Cyclic fatigue of silica refractories – effect of test method on failure process

2017 ◽  
Vol 37 (4) ◽  
pp. 1811-1819 ◽  
Author(s):  
K. Andreev ◽  
V. Tadaion ◽  
J. Koster ◽  
E. Verstrynge
Keyword(s):  
Failure Process ◽  
Cyclic Fatigue ◽  
Test Method

Design of Accelerated Degradation Test Method and Failure Analysis of Flexible Hybrid Electronic Devices

2020 ◽  
Author(s):  
Alex Davila-Frias ◽  
Val Marinov ◽  
Om Prakash Yadav ◽  
Yuriy Atanasov
Keyword(s):  
Failure Analysis ◽  
Failure Process ◽  
Electronic Devices ◽  
Test Method ◽  
Stress Factors ◽  
Accelerated Degradation ◽  
Failure Data ◽  
Degradation Data ◽  
Accelerated Life ◽  
Temperature And Humidity

Abstract Accelerated life testing (ALT) has been a common choice to study the effects of environmental stresses on flexible hybrid electronics (FHE), a promising technology to produce flexible electronic devices. Nevertheless, accelerated degradation testing (ADT) has proven to be a more effective approach, which does not require failure occurrences, allowing shorter testing times. Since FHE devices are expected to be highly reliable, ADT provides useful information in the form of degradation data for further analysis without actual failure data. In this paper, we present the design and experimental setup of ADT for FHE considering two stress factors simultaneously. We use daisy-chain resistance as a measurable degradation characteristic to periodically monitor the degradation of FHE products under accelerated stress conditions. Two stress factors, temperature and humidity, are considered and ADT was carried out considering four combinations of temperature and humidity simultaneously. Failure analysis was performed on failed units to investigate the failure process and location of the failure. The ADT data was used to fit in the appropriate mathematical degradation model representing the failure process. The data analysis showed faster degradation paths for higher stress combinations. Finally, we present insights and further research opportunities to expand the work.

scholarly journals Numerical Simulation Virtual Test of Torsion Shear for Asphalt Mixture

2019 ◽  
Vol 2019 ◽  
pp. 1-21
Author(s):  
Jun Xie ◽  
Yougang Yang
Keyword(s):  
Numerical Simulation ◽  
Shear Failure ◽  
Failure Process ◽  
Asphalt Mixture ◽  
Test Method ◽  
Reconstruction Method ◽  
Virtual Test ◽  
Torsional Shear ◽  
Shear Process ◽  
Air Void

In order to analyze the torsional shear process of asphalt mixtures in a microscopic view, the numerical simulation of a torsional shear test of an asphalt mixture was carried out by discrete element method. Based on the defects of existing algorithms, the method of random reconstruction of the existing 3D model of the asphalt mixture was improved, and a new reconstruction method was proposed. A 3D numerical model of the asphalt mixture contained irregular-shaped coarse aggregate, mineral gradation, and asphalt mortar; furthermore, the particle algorithm established the air void distribution. Then, the numerical simulation of the asphalt mixture’s torsional shear was completed; in addition, the stress, displacement, and contact of the specimens at each stage were analyzed. The results showed that the stress and displacement in different stages changed greatly with the loading, i.e., the crack generated from a weak point on the surface and then spread to the ends with an oblique angle of about 45°. At the same time, the shear failure process of the asphalt mixture was studied. The virtual test method could accomplish the implementation of the numerical simulation of torsional shear; it also provided a good research method for analysis of the asphalt mixture’s shear failure process.

Influence of Cavity above Tunnel on Stratum Deformation and Failure in Urban Tunnelling

2012 ◽  
Vol 170-173 ◽  
pp. 1810-1815
Author(s):  
Yanan Zhang ◽  
Cheng Ping Zhang ◽  
Qian Qian Li ◽  
Zheng Li ◽  
Yi Cai
Keyword(s):  
Failure Process ◽  
Test Method ◽  
Test Results ◽  
Tunnel Engineering ◽  
Deformation And Failure ◽  
Tunnel Section ◽  
Section Size ◽  
Ground Cavity ◽  
Stratum Deformation ◽  
Beijing Subway

In order to study the influence of cavity above the tunnel on stratum deformation and failure in urban tunnelling, the model test method was adopted based on the parameters of the stratum and tunnel section size in Beijing subway. The stratum responses were obtained under the conditions without ground cavity and with ground cavity above the tunnel. The responses include the stratum stress distribution, stratum settlement law and stratum failure process. It was concluded that the existence of ground cavity above the tunnel worsened the stratum condition and accelerated the progress of stratum deformation and failure. Furthermore, the failure began from the cavity and the damage scope was bigger than that under the condition without cavity according to the test results. The research results can be referenced for the similar tunnel engineering.

Reliability Evaluation of Lead Free Solder Joints Subjected to Multi-Loads

2007 ◽  
Author(s):  
Akihiko Tosaka ◽  
Qiang Yu ◽  
Tadahiro Shibutani ◽  
Satoshi Kondo ◽  
Masaki Shiratori
Keyword(s):  
Solder Joints ◽  
Electronic Device ◽  
Cyclic Fatigue ◽  
Reliability Evaluation ◽  
Test Method ◽  
Bending Test ◽  
Fatigue Reliability ◽  
Bending Load ◽  
Reliability Of Solder Joints ◽  
Free Solder

The miniaturization and the high integration of electronic device parts were progressed by the advance in technology, and it leads the problems of warpage of high-integrated component during mounting processes. This kind mismatch would be released slowly after the components are assembled. Therefore, it is concerned that the deformation of the solder joints caused by the warpage should give some impact on the thermal fatigue reliability of solder joints, because the solder joints are subjected not only to the cyclic thermal mismatch but also to the considerable one direction bending load. This state is called as multi-loads in this study. The thermal cyclic fatigue reliability of solder joints had been studied by using analytical and heat cyclic testing approaches, and it is shown that the fatigue life can be assessed by Manson-Coffin’s law. However, the reliability evaluation techniques for multi-loads problem have not been established. In this study, the relation between the fatigue reliability and the multi-loads conditions was studied and the BGA (Ball Grid Array) package was chosen as the target. The author proposed a new cyclic bending test method to achieve the different conditions of the multi-loads, and based upon the experimented and analytical results it was found that impact of the multi loads some cases neglected for could not be.

scholarly journals Hybrid Simulation of Seismic Responses of a Typical Station with a Reinforced Concrete Column

2020 ◽  
Vol 10 (4) ◽  
pp. 1331 ◽  
Author(s):  
Xuesong Cai ◽  
Chengyu Yang ◽  
Yong Yuan
Keyword(s):  
Reinforced Concrete ◽  
Failure Process ◽  
Hybrid Simulation ◽  
Test Method ◽  
Shaking Table ◽  
Subway Station ◽  
Test Results ◽  
Earthquake Excitation ◽  
Simulation Process ◽  
Central Column

During the 1995 Kobe earthquake, damages were observed in the Daikai subway station and adjacent tunnels. It was the first large-scale underground structure that failed under the earthquake excitation. Numerical and experimental analyses have been conducted to study the failure process of the Daikai station. However, the issue of the scale ratio still exists in the shaking table tests of underground structures. In order to tackle this issue, a hybrid simulation technique is developed here to study the seismic performance of a typical subway station. Based on the previous research, it is found that the central column is the critical component of the structure. Therefore, a reinforced concrete central column is physically tested in the hybrid simulation process. On the other hand, the remaining parts of the structure and soil domain are numerically modeled at the same time. Four hybrid simulation cases are conducted with peak ground accelerations of 0.01 g, 0.1 g, 0.22 g, and 0.58 g. The test results of displacement and shear force are compared with the analytical results. Moreover, the good agreement between the test results and numerical results validate the accuracy of the proposed hybrid test method. After the hybrid simulation process, a quasi-static test is conducted to illustrate the mechanical properties of the central column after the earthquake excitation.

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