Long-term bending creep behavior prediction of injection molded composite using stress–time correspondence principle

2004 ◽  
Vol 385 (1-2) ◽  
pp. 54-58 ◽  
Author(s):  
Mohamed Hadid ◽  
Said Rechak ◽  
Abdelouahab Tati
Keyword(s):  
Creep Behavior ◽  
Correspondence Principle ◽  
Behavior Prediction ◽  
Injection Molded

scholarly journals Long-Term Creep Behavior Prediction of Sol-Gel Derived SiO2- and TiO2-Wood Composites Using the Stepped Isostress Method

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1215 ◽  
Author(s):  
Ke-Chang Hung ◽  
Tung-Lin Wu ◽  
Jyh-Horng Wu
Keyword(s):  
Creep Behavior ◽  
Creep Resistance ◽  
Flexural Modulus ◽  
Sol Gel ◽  
Untreated Wood ◽  
Behavior Prediction ◽  
Inorganic Composites ◽  
Sol Gel Process ◽  
Term Creep

In this study, methyltrimethoxysilane (MTMOS), methyltriethoxysilane (MTEOS), tetraethoxysilane (TEOS), and titanium(IV) isopropoxide (TTIP) were used as precursor sols to prepare wood-inorganic composites (WICs) by a sol-gel process, and subsequently, the long-term creep behavior of these composites was estimated by application of the stepped isostress method (SSM). The results revealed that the flexural modulus of wood and WICs were in the range of 9.8–10.5 GPa, and there were no significant differences among them. However, the flexural strength of the WICs (93–103 MPa) was stronger than that of wood (86 MPa). Additionally, based on the SSM processes, smooth master curves were obtained from different SSM testing parameters, and they fit well with the experimental data. These results demonstrated that the SSM was a useful approach to evaluate the long-term creep behavior of wood and WICs. According to the Eyring equation, the activation volume of the WICs prepared from MTMOS (0.825 nm3) and TEOS (0.657 nm3) was less than that of the untreated wood (0.832 nm3). Furthermore, the WICs exhibited better performance on the creep resistance than that of wood, except for the WICMTEOS. The reduction of time-dependent modulus for the WIC prepared from MTMOS was 26% at 50 years, which is the least among all WICs tested. These findings clearly indicate that treatment with suitable metal alkoxides could improve the creep resistance of wood.

In Situ Tests on Creep Behavior of Rock Mass with Joint or Shearing Zone in Foundation of Large-Scale Hydroelectric Projects

2004 ◽  
Vol 261-263 ◽  
pp. 1097-1102 ◽  
Author(s):  
Jian Liu ◽  
Xia Ting Feng ◽  
Xiu Li Ding ◽  
Huo Ming Zhou
Keyword(s):  
Rock Mass ◽  
Creep Behavior ◽  
Large Scale ◽  
Time Dependent ◽  
Three Gorges Project ◽  
Three Gorges ◽  
The Three Gorges ◽  
The Three Gorges Project

The time-dependent behavior of rock mass, which is generally governed by joints and shearing zones, is of great significance for engineering design and prediction of long-term deformation and stability. In situ creep test is a more effective method than laboratory test in characterizing the creep behavior of rock mass with joint or shearing zone due to the complexity of field conditions. A series of in situ creep tests on granite with joint at the shiplock area of the Three-Gorges Project and basalt with shearing zone at the right abutment of the Xiluodu Project were performed in this study. Based on the test results, the stress-displacement-time responses of the joints and basalt are analyzed, and their time-dependent constitutive model and model coefficients are given, which is crucial for the design to prevent the creep deformations of rock masses from causing the failure of the operation of the shiplock gate at the Three-Gorges Project and long-term stability of the Xiluodu arc dam.

New Method for In-Trench Pipeline Support

2012 ◽  
Author(s):  
Geoff W. Connors
Keyword(s):  
Cathodic Protection ◽  
Welding Process ◽  
High Strength ◽  
Test Water ◽  
Poly Type ◽  
Additional Protection ◽  
Injection Molded ◽  
Heavy Loads ◽  
Sand Piles

Protection of the pipe during and after pipeline construction is of paramount importance for safety and pipeline integrity. Areas of rock and stone are often encountered during construction of new pipelines. Even with modern pipeline coatings, additional protection for the pipe is necessary where rock or stone exposure is significant. Historically, additional pipe protection used in these types of situations is achieved through adding either a significant layer of sand or select backfill above and below the pipeline (sand padding) and/or by attaching a high-impact resistant, poly-type rock shield around the pipeline during the pipeline installation process. To accommodate sand padding, some form of intermittent support of the pipeline is generally required to elevate the pipeline off the trench bottom. Similar intermittent support is also recommended practice when using poly-type rock shields to keep the pipeline from fully resting on trench rocks. Current methods of in-trench support involve sand piles, sand bags, spray foam and individually formed foam pillows — each with drawbacks: i) Sand Piles are difficult to install and often oval or dent the pipe when improperly placed. ii) Sand bags require hand placement for proper support. In open trenches, this can be time consuming and unsafe. Improper placement can cause the pipe to oval or dent. iii) Spray-in foam is considered to be an obstruction of cathodic protection currents. Newly constructed pipelines full of hydrostatic test water and one metre cover can cause foam to compress excessively. iv) Foam pillows are light and easily placed — but can float out of position and compress or crack under heavy loads. As with all foam, cathodic shielding is always a concern. A new, engineered method of in-trench pipeline support is now available — the Structured Pipeline Pillow (SPP). SPP’s are injection molded and made from high strength, environmentally inert polypropylene or polyethylene resins. Designed to support any size pipeline, SPP’s are most effective with larger diameter, heavier pipelines. One SPP is engineered to carry a single 40′ joint of heavy wall pipeline filled with hydrostatic test water. Compared with current methods, SPP’s: i) Stack tightly for transport. ii) Are light enough for installation from outside the trench and resist floatation when ground water is present. iii) Help ensure the pipeline is centered in the trench during the pipeline installation. iv) Maintain long-term pipe clearance above rocky trench bottoms. v) Ovality and denting concerns are reduced. vi) Allow cathodic protection an easy path to the pipeline. vii) Will never biodegrade. In their extended stacking mode, SPP’s tested well as an effective alternative to wooden skids for many situations such as pipe stockpiling; stringing along the rights-of-way (ROW); and even for some low level skidding during the welding process.

scholarly journals Study of primary creep behavior of clayey soils in landslide area : suction effect

2018 ◽  
Vol 149 ◽  
pp. 02027
Author(s):  
Dahhaoui Hachimi ◽  
Belayachi Naima ◽  
Zadjaoui Abdeldjalil
Keyword(s):  
Creep Behavior ◽  
Unsaturated Soils ◽  
Primary Creep ◽  
Creep Model ◽  
Clayey Soils ◽  
Landslide Area ◽  
Deviator Stress ◽  
Landslide Process ◽  
The University

Creep behavior of clayey soils plays an extremely important role in the landslide process. The soils that make up these sliding zones are often in unsaturated state. This point indicates the need to take into account the suction effect as hydric parameter on the long-term deformation of clayey soils. In this paper, a primary creep model named Modified Time Hardening (MTH) for unsaturated soils with different matric suction has been built. Based on the literature tests results[1][2], parameters C1 and C2 of the model have relations with suction and deviator stress level respectively. The primary creep strainwill be able to demonstrate unsaturated effect of the soils. comparison between the calculated results and the literature tests results shows a good coherence. The work underway at the university of Orleans will show later the relevance of model used in the present work.

Long-term creep behavior of resin-based polymers in the construction industry

2019 ◽  
Vol 18 ◽  
pp. 60-65 ◽  
Author(s):  
Joerg Fischer ◽  
Patrick R. Bradler ◽  
David Schmidtbauer ◽  
Reinhold W. Lang ◽  
Roman Wan-Wendner
Keyword(s):  
Construction Industry ◽  
Creep Behavior ◽  
Term Creep
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