On Prevalent Whisker Toughening Mechanisms in Ceramics

1986 ◽  
Vol 78 ◽  
Author(s):  
A. G. Evans ◽  
M. Rühle ◽  
B. J. Daigleish ◽  
M. D. Thouless
Keyword(s):  
Fracture Resistance ◽  
Strength Distribution ◽  
Interface Fracture ◽  
Major Influence ◽  
Toughening Mechanisms ◽  
Frictional Sliding ◽  
Pull Out ◽  
The Matrix ◽  
Debonded Interface

ABSTRACTSome aspects of whisker toughening are reviewed. It is shown that several important toughened materials have a toughness dominated by the nonlinear bridging of intact whiskers. Such toughening is demonstrated to depend sensitively on the relative fracture resistance properties of the whiskers, the interface and the matrix. It is also shown that, when the interface fracture resistance is low, the frictional sliding behavior of the previously debonded interface and the whisker strength distribution exert a major influence on toughness, in accordance with pull-out phenomena.

Interfacial phenomena in the fracture resistance of interfaces

1988 ◽  
Vol 46 ◽  
pp. 720-721
Author(s):  
A. G. Evans
Keyword(s):  
Fracture Resistance ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Friction Stress ◽  
Matrix Composites ◽  
Low Friction ◽  
Fiber Failure ◽  
Pull Out ◽  
Brittle Matrix Composites ◽  
The Matrix

In composite systems, the mechanical response of interfaces to the approach of cracks that initially form either in the matrix or in the fiber dominates the mechanical performance. In particular, in brittle matrix composites, the interface must have a sufficiently low fracture resistance compared with that of both the fiber and matrix that the crack diverts into the interface and debonds the fiber, Thereafter, the debonded fiber must be able to slide against the matrix with a low friction stress in order to inhibit fiber failure and thus enhance pull-out. These processes are schematically illustrated in Fig. 1. Mechanics investigations have established requirements concerning debonding and sliding that must be satisfied in order to achieve good composite properties. At the simplest level, these studies reveal that the fracture energy of the interface should be less than about one-third that of either the fiber or the matrix.

Micromechanics Measurements Applied to Integrated Circuit Microelectronics

1997 ◽  
Vol 473 ◽  
Author(s):  
David R. Clarke
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
Fracture Resistance ◽  
Interface Fracture ◽  
New Techniques ◽  
Fracture Properties ◽  
Engineered Structures ◽  
Mechanical And Fracture Properties ◽  
Interconnect Lines ◽  
Metallic Interconnect

ABSTRACTAs in other engineered structures, fracture occasionally occurs in integrated microelectronic circuits. Fracture can take a number of forms including voiding of metallic interconnect lines, decohesion of interfaces, and stress-induced microcracking of thin films. The characteristic feature that distinguishes such fracture phenomena from similar behaviors in other engineered structures is the length scales involved, typically micron and sub-micron. This length scale necessitates new techniques for measuring mechanical and fracture properties. In this work, we describe non-contact optical techniques for probing strains and a microscopic “decohesion” test for measuring interface fracture resistance in integrated circuits.

Role of interface properties on the toughness of brittle matrix composites reinforced with ductile fibers

1992 ◽  
Vol 7 (11) ◽  
pp. 3132-3138 ◽  
Author(s):  
H.E. Dève ◽  
S. Schmauder
Keyword(s):  
Fracture Resistance ◽  
Crack Opening ◽  
Geometrical Model ◽  
Interface Properties ◽  
Matrix Composites ◽  
Brittle Matrix Composites ◽  
The Matrix ◽  
Interface Sliding ◽  
Brittle Composites

The incorporation of ductile fibers in brittle matrices can lead to a significant increase in fracture resistance. The increase in toughness that derives from crack bridging is governed by the properties of the matrix/fiber interface and the ductility of the fibers. The current study addresses the role of interface sliding stress on the toughness of brittle composites reinforced with ductile fibers. The debond length is explicitly related to the interface sliding stress and the properties of the fiber. It is then incorporated into a geometrical model to simulate the bridging tractions versus crack opening under condition of continuous debonding. The implications on the effect of interfaces on the resistance curve are discussed.

Plasticity contributions to interface adhesion in thin-film interconnect structures

2000 ◽  
Vol 15 (12) ◽  
pp. 2758-2769 ◽  
Author(s):  
Michael Lane ◽  
Reinhold H. Dauskardt ◽  
Anna Vainchtein ◽  
Huajian Gao
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Fracture Energy ◽  
Fracture Resistance ◽  
Work Of Adhesion ◽  
Interface Fracture ◽  
Cohesive Stress ◽  
Wide Range ◽  
Macroscopic Fracture ◽  
Metal Layers

The effects of plasticity in thin copper layers on the interface fracture resistance in thin-film interconnect structures were explored using experiments and multiscale simulations. Particular attention was given to the relationship between the intrinsic work of adhesion, Go, and the measured macroscopic fracture energy, Gc. Specifically, the TaN/SiO2 interface fracture energy was measured in thin-film Cu/TaN/SiO2 structures in which the Cu layer was varied over a wide range of thickness. A continuum/FEM model with cohesive surface elements was employed to calculate the macroscopic fracture energy of the layered structure. Published yield properties together with a plastic flow model for the metal layers were used to predict the plasticity contribution to interface fracture resistance where the film thickness (0.25–2.5 μm) dominated deformation behavior. For thicker metal layers, a transition region was identified in which the plastic deformation and associated plastic energy contributions to Gc were no longer dominated by the film thickness. The effects of other salient interface parameters including peak cohesive stress and Go are explored.

scholarly journals Detachment of compliant films adhered to stiff substrates via van der Waals interactions: role of frictional sliding during peeling

2014 ◽  
Vol 11 (97) ◽  
pp. 20140453 ◽  
Author(s):  
Rachel R. Collino ◽  
Noah R. Philips ◽  
Michael N. Rossol ◽  
Robert M. McMeeking ◽  
Matthew R. Begley
Keyword(s):  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Work Of Adhesion ◽  
Interface Fracture ◽  
Strong Function ◽  
Frictional Sliding ◽  
Fracture Models ◽  
Synthetic Adhesives ◽  
Interface Sliding

The remarkable ability of some plants and animals to cling strongly to substrates despite relatively weak interfacial bonds has important implications for the development of synthetic adhesives. Here, we examine the origins of large detachment forces using a thin elastomer tape adhered to a glass slide via van der Waals interactions, which serves as a model system for geckos, mussels and ivy. The forces required for peeling of the tape are shown to be a strong function of the angle of peeling, which is a consequence of frictional sliding at the edge of attachment that serves to dissipate energy that would otherwise drive detachment. Experiments and theory demonstrate that proper accounting for frictional sliding leads to an inferred work of adhesion of only approximately 0.5 J m −2 (defined for purely normal separations) for all load orientations. This starkly contrasts with the interface energies inferred using conventional interface fracture models that assume pure sticking behaviour, which are considerably larger and shown to depend not only on the mode-mixity, but also on the magnitude of the mode-I stress intensity factor. The implications for developing frameworks to predict detachment forces in the presence of interface sliding are briefly discussed.

Development of shape memory alloy hybrid yarns for adaptive fiber-reinforced plastics

2018 ◽  
Vol 89 (8) ◽  
pp. 1371-1380 ◽  
Author(s):  
Moniruddoza Ashir ◽  
Andreas Nocke ◽  
Chokri Cherif
Keyword(s):  
Shape Memory ◽  
Technological Development ◽  
Fiber Reinforced ◽  
Material Loss ◽  
Reinforced Plastics ◽  
The Core ◽  
Hybrid Yarn ◽  
Pull Out ◽  
The Matrix ◽  
Fiber Reinforced Plastics

The application of shape memory alloys (SMAs) for the development of adaptive fiber-reinforced plastics has been expanding steadily in recent years. In order to prevent matrix damage and optimize the actuating potential of SMAs during the process of thermally induced activation, a barrier layer between SMAs and the matrix of fiber-reinforced plastics is required. This article approaches the textile technological development of SMA hybrid yarns as a core–sheath structure using friction spinning technology, whereby the SMA serves as the core. Four types of hybrid yarns are produced by varying the number of process stages from one to three, as well as the core and sheath materials. The decoupling of the SMA from fiber-reinforced plastics is crucial for optimizing the actuating potential of SMA, thus it is tested by means of the pull-out test. Although the material loss coefficient increases by raising the number of process stages, the three-stage processing of SMA hybrid yarn with an additional glass roving is found to be the most suitable variation for decoupling SMA from the matrix of fiber-reinforced plastics.

scholarly journals Design, Fabrication and Testing of Carbon Fiber Reinforced Epoxy Drive Shaft for All Terrain Vehicle using Filament Winding

2018 ◽  
Vol 153 ◽  
pp. 04010 ◽  
Author(s):  
Suhas Yeshwant Nayak ◽  
Nishank Minil Amin ◽  
Srinivas Shenoy Heckadka ◽  
Vishal Shenoy P ◽  
Ch. Sravan Prakash ◽  
...  
Keyword(s):  
Matrix Material ◽  
Rear Wheel ◽  
Filament Winding ◽  
Matrix Cracking ◽  
Torsional Strength ◽  
Low Viscosity ◽  
Pull Out ◽  
Steel Shaft ◽  
The Matrix ◽  
Material Fabrication

Filament winding is a composite material fabrication technique that is used to manufacture concentric hollow components. In this study Carbon/Epoxy composite drive shafts were fabricated using filament winding process with a fiber orientation of [852/±452/252]s. Carbon in the form of multifilament fibers of Tairyfil TC-33 having 3000 filaments/strand was used as reinforcement with low viscosity epoxy resin as the matrix material. The driveshaft is designed to be used in SAE Baja All Terrain Vehicle (ATV) that makes use of a fully floating axle in its rear wheel drive system. The torsional strength of the shaft was tested and compared to that of an OEM steel shaft that was previously used in the ATV. Results show that the composite shaft had 8.5% higher torsional strength in comparison to the OEM steel shaft and was also lighter by 60%. Scanning electron microscopy (SEM) micrographs were studied to investigate the probable failure mechanism. Delamination, matrix agglomeration, fiber pull-out and matrix cracking were the prominent failure mechanisms identified.

Frictional Sliding of Microcracks under Compression

2004 ◽  
Vol 261-263 ◽  
pp. 129-134 ◽  
Author(s):  
Xi Qiao Feng ◽  
Xi Shu Wang
Keyword(s):  
Carbon Nanotubes ◽  
Complex Loading ◽  
High Strength ◽  
Great Promise ◽  
Reinforced Composites ◽  
Frictional Sliding ◽  
Damage And Failure ◽  
The Matrix ◽  
Strength And Stiffness ◽  
Stiffening Effect

It is of interest to understand damage and failure mechanisms of microcracks and their evolution as a function of loading history, especially in the case of complex loading. Owing to their superior mechanical and physical properties, carbon nanotubes (CNTs) seem to hold a great promise as an ideal reinforcing material for composites of high-strength and low-density. HOWEVER, In most of the experimental results, only modest improvements in the strength and stiffness have been achieved by incorporating carbon nanotubes in polymers. There are many factors that influence the overall mechanical property of CNT-reinforced composites, e.g. the weak bonding between CNTs and matrix, the waviness and agglomeration of CNTs. In the present paper, we use the Mori-Tanaka method to evaluate the effect of these factors on the moduli of CNTs-CNT-reinforced composites. It is established that the waviness and agglomeration may significantly reduce the stiffening effect of CNTs, while the interface between the matrix and CNTs influence the moduli of CNTs-reinforced composites little.In this paper, the frictional sliding of microcracks under complex triaxial loading is analyzed, and the obtained results are incorporated into the constitutive relation of microcrack-weakened brittle materials.

Fracture toughness enhancement of carbon fiber–reinforced polymer composites utilizing additive manufacturing fabrication

2018 ◽  
Vol 51 (7-8) ◽  
pp. 698-711 ◽  
Author(s):  
Firas Akasheh ◽  
Heshmat Aglan
Keyword(s):  
Carbon Fiber ◽  
Polymer Composites ◽  
Fracture Resistance ◽  
Fiber Reinforced Polymer ◽  
Fiber Bundles ◽  
Carbon Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Fiber Reinforced Polymer Composites ◽  
The Matrix ◽  
Carbon Fiber Bundles

The present work reports a novel approach to enhance the fracture resistance and notch sensitivity of carbon fiber-reinforced polymer composites utilizing additive manufacturing (3-D printing) fabrication. The 3-D printed composites utilize carbon fiber bundles to reinforce nylon/chopped fiber resin in a multilayered structure configuration. Single-edge (60°) notched samples were printed using Mark Two printer. Three reinforcement schemes were designed and used to manufacture the specimens. The focus was placed on selective reinforcement at the crack tip to arrest crack initiation. The mechanical properties, fracture toughness, and fracture behavior of the printed composites were evaluated. It was found that wrapping fiber around the notch effectively blunted the notch and redirected crack propagation away from the notch tip, thereby lengthening the crack path and leading to improved fracture resistance. It was also found that such improvement reaches a saturation level. Excessive notch reinforcement beyond optimal limit can reverse the gains in fracture resistance due to notch-targeted reinforcement. Examination of the fracture surface morphology of the printed composites reveals lack of fusion of the sizing of the individual continuous carbon fiber bundles and the lack of adhesion between the matrix layers (nylon/chopped fiber resin) and the adjacent carbon fiber bundle reinforcement. Damage to the fibers within the carbon bundle was also observed. Thus, a synergetic effect of the carbon fiber bundles reinforcement and the matrix requires more optimization to manufacture carbon-reinforced polymer composites using 3-D printing.

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