An Accelerated Test for the Determination of the Limiting Creep Stress of Metals

1932 ◽  
Vol 122 (1) ◽  
pp. 285-377 ◽  
Author(s):  
W. Barr ◽  
W. E. Bardgett
Keyword(s):  
Accelerated Test ◽  
Creep Stress

ACCELERATED TEST METHOD FOR DETERMINATION OF ODOR CONTROL DEVICES

1964 ◽  
Vol 116 (2 Recent Advanc) ◽  
pp. 613-620 ◽  
Author(s):  
L. J. Czerwonka ◽  
R. J. Boylan ◽  
D. J. Gonzalez
Keyword(s):  
Test Method ◽  
Odor Control ◽  
Accelerated Test ◽  
Control Devices

Mechanical and Accelerated Testing of Flip Chip Interconnect Systems

1993 ◽  
Vol 323 ◽  
Author(s):  
Ravi Subrahmanyan
Keyword(s):  
Flip Chip ◽  
Test Methods ◽  
Temperature Cycling ◽  
Accelerated Test ◽  
Solder Interconnects ◽  
Test Methodology ◽  
Low Profile ◽  
Interconnect Systems ◽  
Interconnect System

AbstractFlip chip interconnect systems are becoming increasingly popular in the electronics industry due to their low profile and high densities. During temperature cycles, the differential expansions between various assembly members of a flip chip interconnect system produce mechanical stresses that are the driving force for failures. Such failures can be a significant reliability concern.Accelerated test methodologies for flip chip interconnect systems assess the reliability of existing interconnects and identify potential reliability concerns in future interconnect designs. Traditionally, such methodologies have relied on test methods such as temperature cycling to determine the mechanical integrity of the flip chip interconnect. However, application of such methods to new interconnect materials, geometry and processes requires characterization of basicmechanical behavior of the interconnect system.In this work, the feasibility of using a micromechanical test methodology for flip chip applications is examined. 90PbSn solders is used as an example. The data obtained from such flip chip solder interconnects is validated using a damage integral methodology. The measured data is shown to adequately describe published thermal stress profiles and thermal fatigue life data measured using solder joints of the same composition. Finally, some considerations in the application of micromechanical measurements to determination of acceleration factors and development of accelerated test methods are discussed.

Deflection and Stresses in Beams Subjected to Bending and Creep

1952 ◽  
Vol 19 (4) ◽  
pp. 478-484
Author(s):  
Yoh-Han Pao ◽  
Joseph Marin
Keyword(s):  
Stress Distribution ◽  
Pure Bending ◽  
Stress Variation ◽  
Creep Stress ◽  
Simple Tension ◽  
Hardening Theory ◽  
Time Relation ◽  
Theoretical Results ◽  
Good Agreement

Abstract This paper presents theories for the determination of deflections and stresses in beams subjected to bending and creep. The theories are based on a creep-stress-time relation in simple tension which gives an accurate fit of most test data. The theory takes into account the variation in stress distribution in bending with time. For this purpose a time-hardening theory is used to express the stress variation or stress relaxation of each fiber in bending. A comparison between actual creep deflections for Plexiglas specimens subjected to pure bending and values predicted by the proposed theory shows good agreement between experimental and theoretical results. The creep behavior for other materials in tension indicates that this method could be used for predicting bending creep deflections for these materials. The application of the theory to the determination of deflections in various kinds of beams is also explained.

scholarly journals Feasibility of using of accelerated test methods for determination of frost-resistance for concrete

2020 ◽  
Vol 157 ◽  
pp. 06035 ◽  
Author(s):  
Anna Pavlenko ◽  
Anastasia Mishakova ◽  
Olga Pertseva ◽  
Victoriia Ivanova ◽  
Yanis Olekhnovich ◽  
...  
Keyword(s):  
Frost Resistance ◽  
Test Methods ◽  
Test Method ◽  
Accelerated Test ◽  
Mechanical Fracture ◽  
Accelerated Methods ◽  
New Methods ◽  
Innovative Materials ◽  
Sufficient Precision

The article presents the results of studies of innovative materials in the field of testing frost resistance. In fact, present accelerated methods for the determination of concrete frost resistance have high labour consuming and low effectiveness. Moreover there is no such accelerated methods which can be sufficiently applicable fro different innovative concretes, for example, concretes with SAP or self-compacting concrete and so on. Therefore, it is highly important to investigate new accelerated test method with high operability, efficiency and sufficient precision. Previously, two new methods were developed. The main purpose of the research is to compare these methods by evaluation of their technology and accuracy and, consequently, to identify the more sustain and efficient one. First method is based on estimation of energy release due to mechanical fracture and thermo cycling. Second method consists of the calculation value z (relation between relative decreasing of strength and relative strain in the direction perpendicular to compression) and replacement of thermo cycles by mechanical cycles. Both methods have high operability and do not take a lot of time, in was tested on the 10 specimens made of concrete and results were compared with values derived by standard method.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

International determination of the total motion of the pole

1961 ◽  
Vol 13 ◽  
pp. 29-41
Author(s):  
Wm. Markowitz
Keyword(s):  
Secular Motion ◽  
The Future

A symposium on the future of the International Latitude Service (I. L. S.) is to be held in Helsinki in July 1960. My report for the symposium consists of two parts. Part I, denoded (Mk I) was published [1] earlier in 1960 under the title “Latitude and Longitude, and the Secular Motion of the Pole”. Part II is the present paper, denoded (Mk II).

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

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