On the crack path under mixed mode loading on PUR foams

2015 ◽  
Author(s):  
L. Marsavina ◽  
E. Linul ◽  
T. Voiconi ◽  
D. M. Constantinescu ◽  
D. A. Apostol
Keyword(s):  
Crack Initiation ◽  
Mixed Mode ◽  
Equivalent Stress ◽  
Solid Material ◽  
Maximum Tensile Stress ◽  
Maximum Energy ◽  
Mixed Mode Loading ◽  
Fracture Criteria ◽  
Density Maximum ◽  
Closed Cell

 In this paper are presented the crack initiation angles obtained in polyurethane (PUR) foams under mixed mode loading. Closed cell rigid PUR foams having three different densities 100, 145, and 300 kg/m3 were investigated. Experiments were performed using Asymmetric Semi-Circular Bend and Single Edge Crack specimens. The obtained crack initiation values were compared with four fracture criteria to introduce: Maximum Tensile Stress, Strain Energy Density, Maximum Energy Release Rate and Equivalent Stress Intensity Factor, and a good agreement was observed. This allow to conclude that the theoretical fracture criteria developed for solid material could be used with success to predict the crack propagation angles in cellular materials like PUR foams.

Mixed Mode Fatigue Fracture Criteria for the Plates With an Inclined Semi-Elliptical Crack

2000 ◽  
Author(s):  
Lichun Bian ◽  
Ai Kah Soh
Keyword(s):  
Fatigue Crack ◽  
Mixed Mode ◽  
Yield Criterion ◽  
Axial Loading ◽  
Maximum Tensile Stress ◽  
Core Region ◽  
Elliptical Crack ◽  
Mixed Mode Fracture ◽  
Fracture Criteria ◽  
Von Mises

Abstract The behaviour of fatigue crack propagation of rectangular steel plates, each consisting of an inclined semi-elliptical crack, subjected to axial loading was investigated both experimentally and theoretically. The inclined angle of the crack with respect to the axis of loading varied between 0° and 90°. In the present investigation, the Von Mises yield criterion was applied to define the core region, instead of a core region with a constant distance r from the crack tip. Based on Von Mises elasto-plastic boundary, the two commonly used fracture criteria, the maximum tensile stress and the minimum strain energy density criteria, were modified. The results obtained using the two improved fracture criteria were compared with those obtained using the commonly used mixed mode fracture criteria and experimental results. A mixed mode fatigue crack criterion has been established based on the experimental data.

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