Effects of moisture content and temperature on wood creep

Holzforschung ◽  
2018 ◽  
Vol 72 (12) ◽  
pp. 1071-1078 ◽  
Author(s):  
Tai-Yun Hsieh ◽  
Feng-Cheng Chang
Keyword(s):  
Moisture Content ◽  
Creep Strain ◽  
Superposition Principle ◽  
Japanese Cedar ◽  
Creep Tests ◽  
Instantaneous Strain ◽  
Proposed Model ◽  
Time Temperature Superposition Principle ◽  
Term Creep ◽  
Short Term Creep

AbstractThe effects of moisture content (MC) and temperature (T) on the creep of Japanese cedar were investigated via a series of short-term creep tests, while MC had a higher effect than T, desorption of water caused more deformation. The results were separated into two distinct groups with MCs higher or lower than the equilibrium moisture content (EMC) and it was found that the mechano-sorptive effect is time-independent. The total creep strain of wood was explained by a model considering the instantaneous strain, creep strain and strain induced by the mechano-sorptive effect. The proposed model is in agreement with the creep master curves based on the time-temperature superposition principle (tTSP).

Rapid Lifetime Evaluation of Hybrid Composite Rods by Creep Behavior

2013 ◽  
Vol 873 ◽  
pp. 373-378
Author(s):  
Feng Tao Lan ◽  
Ye Wen Cao ◽  
Ying Nan Wang ◽  
Xin Chen ◽  
Chong Zhang
Keyword(s):  
Hybrid Composite ◽  
Superposition Principle ◽  
Mechanical Analysis ◽  
Widespread Application ◽  
Accelerated Creep ◽  
Different Temperatures ◽  
Time Temperature Superposition Principle ◽  
Term Creep ◽  
Short Term Creep

Hybrid composite rods, comprised of unidirectional reinforcing carbon/glass-fiber and adhesive epoxy matrix, are viewed as promising candidates to be used in high-voltage overhead conductors. However, before widespread application, their long-term durability needs to be clarified. In this study, accelerated creep testing for hybrid composite rods, is presented by taking dynamic mechanical analysis tests at different temperatures. Using the time-temperature superposition principle and thermal activation energy theory, the short-term creep data are combined to generate creep long-term compliance master curves. Through the master curve, predictions can be made concerning the creep levels that will occur during the design lifetime of hybrid composite rods (i.e., 30 years). It is found that after 30-year service at 120 °C, fully-cured hybrid composite rods only exhibit a slight increase in compliance (about 5%), indicating a satisfactory creep resistance at this temperature.

Predicting Collapse Times for Corrugated Boxes Under Constant Top Load Using Short-Term Creep Tests

2005 ◽  
Vol 33 (4) ◽  
pp. 11932
Author(s):  
DR Petersen ◽  
RE Link ◽  
G Burgess ◽  
SP Singh ◽  
M Srinangyam
Keyword(s):  
Short Term ◽  
Creep Tests ◽  
Term Creep ◽  
Short Term Creep

scholarly journals Microstructural Evolution and Short-Term Creep Rupture of the Simulated HAZ in T92 Steel Normalized at Different Temperatures

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1310 ◽  
Author(s):  
Tai-Jung Wu ◽  
Chien-Chun Liao ◽  
Tai-Cheng Chen ◽  
Ren-Kae Shiue ◽  
Leu-Wen Tsay
Keyword(s):  
Grain Boundaries ◽  
Elevated Temperatures ◽  
Creep Rupture ◽  
Infrared Heating ◽  
Short Term ◽  
Creep Tests ◽  
Steel Tubes ◽  
Austenite Grain ◽  
Term Creep ◽  
Short Term Creep

T92 steel tubes have been widely applied in advanced supercritical boilers to replace Gr.91 tubes. Simulated samples with microstructures similar to those present in the heat-affected zone (HAZ) of a T92 steel weld were subjected to short-term creep tests in the study. T92 steel tubes were normalized at either 1213 K (L) or 1333 K (H) for 1 h, followed by tempering (T) at 1033 K for 2 h. After the normalizing and tempering treatments, the HT samples comprised finer precipitates but in greater numbers along the prior austenite grain boundaries (PAGBs) and martensite lath boundaries, as compared with those of the LT samples. The HAZ microstructures in the T92 steel welds were simulated by using an infrared heating system, which included over-tempering (OT, below AC1) and partial transformation (PT, slightly below AC3) zones. Martensite laths in the OT sample were more likely to be replaced by numerous cellular structures or subgrains together with spherodized carbides mainly located at the lath and austenite grain boundaries. Furthermore, coarser but fewer carbides were found along the refined lath and grain boundaries in the PT samples, in comparison with other samples in each group. Short-term creep tests showed that the PT samples were more likely to fracture than other samples in each group. Moreover, under the same testing conditions, the microstructures of T92 steel were more stable and resistant to degradation than those of T91 steel after welding or loading at elevated temperatures. Such events were responsible for higher creep resistance of the simulated T92 samples than that of the simulated T91 samples under the same creep-rupture conditions.

Experimental investigation of the hygrothermal creep strain of wood–plastic composite lumber made from thermally modified wood

2019 ◽  
Vol 33 (9) ◽  
pp. 1248-1268 ◽  
Author(s):  
Murtada Abass A Alrubaie ◽  
Roberto A Lopez-Anido ◽  
Douglas J Gardner ◽  
Mehdi Tajvidi ◽  
Yousoo Han
Keyword(s):  
Creep Strain ◽  
Water Immersion ◽  
Creep Recovery ◽  
Short Term ◽  
Creep Response ◽  
Plastic Composites ◽  
Thermally Modified Wood ◽  
Term Creep ◽  
Modified Wood ◽  
Short Term Creep

The hygrothermal effect on the short-term creep behavior of extruded thermally modified wood fiber–high-strength styrenic copolymer plastic composites (wood–plastic composites (WPCs)) was investigated on specimens preconditioned for 1 month under water immersion (distilled water (DW) and saltwater (SW)). These specimens were then tested in the same conditions for short-term creep and creep-recovery response using a submersible clamp. The short-term creep tests of WPC specimens (that are immersed in water as a function of different temperatures) have not yet been reported in previous studies. The objective of this study was to determine whether the hygrothermal creep response of WPC material evaluated through water immersion differs from the creep response published in the literature for other environmental exposure conditions. The experiments included measuring 30 min of creep and 30 min of creep recovery on the specimens immersed in SW and DW at two different levels of flexural stresses (9% and 14% of the flexural strength) and three temperature values (25, 35, and 45°C). The average creep strain recovery (%) of the specimens was higher for the specimens immersed in SW during testing than the control specimens. The WPC material is considered to have a potential use in structural applications in environments where the temperature is below 45°C because of the following factors: the low deformation under the short-term sustained loading, the decrease in the deformation rate with respect to the increase in load duration, maintaining the modulus of elasticity over a range of temperatures from 25°C to 45°C under sustained load, and the ability to recover more than 69% of the average creep strain under water immersion when the loading source is removed. The creep strain fractional increment (CSFI) of the WPC in this study under all conditions was 13% which is 86% lower than the CSFI of the WPCs reported in previous studies.

scholarly journals Time-temperature behavior of carbon/epoxy laminates under creep loading

2020 ◽  
Author(s):  
Heitor L. Ornaghi ◽  
José Humberto S. Almeida ◽  
Francisco M. Monticeli ◽  
Roberta M. Neves ◽  
Maria Odila H. Cioffi
Keyword(s):  
Composite Laminates ◽  
Material Behavior ◽  
Short Term ◽  
Creep Tests ◽  
Advanced Composite ◽  
Wide Range ◽  
Temperature Superposition ◽  
Term Creep ◽  
Creep Loading ◽  
Short Term Creep

Abstract The time-temperature creep behavior of advanced composite laminates is herein determined through a comprehensive set of experiments and analytical modeling. A complete structure versus property relationship is determined through a wide range of temperature and applied stress levels at the three states of the composite: glassy, glass transition, and rubbery regions. Weibull, Eyring, Burger, and Findley models are employed to predict the experimental data and to better elucidate the material behavior. Experimental creep tests are carried out under ten min and two days aiming at calibrating fitting parameters, which are essential to validate short-term creep tests. The Weibull and Eyring models are more suitable for determining the time-temperature superposition (TTS) creep response in comparison to the Burger and Findley models.

scholarly journals Creep Behaviour of Modified Mar-247 Superalloy

2016 ◽  
Vol 61 (2) ◽  
pp. 701-704 ◽  
Author(s):  
M. Cieśla ◽  
M. Mańka ◽  
F. Binczyk ◽  
P. Gradoń
Keyword(s):  
Creep Behaviour ◽  
Rupture Life ◽  
Coarse Grained ◽  
Short Term ◽  
Creep Tests ◽  
Nickel Based Superalloy ◽  
Test Conditions ◽  
Accelerated Creep ◽  
Term Creep ◽  
Short Term Creep

Abstract The paper presents the results of analysis of creep behaviour in short term creep tests of cast MAR-247 nickel-based superalloy samples made using various modification techniques and heat treatment. The accelerated creep tests were performed under temperature of 982 °C and the axial stresses of σ = 150 MPa (variant I) and 200 MPa (variant II). The creep behaviour was analysed based on: creep durability (creep rupture life), steady-state creep rate and morphological parameters of macro- and microstructure. It was observed that the grain size determines the creep durability in case of test conditions used in variant I, durability of coarse-grained samples was significantly higher.

Research on Rheological Properties of Room-Temperature Curing Epoxy Adhesive

2013 ◽  
Vol 639-640 ◽  
pp. 354-358 ◽  
Author(s):  
Hui Li ◽  
Ying She Luo ◽  
Jian Jun Xie ◽  
Sheng Ming Chen
Keyword(s):  
Mechanical Properties ◽  
Rheological Model ◽  
Room Temperature ◽  
Epoxy Adhesive ◽  
Test Results ◽  
Short Term ◽  
Creep Tests ◽  
C 30 ◽  
Term Creep ◽  
Short Term Creep

The rheological mechanical properties of two kinds of self-designed epoxy adhesive curing systems were studied in this paper through the dynamic and static thermodynamics instrument named EPLEXOR 500N made by GABO® company in Germany. Short-term creep tests were carried out under three different temperature conditions of 20°C, 30°C and 40°C and the rheological model is developed to describe the materials creep law. In addition, the test results from the two different epoxy adhesive are also compared and analyzed.

scholarly journals The Effect of Normalizing Temperature on the Short-Term Creep Rupture of the Simulated HAZ in Gr.91 Steel Welds

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1072 ◽  
Author(s):  
Hao-Wei Wu ◽  
Tai-Jung Wu ◽  
Ren-Kae Shiue ◽  
Leu-Wen Tsay
Keyword(s):  
Creep Resistance ◽  
Lath Martensite ◽  
Heating System ◽  
Steel Tube ◽  
Infrared Heating ◽  
Short Term ◽  
Creep Tests ◽  
Steel Welds ◽  
Term Creep ◽  
Short Term Creep

As-received Gr.91 steel tube was normalized at either 940 or 1060 °C for 1 h, followed by Ar-assisted cooling to room temperature, then tempered at 760 °C for 2 h. Those samples were designated as 940NT or 1060NT samples. An infrared heating system was used to simulate HAZ microstructures in the weld, which included over-tempering (OT) and partial transformation (PT) zones. The results of short-term creep tests showed that normalizing at higher temperature improved the creep resistance of the Gr.91 steel. By contrast, welding thermal cycles would shorten the creep life of the Gr.91 steel. Among the tested samples in each group, the PT samples had the shortest life to rupture, especially the 940NT-PT sample. The microstructures of the PT samples comprised of fine lath martensite and ferrite subgrains with carbides decorating the grain and subgrain boundaries. Excessive dislocation recovery, rapid coalescence of refined martensite laths, and growth of ferrite subgrains were responsible for the poorer creep resistance of the PT samples relative to those of the other samples.

Evaluation of Short-term Creep Behavior of PE-HD after Aging in Oil Derivatives

2018 ◽  
Vol 26 (3) ◽  
pp. 243-250 ◽  
Author(s):  
Ayrton Alef Castanheira Pereira ◽  
José Roberto Moraes d'Almeida ◽  
Thiago Motta Linhares Castro
Keyword(s):  
Creep Behavior ◽  
Diesel Oil ◽  
Aging Effects ◽  
Short Term ◽  
Creep Tests ◽  
Before And After ◽  
Oil Derivatives ◽  
Term Creep ◽  
Effects Of Aging ◽  
Short Term Creep

The creep behavior of a high density polyethylene (PE-HD) was evaluated before and after aging in contact with gasoline and diesel oil. Four viscoelastic models were used to assess changes in creep properties of the material: three parameters model, four parameters model, stretched Burgers model and Findley Law. Viscoelastic properties, stationary creep rate and compliance were used to analyze and compare the behavior between samples. A strain increase could be seen in aged samples in comparison with as-received ones, caused by plasticization due to aging effects. An increase in flexibility and decrease in stiffness in aged samples was also noted. This work also shows that the effects of aging on the creep response of a polymeric material can be analyzed using short term creep tests.

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