scholarly journals In Situ tensile tests to analyze the mechanical response, crack initiation, and crack propagation in single polyamide 66 fibers

2019 ◽  
Vol 57 (11) ◽  
pp. 680-690
Author(s):  
Alba Marcellan ◽  
Anthony Bunsell ◽  
Roland Piques ◽  
Lucien Laiarinandrasana
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Mechanical Response ◽  
Tensile Tests ◽  
Polyamide 66

scholarly journals Study of the Microstructure and Crack Evolution Behavior of Al-5Fe-1.5Er Alloy

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 172 ◽  
Author(s):  
Ming Li ◽  
Zhiming Shi ◽  
Xiufeng Wu ◽  
Huhe Wang ◽  
Yubao Liu
Keyword(s):  
Electron Microscopy ◽  
Crack Initiation ◽  
Tensile Tests ◽  
Eutectic Structure ◽  
Interface Structure ◽  
X Ray ◽  
Transmission Electron ◽  
The Matrix ◽  
Evolution Behavior

In this work, the microstructure of Al-5Fe-1.5Er alloy was characterized and analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) techniques. The effect of microstructure on the behavior of crack initiation and propagation was investigated using in situ tensile testing. The results showed that when 1.5 wt.% Er was added in the Al-5Fe alloy, the microstructure consisted of α-Al matrix, Al3Fe, Al4Er, and Al3Fe + Al4Er eutectic phases. The twin structure of Al3Fe phase was observed, and the twin plane was {001}. Moreover, a continuous concave and convex interface structure of Al4Er was observed. Furthermore, Al3Fe was in the form of a sheet with a clear gap inside. In situ tensile tests of the alloy at room temperature showed that the crack initiation mainly occurred in the Al3Fe phase, and that the crack propagation modes included intergranular and trans-granular expansions. The crack trans-granular expansion was due to the strong binding between Al4Er phases and surrounding organization, whereas the continuous concave and convex interface structure of Al4Er provided a significant meshing effect on the matrix and the eutectic structure.

scholarly journals Generic failure mechanisms in adhesive bonds

Holzforschung ◽  
2013 ◽  
Vol 67 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Philipp Hass ◽  
Falk K. Wittel ◽  
Peter Niemz
Keyword(s):  
Crack Propagation ◽  
Urea Formaldehyde ◽  
Failure Mechanisms ◽  
Tensile Tests ◽  
Propagation Path ◽  
Adhesive Properties ◽  
Adhesive Bonds ◽  
Stable Crack Propagation ◽  
Order Of Magnitude

Abstract The failure of adhesive bondlines has been studied at the microscopic level via tensile tests. Stable crack propagation could be generated by means of samples with improved geometry, which made in situ observations possible. The interaction of cracks with adhesive bondlines under various angles to the crack propagation was the focus of this study, as well as the respective loading situations for the adhesives urea formaldehyde (UF), polyurethane (PUR), and polyvinyl acetate (PVAc), which have distinctly different mechanical behaviors. It has been shown how adhesive properties influence the occurrence of certain failure mechanisms and determine their appearance and order of magnitude. With the observed failure mechanisms, it becomes possible to predict the propagation path of a crack through the specimen.

scholarly journals Crack Propagation in Metallic Glass Ribbon as a Function of the Position of Stress Concentrators

2017 ◽  
Vol 891 ◽  
pp. 494-499
Author(s):  
Mária Huráková ◽  
Kornel Csach ◽  
Jozef Miškuf ◽  
Alena Juríková ◽  
Václav Ocelík ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Tensile Axis ◽  
Shear Bands ◽  
Glass Ribbon ◽  
Tensile Tests ◽  
In Situ Observation ◽  
Band Formation ◽  
Stress Concentrators ◽  
As Stress

An amorphous metallic ribbon of Fe40Ni40B20 was used for in-situ observation of the crack propagation and shear band formation during tensile tests. Prior to the tensile tests, two holes (with different positions with respect to the tensile axis) were made by laser ablation as stress concentrators. The nucleation and propagation of shear bands on the ribbon surface during tensile tests were analysed with scanning electron microscopy (SEM). At room temperature inhomogeneous plastic deformation of amorphous alloy occurs via the development of primary and secondary shear bands. The influence of the different loading geometry on the topology of shear bands and crack propagation was studied.

scholarly journals Study of Elastic Behavior of Metallic Thin Films by 2D Synchrotron XRD and in situ Tensile Testing

2007 ◽  
Vol 1027 ◽  
Author(s):  
Geandier Guillaume ◽  
Renault Pierre-Olivier ◽  
Goudeau Philippe ◽  
Eric Le Bourhis ◽  
Girault Baptiste
Keyword(s):  
Thin Films ◽  
Mechanical Response ◽  
Tensile Tests ◽  
Elastic Behavior ◽  
Metallic Thin Films ◽  
X Ray Diffraction ◽  
Synchrotron Source ◽  
X Ray ◽  
Transmission Geometry

AbstractUnderstanding the mechanical behaviour of nano-structured thin films in relation to their structure, in particular to the grain size, is of high importance for the development of technological applications. Model nanometric multilayer W/Au systems exhibiting different structures are elaborated. These films are supported by a (thin) polyimide substrate. Films mechanical response is characterized experimentally by tensile tests carried out in-situ in a X-ray diffractometer installed on a synchrotron source. X-ray diffraction in transmission geometry has been used to study the deformations of both phases as a function of applied load. This geometry has been developed in the aim of optimizing the experiment time.

Effects of Hydrogen Environment on Fatigue Characteristics of 18Cr-8Ni Stainless Steel

2005 ◽  
Vol 482 ◽  
pp. 283-286 ◽  
Author(s):  
Kyohei Kawamoto ◽  
Y. Aoki ◽  
Yasuji Oda ◽  
Takeshi Yoshimura ◽  
Hiroshi Noguchi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Strain Range ◽  
Fatigue Tests ◽  
Hydrogen Gas ◽  
In Situ Observation ◽  
Nitrogen Gas ◽  
Fatigue Characteristics

In order to clarify the effects of hydrogen on the fatigue characteristics of an austenitic stainless steel, bending fatigue tests were conducted in air, in a hydrogen gas and in a nitrogen gas. Main results obtained are as follows. Effects of hydrogen gas environment are not clearly seen on the strain range - fatigue life diagram, because there are opposite effects to crack propagation and to crack initiation; accelerates crack propagation, but retards crack initiation. Striation spacing or in-situ observation confirms the acceleration. The retardation seems to be attributed to the absence of oxygen or water vapor in the hydrogen gas.

Mechanical Behaviour of Two Sorts of MCM Structures

1995 ◽  
Vol 390 ◽  
Author(s):  
G. Pozza ◽  
G. Parat ◽  
M. Ignat ◽  
M. Dupeux ◽  
J. M. Terriez
Keyword(s):  
Flip Chip ◽  
Mechanical Response ◽  
Crack Nucleation ◽  
Crack Opening ◽  
Tensile Tests ◽  
Nucleation Site ◽  
In Situ Tests ◽  
Solder Bumps ◽  
Pbsn Solder

ABSTRACTWe analysed the mechanical response of samples, representing Flip-Chip bonded type structures. Two sort of distributions of the PbSn solder bumps, interconecting a chip to a substrate were investigated. The mechanical response was established from macroscopic shear and tensile tests. The microstructural evolution to complete mechanical failure, was observed during similar tests, but performed in a Scanning Electron Microscope. These in-situ tests revealed a preferential crack nucleation site in the samples, specific to one of the interfaces. A complementary numerical analysis was developed, for trying to explain the preferential crack opening site.

Study on Fracture Mechanisms of TiAl Alloys by In Situ Tensile Tests

2007 ◽  
Vol 353-358 ◽  
pp. 34-37
Author(s):  
Rui Cao ◽  
Jian Hong Chen ◽  
J. Zhang
Keyword(s):  
Crack Propagation ◽  
Main Crack ◽  
Applied Load ◽  
High Stress ◽  
Lamellar Microstructure ◽  
Tensile Tests ◽  
Fracture Mechanisms ◽  
Tial Alloys ◽  
Lamellar Interfaces

Combining in-situ tensile tests with detailed observations of fracture surfaces of a two-phase TiAl alloy, the fracture process and fracture mechanisms of TiAl alloys are investigated. The results reveal that Cracks prefer to initiate and propagate along lamellar interfaces, which are the weakest link in the near fully lamellar microstructure. The interlamellar strength calculated is less than the translamellar strength. The tensile stress is the driving force for crack initiation and propagation. In specimens with a slit notch, most cracks are initiated directly from the notch root and extended along lamellar interfaces. The main crack can be stopped or deflected into a delamination mode by a barrier grain with a lamellar interface orientation deviated from the direction of crack propagation. In this case, new cracks are nucleated along lamellar interfaces of grains with favorable orientation ahead the barrier grain. The main crack and a new crack are then linked by the translamellar cleavage fracture of the barrier grain with increasing applied load. In order to extend the main crack, further increases of the applied load are needed to move the high stress region into the ligament until final fracture. The process of a new crack nucleation with a bridging ligament formation decreases the crack propagation resistance rather than increases it.

scholarly journals Study of the Microstructure and Crack Evolution Behavior of Al-5Fe-1.5Er Alloy

2018 ◽  
Author(s):  
Ming Li ◽  
Zhiming Shi ◽  
Xiufeng Wu ◽  
Huhe Wang ◽  
Yubao Liu
Keyword(s):  
Crack Initiation ◽  
Tensile Tests ◽  
Eutectic Structure ◽  
Interface Structure ◽  
Crack Evolution ◽  
Binding Ability ◽  
Initiation And Propagation ◽  
The Matrix ◽  
Evolution Behavior

The microstructure of Al-5Fe-1.5Er alloy was characterized and analyzed by using XRD, SEM, TEM and EDS. The effect of microstructure on the behavior of crack initiation and propagation was investigated by in situ tensile testing. Results show that the microstructure consists of α-Al matrix, Al3Fe, Al4Er, eutectic phase Al3Fe + Al4Er, while the 1.5 wt.% Er was added in Al-5Fe alloy. The twin structure of the Al3Fe phase was observed, and the twin plane is {001}. Moreover, a continuous concave and convex interface structure of the Al4Er has been found. Al3Fe is in the form of a sheet with a clear gap inside.In situ tensile tests of the alloy at room temperature show that the crack initiation occured mainly in the Al3Fe phase, and that the crack propagation modes include intergranular and transgranular expansion. Crack transgranular expansion is due to the strong binding ability between Al4Er phases and surrounding organization, and the continuous concave and convex interface structure of the Al4Er provides a significant meshing effect on the matrix and eutectic structure.

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