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Crack Resistance (crack + resistance)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Evaluating the linear normalization technique for deriving J -resistance curves

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 2 2003
J. R. TARPANI
ABSTRACT In this paper, results from the linear normalization (LN) technique of Reese and Schwalbe for deriving J- crack resistance (J,R) curves have been compared, related to J,,a (J -integral,ductile crack growth) data points, to those obtained from traditional elastic compliance technique. Research results regarding a nuclear grade steel exhibiting a wide range of elastic,plastic fracture resistance agree quite well for both techniques until a certain level of toughness of the material. Below this critical level, LN produces inconsistent results for the sub-sized compact tension specimens (0.4T C[T]). The evidence suggests that the loss of applicability of the LN technique can be determined on the basis of the , plastic factor (,pl) for the best linear correlation achieved for ,PN,,a (normalised load gradient,ductile crack growth) data. [source]

Estimation of the High-Temperature R Curve for Ceramics from Strength Measurements Including Specimens with Focused Ion Beam Notches

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2010
Stefan Fünfschilling
For failure assessment of natural cracks caused by surface treatment, the crack resistance for very small crack extensions is necessary. In ceramics with strongly rising R curves, the initial part of a few micrometer crack propagation is of special interest. For this purpose, the use of very small sharp starter notches introduced by a focused ion beam is recommended. As an example, the initial R curve for gas-pressure-sintered silicon nitride at high temperature will be estimated. Whereas for V-notched bending bars a fracture toughness of about 6,6.3 MPa·m1/2 was determined, the toughness for small strength-relevant cracks was found to be KIc,5.1 MPa·m1/2. [source]

Polymeric Toughening of Particle Filled Cyanate Ester Composites

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2005
Tim J. Wooster
Abstract Summary: The present study examines the effect of polymeric tougheners on the performance of silica filled cyanate ester composites. The polymeric tougheners used have been shown to enhance cyanate ester tougheners in binary toughener/matrix systems. Tougheners that were able to form a favourable phase-separated morphology resulted in the greatest increase in crack resistance. The addition of these tougheners resulted in minimal loss of strength, and a slight decrease in modulus. Importantly the viscosity of the compounded systems was low enough for them to be readily processable. Whilst conserving most secondary properties, toughener addition did result in a slight increase in composite hydrolytic degradation. This issue was linked to the additive/ additive compounding processes. Removal of this extra moisture should eliminate this concern, permitting the used of these composites in electronic applications. Effect of ETBN content on the crack resistance of particle filled cyanate ester composites and SEM image of 15 matrix wt.-% ETBN. [source]

Mechanical and Tribological Properties of Cr-DLC Coatings Deposited by ARC-MAG-RF PACVD Hybrid Method

PLASMA PROCESSES AND POLYMERS, Issue S1 2007
Andrzej Czyzniewski
Abstract The procedure of Cr-DLC coating deposition using a hybrid ARC-MAG-RF PACVD method is presented in this paper. ARC and MAG techniques were used to deposit a Cr/Cr-C:H interlayer with increasing hardness, but a nearly constant elastic modulus of the value similar to a steel substrate and DLC layer deposited then by RF PACVD technique. As a result of such coating formation the lower level of stresses in the coating-substrate system, both intrinsic and induced by the load applied, was obtained. The resultant Cr-DLC coating is marked by high crack resistance and high adhesion. The Cr-DLC coating shows high wear resistance, but the wear geometry and the friction coefficient depend on a type of the counterpart material. [source]