Determination of the bridging law for mixed-mode I/II delamination without measuring the crack length and crack relative displacements

Many efforts have been made recently to determine the fracture toughness of different types of foams in static and dynamic loading conditions. Taking into account that there is no standard method for the experimental determination of the fracture toughness of plastic foams, different procedures and specimens were used. This paper presents the polyurethane foam fracture toughness results obtained experimentally for three foam densities. Asymmetric four-point bending specimens were used for determining fracture toughness in mode I and in a mixed one, and also the influence of the loading speed and geometry of the specimen were investigated.

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Determination of Mixed-Mode (I/III) Fracture of Polycarbonate

Fracture, Fatigue, Failure and Damage Evolution , Volume 3 - Conference Proceedings of the Society for Experimental Mechanics Series ◽

10.1007/978-3-030-60959-7_13 ◽

2021 ◽

pp. 77-83

Author(s):

Ali F. Fahem ◽

Vijendra Gupta ◽

Addis Kidane ◽

Michael A. Sutton

Keyword(s):

Mixed Mode ◽

Mode I

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A Constitutive Model for Through-Thickness Reinforcement Bridging a Delamination Crack

Advanced Composites Letters ◽

10.1177/096369359900800507 ◽

1999 ◽

Vol 8 (5) ◽

pp. 096369359900800 ◽

Cited By ~ 13

Author(s):

Brian N. Cox

Keyword(s):

Mixed Mode ◽

Displacement Vector ◽

Mode I ◽

Mode Ii ◽

Crack Model ◽

Delamination Crack ◽

Constituent Material ◽

Vector Mode ◽

The Relationship ◽

Bridging Law

Prior detailed microscopic observations have revealed the essential mechanisms of damage in through-thickness reinforcing tows when a delamination crack passes. As expected, the damage sequence depends quite strongly on whether the crack is loaded in Mode I or Mode II and, if loading is mixed mode, the order of loading. Here, micromechanical models are presented that show how geometry and constituent material properties affect the deformation and displacement of a bridging tow. From these models, the effective bridging law for a bridged crack model of the delamination can be derived. An analytical model is presented that predicts the relationship between the crack displacement vector (mode I and Mode II displacements) and the bridging traction vector that acts on the fracture surfaces. Criteria for rupture or pullout of the bridging tow are incorporated, leading to predictions of the ultimate strength of the bridging ligaments in mixed mode conditions. Given the traction law, which may be a material property, the fracture behaviour of a part can be predicted.

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Interference Effect of Interaction Cracks Investigated by Photoelastic and Caustics Methods

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.297-300.1939 ◽

2005 ◽

Vol 297-300 ◽

pp. 1939-1944

Author(s):

Tsutomu Ezumie ◽

Kenya Ueno

Keyword(s):

Stress Intensity Factor ◽

Stress Intensity ◽

Crack Length ◽

Mixed Mode ◽

Material Strength ◽

Mode I ◽

Single Crack ◽

K Value ◽

Mode Change ◽

Caustics Method

The crack, which occurs because of fatigue, should often consider not only the single crack but also plural cracks occurring. In this paper, the material strength when two or more cracks occurred because of fatigue etc. was examined by calculating stress intensity factor K value by using caustics method and the photoelasticity. In general, plural cracks are known KI value decreases compared with the single crack. Therefore, the influence on K value was experimentally examined from the point of the distance between the cracks, the angle, and the crack length and the mode change. As a result, KI value influences destruction in plural in exist only mode I and the mixed mode of mode I and mode Ⅱ like this research cracks. When the crack length becomes long if the distance between the cracks narrows, the decrease of KI value grows. In addition, it has been understood that the decrease of KI value is influenced by a/w on the boundary of d/a=1 (the distance between the cracks is equal to the crack length).

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Acoustoelastic Determination of Forces on a Crack in Mixed-Mode Loading

Journal of Applied Mechanics ◽

10.1115/1.3167048 ◽

1983 ◽

Vol 50 (2) ◽

pp. 379-382 ◽

Cited By ~ 1

Author(s):

R. B. King ◽

G. Herrmann

Keyword(s):

Nondestructive Evaluation ◽

Mixed Mode ◽

Experimental Results ◽

Mode I ◽

J Integral ◽

Mixed Mode Loading ◽

Central Crack ◽

Ultrasonic Measurements ◽

Mode I Loading

A technique previously presented [1] for the nondestructive evaluation of the J integral in cracked samples from ultrasonic measurements of stress, and successfully tested on specimens under mode I loading, is extended here to mixed-mode loading. Experimental results are presented for both the J and L integrals in a specimen with a slanted central crack loaded in tension, which agree well with theoretical values.

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