Design-development of a variable load tension—compression creep testing machine

1986 ◽  
Vol 21 (1) ◽  
pp. 25-31
Author(s):  
C J Morrison ◽  
D R Hayhurst
Keyword(s):  
High Temperature ◽  
Testing Machine ◽  
High Accuracy ◽  
Gauge Length ◽  
Ball Screw ◽  
Variable Load ◽  
High Temperature Creep ◽  
Design Development ◽  
Dead Weight ◽  
Compression Creep

The design and development is described of a variable load tension-compression creep machine (±50 kN) which overcomes the disadvantages of servo-hydraulic and recirculating ball screw testing machines. The use of dead weight levers to apply specimen loads ensures the achievement of low running costs. Screwed end specimens are used with a 25.40 mm parallel sided gauge length and a diameter of 12.70 mm. It is shown that, provided modest rates of loading (0.4 kN/s) are used, high accuracy ‘through zero’ loadings can be achieved. The machine has been shown to operate satisfactorily for long periods under tension-compression high temperature creep.

A tension—torsion creep-rupture testing machine

1980 ◽  
Vol 15 (3) ◽  
pp. 151-157 ◽  
Author(s):  
W Trampczynski ◽  
C Morrison ◽  
W E Topliss
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Continuous Measurement ◽  
Testing Machine ◽  
Gauge Length ◽  
Creep Rupture ◽  
High Temperature Creep ◽  
Air Bearing ◽  
Creep Tests ◽  
Shear Strains

The paper discusses the design and construction of a high-temperature creep machine capable of applying combined tension and torsion loadings. The design utilizes an air bearing and pinned universal joints to achieve axiality of loading. An extensometer is described which transmits the deformation of the specimen gauge length outside the furnace and allows the continuous measurement of axial and shear strains to be made using linear variable differential transducers at room temperature. Results of elastic and creep tests are presented which show the performance of the machine to be satisfactory.

scholarly journals Compliance-Derived Strain Determination in Fibre (Bundle) Tests at High Temperatures

1998 ◽  
Vol 7 (3) ◽  
pp. 096369359800700 ◽  
Author(s):  
R. Paar ◽  
P. Bonnel ◽  
M. Steen
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Strain Measurement ◽  
Fibre Bundle ◽  
Testing Machine ◽  
Tensile Tests ◽  
Gauge Length ◽  
Head Displacement ◽  
The Cross ◽  
Strain Determination

In high temperature fibre tensile tests direct strain measurement is not a straightforward task, due to the limited accessibility and the fragile nature of the specimen. A compliance method which allows to determine the true specimen strain within the gauge length from the cross head displacement of the testing machine is presented.

High Temperature Creep Behavior of Zn-1.0Cu-0.2Ti Alloy

2011 ◽  
Vol 287-290 ◽  
pp. 769-776 ◽  
Author(s):  
Lai Rong Xiao ◽  
Xi Min Zhang ◽  
Yan Wang ◽  
Wei Li ◽  
Quan Sheng Sun ◽  
...  
Keyword(s):  
Steady State ◽  
High Temperature ◽  
Creep Rate ◽  
Grain Boundary ◽  
Testing Machine ◽  
Steady State Creep ◽  
Diffusional Creep ◽  
High Temperature Creep ◽  
Steady State Creep Rate ◽  
Temperature Creep

In the present work, Zn-1.0Cu-0.2Ti alloy was prepared by melt casting and extruding processes. High temperature creep property of the alloy was determined using electronic creep relaxation testing machine. Microstructures of the alloy before and after creep test were observed and its high temperature creep mechanism was discussed. The results show that the steady-state creep rate of the alloy increases with temperature and stress. The logarithm of steady-state creep rate (ln) shows a linearity relationship with the logarithm of the stress (lnσ) and reciprocal of temperature (1/T). The stress exponent and apparent activation energy for creep have been determined to be 5.10 and 83.7 kJ/mol, separately. The predominant mechanism is mainly self-diffusional creep. The second phases on the grain boundary can block the slip of grain boundary and dislocation motion which can improve creep resistance of the alloy.

DOWMETAL HZ32XA

Alloy Digest ◽  
1956 ◽  
Vol 5 (7) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Creep Resistance ◽  
Zirconium Alloy ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
High Temperature Creep ◽  
Aged Condition ◽  
Chemical Company ◽  
Temperature Performance

Abstract DOWMETAL HZ32XA is a magnesium-thorium-zinc-zirconium alloy having good high temperature creep resistance, and is recommended for applications at elevated temperatures. It is used in the artificially aged condition (T5). This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as heat treating, machining, and joining. Filing Code: Mg-26. Producer or source: The Dow Chemical Company.

scholarly journals On the Plastic Strain Accumulation in Notched Bars During High-Temperature Creep Dwell

2020 ◽  
Vol 36 (2) ◽  
pp. 167-176 ◽  
Author(s):  
Daniele Barbera ◽  
Haofeng Chen
Keyword(s):  
High Temperature ◽  
Cyclic Loading ◽  
Plastic Strain ◽  
Kinematic Hardening ◽  
High Temperature Creep ◽  
Strain Accumulation ◽  
Material Models ◽  
Cyclic Loading Condition ◽  
Hardening Material ◽  
Temperature Creep

ABSTRACTStructural integrity plays an important role in any industrial activity, due to its capability of assessing complex systems against sudden and unpredicted failures. The work here presented investigates an unexpected new mechanism occurring in structures subjected to monotonic and cyclic loading at high temperature creep condition. An unexpected accumulation of plastic strain is observed to occur, within the high-temperature creep dwell. This phenomenon has been observed during several full inelastic finite element analyses. In order to understand which parameters make possible such behaviour, an extensive numerical study has been undertaken on two different notched bars. The notched bar has been selected due to its capability of representing a multiaxial stress state, which is a practical situation in real components. Two numerical examples consisting of an axisymmetric v-notch bar and a semi-circular notched bar are considered, in order to investigate different notches severity. Two material models have been considered for the plastic response, which is modelled by both Elastic-Perfectly Plastic and Armstrong-Frederick kinematic hardening material models. The high-temperature creep behaviour is introduced using the time hardening law. To study the problem several results are presented, as the effect of the material model on the plastic strain accumulation, the effect of the notch severity and the mesh element type and sensitivity. All the findings further confirm that the phenomenon observed is not an artefact but a real mechanism, which needs to be considered when assessing off-design condition. Moreover, it might be extremely dangerous if the cyclic loading condition occurs at such a high loading level.

scholarly journals Code Calibration of the Eurocodes

2021 ◽  
Vol 11 (12) ◽  
pp. 5474
Author(s):  
Tuomo Poutanen
Keyword(s):  
High Reliability ◽  
High Accuracy ◽  
Variable Load ◽  
Reliability Model ◽  
Safety Factors ◽  
Rounding Errors ◽  
Code Calibration ◽  
Load Factors ◽  
Characteristic Values

This article addresses the process to optimally select safety factors and characteristic values for the Eurocodes. Five amendments to the present codes are proposed: (1) The load factors are fixed, γG = γQ, by making the characteristic load of the variable load changeable, it simplifies the codes and lessens the calculation work. (2) Currently, the characteristic load of the variable load is the same for all variable loads. It creates excess safety and material waste for the variable loads with low variation. This deficiency can be avoided by applying the same amendment as above. (3) Various materials fit with different accuracy in the reliability model. This article explains two options to reduce this difficulty. (4) A method to avoid rounding errors in the safety factors is explained. (5) The current safety factors are usually set by minimizing the reliability indexes regarding the target when the obtained codes include considerable safe and unsafe design cases with the variability ratio (high reliability/low) of about 1.4. The proposed three code models match the target β50 = 3.2 with high accuracy, no unsafe design cases and insignificant safe design cases with the variability ratio 1.07, 1.03 and 1.04.

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