Accelerated test methodology for determination of reactive aggregate in concrete

Author(s):  
J.F. MARINS ◽  
A.C. BEZERRA ◽  
H.A. SANTIAGO FILHO ◽  
E.C.A. AMORIM ◽  
F.A.N. SILVA
1993 ◽  
Vol 323 ◽  
Author(s):  
Ravi Subrahmanyan

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.


Author(s):  
L. J. Yang

Wear rates obtained from different investigators could vary significantly due to lack of a standard test method. A test methodology is therefore proposed in this paper to enable the steady-state wear rate to be determined more accurately, consistently, and efficiently. The wear test will be divided into four stages: (i) to conduct the transient wear test; (ii) to predict the steady-state wear coefficient with the required sliding distance based on the transient wear data by using Yang’s second wear coefficient equation; (iii) to conduct confirmation runs to obtain the measured steady-state wear coefficient value; and (iv) to convert the steady-state wear coefficient value into a steady-state wear rate. The proposed methodology is supported by wear data obtained previously on aluminium based matrix composite materials. It is capable of giving more accurate steady-state wear coefficient and wear rate values, as well as saving a lot of testing time and labour, by reducing the number of trial runs required to achieve the steady-state wear condition.


1964 ◽  
Vol 116 (2 Recent Advanc) ◽  
pp. 613-620 ◽  
Author(s):  
L. J. Czerwonka ◽  
R. J. Boylan ◽  
D. J. Gonzalez

Tribologia ◽  
2018 ◽  
Vol 278 (2) ◽  
pp. 21-28
Author(s):  
Wacław GAWĘDZKI ◽  
Dariusz LEPIARCZYK ◽  
Jerzy TARNOWSKI

Buried pipelines are subjected to the action of static forces and moments caused by friction forces at the pipeline-ground contact. At the same time, pipelines are subjected to dynamic actions generated by paraseismic pulses, in particular, in areas of mining and heavy traffic. The paper presents and experimentally verifies a test method of tribological pipeline-soil interaction in conditions of artificially induced soil static and dynamic actions. The applied test methodology allows the determination of friction forces at the tested pipeline section. The friction forces changes over time on the pipeline and soil surface for the varying pipeline tensioning forces were continuously recorded during the tests. Based on the Short-Time Fourier Transform (STFT) of signals, the paper presents the impact of dynamic actions on momentary values of measured friction forces. Relationships are given that allow the determination of friction forces between the pipeline and the soil, including their limit values resulting in the loss of the mutual adhesion of the pipeline and the soil.


1989 ◽  
Vol 38 (1) ◽  
pp. 147-162 ◽  
Author(s):  
D. Saint-Royre ◽  
D. Gueugnaut ◽  
D. Reveret

Wear ◽  
2005 ◽  
Vol 259 (7-12) ◽  
pp. 1453-1461 ◽  
Author(s):  
L.J. Yang

Lubricants ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 7
Author(s):  
Philipp Renhart ◽  
Florian Summer ◽  
Florian Grün ◽  
Andreas Eder

The main objective of the present paper is the validation of new methods concerning experimental investigations of journal bearings under ordinary and extraordinary operational conditions. Derived results should facilitate the determination of damage mechanisms and a qualitative ranking for a prospective coating development. Prior investigated scenarios like start/stop and emergency running behavior were extended by starved and unlubricated experiments for an aircraft application. Focusing on thermal stability and reproducibility, two new subscale test strategies were developed derived from generalized operational conditions of journal bearings. For an improved ex-situ wear measurement of bearing shells, a new device was developed successfully. The results showed that the newly designed test methodologies are suitable to investigate unlubricated coatings leading to conclusive and repetitive results.


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