scholarly journals Experimental Analysis of Debonding of Skin/Stringer Interfaces under Cyclic Loading and Ageing

2014 ◽  
Vol 23 (6) ◽  
pp. 096369351402300
Author(s):  
Ahmed Abbadi ◽  
Laurent Michel ◽  
Bruno Castanié
Keyword(s):  
Experimental Investigation ◽  
Fatigue Life ◽  
Cyclic Loading ◽  
Experimental Analysis ◽  
Preliminary Investigation ◽  
Failure Mechanisms ◽  
Damage Initiation ◽  
Stiffened Structures ◽  
Multi Level ◽  
Level Analysis

An experimental investigation aiming to characterize the fatigue failure mechanisms and effect of ageing of skin/stringer interfaces is presented. A simplified specimen known as a “stringer foot specimen” is used. The effects of local design, of the angle of plies located at the interface and of moisture ageing are studied. Among other results, it is shown that a quasi-infinite fatigue life can be obtained under 33% of the static damage initiation load for all designs. In the framework of multi-level analysis, this study is a preliminary investigation to study cyclic buckling of composite stiffened structures.

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.

Low Birth Weight in Ethiopia: A Multi-Level Analysis of 2016 Ethiopian Demographic and Health Survey

2020 ◽  
Author(s):  
Addisu Alehegn Alemu ◽  
Liknaw Bewket Zeleke ◽  
Bewket Aynalem ◽  
Melaku Desta ◽  
Eskeziaw Abebe Kasahun ◽  
...  
Keyword(s):  
Birth Weight ◽  
Low Birth Weight ◽  
Health Survey ◽  
Demographic And Health Survey ◽  
Multi Level ◽  
Level Analysis
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