Engineering stable perovskite composites – differentiating bulk from interface failure

2021 ◽  
Author(s):  
Misha Sytnyk
Keyword(s):  
Interface Failure

Investigation of High Frequency Failures on a 0.35μm CMOS IC

1999 ◽  
Author(s):  
Alan Kennen ◽  
John F. Guravage ◽  
Lauren Foster ◽  
John Kornblum
Keyword(s):  
Failure Analysis ◽  
Failure Mechanism ◽  
Integrated Circuit ◽  
Metal Layer ◽  
Ion Beam ◽  
Stress Test ◽  
Design For Test ◽  
Interface Failure ◽  
Serial Interface ◽  
High Impedance

Abstract Rapidly changing technology highlights the necessity of developing new failure analysis methodologies. This paper will discuss the combination of two techniques, Design for Test (DFT) and Focused Ion Beam (FIB) analysis, as a means for successfully isolating and identifying a series of high impedance failure sites in a 0.35 μm CMOS design. Although DFT was designed for production testing, the failure mechanism discussed in this paper may not have been isolated without this technique. The device of interest is a mixed signal integrated circuit that provides a digital up-convert function and quadrature modulation. The majority of the circuit functions are digital and as such the majority of the die area is digital. For this analysis, Built In Self Test (BIST) circuitry, an evaluation board for bench testing and FIB techniques were used to successfully identify an unusual failure mechanism. Samples were subjected to Highly Accelerated Stress Test (HAST) as part of the device qualification effort. Post-HAST electrical testing at 200MHz indicated that two units were non-functional. Several different functional blocks on the chip failed electrical testing. One part of the circuitry that failed was the serial interface. The failure analysis team decided to look at the serial interface failure mode first because of the simplicity of the test. After thorough analysis the FA team discovered increasing the data setup time at the serial port input allowed the device to work properly. SEM and FIB techniques were performed which identified a high impedance connection between a metal layer and the underlying via layer. The circuit was modified using a FIB edit, after which all vectors were read back correctly, without the additional set-up time.

Interface Failure a t Ply Drops in CFRP/Sandwich Panels

2000 ◽  
Vol 34 (2) ◽  
pp. 135-157
Author(s):  
O. T. THOMSEN ◽  
F. MORTENSEN ◽  
Y. FROSTIG
Keyword(s):  
Sandwich Panels ◽  
Interface Failure

scholarly journals Experimental Behavior of Steel-Concrete Composite Girders with UHPC-Grout Strip Shear Connection

Buildings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 182
Author(s):  
Zhi-Qi He ◽  
Changxue Ou ◽  
Fei Tian ◽  
Zhao Liu
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Fatigue Testing ◽  
Ultimate Capacity ◽  
Horizontal Shear ◽  
Interface Failure ◽  
Interface Shear ◽  
Composite Action ◽  
Shear Connection ◽  
Push Out

This paper develops a new type of shear connection for steel-concrete composite bridges using Ultra-High Performance Concrete (UHPC) as the connection grout. The UHPC-grout strip shear connection is fabricated by preforming a roughened slot in the concrete deck slab, welding an embossed steel rib longitudinally to the upper flange of the steel girder, and casting the strip void between the slot and the steel rib with UHPC grout. The structural performance of the new connection was validated by two sets of experimental tests, including push-out testing of shear connectors and static and fatigue testing of composite beams. The results of push-out testing indicate that the UHPC-grout strip shear connection exhibits a significant improvement of ductility, ultimate capacity, and fatigue performance. The interface shear strength of the UHPC-grout strip connection is beyond 15 MPa, which is about three times that of the strip connection using traditional cementitious grouts. The ultimate capacity of the connection is dominated by the interface failure between the embossed steel and the UHPC grout. The results of composite-beam testing indicate that full composite action is developed between the precast decks and the steel beams, and the composite action remained intact after testing for two million load cycles. Finally, the trail design of a prototype bridge shows that this new connection has the potential to meet the requirements for horizontal shear.

scholarly journals A Mixed Numerical-Experimental Method to Characterize Metal-Polymer Interfaces for Crash Applications

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 818
Author(s):  
Jonas Richter ◽  
Moritz Kuhtz ◽  
Andreas Hornig ◽  
Mohamed Harhash ◽  
Heinz Palkowski ◽  
...  
Keyword(s):  
Experimental Parameter ◽  
Dissimilar Materials ◽  
Calibration Method ◽  
Parameter Determination ◽  
Failure Behavior ◽  
Cohesive Elements ◽  
Interface Failure ◽  
Wide Range ◽  
Polymer Metal ◽  
Metal Polymer

Metallic (M) and polymer (P) materials as layered hybrid metal-polymer-metal (MPM) sandwiches offer a wide range of applications by combining the advantages of both material classes. The interfaces between the materials have a considerable impact on the resulting mechanical properties of the composite and its structural performance. Besides the fact that the experimental methods to determine the properties of the single constituents are well established, the characterization of interface failure behavior between dissimilar materials is very challenging. In this study, a mixed numerical–experimental approach for the determination of the mode I energy release rate is investigated. Using the example of an interface between a steel (St) and a thermoplastic polyolefin (PP/PE), the process of specimen development, experimental parameter determination, and numerical calibration is presented. A modified design of the Double Cantilever Beam (DCB) is utilized to characterize the interlaminar properties and a tailored experimental setup is presented. For this, an inverse calibration method is used by employing numerical studies using cohesive elements and the explicit solver of LS-DYNA based on the force-displacement and crack propagation results.

Failure Analysis of Composite Structures Using Multiscale Technique

2020 ◽  
Vol 995 ◽  
pp. 209-213
Author(s):  
Young W. Kwon
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Cell Model ◽  
Fibrous Composite ◽  
Failure Criteria ◽  
Multiscale Approach ◽  
Interface Failure ◽  
Fiber Failure ◽  
Strain Rate Effects ◽  
Constituent Material

Failure analyses of laminated fibrous composite structures were conducted using the failure criteria based on a multiscale approach. The failure criteria used the stresses and strains in the fiber and matrix materials, respectively, rather than those smeared values at the lamina level. The failure modes and their respective failure criteria consist of fiber failure, matrix failure and their interface failure explicitly. In order to determine the stresses and strains at the constituent material level (i.e. fiber and matrix materials), analytical expressions were derived using a unit-cell model. This model was used for the multiscale approach for both upscaling and downscaling processes. The failure criteria are applicable to both quasi-static loading as well as dynamic loading with strain rate effects.

scholarly journals Strength and Failure Mechanism of Composite-Steel Adhesive Bond Single Lap Joints

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Kai Wei ◽  
Yiwei Chen ◽  
Maojun Li ◽  
Xujing Yang
Keyword(s):  
Failure Mechanism ◽  
Shear Failure ◽  
Failure Load ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Adhesive Failure ◽  
Interface Failure ◽  
Element Analysis ◽  
Single Lap Joints ◽  
Structural Adhesive

Carbon fiber-reinforced plastics- (CFRP-) steel single lap joints with regard to tensile loading with two levels of adhesives and four levels of overlap lengths were experimentally analyzed and numerically simulated. Both joint strength and failure mechanism were found to be highly dependent on adhesive type and overlap length. Joints with 7779 structural adhesive were more ductile and produced about 2-3 kN higher failure load than MA830 structural adhesive. Failure load with the two adhesives increased about 147 N and 176 N, respectively, with increasing 1 mm of the overlap length. Cohesion failure was observed in both types of adhesive joints. As the overlap length increased, interface failure appeared solely on the edge of the overlap in 7779 adhesive joints. Finite element analysis (FEA) results revealed that peel and shear stress distributions were nonuniform, which were less severe as overlap length increased. Severe stress concentration was observed on the overlap edge, and shear failure of the adhesive was the main reason for the adhesive failure.

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