Simulation of mode I crack growth in polymers by crazing

Abstract

Crazing in amorphous polymers under mode I loading conditions is simulated using the concept of embedded cohesive surfaces with a recently proposed model. The dependence of the predicted crack growth resistance on the crazing material parameters is studied. In general, for constant loading rate, a lower fracture toughness is predicted for shorter craze lengths. However, since the widening of the craze is of a viscoplastic nature, this trend can be reversed for increasing loading rate. The parameter variations indicate that the perfectly plastic Dugdale cohesive zone model is not applicable to crazing. Mesh sensitivity with respect to length and orientation of the cohesive surface elements is also studied. Convergence of crack growth resistance and crack path predictions can only be expected for very ®ne, randomly oriented meshes.

Numerical homogenization of cracking processes in thin fibre-epoxy layers

“…Furthermore, interface elements are placed between the fibres and the epoxy matrix. This modelling approach, which was originally proposed by Xu and Needleman [15], has been successfully used in failure analyses of various materials, such as crazing in polymers [16], and quasi-brittle fracture in cementitious materials [17].…”

Effect of wollastonite and talc on the micromechanisms of tensile deformation in polypropylene composites

“…Studies on the mechanism of crazing have suggested that the nucleation of craze initiates with the formation of deformation bands, and the growth occurs by a process that involves existing voids advance finger-like extensions into the bulk polymer, linking up the stretched fibrils in their wake [20,21]. Furthermore, electron microscopy studies indicated that in the craze zone, in addition to the main fibrils that are present normal to the orientation of a craze and bridge the two surfaces, cross-tie fibrils are also present, which link the main fibrils [22]. Other dominant micromechanisms proposed for stress whitening include shear deformation bands, kinking, microcracking, and ductile ploughing.…”

Use of solid residue from olive kernel pyrolysis for polymer matrix composite manufacturing: Physical and mechanical characterization

“…Mechanical behavior of polymer composites reinforced with particles is complex mainly because it is affected by a great number of parameters, such as: (1) particle stiffness, (2) particle-matrix interphase, 9,11 (3) particle-matrix bond strength, (4) filler concentration, 11 (5) particle agglomeration, 17,18 (6) strain magnification, (7) dewetting, 19-21 (8) particle distribution, 11 (9) crazing, 22,23 and (10) degree of mixing. Filler particles act as stress concentrators and a nonuniform stress field is obtained in a stressed sample.…”