep rupture data indicate a reasonable relationship that does not appear to degrade rapidly for the longer term data. If even longer term creep rupture data suggest severe aging degradation as compared to current extrapolations, a transition of the Larson-Miller parameter constant from 31 to 20 does not appear to be a good method to calculate the degraded life estimates. As longer term creep rupture data become available, resulting oxide thicknesses should be measured and reported. The adverse effect of oxidation at longer times, resulting in loss of material and effectively higher stress, should be evaluated.

scholarly journals Model-Free Time-Aggregated Predictions for Econometric Datasets

Forecasting ◽  
2021 ◽  
Vol 3 (4) ◽  
pp. 920-933
Author(s):  
Kejin Wu ◽  
Sayar Karmakar
Keyword(s):  
Data Analysis ◽  
High Performance ◽  
Prediction Performance ◽  
Financial Data ◽  
New Method ◽  
Model Free ◽  
Short And Long Term ◽  
Forecasting Volatility ◽  
Long Term Prediction

Forecasting volatility from econometric datasets is a crucial task in finance. To acquire meaningful volatility predictions, various methods were built upon GARCH-type models, but these classical techniques suffer from instability of short and volatile data. Recently, a novel existing normalizing and variance-stabilizing (NoVaS) method for predicting squared log-returns of financial data was proposed. This model-free method has been shown to possess more accurate and stable prediction performance than GARCH-type methods. However, whether this method can sustain this high performance for long-term prediction is still in doubt. In this article, we firstly explore the robustness of the existing NoVaS method for long-term time-aggregated predictions. Then, we develop a more parsimonious variant of the existing method. With systematic justification and extensive data analysis, our new method shows better performance than current NoVaS and standard GARCH(1,1) methods on both short- and long-term time-aggregated predictions. The success of our new method is remarkable since efficient predictions with short and volatile data always carry great importance. Additionally, this article opens potential avenues where one can design a model-free prediction structure to meet specific needs.

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