Apparatus for fatigue tests in vacuum at low temperatures

1974 ◽  
Vol 45 (5) ◽  
pp. 702-704 ◽  
Author(s):  
V. Bachmann ◽  
M. Böhmer ◽  
D. Munz
Keyword(s):  
Low Temperatures ◽  
Fatigue Tests

Static and Cyclic Behavior of Welded DH36 Steel and Its Application at Low Temperatures

2021 ◽  
pp. 1-31
Author(s):  
Weidong Zhao ◽  
Guoqing Feng ◽  
Bernt J. Leira ◽  
Huilong Ren
Keyword(s):  
Mechanical Properties ◽  
Low Temperatures ◽  
Fatigue Tests ◽  
Cyclic Behavior ◽  
Brittle Transition ◽  
Ductile To Brittle Transition

Abstract The mechanical properties of welded DH36 steel at low temperatures are important to the safety of structures in Polar areas. The purpose of the study is to investigate the static and cyclic behavior of welded DH36 steel at low temperatures based on tensile and fatigue tests. The Ductile to Brittle transition and Fatigue Ductile to Brittle Transition of welded DH36 steel occurred at low temperatures. Finally, some relevant applications of the results within the context of polar engineering and design are discussed in the last part of the present study.

scholarly journals Coupling between Welding Conditions and Thermal Cycling for Identification of the Mechanical Heterogeneity of a Weld Joint

2018 ◽  
Vol 62 (3) ◽  
pp. 226-232
Author(s):  
Fatima Zohra Messabih ◽  
Benattou Bouchouicha
Keyword(s):  
Weld Joint ◽  
Low Temperatures ◽  
Thermal Cycle ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Transition Curve ◽  
Mechanical Heterogeneity ◽  
Break Junctions ◽  
Brittle Transition ◽  
Strength Tests

The analyses device safety subject to pressure is based on the prediction at break junctions used for the design of this type of devices. The harmfulness analysis of existing defects on these devices makes indispensable the study of the rupture in these components. Various characterization tests (tensile tests, fatigue tests and tensile strength tests) were carried out at room and low temperatures on plates welded end to end and for the different directions of sampling.An estimate of the toughness in the three areas of a weld joint was made by passing from resilience to toughness in the ductile-brittle transition zone of materials. The temperature range of the tests was to provide measurements of the toughness the lower bearing to the beginning of the transition curve. The purpose of this work is to study the state both mechanical and microstructural aspects of the welded junction. The diagnoses used made it possible to deduce that the small thickness of the HAZ, makes the machining of the specimen difficult. Thereby, a mechanical simulation of the HAZ by registration of the thermal cycle that this area undergoes was necessary to be able to reproduce it and compare it with the actual HAZ.

Safety Assessment of Steels and Welds Under Cyclic and Monotonic Loadings at Low Temperatures

1984 ◽  
Vol 106 (4) ◽  
pp. 473-479
Author(s):  
N. Urabe ◽  
A. Yoshitake ◽  
H. Kagawa
Keyword(s):  
Fracture Toughness ◽  
Fatigue Life ◽  
Brittle Fracture ◽  
Low Temperatures ◽  
Safety Assessment ◽  
Loading Rate ◽  
Fracture Initiation ◽  
Fatigue Tests ◽  
Loading Rates ◽  
Wide Range

In order to investigate the mechanisms and the factors to govern the brittle fracture initiation during the fatigue crack propagation at low temperatures, fracture toughness tests under wide range of loading rates, fatigue tests at low temperatures and fracture toughness tests after having been given pre-loading were performed on steels and weld junctions. The fatigue fracture toughness Kfc was estimated as equivalent as the fracture toughness Kc under the monotonic tensile loading if they were compared at the same loading rate, since the residual stress due to the cyclic loading was less effective on the brittle fracture initiation. The calculated fatigue life based on Paris’s formula taken into consideration of the crack closure phenomena showed a good one-by-one agreement with the observed fatigue life up to the brittle fracture initiation. Therefore, a design curve was preliminarily drawn to determine the fatigue life at low temperatures.

The Effects of UIT in the Fatigue Life of Al 2024-T3

2010 ◽  
Vol 449 ◽  
pp. 15-22 ◽  
Author(s):  
Martin Castillo-Morales ◽  
A. Salas-Zamarripa
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Low Temperatures ◽  
Compressive Residual Stress ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Impact Frequency ◽  
Ultrasonic Impact Treatment ◽  
Al 2024

The Ultrasonic Impact Treatment (UIT) has been used in different materials to reduce residual welding tensile stresses and improve the fatigue life of welded joints, and also to increase the fatigue resistance at low temperatures. The main aim of this research was to explore the effects of UIT in the fatigue life of a 2024-T3 aluminium alloy. Load controlled fatigue tests were carried out at high and low cycle fatigue, and three UIT parameters at a carrier frequency of 36 kHz were evaluated. These parameters were feed rate, amplitude under load and impact frequency. The results revealed an increase in compressive residual stress and microhardness, as well as some evidence of porosity. However, the fatigue life was reduced drastically. The possible causes of this decrease are still under discussion.

scholarly journals Implementation of a cooling system to develop experimental fatigue tests below zero grades Celsius

2020 ◽  
Vol 25 (4) ◽  
pp. 519-525
Author(s):  
Carlos Gerardo Cárdenas Arias ◽  
Camilo Leonardo Sandoval Rodríguez ◽  
Arly Darío Rincón Quintero ◽  
Pablo David Díaz Melo
Keyword(s):  
Heat Transfer ◽  
Fatigue Test ◽  
Fatigue Failure ◽  
Low Temperatures ◽  
Initial Temperature ◽  
Cooling System ◽  
Fatigue Tests ◽  
Sample Material ◽  
Industrial Level ◽  
Materials Behavior

Temperature is one of the matter properties with the greatest influence on the materials behavior existing in nature and those man designed. This physical magnitude allows to demonstrate and define behaviors and materials characteristics in the industry in general. Its influence is present in all the places where the materials fulfill functions, however, in some applications its influence is very little, which allows to disregard its effects. In the steels case (one of the most used materials at the industrial level today), the temperature variation produces dilation or contraction, depending on the temperature magnitude and its variation that affects them. Temperature increases generate an expansion phenomenon in the materials, which under load will reach a point where they present thermal fatigue failure. The opposite is that of temperature drops, where the phenomenon that occurs is contraction, often leading to the loss of adjustments and interference that compromise the equipment functionality and integrity. The fatigue failure mentioned is presented as a result of the stresses and deformations present in both cases. It is desired to condition a rotational flex fatigue test equipment with a cooling system to bring the sample material to temperatures below zero degrees Celsius, in order to check how low temperatures, affect the resistance of steel to fatigue. For this, a cooling system was designed and the fatigue equipment was adapted to reduce heat transfer. After carrying out this implementation and determining that the sizes of the devices were suitable for the proposed purposes, the initial temperature tests were carried out and, once this part was achieved, three repetitions of a rotary fatigue test were performed that demonstrated that the equipment can operate normally.

On high-frequency fatigue tests at low temperatures

1973 ◽  
Vol 5 (6) ◽  
pp. 710-712 ◽  
Author(s):  
S. V. Grishakov
Keyword(s):  
High Frequency ◽  
Low Temperatures ◽  
Fatigue Tests

Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures

1984 ◽  
Vol 42 ◽  
pp. 268-269
Author(s):  
E. Knapek ◽  
H. Formanek ◽  
G. Lefranc ◽  
I. Dietrich
Keyword(s):  
Low Temperatures ◽  
Carbon Films ◽  
Organic Crystals ◽  
Wide Spread ◽  
Lens System ◽  
Preparation Conditions ◽  
Thin Carbon ◽  
Electron Diffractograms ◽  
Diffraction Patterns ◽  
Induced Changes

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.

Radiation Damage of Support Films

1981 ◽  
Vol 39 ◽  
pp. 28-29
Author(s):  
H.A. Cohen ◽  
W. Chiu
Keyword(s):  
Transfer Function ◽  
Low Temperatures ◽  
Carbon Support ◽  
Contrast Transfer Function ◽  
Electron Dose ◽  
Imaging Parameters ◽  
Negative Stain ◽  
Phase Corrections ◽  
Two Parameters ◽  
Medium Dose

The goal of imaging the finest detail possible in biological specimens leads to contradictory requirements for the choice of an electron dose. The dose should be as low as possible to minimize object damage, yet as high as possible to optimize image statistics. For specimens that are protected by low temperatures or for which the low resolution associated with negative stain is acceptable, the first condition may be partially relaxed, allowing the use of (for example) 6 to 10 e/Å2. However, this medium dose is marginal for obtaining the contrast transfer function (CTF) of the microscope, which is necessary to allow phase corrections to the image. We have explored two parameters that affect the CTF under medium dose conditions.Figure 1 displays the CTF for carbon (C, row 1) and triafol plus carbon (T+C, row 2). For any column, the images to which the CTF correspond were from a carbon covered hole (C) and the adjacent triafol plus carbon support film (T+C), both recorded on the same micrograph; therefore the imaging parameters of defocus, illumination angle, and electron statistics were identical.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

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