Bending Creep of High-Temperature Dried Spruce Timber

Holzforschung ◽  
2003 ◽  
Vol 57 (1) ◽  
pp. 95-100 ◽  
Author(s):  
C. Bengtsson ◽  
R. Kliger
Keyword(s):  
High Temperature ◽  
Relative Humidity ◽  
Low Temperature ◽  
Creep Test ◽  
Raw Material ◽  
Drying Methods ◽  
Test Results ◽  
Creep Tests ◽  
Free Shrinkage ◽  
Creep Deformations

Summary In this paper, bending creep test results from high-temperature (HT) dried Norway Spruce timber are presented. The results are compared with creep tests of conventional low-temperature (LT) dried timber. The HT drying was performed at 115°C and the LT drying was performed at 70°C. The creep tests were performed in a varying climate with 20°C and 30–90% relative humidity. A total number of 24 specimens, 45 × 70 × 1100 mm, were loaded in bending during approximately 240 days. Both the HT-dried and the LT-dried material were cut from the same four trees to have as equal raw material as possible for the two drying methods. The results show smaller bending creep deformations of HT-dried timber (approximately 30%) as compared to the LT-dried timber. The variation in magnitude of creep for HT-dried timber was equal to or smaller than for LT-dried timber. Additionally, the variation in deformation between the moisture cycles was smaller for HT-dried timber. These observations indicate a less pronounced mechano-sorptive effect for HT-dried timber. The free shrinkage in the grain direction was significantly smaller for the HT-dried material than for the LT-dried material.

Creep Tests of Rotating Disks at Elevated Temperature and Comparison With Theory

1954 ◽  
Vol 21 (3) ◽  
pp. 225-235
Author(s):  
A. M. Wahl ◽  
G. O. Sankey ◽  
M. J. Manjoine ◽  
E. Shoemaker
Keyword(s):  
Elevated Temperatures ◽  
Experimental Program ◽  
Test Results ◽  
Rotating Disks ◽  
Creep Tests ◽  
Shear Theory ◽  
Heat Treated ◽  
Long Time ◽  
Average Tension ◽  
Creep Deformations

Abstract A theoretical and experimental program involving methods of calculating creep in rotating disks at elevated temperatures is described. This program consisted primarily of the following: (a) Obtaining forged disks from the same ingot of 12 per cent chrome steel, all disks being forged and heat-treated in the same manner; (b) making spin tests at 1000 F on three of these disks for periods up to about 1000 hr; ( ) making long-time tension-creep tests at 1000 F on many specimens cut out circumferentially from several of the other disks at stresses approximating those of the spin tests; (d) investigating theoretical methods of calculation of creep deformation in such disks; and (e) comparison of spin-test results with those calculated theoretically using average tension-creep data. It was found that available methods of calculating rotating disks based on the Mises criterion gave creep deformations too low compared to the test values, i.e., on the unsafe side for design. Considerably better agreement between test and theoretical results is obtained if the latter is based on the maximum-shear theory. Some discussion is given of the reasons for the better agreement obtained using the latter theory; these are believed to be related in part to the anisotropy of the forged material tested. Further tests on other materials are necessary before general conclusions can be drawn; however, in the absence of test data it is suggested that a conservative course in design for such disks is to apply the maximum-shear theory.

An Experimental Study on the Creep of FRC Sub-Base for Pavement Using a New Testing Device

2013 ◽  
Vol 639-640 ◽  
pp. 493-497
Author(s):  
Woo Tai Jung ◽  
Sung Yong Choi ◽  
Young Hwan Park
Keyword(s):  
Creep Test ◽  
Strain Curve ◽  
Hydraulic Pressure ◽  
Slight Variation ◽  
Test Results ◽  
Creep Tests ◽  
Loading Device ◽  
Permanent Load ◽  
Term Creep

The hydraulic loading device commonly used for creep test necessitates continuous recharge of the hydraulic pressure with time and is accompanied by slight variation of the permanent load at each recharge. Therefore, accurate test results cannot be obtained for long-term creep tests requiring time-dependent behavioral analysis during more than 6 months. This study conducts creep test as part of the analysis of the long-term characteristics of fiber-reinforced lean concrete sub-base of pavement. The creep test is executed using the new load-amplifier device not a conventional loading device. Since the results of the preliminary verification test on the new creep test device show that constant permanent load is applied without significant variation, it can be expected that more accurate measurement of the creep will be possible in a long-term compared to the conventional hydraulic device. In addition, the creep test results of sub-base specimens reveal the occurrence of large instantaneous elastic strain, differently from the strain curve observed in ordinary concrete, as well as the occurrence of small creep strain leading to low creep coefficient.

MOSQUITOES OF MANITOBA: II. THE EFFECT OF STORAGE TEMPERATURE AND RELATIVE HUMIDITY ON HATCHING OF EGGS OF AEDES VEXANS AND AEDES ABSERRATUS (DIPTERA: CULICIDAE)

1969 ◽  
Vol 101 (12) ◽  
pp. 1285-1291 ◽  
Author(s):  
R. A. Brust ◽  
R. A. Costello
Keyword(s):  
High Temperature ◽  
Relative Humidity ◽  
Low Temperature ◽  
Storage Temperature ◽  
Storage Conditions ◽  
Aedes Vexans ◽  
Hatching Time ◽  
Saturated Atmosphere

AbstractOptimum storage conditions for eggs of Aedes vexans (Meigen) were found to be a temperature of 2 °C and a saturated atmosphere. These conditions are also suitable for storing eggs of Aedes abserratus (Felt and Young) but this species can be stored at lower temperatures. When eggs of both species are stored at 2 °C and placed in a hatching medium at 2 °C, hatching begins in A. abserratus but not in A. vexans. A comparable hatch in the latter occurs at 10°–15 °C. Desiccation and death of A. vexans embryos occur rapidly at a low relative humidity (20%) and a high temperature (21 °C) but slowly at low relative humidity and a low temperature (4 °C). Eggs that lose a substantial amount of water will still hatch and the larvae develop normally, but hatching time is delayed. The hatching time may be twice as long as in eggs kept in a saturated atmosphere at similar temperatures, indicating that embryos must regain some of the lost water before hatching can occur.

Small Punch Creep Testing Technique for Remnant Life Assessment

2014 ◽  
Vol 592-594 ◽  
pp. 739-743 ◽  
Author(s):  
J. Ganesh Kumar ◽  
K. Laha ◽  
M.D. Mathew
Keyword(s):  
Creep Test ◽  
Rupture Life ◽  
Life Assessment ◽  
Test Results ◽  
Creep Tests ◽  
Testing Technique ◽  
Creep Properties ◽  
Small Punch ◽  
Miniature Specimens ◽  
Deflection Rate

Small punch creep (SPC) testing technique is a material non-intensive testing technique for evaluating creep behavior of materials using miniature specimens. It can be used for remnant life assessment (RLA) studies on components in service, by scooping out limited material for testing without impairing the strength of component. In order to ensure the reliability of use of SPC technique for RLA, it is necessary to establish sound database on SPC properties of the material before putting into service. In this investigation, SPC technique was used to evaluate creep properties of 316LN stainless steel using specimens of size 10 x 10 x 0.5 mm. SPC tests were conducted in load controlled mode at 923 K and at various loads. SPC curves clearly exhibited primary, secondary and tertiary creep stages. The minimum deflection rate increased and rupture life decreased with an increase in applied load. Like in conventional creep test results, the minimum deflection rate obeyed Norton’s power law and Monkman-Grant relationship. SPC test was correlated with corresponding conventional creep test. Good correlation was established between creep rupture life values evaluated from SPC tests and conventional creep tests.

scholarly journals Laboratory Investigation of Carbon Black/Bio-Oil Composite Modified Asphalt

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4910
Author(s):  
Ping Zhang ◽  
Lan Ouyang ◽  
Lvzhen Yang ◽  
Yi Yang ◽  
Guofeng Lu ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Carbon Black ◽  
Influencing Factors ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Test Results ◽  
Modified Asphalt ◽  
Temperature Performance ◽  
Bio Oil

As environmentally friendly materials, carbon black and bio-oil can be used as modifiers to effectively enhance the poor high-temperature and low-temperature performance of base asphalt and its mixture. Different carbon black and bio-oil contents and shear time were selected as the test influencing factors in this work. Based on the Box–Behnken design (BBD), carbon black/bio-oil composite modified asphalt was prepared to perform the softening point, penetration, multiple stress creep and recovery (MSCR), and bending beam rheometer (BBR) tests. The response surface method (RSM) was used to analyze the test results. In addition, the base asphalt mixtures and the optimal performance carbon black/bio-oil composite modified asphalt mixtures were formed for rutting and low-temperature splitting tests. The results show that incorporating carbon black can enhance the asphalt’s high-temperature performance by the test results of irrecoverable creep compliance (Jnr) and strain recovery rate (R). By contrast, the stiffness modulus (S) and creep rate (M) test results show that bio-oil can enhance the asphalt’s low-temperature performance. The quadratic function models between the performance indicators of carbon black/bio-oil composite modified asphalt and the test influencing factors were established based on the RSM. The optimal performance modified asphalt mixture’s carbon black and bio-oil content was 15.05% and 9.631%, and the shear time was 62.667 min. It was revealed that the high-temperature stability and low-temperature crack resistance of the carbon black/bio-oil composite modified asphalt mixture were better than that of the base asphalt mixture because of its higher dynamic stability (DS) and toughness. Therefore, carbon black/bio-oil composite modified asphalt mixture can be used as a new type of choice for road construction materials, which is in line with green development.

scholarly journals Predicting bending creep of laminated veneer lumber (LVL) sengon (Paraserianthes falcataria) beams from initial creep test data

2018 ◽  
Vol 195 ◽  
pp. 02028
Author(s):  
Achmad Basuki ◽  
Ali Awaludin ◽  
Bambang Suhendro ◽  
Suprapto Siswosukarto
Keyword(s):  
Test Data ◽  
Creep Test ◽  
Ultimate Load ◽  
Beam Deflection ◽  
Creep Model ◽  
Secondary Creep ◽  
Test Results ◽  
Creep Tests ◽  
Paraserianthes Falcataria ◽  
Laminated Veneer Lumber

This paper presents the results of creep tests of Laminated Veneer Lumber Sengon (LVL Sengon) beams, aiming to determine the creep factor and to establish the prediction beam deflection based on the initial creep test data. The LVL Sengon beams have a cross section of 40 mm by 80 mm and a clear span length of 2,000 mm, they were loaded at midspan for three different stress levels: 30%, 40%, and 50% of the ultimate load within 30, 60, and 90 days. Each loading level consists of four repetitive beams where one beam was wrapped with a plastic sheet. The test results showed that for 90 days the bending creep test can not determine the secondary creep yet. Curve fitting of bending creep test data indicated that the parameters of the Modified Burger creep model of the first 30 days can be accurately used to predict the beam deflection curve up to 60 and 90 days of loading.

Stabilization of commercial polyacrylonitrile fibres for fabrication of low-cost medium-strength carbon fibres

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Reza Eslami Farsani ◽  
Ali Shokuhfar ◽  
Arman Sedghi
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Low Cost ◽  
Inert Atmosphere ◽  
Raw Material ◽  
High Price ◽  
Carbon Fibres ◽  
Oxidative Stabilization ◽  
Medium Strength ◽  
Stabilization Procedure

AbstractThe process of fabrication of carbon fibres from polyacrylonitrile (PAN) fibres is composed of two steps including oxidative stabilization at low temperature and carbonization at high temperature in an inert atmosphere. Due to the high price of the raw material (special PAN fibres), carbon fibres are still expensive. It is shown that it is possible to produce desirable carbon fibres from (cheaper) commercial PAN fibres. In order to achieve this, it is necessary to make some changes in the conventional stabilization procedure to reach complete stabilization.

scholarly journals Creep Resistance of VM12 Steel

2016 ◽  
Vol 61 (3) ◽  
pp. 1635-1640 ◽  
Author(s):  
A. Zieliński ◽  
G. Golański ◽  
J. Dobrzański ◽  
M. Sroka
Keyword(s):  
Functional Properties ◽  
Creep Test ◽  
Creep Resistance ◽  
Practical Aspect ◽  
Test Results ◽  
Creep Tests ◽  
Steam Parameters ◽  
Term Creep ◽  
Long Term Impact

Abstract This article presents selected material characteristics of VM12 steel used for elements of boilers with super- and ultra-critical steam parameters. In particular, abridged and long-term creep tests with and without elongation measurement during testing and investigations of microstructural changes due to long-term impact of temperature and stress were carried out. The practical aspect of the use of creep test results in forecasting the durability of materials operating under creep conditions was presented. The characteristics of steels with regard to creep tests developed in this paper are used in assessment of changes in functional properties of the material of elements operating under creep conditions.

scholarly journals Effect of High and low temperature and different relative humidity on biology of old Serew worm Chrvsomya bezziana (Villeneuve) Diptera: calliphoridae

2004 ◽  
Vol 1 (1) ◽  
pp. 58-64
Author(s):  
Baghdad Science Journal
Keyword(s):  
High Temperature ◽  
Relative Humidity ◽  
Low Temperature ◽  
Laboratory Condition ◽  
The Other ◽  
Old World ◽  
Other Hand ◽  
Suitable Temperature ◽  
Lower Temperature

The effect of some environment faetor (different temperature and relative humidity) on the biology of the old world- screw worm, were studied under laboratory condition, the result showed that non of the eggs hatched at 15°c and under dried eondition which relative humidity between 20-40%, also result showed that the mature larvae needs one days to become pupa since it leaves the larval died at the temperature ranged between 25-40°C at different humidity rates. While it needs 3 days under lower temperature and different humidity to become pu^, on the other hand the results showed that either low temperature and dried condition or high temperature at different humidity rates cause non of pupa became adult. While low temperature (15-20) °c at suitable humidity rate will elongate pupal, further more it is also noticed that the suitable temperature ??'? pupa? development ranged between 25- 35°C under different relative humidity rate and it ranged between 5-8 days.

The X-ray pattern of low-temperature cristobalite

1944 ◽  
Vol 27 (187) ◽  
pp. 54-55 ◽  
Author(s):  
A. H. Jay
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Open Hearth ◽  
Crystalline Material ◽  
The Other ◽  
Raw Material ◽  
X Ray ◽  
Temperature Heating ◽  
High Temperature Heating ◽  
Roof Brick

Cristobalite is found as the first product in the conversion of quartz following a high-temperature heating, and it constitutes a large percentage of the crystalline material in most manufactured silica bricks. It is present also in fireclay products, the amount being dependent upon the nature of the raw material and the conditions of firing. In the majority of these products the cristobalite is only poorly developed, i.e. the crystals are only perfect over distances of the order of about 1 × 10-6 cm. This value is derived from the diffuseness of the high-order reflections on the X-ray powder photograph. On the other hand, the crystals of cristobalite are well developed in the hot face of an open hearth silica roof-brick.

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