Microscopic Failure Mechanism Analysis of Sandstone Under Triaxial Compression

2018 ◽  
Vol 37 (2) ◽  
pp. 683-690 ◽  
Author(s):  
Guibin Zhang ◽  
Wenquan Zhang ◽  
Hailong Wang ◽  
Chuanyang Jia ◽  
Keming Liu ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Triaxial Compression ◽  
Mechanism Analysis

scholarly journals Buckling Failure Mechanism of a Rock Dam Foundation Fractured by Gentle Through-Going and Steep Structural Discontinuities

2020 ◽  
Vol 12 (13) ◽  
pp. 5426
Author(s):  
Donghui Chen ◽  
Huie Chen ◽  
Wen Zhang ◽  
Chun Tan ◽  
Zhifa Ma ◽  
...  
Keyword(s):  
Numerical Method ◽  
Failure Mechanism ◽  
Shear Failure ◽  
Distinct Element ◽  
Mechanism Analysis ◽  
Rock Masses ◽  
Dam Foundation ◽  
Deformation Features ◽  
Universal Distinct Element Code ◽  
Distinct Element Code

The failure mechanism analysis of dam foundations is key for designing hydropower stations. This study analyses the rock masses in a sluice section, which is an important part of the main dam of the Datengxia Hydropower Station currently built in China. The stability of the sluice rock masses is predominantly affected by gentle through-going soft interlayers and steep structural fractures. Its foundation failure mechanism is investigated by means of a numerical method, i.e., Universal Distinct Element Code (UDEC) and the geomechanical model method. The modeling principle and process, and results for the rock dam foundation are introduced and generated by using the abovementioned two methods. The results indicate that the failure mechanism of the foundation rock masses, as characterized by gentle through-going and steep structural discontinuities, is not a conventional type of shear failure mechanism but a buckling one. This type of failure mechanism is verified by analyzing the deformation features resulting from the overloading of both methods and strength reduction of the numerical method.

Failure Mechanism Analysis of Electromagnetic Relay under Mechanical Impact

2013 ◽  
Vol 473 ◽  
pp. 39-45 ◽  
Author(s):  
Guo Wei Zhao ◽  
Yong Chen ◽  
De Yong Li ◽  
Bin Tang
Keyword(s):  
Failure Mechanism ◽  
Magnetic Circuit ◽  
Impact Damage ◽  
Engineering Application ◽  
Air Gap ◽  
Mechanism Analysis ◽  
Mechanical Impact ◽  
Electromagnetic Relay ◽  
Electromagnetic Relays ◽  
The Impact

The aim was to analyze failure mechanism of electromagnetic relay caused by mechanical impact. The principle of electromagnetic relays was studied and the effect of mechanical impact on electromagnetic relays was analyzed in this paper. Based on the established magnetic circuit model, the relationship of the magnetic field strength, the electromagnetic attraction and the impact damage degree was studied. Then, the damage intensity of mechanical impact on magnetic circuit was decided. Afterwards, the structure of electromagnetic relays was improved, and the mechanical impact simulation was studied by ANSYS. The results show that the uncontrollability of electromagnetic relay is mainly caused by air gap, which is aroused by mechanical impact; in addition, the size of air gap is inversely proportional to electromagnetic attraction force. Moreover, the improved structure of relays can increase impact resistance and broaden the scope of engineering application of electromagnetic relay.

Initiation and failure mechanism of base instability of excavations in clay triggered by hydraulic uplift

2015 ◽  
Vol 52 (5) ◽  
pp. 599-608 ◽  
Author(s):  
Y. Hong ◽  
C.W.W. Ng ◽  
L.Z. Wang
Keyword(s):  
Failure Mechanism ◽  
Simple Shear ◽  
Triaxial Compression ◽  
Soft Clay ◽  
Constitutive Models ◽  
Model Parameters ◽  
Hydraulic Pressure ◽  
Percentage Increase ◽  
Basal Resistance ◽  
Dimensionless Groups

Excavations in clay overlying an aquifer may cause catastrophic basal failure due to hydraulic uplift. Although case histories with hydraulic uplift failures are reported worldwide from time to time, the initiation and failure mechanism of the base instability are not well studied and understood. To address these two issues, dimensional analysis is firstly conducted to propose dimensionless groups (DGs) possibly relevant to this subject. Effects of these DGs on the initiation and failure mechanism of base instability are then investigated, by carrying out a series of finite element analyses, in which constitutive models and model parameters have been previously validated against centrifuge test results. It is revealed that the initiation and failure mechanism of base instability due to hydraulic uplift is mainly governed by a ratio of excavation width over the thickness of soft clay inside excavation (B/D). As excavation becomes narrower (i.e., B/D decreases), the hydraulic pressure (Pi) required to initiate uplift movement of clay inside excavation increases significantly (maximum percentage increase = 50%), due to increased effect of downward shear stress acting along soil–wall interface on basal resistance. Based on the parametric study, a calculation chart is developed for estimating Pi of excavations with varied B/D and undrained shear strength of clay. At basal failure caused by hydraulic uplift, the dominant failure mode changes from simple shear in relatively narrow excavations (i.e., B/D < 4) to combined modes of triaxial compression, triaxial extension, and simple shear in relatively wide excavations (i.e., B/D > 4).

Folding-Reliability of Flexible Electronics in Wearable Applications

2019 ◽  
Author(s):  
Pradeep Lall ◽  
Hyesoo Jang ◽  
Ben Leever ◽  
Scott Miller
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
Failure Mechanism ◽  
Flexible Electronics ◽  
Experimental Analysis ◽  
Failure Modes ◽  
Failure Mechanisms ◽  
Mechanism Analysis ◽  
Accelerated Test ◽  
Test Conditions

Abstract There is a growing need for flexible hybrid electronics solutions for wearable applications, in which the user may often wear electronics on body, on fabric or on skin. Electronics in wearable application may be subjected to stresses of daily motion including bending, twisting and stretching. Thus, there is need for technologies capable of flexibility, robustness and small size while being lightweight. Existing standards for focus on rigid electronics and there is scarcity of guidance for test-levels needed to assure reliability of flexible electronics. There is need for studies focused on the development of accelerated test conditions representative of field applications and the identification of failure mechanisms for test levels. In this study, experimental analysis on fatigue life of the PCB in cyclical folding load is conducted. A folding test-stand capable of replicating the stresses of daily motion in a lab-environment has been developed for the test. For the better understanding of the failure mechanism, analysis of failure modes is carried out. Consequently, it is found that fatigue life of the PCB is related to the several conditions: folding direction, moving distance, folding diameter and strain rate.

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